[Federal Register: December 20, 2004 (Volume 69, Number 243)]
[Rules and Regulations]
[Page 76297-76337]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr20de04-25]
[[Page 76297]]
-----------------------------------------------------------------------
Part IV
Department of Transportation
-----------------------------------------------------------------------
National Highway and Traffic Safety Administration
-----------------------------------------------------------------------
49 CFR Part 571
Federal Motor Vehicle Safety Standards; Brake Hoses; Final Rule
[[Page 76298]]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
49 CFR Part 571
[Docket No. NHTSA-2003-14483]
RIN 2127-AH79
Federal Motor Vehicle Safety Standards; Brake Hoses
AGENCY: National Highway Traffic Safety Administration (NHTSA),
Department of Transportation (DOT).
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: This rule updates the Federal motor vehicle safety standard on
brake hoses to incorporate the substantive specifications of several
Society of Automotive Engineers (SAE) Recommended Practices relating to
hydraulic brake hoses, vacuum brake hoses, air brake hoses, plastic air
brake tubing, and end fittings. The agency initiated this rulemaking in
response to a joint petition from several brake hose and tubing
manufacturers.
DATES: This final rule becomes effective December 20, 2006. The
incorporation by reference of certain publications listed in the
regulations is approved by the Director of the Federal Register as of
December 20, 2006.
Optional early compliance is permitted as of February 18, 2005.
Any petitions for reconsideration of today's final rule must be
received by NHTSA not later than February 3, 2005.
ADDRESSES: Petitions for reconsideration should refer to the docket
number for this action and be submitted to: Administrator, National
Highway Traffic Safety Administration, 400 Seventh Street, SW.,
Washington, DC 20590.
FOR FURTHER INFORMATION CONTACT:
For non-legal issues, Mr. Jeff Woods, Vehicle Dynamics Division,
Office of Vehicle Safety Standards (Telephone: (202) 366-6206) (Fax:
(202) 366-4921).
For legal issues, Ms. Dorothy Nakama, Office of the Chief Counsel
(Telephone: (202) 366-2992) (Fax: (202) 366-3820).
You may send mail to both of these officials at: National Highway
Traffic Safety Administration, 400 Seventh St., SW., Washington, DC
20590.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. Background
II. Notice of Proposed Rulemaking
III. Summary of Comments
IV. Agency Decision to Issue a Final Rule
V. Issues Raised by Commenters and NHTSA's Responses
A. Issues Relating to All Types of Brake Hose
1. Use of the term ``burst''
2. Use of the term ``any''
3. Constriction test method
4. Specification of ozone concentration
B. Hydraulic Brake Hoses
1. General hydraulic brake hose comments in response to the NPRM
2. Hydraulic brake hose manufacturer identification requirements
3. Expansion and burst strength (volumetric expansion) test
4. Tensile strength
5. Water absorption and pressure test, tensile strength, and
whip resistance
6. Low temperature resistance test
7. Brake fluid compatibility, constriction, and burst strength
8. End fitting corrosion resistance
9. High temperature impulse test
C. Air Brake Hoses
1. Construction and labeling
2. High temperature resistance
3. Low temperature resistance
4. Ozone resistance
5. Adhesion
6. Air pressure (leakage)
7. Tensile strength
8. Minimum bend radius
D. Vacuum Brake Hoses
1. Swell (fuel resistance)
E. Plastic Air Brake Tubing
1. General comments
2. Construction
3. Labeling
4. Dimensions and tolerances
5. One hundred percent leak test
6. Burst test
7. Moisture absorption
8. Ultraviolet resistance
9. Resistance to zinc chloride and methyl alcohol
10. Stiffness
11. Heat aging adhesion
12. Collapse resistance
13. Oil resistance
14. Ozone resistance
F. Plastic Air Brake Tubing Assemblies and End Fittings
1. General comments
2. Tensile strength
3. Hot tensile strength
4. Vibration leak test
5. Proof and burst test (end fitting retention)
6. Serviceability test
7. End fitting dimensional requirements
8. End fitting corrosion resistance
G. New Types of Brake Hose
H. Metallic Tubing and Pipe
VI. Statutory Bases for the Final Rule
VII. Effective Date
VIII. Rulemaking Analyses and Notices
A. Executive Order 12866 and DOT Regulatory Policies and
Procedures
B. Regulatory Flexibility Act
C. National Environmental Policy Act
D. Executive Order 13132 (Federalism)
E. Civil Justice Reform
F. Paperwork Reduction Act
G. National Technology Transfer and Advancement Act
H. Unfunded Mandates Reform Act
I. Plain Language
J. Regulation Identifier Number
Final Rule Regulatory Text
I. Background
On October 30, 1998, three brake hose manufacturers, Elf Atochem
North America, Inc., Mark IV Industrial/Dayco Eastman, and Parker
Hannifin Corporation,\1\ filed a joint petition for rulemaking with
NHTSA. The petitioners requested that certain requirements relating to
brake hoses, brake hose tubing, and brake hose end fittings that are
presently administered by the Federal Motor Carrier Safety
Administration (FMCSA) be incorporated into the brake hose standard
that is administered by NHTSA. The Federal Motor Carrier Safety
Regulations (FMCSR) requirements for brake hoses at 49 CFR 393.45
(Brake tubing and hose, adequacy) and 49 CFR 393.46 (Brake tubing and
hose connections) reference several Society of Automotive Engineers
(SAE) standards that describe the dimensions and performance
requirements for brake hoses and end fittings for hydraulic, vacuum,
and air brake hoses, and also metal and plastic tubing and end fittings
used in brake systems. Specifically, the petitioners requested that the
SAE standards referenced in the FMCSRs be incorporated into 49 CFR
571.106 (Brake hoses) of the Federal Motor Vehicle Safety Standards
(FMVSS) that are administered by NHTSA.
---------------------------------------------------------------------------
\1\ Since the petition was filed, mark IV Industrial/Dayco
Eastman has been acqired by Parker Hannifin Corporation. Elf Atochem
North American, Inc. was integrted into Atofina Chemical, Inc. The
successor petitioning companies are referred to as Parker/Atofina.
---------------------------------------------------------------------------
The petitioners requested that the application of these SAE
specifications be limited to hose, tubing, and fittings used on trucks,
truck-trailer combinations, and buses with either a GVWR greater than
10,000 pounds or which are designed to transport 16 or more people,
including the driver. In addition, the petitioners requested that the
current versions of the SAE specifications be adopted instead of the
older versions cited in the FMCSRs.
The joint petition was submitted in light of a 1997 proposal by the
Federal Highway Administration (FHWA), which then administered the
FMCSRs, to delete these provisions. The FHWA stated that because it has
no statutory authority to regulate vehicle manufacturers or
manufacturers of brake hose, tubing, or fittings, all such regulations
should be included in NHTSA's FMVSS rather than in the FMCSRs. The FHWA
proposed adopting a requirement that commercial motor vehicles be
maintained in compliance
[[Page 76299]]
with FMVSS No. 106. However, many of the provisions included in the
FMCSRs in this subject area were not included in FMVSS No. 106.
In a 1998 public meeting on the subject, representatives from NHTSA
and FHWA said that they favored consolidating all requirements for
brake hose, brake tubing, and fittings in FMVSS No. 106, instead of
maintaining separate requirements under the jurisdiction of two
different agencies. They explained that consolidation of the
requirements would, among other things, make them more enforceable.
Some of the brake component manufacturers stated their opposition to
deleting the SAE specifications for their products. FHWA and NHTSA
indicated that anyone opposed to FHWA's proposal was welcome to file a
petition for rulemaking requesting that the SAE specifications proposed
for deletion from the FMCSRs be incorporated into FMVSS No. 106.
For details about FMCSR's brake hose requirements and additional
background behind the joint petitions, please see NHTSA's notice of
proposed rulemaking (NPRM) of May 15, 2003 (68 FR 26384, at pages 26384
to 26385).
II. Notice of Proposed Rulemaking
In an NPRM published on May 15, 2003 (68 FR 26384) [DOT Docket No.
03-14483] NHTSA announced that it had granted the joint petition for
rulemaking to amend FMVSS No. 106. The agency agreed with the
petitioners that there was a safety need to transfer the brake hose,
tubing, and fitting requirements in Sections 393.45 and 393.46 of the
FMCSRs to FMVSS No. 106, before those requirements were removed. NHTSA
tentatively concluded that to ensure the continued safety of commercial
motor vehicle braking systems, the substantive specifications of the
SAE Recommended Practices should be incorporated into FMVSS No. 106,
with a few exceptions. This would involve, among other changes,
establishing a new category in FMVSS No. 106 for plastic air brake
tubing, end fittings, and tubing assemblies.
NHTSA's decision to grant the petition was also based on the fact
that FMVSS No. 106 had not been substantially updated in many years.
The agency noted that most of the substantive requirements currently in
FMVSS No. 106 were originally based on SAE standards and American
Society for Testing and Materials (ASTM) standards referenced therein.
While the SAE and ASTM standards have been modified over time to keep
pace with technological developments in the industry, the substantive
requirements of FMVSS No. 106 have remained relatively unchanged.
Therefore, NHTSA's proposed changes to FMVSS No. 106 took into account
the substantial technological developments that have occurred and
sought to align the standard's requirements with standard industry
practices. Incorporating many of the SAE standards' performance
requirements is consistent with Office of Management and Budget (OMB)
Circular A-119, which directs federal agencies to use and/or develop
voluntary consensus industry standards, in accordance with Pub. L. 104-
113, the ``National Technology Transfer and Advancement Act of 1995.''
The agency's proposal differed as follows from the petition:
First, instead of simply incorporating complete SAE standards by
reference as the FMCSRs currently do, NHTSA proposed to incorporate
only the specific requirements/specifications of the SAE standards that
are either more rigorous than those in FMVSS No. 106 or are not present
at all in FMVSS No. 106.
Second, the agency did not propose to limit the application of
those SAE requirements/specifications to brake hose, tubing, and
fittings used on commercial motor vehicles. NHTSA tentatively concluded
that all brake hose, tubing, and fittings can and should meet the SAE
requirements/specifications, regardless of their end use.
Third, although NHTSA agreed with the petitioners that proposed
changes to FMVSS No. 106 should be based on the most recent versions of
the SAE standards instead of the older versions cited in the FMCSRs,
the agency noted that a number of SAE's standards had been updated
since the joint petition was filed. Accordingly, NHTSA proposed to rely
on the most recent versions of the SAE standards.
Fourth, the agency did not propose to incorporate SAE standards
relating to copper tubing, galvanized steel pipe, or end fittings used
with metallic or non-metallic tubing. These materials are occasionally
used in chassis plumbing and since these products are not considered to
be brake hoses, NHTSA stated its belief that they are inappropriate for
inclusion in FMVSS No. 106.
Fifth, NHTSA did not propose to incorporate the material and
construction specifications for Type A and Type B tubing contained in
SAE J844, Nonmetallic Air Brake System Tubing, and SAE J1394, Metric
Nonmetallic Air Brake System Tubing because the agency tentatively
concluded that incorporating those material specifications would be
design-restrictive.
Sixth, NHTSA did not propose to incorporate the manufacturer
identification requirements in SAE J1401, Hydraulic Brake Hose
Assemblies for Use with Nonpetroleum-Base Hydraulic Fluids, because it
tentatively concluded that the manufacturer identification requirements
already present in FMVSS No. 106 are sufficient.
III. Summary of Comments
In response to the May 15, 2003 NPRM, NHTSA received comments from
the following eleven organizations and companies: SAE International
(SAE) and ASTM International (ASTM), which are automotive and
industrial standards organizations; Intertek Testing Services
(Intertek), a company that tests brake hoses and other products; and
the following manufacturers of brake hose products; Goodyear Engineered
Products (Goodyear), Dana Coupled Products (Dana), Saint-Gobain
Performance Plastics (SGPPL), Degussa High Performance Polymers (HPP),
Parker Hanifin Corporation and Atofina Chemical, Inc. (Parker/Atofina),
SMC Corporation of America (SMC), and DuPont Engineered Polymers
(DuPont).
Parker/Atofina submitted joint comments to the NPRM and are the
successor companies to the parties to the joint petition for rulemaking
submitted to NHTSA in 1998. Intertek Testing Services conducts
laboratory testing of various products, including brake hoses, and also
contracts with NHTSA to perform compliance testing of brake hoses.
DuPont submitted comments on June 16, 2004, after the NPRM's comment
closing date of July 14, 2003. However, NHTSA has fully considered
DuPont's comments.
The commenters generally supported NHTSA's proposal to amend FMVSS
No. 106 to include the latest requirements in the SAE brake hose
standards for hydraulic, vacuum, and air brake hose and tubing. The
commenters raised numerous technical issues, however. For many of
proposed tests, commenters provided detailed information on test
methods and procedures. The comments also generally supported NHTSA's
proposal to specify requirements for plastic brake tubing, and plastic
air brake tubing assemblies and end fittings.
IV. Agency Decision To Issue a Final Rule
In this document, NHTSA announces that it has decided to issue a
final rule. We have made this decision after we
[[Page 76300]]
have thoroughly reviewed the public comments. We have made a number of
changes in response to the comments. In the few instances where we did
not adopt a comment, we explain why, in light of the need for safety.
We believe that the updated brake hose standard, which combines the
most rigorous requirements of the latest SAE standards, and of FMVSS
No. 106, meets the need for safety. Significant changes have been made
to existing brake hose standards, with the effect of upgrading the
performance requirements and test procedures relating to: (a) Hydraulic
brake hose; (b) air brake hose; and (c) vacuum brake hose. In addition,
we are establishing requirements more specifically tailored for plastic
air brake tubing, plastic air brake tubing assemblies and end fittings.
NHTSA seeks to ensure safe plastic air brake tubing, and plastic air
brake tubing assemblies and end fittings.
In the following sections, we discuss the public comments to the
NPRM, our response to the comments, and how (if this is the case) the
proposed language in the NPRM has been amended in response to the
comments.
V. Issues Raised by Commenters and NHTSA's Responses
A. Issues Relating to All Types of Brake Hose
1. Use of the Term ``Burst''
Intertek stated that several proposed requirements in the NPRM
referred to the word ``burst'' and noted that ``burst'' was not defined
in the proposed regulatory text. Intertek cited SAE J1401, stating that
leaks or burst is ``loss of test fluid from the brake hose assembly
other than by designated inlet(s) and outlet(s).'' NHTSA notes that in
S4 of FMVSS No. 106, ``rupture'' is defined as any failure that results
in separation of a brake hose from its end fitting or in leakage. In
this final rule, NHTSA retains ``burst'' as a term that is presently
used in FMVSS No. 106 to describe a required test or test pressures (as
in, for example, a table of burst pressures). Whenever the performance
requirement of a brake hose is specified, the word ``rupture'' has been
substituted. This is consistent with existing FMVSS No. 106 text and
avoids the need to add a definition of ``burst'' to S4.
2. Use of the Term ``Any''
SMC Corporation commented that S11.3 Test requirements (for plastic
air brake tubing, plastic air brake tubing assemblies, and plastic air
brake tubing end fittings) stating ``* * * capable of meeting any of
the requirements'' should be changed to ``all of the requirements.''
[Emphasis added.] NHTSA is not making this recommended change. The term
``any'' has a very specific meaning in the Federal motor vehicle safety
standards, including FMVSS No. 106. 49 CFR Part 571.4 specifies that
``(t)he word any, used in connection with a range of values or set of
items in the requirements, conditions, and procedures of the standards
or regulations in this chapter, means generally the totality of the
items or values, any of which may be selected by the Administration for
testing. * * * Thus, use of the term ``any'' has the effect of
including all of the requirements.
3. Constriction Test Method
The constriction test is conducted to ensure the opening in the
brake hose is large enough for the medium (i.e., brake fluid or air) to
flow through unimpeded. In the NPRM, NHTSA noted that while the
existing FMVSS No. 106 includes constriction requirements, i.e.,
requirements for minimum pass-through diameter, it does not specify a
test procedure. The agency noted that two different constriction test
procedures are available: A drop-ball test and a plug gauge test. The
agency proposed to use a plug gauge method, similar to that in SAE
J1401, that consists of a spherical end (sized at 64 percent of the
brake hose nominal inside diameter for hydraulic brake hose and 66
percent of nominal inside diameter for air brake hose) with a shank and
handle that can be inserted into the brake hose end fitting. The weight
of the gauge is specified as two ounces, and this weight assists the
passage of the spherical end through the fitting. The agency stated
that it welcomed comments both on its proposal to specify a plug gauge
test instead of a drop-ball test and on the differences between the
plug gauge test specified in SAE J1401 and the one the agency proposed.
Goodyear commented on the proposed constriction test method for air
brake hoses, and Dana similarly commented on the constriction testing
for hydraulic brake hoses.
Goodyear stated that air brake hose manufacturing may result in
curvature in the hose that could impede the gauge from fully entering
the brake hose. The agency notes that the proposed regulatory text at
S6.12 provided that the brake hose is held in a straight position to
overcome such a problem. Holding the brake hose in a straight position
allows the gauge to fully enter the brake hose. Goodyear stated that
the general practice is to use the rolling ball test (also described in
the NPRM, but not proposed as a test method), and recommended that the
constriction test method be left to the discretion of the hose/assembly
manufacturer. NHTSA notes that the rolling ball test is similar but not
identical to the drop ball test. The drop ball test relies on the force
of gravity for the ball to drop vertically through the hose; the
rolling ball test relies on a side-to-side motion by the tester to go
through the hose.
Dana agreed with the plug gauge test but recommended including the
option of a drop ball test or an extended plug gauge for hose assembly
end fittings that by design do not offer a passage through which a plug
gauge can be readily inserted. Dana stated that either the extended
plug gauge or the rolling ball would permit constriction inspection
without cutting the hose.
In response to the comments about the drop ball test vs. the
extended plug gauge test, NHTSA begins by noting that S5.3 Test
requirements in both the existing FMVSS No. 106 and proposed regulatory
text for FMVSS No. 106 indicate that a hydraulic brake hose is only
subjected to one of the test conditions in S5.3.2 through S5.3.11
(existing text) or through S5.3.13 (proposed text) after having met the
constriction test requirement in S5.3.1. There is a similar provision
for air brake hoses in S7.3 Test requirements. Thus, each brake hose
tested to any of the conditions in FMVSS No. 106 would first be
inspected for constriction test compliance. If the end fittings or
other features of the brake hose do not permit the plug gauge to be
used, or would require cutting of the brake hose or end fitting to do
so, then constriction testing cannot be conducted prior to one of the
other performance tests. Therefore, NHTSA is including the drop ball
test in the final rule to provide NHTSA and the manufacturers an
alternative to the plug gauge test. In addition, the use of an extended
length plug gauge is also included for similar reasons. This will
provide some flexibility in the constriction test method for the
variety of end fittings likely to be encountered in compliance testing.
None of these provisions would preclude a brake manufacturer or
assembler from using other means to perform constriction testing, since
the purpose of the constriction test is to verify the final inside
diameter of a brake hose assembly in a pass-fail manner.
4. Specification of Ozone Concentration
Many commenters noted an incorrect specification of ozone
concentration in the preamble to the NPRM, where the
[[Page 76301]]
units ``parts per million'' were stated, rather than the correct
``parts per hundred million.'' The agency agrees that this was an
oversight, and notes that a change to the regulatory text is not
needed, as the proposed text specified the correct units.
B. Hydraulic Brake Hoses
1. General Hydraulic Brake Hose Comments in Response to the NPRM
In general, the commenters agreed with the agency's proposal to
upgrade the hydraulic brake hose requirements in FMVSS No. 106 to those
requirements in SAE J1401. In the NPRM, the agency proposed to keep all
hydraulic brake hose requirements in one section, rather than creating
separate categories of brake hoses for commercial vehicles and non-
commercial vehicles. Dana stated that it agrees with this position, and
does not see this as burdensome to the industry as a whole, as most
brake hose manufacturers and light vehicle original equipment
manufacturers (OEM) requirements currently exceed the SAE
specifications. Goodyear stated that it currently brands, tests, and
certifies its brake hoses to both FMVSS No. 106 and SAE requirements.
Parker/Atofina was the only commenter to oppose the upgrade in
performance standards for all hydraulic brake hoses, stating that
hydraulic brake hoses used on recreational boat trailers, motorcycles,
all-terrain vehicles (ATVs), snowmobiles, and off-road tractors/
trailers and farm implements do not require the same level of severe
service performance requirements. NHTSA notes that of the vehicle types
listed by Parker/Atofina, the upgraded requirements would only apply to
``motor vehicles,'' (i.e., boat trailers and on-road motorcycles). The
other vehicle types are not ``motor vehicles'' regulated by NHTSA.
Parker/Atofina also asserted that the FMVSS No. 106 upgrade for all
hydraulic brake hoses is unnecessarily cost prohibitive, but provided
no cost data for the agency to evaluate.
NHTSA is not adopting Parker/Atofina's recommendation because NHTSA
does not wish to create separate categories of hydraulic brake hose
(e.g., ``commercial'' and ``non-commercial.'') To avoid brake system
failures caused by brake hose ruptures, we believe there is a safety
need for all motor vehicle brake hose to meet rigorous performance
requirements.
2. Hydraulic Brake Hose Manufacturer Identification Requirements
Parker/Atofina requested that the agency incorporate into FMVSS No.
106 the full manufacturer identification requirements as provided in
SAE J1401. Parker/Atofina states that the agency may not realize that
hydraulic brake hoses as defined in SAE J1401 more clearly describe the
performance, markings, and requirements for hydraulic brake hose
compared with those currently existing in FMVSS No. 106.
In response, NHTSA notes that the requirements for hose
manufacturer identification in SAE J1401 are that the hose shall be
either embossed or imprinted (three-dimensional) on the brake hose
cover with the manufacturer's name, or employ the market yarn color
scheme (Appendix A) as registered with the Rubber Manufacturers
Association. In addition, the marker yarn color scheme or name
trademark on the brake hose cover shall be registered with the SAE. SAE
J1401 does not include any provision for a brake hose assembler to add
identifying markings to the end fittings or by means of a band placed
around the brake hose assembly; only requirements for the manufacturer
of the brake hose material are specified.
NHTSA further notes that the FMVSS No. 106 requirements for
hydraulic brake hose manufacturer or assembler identification are
specified in S5.2 Labeling. The brake hose manufacturer's designation
(symbol, text, etc.) is registered with NHTSA and labeled on the
outside of the hose. The brake hose assembler's designation is included
on a band placed around the brake hose assembly, or may be stamped into
an end fitting. Labeling exceptions are provided for brake hose
assemblies included as part of a newly-manufactured vehicle. For these
reasons, NHTSA determines that the current labeling requirements fully
meet the agency's needs for identifying the manufacturers of brake hose
or brake hose assemblers. Therefore, in this final rule, NHTSA will not
require any additional labeling or manufacturer identification
requirements for hydraulic brake hoses.
3. Expansion and Burst Strength (Volumetric Expansion) Test
NPRM--The expansion test is conducted at test pressures of 1,000
psi and 1,500 psi and is followed by a burst strength test. NHTSA
proposed to add language to S5.3.2 specifying that after the hydraulic
brake hose assembly withstands water pressure of 4,000 psi for two
minutes without rupture, it must ``not rupture at less than 7,000 psi
for 1/8 inch, 3 mm, or smaller diameter hose, or at less than 5,000 psi
for a hose with a diameter larger than 1/8 inch or 3mm (S6.).''
Public Comments and NHTSA Response--Goodyear indicated that in
addition to the expansion test pressures of 1,000 psi and 1,500 psi,
SAE J1401 includes a third test at a higher pressure of 2,900 psi, and
recommended that it be added to FMVSS No. 106.
In considering this issue, we note that it was an oversight not to
include the third pressure in the NPRM. We did, however, explain that
we were generally proposing to incorporate those SAE J1401 requirements
that are more rigorous than FMVSS No. 106. We therefore believe it is
reasonable to add this pressure for the final rule. We are therefore
adding the third test at 2,900 psi to S5.3.2 and to Table 1.
We note, however, that SAE J1401 does not include any expansion
requirements for the larger, \1/4\ inch and 6 mm brake hose sizes that
are included in FMVSS No. 106. Further, the agency is not able to
extrapolate the existing values in FMVSS No. 106, Table 1, Maximum
Expansion of Free Length Brake Hose, to determine what expansion limits
would be appropriate for the larger brake hose sizes tested at the
2,900 psi expansion test. We are therefore not including at this time
expansion requirements for the larger brake hose sizes tested at the
2,900 psi expansion test.
Intertek stated that for the final burst strength requirement in
the expansion and burst strength tests, the proposed regulatory text
included a 7,000 psi burst strength for \1/8\ inch, 3 mm or smaller
diameter brake hoses, and a 5,000 psi burst strength for \3/16\ inch, 4
mm, or larger diameter brake hoses. Intertek noted that this does not
include a defined specification for those brake hoses with diameters
falling between \1/8\ inch and \3/16\ inch, or between 3 mm and 4 mm.
To clarify this issue, in the final rule, the agency has changed the
regulatory text to state that brake hoses with diameters greater than
\1/8\ inch or 3 mm shall not rupture at less than 5,000 psi.
4. Tensile Strength
NPRM--NHTSA proposed that the SAE J1401 fast-pull test and 370
pound strength requirement be incorporated into FMVSS No. 106. The
agency also proposed to update the ASTM reference for tension testing
machines to the latest version of the standard practice.
The agency notes that in the NPRM, the water absorption and tensile
strength requirements were labeled as S5.3.5. However, S5.3.5 as
currently specified in FMVSS No. 106 are the water absorption and burst
strength
[[Page 76302]]
requirement test. In this final rule, NHTSA corrects the error. The
water absorption and tensile strength requirements are at S5.3.6.
Public Comment and NHTSA's Response--At S6.4 of FMVSS No. 106, the
tensile strength test procedures are specified. ASTM commented that the
latest version of ASTM standard E 4 Standard Practices for Force
Verification of Testing Machines was E 4-02. In preparing this final
rule, NHTSA determined that E 4 has been revised to E 4-03. NHTSA is
therefore incorporating by reference ASTM standard E 4-03 into FMVSS
No. 106 at S6.4.
5. Water Absorption and Pressure Test, Tensile Strength, and Whip
Resistance
NPRM--NHTSA did not propose any changes to the existing water
absorption requirements of FMVSS No. 106 but did propose to incorporate
SAE J1401's fast-pull test and 370-pound strength requirement into
Standard No. 106's tensile strength test procedure. Accordingly, after
being conditioned in water for 70 hours, hydraulic brake hose assembly
would be required to meet these heightened tensile strength
requirements.
The agency stated that the immersion of the brake hose in water for
70 hours as specified in S6.5 of FMVSS No. 106 is the same as that
specified in SAE J1401. However, while the time specification of 70
hours is the same, the preparation of the brake hose specimen and the
water soak method are different between the two standards. The
preparation in FMVSS No. 106 specifies removal of 1 \1/8\ inches of
outer brake hose cover (if present) at the center of the brake hose,
without damage to any reinforcing material. Brake hoses tested to SAE
J1401 do not have any cutting of the hose. Another difference between
SAE J1401 and FMVSS No. 106 is that FMVSS No. 106 specifies soaking the
brake hose in distilled water at room temperature (75 degrees
Fahrenheit) while J1401 specifies an elevated water temperature of 185
degrees Fahrenheit.
Public Comments and NHTSA Response--Intertek commented that water
temperature is not a great factor regarding the degradation of brake
hoses, but that removal of the outer cover may influence the test
results because of the possibility of damage to the reinforcing braid
when the cover is cut. Goodyear stated that the SAE J1401 procedure was
developed to eliminate the potential of yarn damage that may occur when
the outer cover of the brake hose is removed by cutting. Goodyear
recommended that the water soak procedure in SAE J1401 be used in FMVSS
No. 106. Dana noted the discrepancies in the two standards, and stated
that it prefers the SAE procedure because it is easier for the
technician to perform and has less risk of inadvertent damage to the
brake hose. Further, Dana stated its belief that the results of the SAE
J1401 and FMVSS No. 106 test methods are similar although the
comparison data is about a decade old.
NHTSA agrees with the commenters that by using the SAE J1401 water
soak procedure, the likelihood of unintended damage to the brake hose
during the process of removing the cover will be eliminated. Thus, in
the final regulatory text, NHTSA adopts the water soak procedure in SAE
J1401.
6. Low Temperature Resistance Test
NPRM--NHTSA did not propose any changes in Standard No. 106's low
temperature resistance requirements/procedures.
Public Comments and NHTSA's Response--Dana and Goodyear stated that
while FMVSS No. 106 specifies a temperature of minus 40 degrees
Celsius, SAE J1401 specifies a lower temperature range of minus 45
degrees Celsius to minus 48 degrees Celsius. Both Dana and Goodyear
recommended the use of the lower test temperature as better reflecting
the capabilities of the materials used in current day brake hoses.
In the final rule, NHTSA adopts the lower temperature specification
recommended by Dana and Goodyear and as provided in SAE J1401.
7. Brake Fluid Compatibility, Constriction, and Burst Strength
NPRM--In the NPRM, NHTSA proposed to use the latest SAE reference
RM brake fluid for the brake fluid compatibility test. Because the RM-
66-05 fluid has superseded the RM-66-03 fluid, NHTSA did not propose
any change in the type of fluid specified for conditioning the hose.
NHTSA proposed, however, to increase the conditioning temperature in
FMVSS No. 106 to 248 degrees Fahrenheit.
Public Comments and NHTSA's Responses--Goodyear indicated in its
comments that the NPRM language regarding compatibility fluid was
incorrect with respect to the version of the SAE compatibility fluid
referenced in the existing FMVSS No. 106 and SAE J1401. NHTSA notes
that SAE RM-66-04 is currently referenced in FMVSS No. 106, and SAE RM-
66-05 is referenced in SAE J1401 (June 2003). The agency correctly
identified the compatibility fluid in the proposed regulatory text as
SAE RM-66-05 and therefore will make no change in the final rule.
Goodyear recommended that FMVSS No. 106 reference the latest or
current SAE fluid and not cite the specific version (e.g., -04 or -05).
NHTSA will not adopt this recommendation. NHTSA will maintain the
current system of referencing a specific version of the compatibility
fluid, and perform periodic rulemaking as new versions of the test
fluid are developed. In this way, the public will have an opportunity
to comment on new versions of the compatibility fluid before it is
incorporated by reference into FMVSS No. 106.
8. End Fitting Corrosion Resistance
NPRM--Instead of referencing either ASTM B117-64 or ASTM B 117
Appendix B, both of which are outdated, NHTSA proposed to change the
reference in FMVSS No. 106 to the most recent set of ASTM
specifications for salt spray chambers, which are found in ASTM B117-
97. NHTSA did not propose any other changes to the end fitting
corrosion resistance requirements/procedures in FMVSS No. 106.
Public Comment and NHTSA Response--ASTM commented that the latest
revision of ASTM standard B 117 Standard Practice for Operating Salt
Spray (Fog) Apparatus is B 117-02. In preparing this final rule, the
agency determined that B 117 has been revised to B 117-03, and is
incorporating B 117-03 in FMVSS No. 106 at a new S6.11, End fitting
corrosion test. There are no substantive differences between B 117-02
and B 117-03.
9. High Temperature Impulse Test
NPRM--NHTSA proposed incorporating the high temperature impulse
test from SAE J1401 into FMVSS No. 106.
Public Comment and NHTSA Response--Goodyear noted that in the
NPRM's preamble, the text incorrectly stated that the impulse test is
conducted in an air chamber at 259 degrees Fahrenheit, while the
correct specification is 295 degrees Fahrenheit. No change is needed to
the final rule regulatory text, as the correct temperature was
specified in the NPRM's draft regulatory text.
C. Air Brake Hoses
1. Construction and Labeling
NPRM--NHTSA proposed that plastic air brake tubing be regulated in
its own section in FMVSS No. 106 since it differs significantly in
construction and material properties from elastomeric
[[Page 76303]]
rubber hoses. Therefore, NHTSA proposed that any references to
synthetic or natural elastomeric rubber be deleted from S7
Requirements--Air brake hose, brake hose assemblies, and brake hose end
fittings of FMVSS No. 106 since it will no longer be necessary to
differentiate rubber hoses from plastic tubing in S7 and S8. The
proposed text in the NPRM also removed references to ``outside diameter
(OD)'' from S7 and S8 of FMVSS No. 106 since OD measurements are
generally only applicable to tubing, which NHTSA proposed to address in
the new section for plastic tubing.
NHTSA also proposed to specify in S7.2.1(e) of FMVSS No. 106 the
labeling scheme that is to be used for air brake hose that meets the
dimensional requirements of more than one type of end fitting (A, AI,
or AII). The proper labeling of such hose has been addressed in several
of the agency's legal interpretation letters, and including this
language in FMVSS No. 106 would serve to minimize confusion on this
issue. The proposed text also stated that a hose intended for use with
more than one type of end fitting may be labeled as such, but is not
required to be so labeled. This provides flexibility for hose
manufacturers to determine how they intend their hoses to be used, and
would not require them to label hoses for multiple end fitting
designations unless they so desire.
Public Comments and NHTSA's Response--The SAE and Parker/Atofina
stated that it is necessary to keep the references to synthetic or
natural rubber in order to clearly indicate that the fittings intended
for use with rubber air brake hose are not to be used with any type of
plastic hose (which is similar to plastic tubing but is sized by inside
diameter rather than outside diameter). Based upon the comments
received, the agency determines that retaining the references to rubber
provides beneficial information regarding the use of these brake hoses,
and is retaining the existing FMVSS No. 106 language in the final rule.
Comments from the SAE and Parker/Atofina describe the differences
in the three types of air brake hose designated as Type A, Type AI, and
Type AII. The SAE suggested notes for Table III describing the
application of reusable and permanent crimped fittings to each type of
hose. The SAE also recommended that the dimensional requirements for
Type A hose for use with both reusable and permanent fittings be
included in Table III. Parker/Atofina also recommended that the correct
dimensions for Type A, AI, and AII hose be included in FMVSS No. 106,
and that FMVSS No. 106 should conform to the specifications in SAE
J1402 for these dimensions.
Historically, NHTSA has declined to specify dimensions of end
fittings, as there are too many different end fitting thicknesses and
too many different types. NHTSA notes that the industry has
standardized brake hose end fittings. Therefore, on the issue of
dimensional requirements for air brake hose intended for use with
permanently attached fittings, NHTSA has stated its belief in the May
15, 2003 NPRM and in other rulemaking documents that it was not
necessary to include those dimensional requirements in FMVSS No. 106.
In the May 15, 2003 NPRM, NHTSA also stated that it believes that many
of the brake hose assemblers are truck repair facilities that may be
assembling brake hoses with permanently attached end fittings. It
follows that these truck repair facilities must pay attention to the
type of air brake hose being assembled, to ensure that the hose and end
fitting are compatible. In the NPRM, NHTSA stated that it believes that
air brake hose conforming to SAE J1402 is presently in use because of
FMCSR requirements at 49 CFR 393.45.
Regarding metric sizes of air brake hose, in the NPRM, NHTSA noted
that dimensions for metric air brake hoses are not included in FMVSS
No. 106, and solicited comments on the dimensions for metric air brake
hose (for use with permanently attached, or reusable end fittings) that
may be appropriate to include in FMVSS No. 106. Since it received no
comments on this subject, NHTSA will not include metric air brake hoses
in Table III.
In the final rule, the agency is adopting the dimensional
requirements for Type A air brake hose in Table III, as recommended by
the SAE and Parker/Atofina, and is including the suggested notes for
Table III. Table III's title, and its reference in S7.1, Construction,
are changed to no longer reference ``reusable'' end fittings because,
as the SAE indicates, the air brake hose in the table may be used with
either reusable or permanent fittings. The agency concludes that it is
also appropriate to slightly revise the regulatory text for S7.2.1(e)
in Labeling to indicate that the markings on the air brake hose
directly relate to its type as specified in Table III. As metric air
brake hose is not included in Table III, the agency is specifying that
it continue to be designated with the letter ``A.''
NHTSA proposed in the brake hose labeling requirements in
S7.2.1(e), a labeling provision for brake hoses manufactured for use
with more than one type of end fitting, e.g., AI and AII. Upon further
review and in light of the comments from the SAE and Parker/Atofina,
NHTSA now believes that no such applications exist, because of the
large differences in outside diameters between, for example, Type AI
and Type AII brake hose. For these reasons, the multiple labeling
provisions proposed in the NPRM are removed in the final rule.
2. High Temperature Resistance
NPRM--The high temperature resistance test for air brake hose
ensures that there are no cracks or disintegration due to proximity to
high temperatures of vehicle components such as engines and
transmissions. NHTSA proposed that FMVSS No. 106 adopt the smaller
radii test cylinders from SAE J1402 and, for \1/8\ inch and 3 mm, 4 mm,
and 5 mm hose, NHTSA proposed that the test cylinder radius of 1 inch
as specified in SAE J1402 for \3/16\ inch hose also be used for these
hose sizes. As currently indicated in Table IV of FMVSS No. 106, the
larger metric sizes of hose (6 mm and above) numerically correspond
closely to inch sizes of hose, for example, 6 mm (0.236 inch) is very
close to \1/4\ inch (0.250 inch). Accordingly, NHTSA proposed to apply
the test cylinder values from SAE J1402 to metric sizes of hose as
currently specified in Table IV of FMVSS No. 106. As to SAE J1402's
exclusion of fabric-covered air brake hose from the external inspection
requirement, NHTSA disagreed that external inspection of such hose is
impractical and, therefore, did not propose to incorporate SAE J1402's
exclusion.
Public Comments and NHTSA's Response--The SAE and Parker/Atofina
provided similar comments regarding the proposed test cylinder radii
that NHTSA raised in the NPRM. The test cylinder radii were proposed to
be decreased from the current values in FMVSS No. 106, Table IV, to
smaller values from SAE J1402, Table 4--Radius for High Temperature
Resistance Test (small radius). For example, the test cylinder radius
for a \3/8\-inch air brake hose in existing FMVSS No. 106 is 3\1/2\
inches while the test cylinder radius in SAE J1401 for the high
temperature resistance test is 1\3/4\ inches, or one-half the size.
The SAE and Parker/Atofina stated that SAE J1402 is going to be
revised to remove the small radius test cylinders from the high
temperature resistance test. However, in this final rule, the agency is
making FMVSS No. 106 consistent with the current version of SAE J1402,
but will be willing to
[[Page 76304]]
consider future alignments between the two standards in future
rulemaking.
The agency also notes that in the NPRM, the incorrect value of 3
inches for the large test cylinder was specified for \3/8\ inch hose.
NHTSA has corrected the value to 3\1/2\ inches in this final rule.
NHTSA notes that in the NPRM, incorrect test cylinders were
included in the proposed Table IV for the adhesion test of wire-
reinforced hose. The agency stated that the values from SAE J1402,
Table 4, should be used (small radius), while in fact SAE J1402
references the radii in Table 1 for this test (large radius). In the
final rule, NHTSA retains the correct test cylinder values without
change.
Comments from the SAE and Parker/Atofina note that the \1/8\ inch
size of air brake hose is not produced, therefore, the test cylinder
specification for that size hose is not needed in Table IV of FMVSS No.
106. The agency agrees and in the final rule, removes references to \1/
8\ inch size of air brake hose from Table IV.
As currently stated in FMVSS No. 106, the required performance of a
brake hose after being subjected to the test requirements in the high
temperature test is that the brake hose shall not show external or
internal cracks, charring, or disintegration visible without
magnification. Under the high temperature resistance requirements in
SAE J1402, the external surface of fabric-covered hoses is excluded
from this inspection, stating that visual inspection is not practical.
The agency proposed in the NPRM to keep the requirements in FMVSS No.
106 for external inspection and not include the SAE J1402 exclusion.
Both the SAE and Parker/Atofina commented that the SAE J1402 exclusion
be kept in place. SAE commented that for hoses covered with a textile
braid (fabric-covered), this braid does not show cracks from exposure
to ozone nor does it crack due to the high temperature test.
NHTSA does not understand the need to exclude external inspection
of the hose if, as Parker/Atofina and the SAE comments indicate, those
hoses with textile braid covering will not crack. The inspection is
visual, and does not require special equipment or magnification, nor
does it require removal of the fabric covering to inspect the hose
beneath it. By having such an exclusion, conceivably, a fabric-covered
brake hose that did show external cracks would be considered to have
passed the test. NHTSA does not believe there is any reason to add the
exclusion for external inspection. Further, the agency is specifying
only the larger test cylinder sizes for this test, and this should
further minimize the likelihood of failure compared to the requirements
currently in SAE J1402.
3. Low Temperature Resistance
NPRM--NHTSA proposed that the internal surface inspection of air
brake hose, as specified in SAE J1402, be incorporated into FMVSS No.
106. However, the agency did not propose to incorporate SAE J1402's
exclusion of fabric-covered air brake hose from external inspection.
Public Comments and NHTSA's Response--The SAE and Parker/Atofina
commented that the \1/8\ inch size of brake hose does not need to be
included in Table IV of FMVSS No. 106. NHTSA agrees and has removed the
\1/8\ inch size of brake hose from Table IV in the final rule. Both SAE
and Parker/Atofina also asked that the external inspection of the hose
for cracks excluded fabric-covered hoses, but for the same reasons as
described in the discussion on high temperature test requirements,
NHTSA does not include this exemption in the final rule.
4. Ozone Resistance
NPRM--Since NHTSA proposed that the ozone concentration for
hydraulic brake hose be changed from 50 pphm to 100 pphm, NHTSA
proposed to specify the higher ozone concentration (100 pphm) for air
brake hose as well. The agency tentatively concluded it is appropriate
to specify the same concentration of ozone for testing all types of
brake hoses.
Public Comments and NHTSA's Response--SAE, Parker/Atofina, and
Goodyear correctly indicated that the proposed ozone concentration
should be specified as 100 parts per hundred million, not by parts per
million. The correct concentration (100 parts per hundred million) is
specified in this final rule.
NHTSA notes that in the NPRM, the ozone test for air brake hose was
incorrectly identified as S8.14. A new section of FMVSS No. 106 for the
ozone resistance test is not needed since the ozone test is already
included in S8.4. In this final rule, the ozone test is correctly
identified as S8.4. Thus, the constriction requirements that were
proposed to be in S8.15 are now in S8.14.
5. Adhesion
NPRM--NHTSA proposed to incorporate the SAE J1402 adhesion test for
wire-reinforced air brake hose into FMVSS No. 106, with the exception
of the steel ball sizes as discussed below. Also, to incorporate SAE
J1402's specifications into FMVSS No. 106, NHTSA proposed that rather
than specifying steel ball diameters for each hose size, the steel ball
should be specified as having a diameter that is 75 percent of the
nominal inside diameter of the hose. This would allow for testing of
any and all sizes of hose.
The agency also proposed to specify use of a plug gauge rather than
a steel ball for constriction testing of other types of hose to which
FMVSS No. 106 applies. For the adhesion test, however, it would not be
possible to use a plug gauge because the hose is closed off at both
ends during the test. Accordingly, NHTSA proposed to specify the use of
a steel ball to test air brake hose for adhesion. Finally, the agency
proposed to update the ASTM tension testing machine reference in S8.9
from the 1964 version currently in FMVSS No. 106 to the latest revision
of that standard, Standard Practices for Force Verification of Testing
Machines, Designation E4-99.
Public Comments and NHTSA's Response--The SAE and Parker/Atofina
commented that they prefer the 73 percent of nominal inside diameter
specification, which would allow the use of standard size test balls.
Also, the size difference between a 73 and 75 percent ball size is
small (0.008 inches for a \13/32\-inch brake hose). NHTSA agrees that
the difference is not significant and adopts the 73 percent requirement
in the final rule.
NHTSA also notes that the incorrect test cylinder radii were
proposed for the adhesion test of wire-reinforced air brake hose. The
small test cylinders from SAE J1402 Table 4 were proposed in the NPRM,
but the correct radii from SAE J1402 Table 1 are included in this final
rule.
6. Air Pressure (Leakage)
NPRM--The SAE J1402 specifications for hose leakage are more severe
than those presently in FMVSS No. 106. NHTSA proposed incorporating the
flexure/pressure test from SAE J1402 into FMVSS No. 106, with some
modifications. NHTSA noted that the test procedure in SAE J1402
includes tolerances on the pressure requirements for determining
whether the hose leakage rate is acceptable upon completion of the
flexure test. The agency described how, if these tolerances were
applied in various manners, it may not be possible to determine the
pass/fail performance of a brake hose during a test.
Therefore, in the NPRM, we proposed an alternative, to modify the
requirements to ensure there would be a pass or fail criterion. NHTSA
also proposed to modify SAE J1402's test
[[Page 76305]]
procedures by specifying the thickness of the orifice during the final
leak check. The thickness of the orifice, and not only the diameter of
the orifice, affects the rate at which air can be supplied to the hose.
The rate at which air is supplied to the hose would be critical if a
small amount of hose leakage is present during the final leakage test.
NHTSA proposed specifying an orifice thickness of 0.032 inches (\1/32\
inch), which is the same thickness specified for the orifice in FMVSS
No. 121 at S5.3.5, Control signal pressure differential for converter
dollies and trailers designed to tow another vehicle equipped with air
brakes. NHTSA tentatively concluded that this proposed orifice
dimension would supply air at a greater rate than any thicker orifice
while still providing sufficient mechanical strength to withstand the
test conditions.
The agency proposed to adopt the lowest test pressure (140 psi) in
the brake hose during the leakage test from the range provided in SAE
J1402 (140 to 160 psi). The applied supply pressure to a restrictive
orifice was proposed to be at the midpoint of the pressure range, 150
psi. Thus, the supply pressure exceeds the required pressure that is to
be maintained in the brake hose, allowing a small amount of leakage to
be present, but not permitting excessive leakage to be present.
Public Comments and NHTSA's Responses--The SAE and Parker/Atofina
both stated that the agency is proposing to change the SAE test,
creating a new requirement. The commenters stated that it does not
reflect good test methodology to require 150 psi supply pressure with
no tolerance, or 140 psi with no tolerance in the brake hose within the
two minute period. However, neither commenter recommended an
alternative to NHTSA's proposal, other than to adopt the exact
procedure in SAE J1402. Both commenters stated that the agency's
proposal to adopt a thickness requirement for the orifice has some
technical value.
While the agency has considered the comments, the commenters did
not provide recommendations as to test pressures that the agency could
adopt in the final rule. The agency believes that by specifying the
minimum required pressure of 140 psi in the brake hose, while supplying
air at the mid-point pressure of 150 psi through an orifice of minimal
thickness that is least restrictive to air flow, a reasonable balance
in test conditions is achieved. Therefore, NHTSA is making final the
air pressure (leakage) test that it proposed in the NPRM.
NHTSA believes that measuring the leakage using a mass flow meter,
as is done for test leaks of plastic air brake tubing, may be
preferable to the method in this final rule. NHTSA may consider raising
this issue in a future rulemaking.
7. Tensile Strength
NPRM--As currently in effect, FMVSS No. 106 includes different
tensile strength requirements for air brake hoses if those hoses are
used: (a) Between the vehicle frame and axle, or between a towing and
towed unit; or (b) in any other application. The tensile strength
requirements for brake hose assemblies in the former case are
significantly higher than those requirements in the latter case.
Because the agency proposed separate requirements for plastic tubing in
a new section of FMVSS No. 106, NHTSA proposed to delete the lower
tensile strength limits for hoses that are used for purposes other than
connections between a frame and axle or between a towed and towing
unit, and require the higher tensile strength requirements for all
brake hoses. SAE J1402 only includes the higher tensile strength
requirements.
The agency proposed that all rubber brake hoses meet the
requirements for a hose that is used between a frame and an axle or
between a towed and a towing unit. NHTSA tentatively concluded that
rubber hoses are no longer used extensively for other purposes on heavy
vehicles, as plastic tubing is used for most chassis plumbing of air
systems. NHTSA tentatively concluded that these rubber hoses are of
sufficient diameter to have the mechanical strength to meet the higher,
frame-to-axle tensile strength requirements. NHTSA also solicited
comments on any alternate tensile strength requirements that might be
appropriate for rubber hoses.
Public Comments and NHTSA's Response--The SAE recommended that the
SAE J1402 tensile strength testing be adopted. SAE did not elaborate on
its recommendation. Parker/Atofina recommended keeping the current
FMVSS No. 106 requirements with the high and low tensile strength
requirements depending on application of the hose assembly. Parker/
Atofina stated that the lower tensile strength requirements are still
used in applications other than connections between a towed and a
towing unit, and to raise these requirements to the higher tensile
strength would add significantly to hose cost. No cost data was
provided for the agency to evaluate.
In evaluating the tensile strength test requirements, NHTSA notes
that it proposed different tensile strength requirements for plastic
air brake tubing depending on the application of the product (e.g.,
between towing and towed unit, or in chassis plumbing applications),
based on the current tensile strength requirements for air brake hoses
in S7.3.10 of FMVSS No. 106. The reason for the different strength
requirements is to accommodate different styles of end fittings. Thus,
the end fittings for a brake hose or plastic tubing used between a
towing and towed vehicle provide the highest tensile strength possible
to prevent separation of the end fittings. In other applications, such
as chassis plumbing, lower tensile strength requirements apply that
permit the use of fittings designed for ease of assembly on chassis
plumbing (such as push-to-connect fittings used with plastic tubing).
NHTSA did not believe that air brake hose is for chassis plumbing
(having been replaced by plastic tubing) and therefore proposed to
delete the lower tensile strength requirements for this type of brake
hose. Parker/Atofina however, states that this is not the case, and the
agency believes that Parker/Atofina is referring to the higher cost of
high-strength end fittings and/or the longer assembly time required for
these fittings. Therefore, in this final rule, the agency is not
deleting the lower tensile strength requirements for end fitting
retention for air brake hose, to avoid changes to vehicle manufacturing
in situations where this type of air brake hose is used for chassis
plumbing. The end fitting tensile strength requirements will therefore
be similar for air brake hose and plastic air brake tubing.
8. Minimum Bend Radius
NPRM--NHTSA tentatively concluded it would not be appropriate to
add SAE J1402 requirements for minimum bend radius to FMVSS No. 106
because FMVSS No. 106 regulates the properties of brake hoses as stand-
alone motor vehicle equipment rather than use requirements. NHTSA did
not propose to include a reference to the minimum bend radii from Table
1 in SAE J1402 as the minimum installation bend radii for brake hose as
installed on vehicles.
Public Comments and NHTSA's Response--Both the SAE and Parker/
Atofina asked that the minimum bend radii from Table 1 in SAE J1402 as
the minimum installation bend radii for brake hose installed on
vehicles be included to benefit users (installers) of the brake hose.
The agency notes that in Section 3.3.1 of J1402, smaller installation
radii may be appropriate for
[[Page 76306]]
some brake hoses. Therefore, in the final rule, NHTSA is not specifying
installation bend radii. NHTSA believes individual brake hose
manufacturers are in the best position to determine minimum bend radii
for hose to be installed in motor vehicles.
D. Vacuum Brake Hoses
1. Swell (Fuel Resistance)
NPRM--NHTSA proposed that Reference Fuel B as specified in SAE
J1403 be used for the swell test in FMVSS No. 106. NHTSA also proposed
that the plug gauge method (in lieu of the steel drop-ball method) be
kept in place in TP-106 for swell testing of vacuum brake hoses.
NHTSA proposed that the specifications of FMVSS No. 106 and SAE
J1403 be combined as follows. Following the fuel conditioning using
Reference Fuel B and the constriction test, each vacuum hose would be
subjected to a vacuum of 26 inches of Hg for ten minutes, with no
visible collapse or leakage of the hose permitted (as currently
specified by FMVSS No. 106). Then, for hoses constructed of two layers
or more, a layer adhesion test would be conducted with a specified
performance of 8 pounds-per-inch minimum separation force (as specified
by SAE J1403). NHTSA proposed that this adhesion test only be applied
to multi-layer hoses for two reasons. First, the agency tentatively
concluded that single layer hose cannot be tested easily. Second, NHTSA
tentatively concluded that single layer hose that have lost mechanical
integrity would not be able to pass the visual collapse or no leakage
specification during the vacuum test and, as such, failure would
already be detected prior to completion of the vacuum test.
NHTSA also proposed to update the ASTM test procedure referenced in
S10.7 for the swell test to the current revision, D471-98e1.
Public Comments and NHTSA's Response--Goodyear supported the
current SAE J1403 test sequence consisting of fuel soak, restriction
(constriction) ball test, vacuum collapse test, and layer adhesion test
with a minimum separation strength of 6 pounds per inch. Goodyear
commented that the agency's proposed plug gauge for constriction
testing, shown as Figure 4, has only three inches of length and would
not be able to pass through a test sample of vacuum hose that is 12
inches in length. Further, the vacuum brake hose may have some
curvature that would not permit a straight gauge to pass through it.
For these reasons, Goodyear recommended that a rolling ball be used to
verify the internal dimensions of vacuum brake hose during the swell
test.
In responding, the agency begins by noting that pre-formed vacuum
brake hoses would have significant curvature molded into them, and
standard vacuum brake hose may also have some natural curvature as
described by Goodyear. NHTSA also notes that in the existing and
proposed FMVSS No. 106 regulatory text, the method of verifying the
inside diameter of the vacuum brake hose is not provided. As noted in
the NPRM, the method is identified as a plug gauge in the agency's
current test procedure, TP-106. For the final rule, the agency has
decided to provide the option of using a drop ball for both
constriction tests and verification of the inside diameter during the
swell test, and to also permit the use of a standard plug gauge or an
extended length plug gauge. The fact that several options are provided
to brake hose manufacturers is consistent with constriction testing for
other types of brake hoses in FMVSS No. 106, where more than one method
may be employed (by NHTSA and brake hose manufacturers) due to the
variety of end fitting designs that may preclude the use of the plug
gauge. In this final rule, NHTSA is incorporating into FMVSS No. 106
the three constriction test methods to be used in the swell test.
In the NPRM, NHTSA proposed an adhesion strength test requirement
of 8 pounds per inch. Goodyear stated that the value should be 6 pounds
per inch, as stated in SAE J1403. The correct value of 6 pounds per
inch adhesion strength requirement is in this final rule.
E. Plastic Air Brake Tubing
1. General Comments
In the NPRM, NHTSA stated that plastic air brake tubing is
generally manufactured from nylon but the generic term, ``plastic'' is
used to account for other types of plastic that may be used for air
brake tubing. The comments on the proposal for requirements for plastic
air brake tubing, plastic air brake tubing assemblies, and plastic air
brake tubing end fittings fell into two groups: (a) Manufacturers
currently manufacturing air brake tubing from polyamide (nylon)
requesting that this material specification be included in FMVSS No.
106; and (b) manufacturers that may be considering manufacturing air
brake tubing from materials other than nylon, that did not support
including this material specification (plastic) in FMVSS No. 106.
Parker/Atofina stated that by not including additional material
property tests into FMVSS No. 106, there would be insufficient
safeguards for the performance of alternate tubing made from unproven
and unspecified polymers that would create a significant product design
risk. It also stated that the material specification of generic nylon
is not design restrictive, but offers thermoplastic tubing
manufacturers great latitude in product design options.
SMC stated that not including the material specification in FMVSS
No. 106 leads to an issue that is being addressed in the SAE committee
that is responsible for SAE J2547, Alternate Nonmetallic Air Brake
System Tubing. Namely, the test should be application specific and not
a material validation test like the burst pressure test in SAE J844.
Different tube material may affect the retention of the tubing in the
fitting per the SAE J1131 requirements. Until further evaluation is
conducted on the new tubing materials with all fitting supplied in the
industry, leaving the material open to the tubing manufacturers'
discretion may lead to problems with the tube connection.
HPP stated that SAE J844 takes into account that the materials are
polyamides. To exclude this requirement, additional tests would need to
be introduced to ensure that long-term properties of tubing made from
other materials meet the in-use requirements. HPP cited, for example,
that there is no requirement for a high-temperature burst test at
elevated pressures, while polyamides are known to possess the long-term
properties for this requirement.
DuPont stated that the agency correctly points out in the NPRM that
a material and construction specification is design restrictive. It
notes that while polyamides used under SAE J844 have performed with an
admirable safety record, it has a negative impact on innovation and
commerce. DuPont also encouraged the elimination of any reference to
specific types of construction, specifically regarding Type A
(unreinforced) and Type B (reinforced) tubing. DuPont stated that any
style of construction that passes the rigorous test procedures and
dimensional requirements set forth in the proposal should be
permissible.
In this final rule, NHTSA has decided to keep the generic
terminology of plastic air brake tubing, rather than adopt the
specification for nylon (polyamide) material. Regarding concerns that
materials other than nylon might be inferior when used in air brake
tubing, NHTSA notes that it proposed 24 performance test requirements
[[Page 76307]]
(proposed S11.3.1 through proposed S11.3.24), and is adopting twenty-
two of those requirements in the final rule. NHTSA believes that these
extensive requirements will ensure that alternative air brake tubing
materials are subjected to rigorous testing to provide safe service in
air brake systems.
HPP stated that if the requirements in SAE J844 are performed on
air brake tubing made from materials other than nylon, additional tests
might be appropriate, such as a high-temperature burst test. However,
HPP did not provide any test parameters that the agency could evaluate.
NHTSA notes in the section below that high-temperature conditioning
requirements for plastic air brake tubing have been included for
adoption in FMVSS No. 106.
With regard to the agency's statements in the NPRM that air brake
tubing must be either Type A, single layer, unreinforced construction,
or Type B, two layer, reinforced construction, the agency has reviewed
the comments on this subject and has decided not to adopt these
requirements in the final rule. Additional details that formed the
agency's decision on this subject are included in the sections below.
2. Construction
NPRM--The NPRM solicited comments on whether air brake tubing
should be designated as Type A--a non-reinforced, single-layer tubing
(designated for small diameter tubing in SAE J844), or as Type B--
constructed from two layers of material with a reinforcing braid at the
interface of the two layers (designated for large diameter tubing in
SAE J844).
Public Comments and NHTSA's Response--SMC cited the SAE J2547 as a
standard currently in draft that will not restrict the tubing to have
either a single wall or two walls with a reinforcement braid, but SMC
did not provide any additional details on the SAE effort that the
agency could consider regarding the final rule. SMC stated that Europe
is currently using single wall tubing for all sizes used in the
trucking industry. SGPPL proposed that if references to nylon are not
included for air brake tubing, one solution would be to also eliminate
references to reinforced, unreinforced, and single- or multi-layer
tubing construction, but retain dimensional values including inside
diameter, outside diameter and/or wall thickness.
HPP stated that single layer tubing with an outside diameter of 10,
12 and 16 millimeters, or \3/8\, \1/2\, \5/8\ and \3/4\ inches, can
meet SAE J844 requirements and should be permitted in FMVSS No. 106.
HPP stated that from technical and safety standpoints, there is no need
for reinforced tubing for the larger diameter applications.
As earlier noted, DuPont believed that there was no need to include
references to specific types of construction in FMVSS No. 106, because
any style of construction that passes the rigorous test procedures and
dimensional requirements as described in the NPRM should be
permissible.
The agency agrees with the comments from SMC, SGPPL, HPP, and
DuPont that construction and reinforcement requirements do not need to
be included in FMVSS No. 106. NHTSA believes that the safety of plastic
air brake tubing will be ensured by the 22 tests specified in this
final rule.
Parker/Atofina stated that the NHTSA proposal not to include the
construction and material specifications for Type A and Type B tubing
as specified in SAE J844 is inappropriate and potentially unsafe to
users. It stated that by not including additional material property
tests into FMVSS No. 106 to safeguard the performance of alternate
tubing made from unproven and unspecified polymers creates a
significant product design risk. It suggested including test
requirements for battery acid resistance, high temperature burst, high
temperature heat aging, and moisture absorption to help prevent the use
of unsuitable materials. HPP made similar comments regarding the need
for additional tests such as an elevated temperature burst test if
nylon is not specified as the tubing material. HPP stated that air
brake tubing can be exposed to temperatures in the 80 to 100 degree
Celsius (176 to 212 degrees Fahrenheit) range.
NHTSA notes that the NPRM proposed to amend FMVSS No. 106 by
including, for plastic air brake tubing, tests for moisture absorption,
high temperature resistance, high temperature conditioning with low
temperature impact resistance, boiling water conditioning with low
temperature impact resistance, and high temperature conditioning and
collapse resistance. All of these test requirements have been
incorporated into the final rule. Parker/Atofina did not identify the
parameters of the suggested battery resistance test, nor did they
indicate why the test conditions proposed in NPRM involving, for
example, high temperature conditioning of plastic air brake tubing, are
insufficient for materials other than nylon. HPP indicated that
temperatures up to 100 degrees Celsius (212 degrees Fahrenheit) can be
experienced by plastic air brake tubing in use, and the agency has
included high temperature conditioning tests for tubing in the 100 to
110 degrees Celsius (212 to 230 degrees Fahrenheit) temperature range.
NHTSA believes that the extensive series of test requirements that
it is adopting in the final rule will be sufficient to ensure the safe
performance of plastic air brake tubing made from materials other than
nylon, and, as discussed in the section below on zinc chloride and
methyl alcohol resistance, the agency may consider additional chemical
resistance tests for plastic air brake tubing in the future. For
example, DuPont cited the use of copolyester elastomer in air brake
tubing. Therefore, in this final rule, the agency is not specifying
that air brake tubing must be manufactured from nylon.
NHTSA believes that although materials other than nylon, possibly
constructed as unreinforced, single-layer tubing, have been developed
and used (for example, in Europe), it does not automatically mean that
these other materials or constructions (such as alternate plastic/non-
nylon tubing) can be applied to FMVVSS No. 106 without careful
consideration. One of the main purposes of the agency's undertaking
rulemaking on FMVSS No. 106 is to implement dimensional specifications
for air brake tubing that currently do not exist in the standard, to
preclude the sale or use of tubing that is not compatible with existing
SAE J844 (or SAE J1394) tubing and end fittings used extensively in the
United States. Alternate air brake tubing products that are developed
will have to meet the extensive performance requirements for air brake
tubing that are included in this final rule, and will also have to do
so within the dimensional specifications that are also being adopted.
NHTSA does not expect that inferior products of any type or size will
meet these extensive requirements.
3. Labeling
NPRM--NHTSA proposed to require air brake tubing to be labeled with
the manufacturer identifying information at intervals of not more than
6 inches, from the end of one legend to the beginning of the next. This
represented no change from the FMVSS No. 106 labeling method already
specified for brake tubing.
Public Comments and NHTSA's Response--Parker/Atofina commented that
based on their experience, the vast majority of plastic air brake
tubing assembly lengths are greater than 15 inches. The tubing would be
sufficiently marked for product tracking if the text marking repeat
interval is not more than 15 inches. NHTSA believes that to facilitate
identification of the hose
[[Page 76308]]
manufacturer, all brake hoses must be labeled to identify the
manufacturer. To increase the labeling interval to 15 inches may
increase the likelihood that a particular brake hose may not include
the labeling information. Therefore, NHTSA will not adopt the
suggestion of a 15-inch repeat interval for brake hose labeling.
Parker/Atofina commented that the agency's proposal is too
restrictive on manufacturers in order to maintain complete marking
context and text liability on small diameter plastic tubing.
Presumably, Parker/Atofina is referring to the requirement that the
height of the labeling information be at least one-eighth of an inch.
NHTSA notes the one-eighth inch height requirement has been in FMVSS
No. 106 for many years. Further, Parker/Atofina did not suggest an
appropriate lettering height for small diameters of air brake tubing.
NHTSA is not changing the lettering height requirements in this final
rule.
4. Dimensions and Tolerances
NPRM--NHTSA proposed to incorporate into FMVSS No. 106 the
dimension and tolerance requirements contained in SAE J844, and also
SAE J1394 covering metric sizes of tubing, as Table VII of FMVSS No.
106.
Public Comments and NHTSA's Response--Parker/Atofina provided
several recommendations for changes to Table VII, stating that for
example, the tolerance for wall thickness should be similar for metric
tubing that is close in size to that of an inch-sized tubing. The
recommended changes are for the dimensional specifications of 10, 12,
and 16 millimeter brake tubing. Parker/Atofina stated that these
revisions are currently in process by the SAE under project S4-J844-01-
01. The agency has reviewed the recommended changes and notes in
general that they serve to tighten the tolerances, compared to the
values published in the NPRM. The agency is adopting Parker/Atofina's
recommended changes.
Parker/Atofina also noted that in Table VII, the outside diameter
of the 3/8-inch brake tubing is specified as 9.69 millimeters, but the
value should be 9.63 millimeters (as it appears in SAE J844). The
agency notes this correction and includes it in the final rule.
5. One Hundred Percent Leak Test
NPRM--NHTSA did not propose to incorporate the requirement in SAE
J844 that requires tubing manufacturers to subject all air brake tubing
to a 200-psi leak test. The agency stated its belief that this is a
quality control test and not a measure appropriate to include in FMVSS
No. 106.
Public Comments and NHTSA's Response--Parker/Atofina commented that
it believes that unless this requirement is mandated in FMVSS No. 106,
manufacturers will not continue to perform the current quality
inspections and controls, since the procedures represent added cost and
require additional resources. NHTSA does not agree with this view.
Manufacturers are required to take whatever steps are necessary to
ensure that all of their plastic air brake tubing meets the full burst
strength requirements in the standard ranging from 800 to 1,400 psi.
NHTSA sees no additional safety need is met by requiring a 200 psi leak
test in addition to a full strength burst test.
6. Burst Test
NPRM--NHTSA noted that in the existing FMVSS No. 106 test
procedures, water is specified as a test medium, but that SAE J844 does
not specify a medium. NHTSA considered air to be the more appropriate
test medium for plastic air brake tubing rather than water. NHTSA
proposed changing the burst strength requirements in FMVSS No. 106 to
the higher values in SAE J844, and specifying air as the test medium
rather than water. NHTSA proposed that the pressure in the tubing be
increased in a period of 5 seconds because using the range of 3 to 15
seconds in SAE J844 would specify testing at both 3 and 15 seconds and
therefore would be too broad of a specification for use in FMVSS No.
106.
Public Comments and NHTSA's Response--HPP, SMC, Parker/Atofina and
SGPPL all recommended water (HPP recommended water or oil) as the
preferred test medium because of concerns for the safety for the person
conducting the test and cost factors. After considering this concern,
NHTSA has decided to specify water as a test medium in all burst tests
in this final rule, except for one test where oil is specified due to
very low test temperatures.
SGPPL believes that FMVSS No. 106 should include a provision to
prevent any conditioning of the air brake tubing sample prior to
testing. SGPPL stated that polyamide material is hygroscopic and over
time, will absorb water that will decrease the burst strength of the
tubing. SGPPL recommended that the samples of tubing for the burst test
be conducted on tubing as it is extruded from the production line.
NHTSA does not agree that samples of tubing should be tested to
burst strength requirement only at the point of production. Typically,
the agency or test laboratories contracted to do testing for the agency
will purchase samples of brake hose at a retail point of sale and those
samples are required to meet the requirements in FMVSS No. 106. This is
also reflective of the condition of brake hose when it is sold to and
used by the public. The agency notes that this may require some
diligence by the brake hose manufacturer to ensure that the
manufacturer's distribution methods do not permit excessive degradation
of brake hose products between manufacture and retail sale. NHTSA
retains the existing FMVSS No. 106 requirement under S11 Test
conditions (S13 in the NPRM) that brake hoses and brake hose assemblies
must be at least 24 hours old, and unused.
In the NPRM, NHTSA proposed to apply the test pressure in the brake
tubing in 5 seconds during a burst test, instead of within the range of
3 to 15 seconds as specified in SAE J844. NHTSA stated that if it were
to adopt such a range, when NHTSA conducts the testing, the brake
tubing would be required to meet the burst test at 3 seconds, at 15
seconds, and at any point in between 3 and 15 seconds. NHTSA stated
that the specification ``would be too broad of a specification for use
in FMVSS No. 106.'' (See May 15, 2003 NPRM at page 26,398.) SGPPL
stated that it does not exactly understand the agency's reasoning, but
finds a range of 10 to 12 seconds to yield reliable, consistent
results. SMC stated that instead of a timing requirement, a fixed flow
rate should be specified rather than a time constraint, so that
variable flow rates would not have to be used. However, SMC did not
provide any details on what a suitable flow rate might be. Parker/
Atofina stated that thermoplastic tubing possesses strain rate
dependent properties such that if a tubing burst pressure is achieved
under 3 seconds, a higher burst strength without failure can be
achieved. It further stated that there is no one standard burst test
apparatus that manufacturers could use, and specifying an exact 5
second timing requirement would require most costly and higher
precision test equipment.
NHTSA believes that based on the comments, it may be difficult to
achieve the 5-second timing with the existing test equipment in use.
The agency notes that in the case of the burst strength test for a
hydraulic brake hose as specified in FMVSS No. 106 at S6.2, the
pressure in the brake hose is increased at a constant rate of 15,000
psi per minute. The precedent here is that a constant pressure increase
rate is specified. Due to the costs and difficulty of achieving
[[Page 76309]]
the 5-second timing, in this final rule, NHTSA is going from a time
increment to a pressure rate specification, as follows.
The burst strength pressures proposed for plastic air brake tubing
are specified in Table VIII, and the specified burst strength pressures
range from a low of 800 psi for \3/4\3/4 -inch outside diameter tubing,
to a high of 1,400 psi for 3/8-inch outside diameter tubing. To achieve
an 800 psi pressure in 15 seconds, the application rate would be 3,200
psi per minute. To achieve a 1,400 psi pressure in 15 seconds, the
application rate would be 5,600 psi per minute. NHTSA agrees with
Parker/Atofina's comment that faster pressure application rates can
affect the outcome of the test results. Therefore, in the final rule,
the agency is adopting a test pressure application rate of 3,000 psi
per minute (3,200 psi per minute rounded down to 3,000 psi). The test
pressure application rate of 3,000 psi per minute is consistent with
SMC's stated preference for a fixed flow rate, and should not result in
manufacturers' having to purchase new test equipment, as 3,000 psi per
minute is a relatively slow pressure increase rate.
7. Moisture Absorption
NPRM--NHTSA proposed incorporating the moisture absorption
specification from SAE J844 into FMVSS No. 106. SAE J844 specifies a
sample of air brake tubing is conditioned in a humidity chamber for 100
hours, and the required performance is that the sample cannot exceed a
two percent weight gain of absorbed moisture.
Public Comments and NHTSA's Response--SGPPL stated that it believes
the moisture absorption test is designed around polyamide (nylon)
material and is design restrictive. SGPPL stated that the moisture
absorption test is not performance-based and does not indicate failure.
SGPPL also believed that the heat aging test, cold impact test, boiling
water stabilization and burst tests would be satisfactory for
evaluating the effects of moisture exposure on the properties of
tubing. DuPont stated that although it has no objections to the
moisture absorption test, it believed that it may be redundant to both
the heat aged burst pressure test and the dimensional specifications
test (boiling water conditioning and dimensional stability).
Based on the information it received, NHTSA does not agree that
this proposed requirement is design restrictive in favor of nylon
tubing. NHTSA agrees, however, that as SGPPL states, failure of the
moisture absorption test (excessive weight gain) does not directly
indicate that the tubing has failed (e.g., ruptured). In its prior
comments regarding burst strength testing, SGPPL indicated that
moisture absorption can affect burst strength. While DuPont believes
that the moisture absorption test is redundant to other proposed test
requirements, NHTSA notes that these tests involve soaking the tubing
in boiling water for 2 hours, whereas the moisture absorption test
involves a humidity soak of 100 hours. The outcome of these soakings
would be affected if there were a difference in the water or moisture
absorption rate of different materials.
NHTSA notes that in FMVSS No. 106 for hydraulic brakes, there are
three performance requirements for hydraulic brake hose related to
water absorption. After the hose is immersed in hot water for 70 hours
(as specified in this final rule), brake hoses must pass a burst
strength test, a tensile strength test, and a whip resistance test
(separate tests, not conducted on the same hose).
If a sample of plastic air brake tubing were to fail the proposed
moisture absorption test, the agency would then be able to show how
that failure relates to a lessening of motor vehicle safety. If the
agency could demonstrate a corresponding reduction in one or more
mechanical properties of the tubing, NHTSA would be better able to
demonstrate a relationship to motor vehicle safety. Therefore, in this
final rule, NHTSA adopts a burst pressure strength requirement, rather
than a weight gain limit, as the required performance criteria for this
test requirement. NHTSA is using the same burst pressure requirement as
for other tests that involve conditioning of the tubing, which is 80
percent of the burst strength in Table VIII.
8. Ultraviolet Resistance
NPRM--NHTSA tentatively concluded that the plastic material used in
nylon air brake tubing is significantly different from the materials
used in rubber air brake hoses, and that plastic is susceptible to
deterioration that can cause embrittlement due to exposure to
ultraviolet light. NHTSA proposed to incorporate SAE J844's ultraviolet
resistance test into FMVSS No. 106. SAE J844 includes an ultraviolet
(UV) resistance test using an accelerated weathering device specified
as the Q-Panel QUV test apparatus equipped with Phillips lamps, type
UVS-340. NHTSA did not refer to any brand name of equipment in the
proposed regulatory text of FMVSS No. 106. Presumably this test
equipment, except for the special UV lamps, can be custom manufactured
or purchased from a company such as Q-Panel.
The agency proposed to reference the apparatus specified in ASTM
G154-00, Standard Practice for Operating Fluorescent Light Apparatus
for UV Exposure of Nonmetallic Materials, rather than the one specified
in ASTM G53 because ASTM G154-00 is an updated version of ASTM G53.
NHTSA also proposed to reference two additional ASTM standards: ASTM
D4329-99, Standard Practice for Fluorescent UV Exposure of Plastics,
which is currently referenced in SAE J844, and ASTM G151-97, Standard
Practice for Exposing Nonmetallic Materials in Accelerated Test Devices
that Use Laboratory Light Sources, which is not currently referenced in
SAE J844, but may provide useful guidance for conducting UV testing.
Public Comments and NHTSA's Response--SMC stated that the cost of
purchasing a new system and performing the validation test on all sizes
and configurations will need to be considered. SMC did not specify
whether it has an older system that would need to be updated, or
whether it has UV testing equipment. Parker/Atofina stated that the
agency's proposal to require ASTM G-154-00 equipment will mandate that
manufacturers will have to purchase a Q-Panel test apparatus with the
Solar Eye irradiance measurement device. Parker/Atofina stated that
this optional measurement device is not significantly relevant to the
outcome or testing procedures required in the UV test for plastic
tubing. Parker/Atofina stated that the alternate procedures in ASTM G53
and in SAE J844 are sufficient to display compliance with the current
SAE J844 specification.
NHTSA disagrees that manufacturers will have to purchase new
equipment that has the automatic irradiance control device. The
requirement for the automatic irradiance control device is added to
FMVSS No. 106 because the agency believes the device will provide the
best available control of the UV irradiance level during the testing
and reduce the likelihood of overexposure to UV light, compared to the
alternate method of not using automatic irradiance control and rotating
the lamps every 400 hours, discarding them after 1600 hours, and the
other specified steps. NHTSA believes inclusion of automatic irradiance
control will reduce variability in test results.
NHTSA believes that air brake tubing manufacturers will be able to
use their existing UV test equipment if they are able to maintain the
minimum specified irradiance level of 0.85 watts per square
[[Page 76310]]
meter. It is possible that equipment without irradiance measurement and
control would result in higher irradiance levels and thus be more
severe than the agency's required UV exposure requirement.
SMC commented that in the NPRM's section on Rulemaking Analyses and
Notices, the capital cost to purchase a new ultraviolet test apparatus
should be taken into consideration. SMC cited Executive Order 12866 for
its position. In the NPRM, NHTSA discussed the cost issues resulting
from the brake hose rulemaking and estimated the cost of upgrading
brake hoses to meet with proposals in the NPRM to be in the range of
zero dollars to $1.6 million annually. Further, the agency stated that
it did not believe that the rulemaking would have a significant
economic impact on a substantial number of small entities. Regarding
SMC's comments on the cost of purchasing new test equipment, NHTSA
believes that the cost of such equipment may be on the order of $5,000
to $10,000, a sum that would not have a significant effect on NHTSA's
estimated cost of this rulemaking.
Parker/Atofina stated that it believes NHTSA's proposed inclusion
of ASTM D4329-99 and G 151-97 offer education to the reader, but do not
add significantly to the testing procedure or to the requirements
specified in SAE J844. Parker/Atofina recommended that references to
ASTM G 53, as referenced in SAE J844, are sufficient. As NHTSA noted in
the NPRM, G 53 has been replaced by G 154. NHTSA believes that it
should reference the most current of these two ASTM standards, since a
goal of the agency's rulemaking is to update FMVSS No. 106 and remove
obsolete references.
The NPRM referred to three ASTM standards: G 154-00, which provides
information on the spectral output of the UVA-340 lamps; G 151-97,
which provides practices to maintain control of irradiance within a
test device; and D 4329-99, which provides guidance on preparation of
test samples, positioning in the test device, and interpreting test
results. NHTSA believes that because these three ASTM standards are
interrelated, they should all be included in FMVSS No. 106. Therefore,
in the final rule, the agency is keeping references to all three ASTM
standards.
ASTM commented that the latest revision of ASTM standard G 151
Standard Practice for Exposing Nonmetallic Materials in Accelerated
Test Devices that Use Laboratory Light Sources was G 151-00. NHTSA
agrees that ASTM G 151-00 is the latest revision and probatively tests
plastic tubing for ultraviolet resistance. In this final rule, NHTSA is
incorporating ASTM G 151-00 in S12.7 Ultraviolet light resistance test.
9. Resistance to Zinc Chloride and Methyl Alcohol
NPRM--NHTSA proposed to incorporate the zinc chloride and methyl
alcohol resistance requirements and test procedures from SAE J844 into
FMVSS No. 106.
Public Comments and NHTSA's Response--DuPont stated that the
agency's proposed test proposal was marginally adequate for FMVSS No.
106. It suggested considering adopting the requirements of ISO 7628 at
S7.9.2, that includes resistance testing to zinc chloride, copper
chloride, sodium chloride, and potassium chloride. In addition, testing
discrete samples of brake tubing may be appropriate to evaluate all
layers of the tubing, as may be found with cut ends of tubing or if an
outer layer of the tubing is compromised. SGPPL also referenced the
test in ISO 7628 and suggested that the agency may wish to review the
test requirements. SGPPL stated that SAE is currently reviewing the ISO
7628 requirements and the ISO 7628 test may be needed, given the
various chemicals used on roads today.
SGPPL requested a clarification that in the agency's proposed zinc
chloride test, only the outside of the tubing is to be exposed during
the test. SGPPL stated that the outside is the only part of the tubing
that is exposed to zinc chloride while in operation on a motor vehicle.
NHTSA agrees with this comment, and provides additional text in the
final rule to clarify that the zinc chloride test is only conducted on
the exterior of the tubing.
Regarding the incorporation of additional chemical resistance tests
into FMVSS No. 106, the agency does not have sufficient information to
include such incorporation in the final rule. NHTSA would also provide
the public with an opportunity for comment before adopting additional
chemical resistance tests.
HPP stated that the bend radius for the zinc chloride and methyl
alcohol resistance tests (and also the high temperature flexibility
tests) should be the test bend radius as specified in Table 2 of SAE
J844, rather than two times the nominal outside diameter of the tubing
as specified in the NPRM. This was also noted by Parker/Atofina. NHTSA
has concluded that the commenters are correct and for the zinc
chloride, methyl alcohol resistance, and high temperature flexibility
tests, is referencing the bend radii from FMVSS No. 106's Table VIII in
the final rule.
10. Stiffness
NPRM--Because FMVSS No. 106 does not contain a similar set of
procedures/requirements, NHTSA proposed to incorporate the stiffness
procedures/requirements from SAE J844 into FMVSS No. 106. The stiffness
test requires that a section of tubing is conditioned in a straight
position at 230 degrees Fahrenheit for 24 hours, and after cooling and
by using a special test fixture, the force required to deflect the
tubing 2 inches at its ends is measured. The resulting force may not
exceed a specified amount that ranges between one pound and 80 pounds
depending on the diameter of the tubing. In the NPRM, the agency stated
its belief that this test would ensure that the flexibility of the
tubing is not reduced when the tubing is subjected to elevated
temperatures.
Public Comments and NHTSA Response--SGPPL commented that it sees
reasons to both include and exclude this test requirement from FMVSS
No. 106. It believes that the stiffness test is not a true performance
criterion for the tubing, and that stiffness is not linked to any
failure mode. Stiffness also does not gauge form, fit, or function of
the product. Historically, thermoplastic air brake tubing has replaced
traditional steel and copper tubing air lines, and although much less
stiff, plastic tubing stiffness does not affect the end functionality
of the tubing. SGPPL stated that this test could be considered design
restrictive and written around the use of plasticized polyamide
material. SGPPL stated that the stiffness test does serve a purpose
from the perspective of a truck original equipment manufacturer (OEM)
in that overly stiff tubing would be too difficult to route during
truck assembly.
SGPPL noted that the stiffness test as proposed in the NPRM did not
include a pull rate specification that can affect the results of the
test. It stated that it consistently uses a pull rate of one inch per
minute.
NHTSA has considered SPPL's comments and agrees that it would be
difficult to identify how failures of the stiffness test would be
detrimental to motor vehicle safety. The agency agrees that the
stiffness test may serve a purpose for vehicle manufacturers that
desire to specify a particular stiffness in their specifications for
its airbrake tubing. NHTSA also believes that specific stiffness
characteristics may be desirable for tubing used in applications such
as when long runs of tubing are used on semitrailers versus tubing used
[[Page 76311]]
to plumb tractors. Therefore, NHTSA is not including the stiffness test
in this final rule. In lieu of the stiffness test, NHTSA specifies a
test for collapse resistance as a measure of brake tubing performance
when subjected to elevated temperatures.
11. Heat Aging Adhesion
NPRM--NHTSA proposed to incorporate the heat aging adhesion test
procedures from SAE J844. NHTSA also proposed that the minimum adhesion
performance requirement for Type B tubing be changed from the SAE
requirement of ``no separation'' to 25 pounds per linear inch. NHTSA
described several problems in directly applying the SAE J844
requirements. Foremost is that during the adhesion test, in which air
brake tubing made of two layers is separated at the layer interface by
cutting it apart and then subject to being pulled apart at this
juncture, SAE J844 states that no separation at the layer interface is
permitted. NHTSA pointed out that this could not be adopted because the
tubing will ultimately fail at some point during the test. NHTSA
proposed a metric of 25 pounds minimum separation force per linear
inch, based in part on a similar test that is contained in FMVSS No.
106 to measure the layer separation performance of elastomeric air
brake hoses.
The agency proposed that rather than having a stand-alone adhesion
test, the adhesion test would only be performed as specified in SAE
J844 that includes a heat aging conditioning test. This would eliminate
the need to run an adhesion test, and also a heat aging and adhesion
test.
The agency also deviated from SAE J844 in that rather than
preparing a test sample from a helical section of hose, with the cut
line following one of the reinforcing braids in the tubing, NHTSA
proposed that the sample be prepared from an inch-long sample of tubing
cut through one side along its longitudinal centerline.
Public Comments and NHTSA's Response--SMC commented that the
agency's proposal to include a process that generates numerical data is
superior to what it used in SAE J844. SAE noted that the separation
requirement for elastomeric air brake hose is 8 pounds per linear inch,
and stated that the separation requirement in SAE J2547 (a draft
document in committee) is 4.4 pounds per linear inch. SMC stated that
the reason that air brake tubing layers would separate would be
relative motion between the connections (end fittings). NHTSA notes
that plastic air brake tubing is used in applications that involve
relative motion between components (e.g., the connections between
tractors and trailers), but in those applications the tubing is in
coiled form that generally distributes torsional and bending stresses
over a great length of tubing. SMC also stated that the method of
performing adhesion testing in SAE J2547 is still being drafted, and it
did not provide any details as to what it might include.
DuPont stated that it agrees with the agency's proposed adhesion
strength of 25 pounds per linear inch. It also stated that it believed
the adhesion test to be potentially redundant since the performance in
both the low temperature impact and heat age burst pressure tests would
presuppose adequate bond strength.
SGPPL wrote in favor of adopting the 25 pounds per linear inch bond
strength. It noted the difference between the sample preparation in SAE
J844 which requires the cutting of a strip of tubing into a 6
millimeter wide helical coil (and other requirements) versus the NPRM
proposal to cut a one-inch length of tubing cut lengthwise and cutting
two flaps of material using a sharp knife to permit the test sample to
be clamped in a tensile testing machine. SGPPL noted that if what is
now a Type B tubing consisting of two layers were made as a single
layer tubing, the bond strength test might not be needed. In addition,
it posed the questions that if tubing were to be manufactured from
several layers of different material bonded together, how would the
adhesion levels be evaluated, and would it only be required at the bond
interface of reinforcing material? SGPPL stated that it would be even
more difficult to test between unreinforced layers of plastic than
between a reinforced inner and outer layer.
HPP stated that there is no technical reason for a higher
requirement for plastic tubing compared to elastomeric hoses. HPP has
developed a method to determine the adhesion between layers of tubing,
and references a ballot version of SAE J2260. However, HPP did not
describe their test method, nor did it provide any further information
about SAE J2260 that the agency could evaluate.
Parker/Atofina stated that the performance strength of Type B
tubing is historically predicated on maintaining an inseparable bond
between polymer layers across the yarn reinforcement interstitial areas
within the tubing. Permitted separation between these tube and cover
layers at the bond interface will result in tubing which kinks easily
under mechanical stress. It states that the agency's proposal of 25
pounds per linear inch is insufficient to ensure consistent plastic
tubing and assembly performance. According to Parker/Atofina, the SAE
J844-mandated inseparable bond test is intended to evaluate the
integrity and manufactured quality of the Type B thermoplastic air
brake tubing construction.
Regarding the agency's proposed test sample preparation method,
Parker/Atofina stated that the preparation of an inch-long specimen is
impractical and impossible with properly manufactured and inseparably
bonded Type B tubing. It stated that the test sample must be cut
through the entire tubing wall in a helical path nearly parallel to the
reinforcement yarn lay pattern in order to gain access to the layer
interface and allow physical and visual evaluation of the bond between
the polyamide layers in the interstitial areas formed away from where
the yarn lay patterns cross. The agency notes by examination of a
typical \1/2\ inch O.D. Type B air brake tube, the sample size defined
in SAE J844 for this size tubing would be 0.25 inches by 7.85 inches.
The agency does not know if this sample size would be large enough to
mount in a tensile testing machine for evaluation. Under the agency's
NPRM, the sample size would be approximately 1 inch by 1\1/2\ inches
for \1/2\ inch O.D. air brake tubing.
Parker/Atofina stated that the SAE J844 adhesion test does not
require a force measurement because the criterion for passing is an
intimate bond as if the two layers were one. The need to specify a load
is replaced by the visual examination between the two layers of
contrasting colors.
The agency has reviewed all of the comments regarding adhesion
testing and decided not to include the heat aging and adhesion test
requirement in the final rule. It appears that the actual strength of
the bond between layers of plastic tubing falls somewhere between 4.4
pounds per linear inch and something larger than 25 pounds per linear
inch. The agency's proposed test method seemed acceptable to some
commenters, but there were wide ranging viewpoints on what the
acceptable adhesion strength should be. The SAE J844 test method
appears unenforceable to NHTSA because it does not have any objective
pass/fail metrics, such as a pounds force per linear inch strength
requirement. The ``no separation'' specification in SAE J844, confirmed
by visual inspection and not by a force measurement, does not seem to
be a useful metric to determine the strength of the bond between tubing
layers. In addition, as noted by SGPPL, alternate methods for
[[Page 76312]]
producing air brake tubing may include significantly different
construction methods (more than two layers, or constructed without
reinforcing braid) that would not be able to be easily tested to the
procedure in SAE J844. It appears to NHTSA that the SAE committee
working on SAE J2547 may be able to develop an alternate adhesion test
method that the agency may be able to consider using in future
rulemaking.
12. Collapse Resistance
NPRM--NHTSA proposed to incorporate the collapse resistance test
procedures/performance requirements from SAE J844 into FMVSS No. 106,
with two changes. First, the length of the pins that are used to attach
the tubing in a bent position to the test fixture were specified as 1-
inch or 50 millimeters in length, rather than left unspecified as in
SAE J844. Second, the bend radii from Table 2 of SAE J844 were proposed
to be adopted rather than the bend radii from SAE J844 Table 3, in
order to have just one table of bend radii in FMVSS No. 106. The
differences in the radii tables are slight, for example, for a \1/2\
inch O.D. tube, Table 2 specified 2.00 inches versus 2.50 inches in
Table 3, although for some other sizes of tubing, the radii in the two
tables are the same. This made the proposal in FMVSS No. 106 slightly
more rigorous than SAE J844, because in the collapse resistance test
the tubing is bent without being supported by a test cylinder, and the
bend radii in Table 2 are for bends that use a test cylinder for
support as the tubing is bent around the cylinder.
Public Comments and NHTSA's Response--SMC stated that it find the
agency's proposal acceptable. Parker/Atofina stated that the tubing
sample length formulas specified in FMVSS No. 106 at S12.17(b) are less
severe than in SAE J844. The diameter measurements in SAE J844 to
validate the collapse resistance of tubing have been replaced with
nominal diameters, lessening the severity of the bend test. NHTSA has
carefully compared the requirements in SAE J844 with the NPRM, and
cannot verify Parker/Atofina's statements. The diameter collapse
measurement procedures proposed in Standard No. 106 at S12.15(c)
Calculation are in fact the same calculation as used in SAE J844 at
S9.14.5, and do not refer to a nominal diameter specification. The
tubing samples specified in FMVSS No. 106 at S12.15(b) are the same as
those in SAE J844. However, in FMVSS No. 106, the length of the
supporting pins is specified while in SAE J844, the length of the
supporting pins is not specified. For both FMVSS No. 106 and SAE J844,
the length of the supporting pins is considered in the length of the
prepared tubing sample. NHTSA used different wording in the NPRM to
amend FMVSS No. 106 than in SAE J844, partly to better describe the
test procedure, and to avoid having to adopt Figures 3 and 4 from SAE
J844 into FMVSS No. 106. NHTSA determined only that the collapse
resistance proposed in FMVSS No. 106 is slightly more rigorous than in
SAE J844 because of minor reductions in the bend radii used during the
evaluation of collapse resistance for a few particular sizes of tubing.
Parker/Atofina also commented that the minimum kink radii from
Table 3 of SAE J844 should be used for the collapse resistance test,
and that Table VIII should be labeled ``minimum kink radius'' rather
than ``bend radius'' as proposed in the NPRM.
For this final rule, after reviewing the proposed collapse
resistance test and the comments provided, NHTSA has decided to amend
the requirements from those proposed in the NPRM. Table VIII has been
modified to include both sets of bend radii from SAE J844 (Table 2,
Mechanical Properties, Test Bend Radius adopted into Table VIII of
FMVSS No. 106 as ``Supported Bend Radius,'' and Table 3, Minimum Kink
Radius adopted into Table VIII of FMVSS as ``Unsupported Bend
Radius.''). The supported bend radius values for metric sizes of brake
tubing in Table VIII are taken directly from Table 2 in SAE J1394, but
there are no values provided for Minimum Kink Radius in SAE J1394 that
can be used for unsupported bend radius values in Table VIII in FMVSS
No. 106.
NHTSA used the following approach to determine the unsupported bend
radius values for metric sizes of air brake tubing for Table VIII:
1. The nominal diameter of 6 mm tubing is 0.236 inches, and is
closer to \1/4\ inch tubing (0.250 inches), so the 1.00 inch
unsupported bend radius for \1/4\ inch tubing was adopted.
2. The nominal diameter of 8 mm O.D. tubing is 0.315 inches, and is
close to \5/16\ inch tubing (0.313 inches), so the 1.50 inch
unsupported bend radius for \5/16\ inch tubing was adopted.
3. The nominal diameter of 10 mm O.D. tubing is 0.393 inches, and
is close to \3/8\ inch tubing (0.375 inches), so the 1.50 inch
unsupported bend radius for \3/8\ inch tubing was adopted.
4. The nominal diameter of 12 mm O.D. tubing is 0.472 inches, and
is close to \1/2\ inch tubing (0.500 inches), so the 2.5 inch
unsupported bend radius for \1/2\ inch tubing was adopted.
5. The nominal diameter of 16 mm O.D. tubing is 0.629 inches, and
is close to \5/8\ inch tubing (0.625 inches), so the 3.00 inch
unsupported bend radius for \5/8\ inch tubing was adopted.
The agency adopts the term ``unsupported bend radius'' rather than
Parker/Atofina's recommended ``minimum kink radius'' because during the
collapse resistance test, the tubing is not permitted to kink. To use
the term ``kink'' in FMVSS No. 106 may prove to be confusing.
The regulatory text of the test procedure in S12.15 has been
modified in three respects from that proposed in the NPRM. First, the
two supporting pins of the test fixture are not required to be
adjustable, since pins only need to be set at a specified spacing as
shown in Figure 5--Bend Test Fixture of SAE J844. The pin spacing
requirement is now defined as twice the unsupported bend radius plus
the nominal O.D. of the tubing, consistent with what is depicted in
Figure 5 of SAE J844. In the NPRM, the pins were to be adjusted until
the approximate bend radius was achieved on the brake tubing. The
language in the final rule is simpler and has less opportunity for
introducing variability. Second, a provision is added that the tubing
should be bent in the direction of its natural curvature, consistent
with SAE J844. Third, the term ``elliptical minor diameter'' is used
rather than ``minor diameter'' to better indicate in geometric
terminology where the initial and final diameter measurements of the
tubing are to be taken.
13. Oil resistance
NPRM--NHTSA tentatively concluded that in the case of plastic air
brake tubing, it would be more appropriate to evaluate a mechanical
property of the tubing such as the ability to pass a burst test after
conditioning in oil. NHTSA also concluded it is critical that plastic
air brake tubing be resistant to oil exposure. Therefore, NHTSA
proposed a test procedure for plastic tubing that combines existing
FMVSS No. 106 oil conditioning criteria with the burst strength
requirements of SAE J844. The proposed test procedure involved
preparation of a tubing assembly, conditioning it in ASTM IRM 903 oil
(which supercedes ASTM No. 3 oil as described in ASTM D471-98e1,
Standard Test Method for Rubber Property-Effect of Liquids), and then
subjecting the tubing to the burst test specified in SAE J844. NHTSA
proposed that the tubing not burst at less than 80 percent of the burst
pressure listed in Table 2 of SAE J844.
Public Comments and NHTSA's Response--HPP stated that the proposed
oil resistance test should apply to
[[Page 76313]]
elatostomeric brake hoses in addition to air brake tubing. SMC stated
that the burst pressure of SAE J844 is more suited to testing tubing,
and that the oil needs to be changed to stay consistent with the ASTM
changes. SGPPL agreed that it is critical that plastic air brake tubing
is resistant to oil, but stated that it has not performed any such
testing as proposed in the NPRM. SGPPL asked if both the inner diameter
and the outer diameter of the tubing were to be submerged in oil, and
questioned whether the oil resistance requirements would be more
suitable to brake hose assemblies as described in Section E, Plastic
Air Brake Tubing Assemblies and End Fittings, of the NPRM. It stated
that as proposed in the NPRM, it is a tubing material test, rather than
a test for the mechanical properties of end fittings.
DuPont agreed with the addition of an oil resistance test to FMVSS
No. 106. Parker/Atofina asked that its previous comments relating to
the burst test (water used as the test medium and timing of pressure
rise be measured) be considered for the oil resistance test as well.
After reviewing the comments, NHTSA also reviewed the proposed
requirements for the end fitting retention test in S11.3.23, which was
adopted from SAE J1131. This test evaluates the retention of end
fittings that are used with plastic air brake tubing. A sample air
brake tubing assembly is prepared, filled with hydraulic fluid and then
pressurized to 50 percent of the burst strength pressure. This pressure
is held for 30 seconds, and then the pressure is increased to 100
percent of the burst strength pressure. No leakage or separation is
permitted.
The agency also reviewed the proposed thermal conditioning and end
fitting retention test in S11.3.24 that was proposed to be adopted from
SAE J1131. In this test, an air brake tubing assembly is prepared with
end fittings, filled with hydraulic oil, and connected to a source of
hydraulic pressure. The assembly is then conditioned in air at 200
degrees Fahrenheit for 25 hours with atmospheric pressure inside the
tubing. The pressure is then increased to 450 psi while still at the
elevated temperature, and held for five minutes. The pressure is
reduced to atmospheric and the temperature reduced to 75 degrees
Fahrenheit for one hour, and then the temperature is decreased to minus
40 degrees Fahrenheit for 24 hours. While at that temperature, the
pressure is increased to 450 psi and held for five minutes, and the
required performance is that no leakage or separation from the end
fittings is permitted.
Parker/Atofina's only recommendation for the thermal conditioning
and end fitting retention test was to increase the pressure within 5 to
30 seconds during the pressure cycles to not hydraulically shock the
system.
NHTSA evaluated all of the comments, reviewed the proposed test
requirements, and reached the following conclusions. NHTSA has
determined that the oil resistance test is intended to evaluate the
properties of the tubing (S11.3.18 specifies that the air brake tubing
shall not rupture or burst) although it may also evaluate the oil
resistance properties of the end fittings, since end fittings must be
installed to attach the tubing to the pressure test machine. Whether
those end fittings are the same as the end fittings used on a vehicle,
or are fittings designed to adapt the tubing to the pressure test
device, is a decision to be made by the test sponsor. Both oil and
water are non-compressible and will provide the same measure of
performance. Therefore, the oil resistance test will be made final in
this rule, but the pressure test medium (after the conditioning by
soaking in oil) can be either water as suggested by Parker/Atofina for
the final burst test, or oil at the manufacturer's option if cross-
contamination of the water pressure source for the burst testing
specified in S12.5 is a concern of the manufacturer.
The thermal conditioning and end fitting retention test is kept in
the final rule for the purpose of evaluating end fitting retention when
subject to thermal and pressure cycling. Water cannot be used in the
thermal conditioning and end fitting retention test because of the low
temperatures (minus 40 degrees Fahrenheit (minus 40 degrees Celsius))
involved. NHTSA noted in the NPRM that the hydraulic fluid in SAE J1131
did not have any particular specifications. NHTSA believes that if it
changed the specification in the thermal conditioning and end fitting
retention test to the ASTM IRM 903 oil, the test would be more suited
towards ensuring that the end fitting retention test also provides a
measure of oil resistance as well. The conditioning at 200 degrees
Fahrenheit for 70 hours is similar to the requirements proposed for the
oil resistance test except that a slightly higher oil soak temperature
of 212 degrees Fahrenheit was proposed for the oil resistance test.
NHTSA adopts a constant pressure application and reduction rate of
3,000 psi per minute for all burst tests and pressure increases or
decreases, to eliminate variability in the time of the pressure
application. NHTSA believes it has thus addressed Parker/Atofina's
suggestion of a longer time limit for the pressure increases in the
thermal conditioning and end fitting retention test.
NHTSA believes that with these changes, the plastic air brake
tubing material and the end fittings of tubing assemblies will be able
to be evaluated for oil resistance. NHTSA believes that both the
outside and inside sections of brake hose tubing should be oil
resistant, and includes this requirement in the oil resistance test.
The thermal conditioning and end fitting test will only evaluate the
oil resistance of those portions of the end fittings that are exposed
to internal pressure in the tubing.
Finally, NHTSA notes that it may revisit the issue of the oil
resistance test in a future rulemaking if this should become necessary.
NHTSA proposed that ASTM IRM 903 be the test medium for gauging air
brake tubing and assemblies for oil resistance properties. NHTSA has
reviewed the oil compatibility test in S3.7 of SAE J2494-3 Performance
Requirements for SAE J844 Non-Metallic Air Brake Tubing and Push-to-
Connect Tube Fittings, with SAE J844 Air Brake Tubing as Used in
Vehicular Air Brake Systems, (described in more detail below), and
notes that it is conducted using a mixture of 11 parts SAE 15W40CD type
oil and one part SOFTC-2A contaminant. No commenter made note of this
different reference oil specification. NHTSA is therefore keeping the
ASTM oil specification in this final rule.
Regarding the end fitting retention test that was proposed as
S12.24 in the NPRM (designated as S12.22 in this final rule), NHTSA is
adopting Parker/Atofina's suggestion that water be used as the test
medium rather than oil. Parker/Atofina stated that water is a cleaner
test medium than hydraulic oil, and the agency believes that there are
no special temperature requirements that preclude the use of water in
this test. The pressure increase rate is being specified as 3,000 psi
per minute as it is for all other test requirements relating to
pressure tests for air brake tubing.
NHTSA is not adopting HPP's suggestion to subject elastomeric air
brake hoses to the oil resistance test in this final rule. NHTSA notes
that these types of brake hoses are subjected to a different type of
oil resistance performance test that appears to be effective in
ensuring adequate safety of these brake hoses.
[[Page 76314]]
14. Ozone resistance
NPRM--NHTSA proposed an ozone test for plastic air brake tubing in
which a sample of tubing is bent around a test cylinder and exposed to
ozone at a concentration of 100 parts ozone per hundred million parts
of air, for 70 hours at a temperature of 104 degrees Fahrenheit. The
required performance is that no cracks are visible when the tubing is
viewed under 7x magnification.
Public Comments and NHTSA's Response--Parker/Atofina stated that
thermoplastic air brake tubing does not require ozone testing because
polyamide nylon is not affected by ozone. HPP stated that it supports
the ozone test for plastic tubing, but it recommended that for tubing
used with barbed end fittings, a test of the tubing with the end
fittings attached should be conducted with a longer exposure time of
500 hours. DuPont acknowledged the importance of having an ozone
resistance test in FMVSS No. 106. Several commenters noted that the
agency had incorrectly stated the proposed ozone concentration in parts
per million rather than parts per hundred million (pphm). The correct
ozone concentration level of 100 pphm is included in this final rule.
NHTSA notes that for all types of brake hoses in FMVSS No. 106, the
ozone concentration is being increased from 50 to 100 pphm in
accordance with the latest SAE standards. As such, this represents an
increase in the severity of the test condition. NHTSA does not believe
that it would be appropriate to increase the exposure time from 70 to
500 hours at this time, as recommended by HPP. NHTSA believes that
there is little or no use of barbed hose fittings on air braked
vehicles in the United States, as the most common styles are push-to-
connect and flanged sleeve compression fittings.
F. Plastic Air Brake Tubing Assemblies and End Fittings
1. General Comments
In the NPRM, NHTSA proposed to incorporate the substantive
requirements of SAE J1131 Performance Requirements for SAE J844
Nonmetallic Tubing and Fitting Assemblies Used in Automotive Air Brake
Systems into FMVSS No. 106. NHTSA noted that the petitioners did not
ask NHTSA to adopt the requirements of this SAE standard into FMVSS No.
106. The petitioners had instead asked that NHTSA adopt the
requirements of SAE J512 Automotive Tube Fittings and SAE J246
Spherical and Flanged Sleeve (Compression) Tube Fittings. These two
latter standards include specific dimensional requirements for the end
fittings and components of fittings. The agency tentatively determined
that rather than specifying the dimensions of the fittings, it would be
more appropriate to specify the performance of the fittings per SAE
J1131, to assure that the end fittings used along with air brake tubing
work properly as an assembly.
Parker/Atofina stated that it believes that end fitting
dimensional, material, performance and safety requirements referenced
in SAE J246 and SAE J512 specifications should be retained, so that the
components of end fittings from different manufacturers would continue
to be compatible. As stated in the NPRM, the agency does not desire to
include these dimensional specifications (which are in effect design
specifications), but proposed instead to adopt the performance
requirements for these fittings when used with plastic air brake
tubing.
SMC, SGPPL, and Parker/Atofina made reference to three SAE
Standards: J2494-1 Push-to-Connect Tube Fittings for Use in the Piping
of Vehicular Air Brake, Rev. May 2000; J2494-2 Dimensional
Specifications for Non-Metallic Body Push-to-Connect Fittings Used on a
Vehicular Air Brake System, Rev. October 2002; and J2494-3 Performance
Requirements for SAE J844 Non-Metallic Air Brake Tubing and Push-to-
Connect Fitting Assemblies Used in Vehicular Air Brake Systems, Rev.
July 2002. SMC stated that incorporation of SAE J2494-3 would benefit
the evaluation of the FMVSS No. 106 revision. SGPPL stated that since
push-to-connect fittings are widely used in both preformed air brake
tubing assemblies and in routing bulk air brake tubing lines in trucks,
NHTSA should consider the use of both push-to-connect and compression
fittings. Parker/Atofina recommended that FMVSS No. 106 include the
sample size requirements of SAE J2494-3 and the performance
requirements of SAE J1131. Regarding Parker/Atofina's issue with sample
sizes for testing, the agency has already described that sampling as an
issue for manufacturers to use for quality control methods, but that
every brake hose that is DOT certified must meet the requirements of
FMVSS No. 106.
The agency was not aware of the SAE J2494 series of standards for
push-to-connect fittings when it published its NPRM. After reviewing
these standards, NHTSA believes that adding the substantive end fitting
performance requirements of SAE J2494-3 to FMVSS No. 106 would help
ensure safety. However, NHTSA notes that incorporating SAE J2494-3
requirements into FMVSS would encompass an extensive series of test
procedures including a tensile test (with high temperature, boiling
water, and water absorption conditioning); thermal and pressure cycling
and air leakage; vibration test; fitting pressure test; frozen water
retention test; reassembly test; oil compatibility test; corrosion
resistance test; side load leakage; moisture absorption; ultraviolet
light resistance; zinc chloride and methyl alcohol resistance; and cold
temperature impact. NHTSA would not issue a final rule amending FMVSS
No. 106 by incorporating these tests without first putting forth a
notice soliciting public comments on its proposal to include the tests.
Some of the performance requirements included in the NPRM and this
final rule provide similar coverage of the SAE J2494 requirements.
Therefore, NHTSA will first complete its May 15, 2003 proposed
rulemaking by issuing this final rule. At future date, NHTSA may
consider proposing to add the outstanding requirements from SAE J2494.
2. Tensile Strength
NPRM--NHTSA proposed adopting similar tensile strength requirements
for plastic air brake tubing as FMVSS No. 106 currently specifies for
elastomeric air brake hose. The NPRM included slight reductions in
tensile strength for the smallest sizes of plastic air brake tubing,
proposing 35 pounds for \1/8\ inch and 40 pounds for \5/32\ inch
tubing, in applications that are not between the frame and axle of a
vehicle or between a towing and towed vehicle. The lowest specification
for elastomeric brake hoses in the same application is 50 pounds if it
is \1/4\ inch or less nominal inside diameter.
NHTSA developed its proposed requirements for small diameters of
plastic air brake tubing based in part on a comparison of brake hose
and tubing. Air brake tubing is sized by outside diameter rather than
inside diameter (as brake hose is sized), and therefore, the sizes are
not directly comparable. A \1/4\ inch outside diameter brake tube would
be smaller than a \1/4\ inch inside diameter brake hose, and therefore
would not be expected to have the same tensile strength.
NHTSA noted that in the text on page 26403 of the NPRM that it
correctly stated its intentions of a 35-pound strength for \1/8\ inch
tubing and 40 pounds for \3/32\ inch tubing. However, Table VIII on
page 26417 included incorrect values of 15 pounds for \1/8\ inch tubing
(which should have been 35
[[Page 76315]]
pounds) and of 40 pounds for \3/16\ inch tubing (it should have been 50
pounds). These are corrected in the final rule. The values in Table
VIII for \3/32\ inch tubing were correct in the NPRM.
Public Comments and NHTSA's Response--SGPPL stated in its comments
that it agrees with NHTSA's proposed reduction in tensile strength for
\1/8\ inch and \5/32\ inch tubing. SGPPL stated that the 50-pound value
used by SAE for \1/8\ inch tubing and \5/32\ inch tubing are not
achievable using current products in the market place, as the tubing
yields and breaks before a 50-pound value is attained in testing. SGPPL
stated that the proposed values of 35 pounds and 40 pounds respectively
are achieva