[Federal Register Volume 63, Number 232 (Thursday, December 3, 1998)]
[Rules and Regulations]
[Pages 66762-66766]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-31773]
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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
49 CFR Part 571
[Docket No. NHTSA-98-4807]
RIN 2127-AF51
Federal Motor Vehicle Safety Standards; Compressed Natural Gas
Fuel Containers
AGENCY: National Highway Traffic Safety Administration (NHTSA),
Department of Transportation (DOT).
ACTION: Final rule.
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SUMMARY: This final rule deletes the material and manufacturing process
requirements in the standard on compressed natural gas fuel container
integrity. The agency believes that this amendment will facilitate
technological innovation, without adversely affecting safety.
DATES: This final rule is effective January 4, 1999. Petitions for
Reconsideration must be received by January 19, 1999.
ADDRESSES: Petitions should refer to the docket number of this rule and
be submitted to: Administrator, National Highway Traffic Safety
Administration, 400 7th Street, SW, Washington, DC 20590.
FOR FURTHER INFORMATION CONTACT: For non-legal issues: Mr. Charles
Hott, NPS-12, Office of Crashworthiness Standards, National Highway
Traffic Safety Administration, 400 Seventh Street, S.W., Washington,
D.C. 20590 (Telephone 202-366-0247) (FAX 202-366-4329).
For legal issues: Ms. Nicole H. Fradette, NCC-20, Rulemaking
Division, Office of Chief Counsel, National Highway Traffic Safety
Administration, 400 Seventh Street, SW., Washington, D.C. 20590
(Telephone 202-366-2992) (FAX 202-366-3820).
SUPPLEMENTARY INFORMATION:
I. Background
Federal Motor Vehicle Safety Standard No. 304, Compressed natural
gas fuel container integrity, serves to reduce the risk of deaths and
injuries occurring from fires resulting from fuel leakage during and
after motor vehicle crashes. The Standard was patterned after the
American National Standards Institute's (ANSI's) voluntary industry
standard known as ANSI/NGV2 and developed by the Natural Gas Vehicle
Coalition (NGVC). Standard No. 304 specifies detailed material and
manufacturing process requirements for different types of CNG
containers, including those made with aluminum alloys. The Standard
also specifies burst, bonfire, and pressure cycling tests for the
purpose of ensuring the durability, initial strength, and venting of
CNG containers.
The burst test evaluates a container's initial strength
and resistance to degradation over time by specifying, for each type of
container, a unique safety factor for determining the internal
hydrostatic pressure that the container must withstand during the burst
test. This requirement helps to ensure that a container's design and
selected material are sufficiently strong over the life of the
container.
The bonfire test evaluates a container's pressure relief
characteristics when pressure builds up in a container, primarily due
to an increase in temperature.
Finally, the pressure cycling test evaluates a container's
durability by requiring a container to withstand without leakage,
18,000 cycles of pressurization and depressurization. This requirement
helps to ensure that a CNG container is capable of sustaining the
cycling loads imposed on the container during refueling over its entire
service life.
In addition, the Standard specifies labeling requirements for CNG fuel
containers.
Standard No. 304 specifies certain material and manufacturing
characteristics for aluminum containers using alloy 6010 and alloy
6061, based on the specifications set forth in ANSI/NGV2. The material
characteristics specify the percentage of various elements, including
magnesium, silicon, copper, and manganese. On November 24, 1995, NHTSA
issued a final rule amending the labeling and the bonfire test
requirements in Standard No. 304, Compressed Natural Gas fuel container
integrity. In the final rule, the agency decided to defer consideration
of two
[[Page 66763]]
rulemaking petitions to add additional aluminum alloys to Standard No.
304, until the new version of the ANSI/NGV industry standard was
issued. Northwest Aluminum Association requested that the standard be
amended to add 6069 aluminum alloy, and Luxfer requested the addition
of 7032 aluminum alloy. In explaining its decision to defer
consideration of the petitions, the agency noted that the new ANSI/NGV2
industry standard may not specify CNG fuel container material and may
be more performance-oriented than the current version, thereby allowing
manufacturers more flexibility to improve container design with respect
to cost and performance. The agency also noted that adopting some of
the new provisions of the revised voluntary industry standard may
eliminate the need to amend the standard to allow the use of two new
aluminum alloys in CNG containers.
II. Summary of NPRM
In a May 30, 1997 notice of proposed rulemaking (NPRM), NHTSA
proposed amending Standard No. 304 to eliminate the Standard's detailed
material and manufacturing process requirements. The agency explained
it had tentatively determined that CNG fuel container manufacturers
should be allowed to use materials other than those materials currently
listed in the standard. NHTSA explained that such an amendment would
provide manufacturers with the flexibility to design lighter weight,
higher capacity fuel containers using the latest innovations, without
having to petition the agency to amend the standard each time a new
material or manufacturing process is developed.
The agency also noted that the proposal to remove the material and
manufacturing requirements was consistent with the proposed revision to
ANSI/NGV, which removed many of the design restrictions that were in
the 1992 version of NGV2 on which Standard No. 304 was initially
modeled. In October 1996, the ANSI committee working on the revised
standard completed its revisions and sent the revised document to its
members for review. The proposed revision of ANSI/NGV2 removed many of
the detailed material and manufacturing restrictions, but retained the
impurity limits for certain materials. NHTSA explained that it
understood that although the industry had not reached a consensus with
respect to certain environment testing procedures, the industry had
tentatively agreed to eliminate the material and manufacturing
requirements.
NHTSA also stated it believed that eliminating the material and
manufacturing process requirements would have no detrimental affect on
safety. The agency explained that Standard No. 304's performance
requirements, including those requirements that evaluate initial
strength and resistance to degradation over time, would still apply to
CNG containers. Thus, CNG container manufacturers would have to comply
with the standard's pressure cycling, burst, and bonfire tests. NHTSA
further explained that such containers would be subject to recall if
they failed for any reason, including the degradation of material.
NHTSA proposed deleting the following sections from the standard:
Section S5.2 Material designations. This section
specifies the material requirements for the various types of CNG
fuel containers.
Section S5.3 Manufacturing processes for composite
containers. This section specifies the manufacturing process for
each type of composite CNG fuel container.
Section S5.4 Wall thickness and Section S5.5 Composite
Reinforcement for Type 2, Type 3, and Type 4 containers. These
sections contain the design criteria for specifying the wall
thicknesses and stresses for each type of CNG fuel container. These
sections also specify procedures for designing CNG fuel container
walls along with the theoretical formula for calculating maximum
wall stress.
Section S5.6 Thermal Treatment, and S5.7 Yield
Strength. These sections contain detailed manufacturing process
requirements for chrome-moly and carbon-boron steels, including
specifying the temper temperatures for each steel.
In June 1998, ANSI published the new ANSI/NGV2 industry standard.
The new standard is similar to the proposed standard in that much of
the design restrictive language has been removed. ANSI/NGV2 now
specifies that the material composition for steels should be known and
defined by at least the contents of certain elements such as carbon,
manganese, aluminum and the other alloying elements that are added to
enhance the material properties. For aluminum, ANSI/NGV2 simply states
that it should be in line with the Aluminum Association's practice and
the 6xxx series with yield strengths above 250 MPa should not be used.
It also specifies impurity limits for steels and aluminums.
III. Summary of Comments
Eight comments were submitted in response to the NPRM from the
following companies/organizations: Chrysler Corporation (Chrysler),
General Motors (GM), Gas Technology Canada (GTC), the Natural Gas
Vehicle Coalition (NGVC), Lincoln Composites (Lincoln), Pressed Steel
Tank Co. (PST), Structural Composites Industries (SCI), and New York
City Transit (NY Transit).
Chrysler, GM, and GTC supported the proposed rule. Chrysler and GM
stated that deleting the material and manufacturing process
requirements would facilitate technological innovation without reducing
safety. GTC stated that CNG containers sold in Canada that are
manufactured from at least four material types that are not offered for
sale in the United States have performed well in service. GTC
cautioned, however, that additional performance tests might be needed
to prevent in-service failures. Chrysler also commented that S7.2.2 of
Standard No. 304 refers to S5.5.1, which is proposed for deletion, and
suggested that S7.2.2 be revised accordingly.
NGVC and Lincoln also supported NHTSA's efforts to facilitate
technological innovation, but were concerned that deletion of the
material performance requirements without including the additional
tests from the draft revision of ANSI/NGV2 industry standard, could
lead to a serious safety problem. The latest draft standard, while
deleting many of the specific material design requirements, includes
the following three enhanced material performance test requirements:
1. Sulfide stress cracking resistance of high strength steels
using the methods of NACE Standard TM0177-90;
2. Sustained load cracking for aluminum alloys in accordance
with Annex D of ISO/DIS 7866; and
3. Intercrystalline corrosion and stress corrosion tests for
aluminum alloys in accordance with Annex A of ISO/DIS 7866.
NGVC stated that these tests are needed to ensure the integrity of the
materials that were previously excluded by the standard while Lincoln
argued that these requirements were needed to reduce the risk of in-
service leakage or rupture and inadequate shear strength of resins over
the life of the CNG container. NGVC argued that NHTSA should retain
Standard No. 304's current requirements until the industry's revision
of ANSI/NGV2 is complete. Lincoln argued that NHTSA should simply amend
Standard No. 304 to include the materials requested by Northwest
Aluminum Association and Luxfer, aluminum alloys 6069 and 7032
respectively, rather than delete the material and manufacturing
requirements.
PST supported removing the thermal treatment, wall thickness, and
manufacturing process requirements from the standard, but argued that
the standard should continue to limit materials to specific alloys and
reinforcing fibers. PST argued that most
[[Page 66764]]
CNG container failures occurred because the CNG manufacturer used
materials with insufficient toughness, damage tolerance, long term
stability and environmental resistance. PST argued that a single safety
factor cannot protect against such material deficiencies. PST further
claimed that high-strength aluminum alloys were originally excluded
from Standard No. 304 because of their susceptibility to sustained load
cracking (SLC) and stress corrosion cracking (SCC). PST noted that the
draft ISO/DIS 7866 standard, which is included in the proposed revision
to NGV2, includes material tests intended to exclude SLC and SCC
susceptible materials. PST argued that NHTSA should evaluate the SLC,
SCC and accelerated stress rupture tests, and amend the standard to
include these tests, as well as a resistance to impact requirement.
Finally, PST asserted that the agency must address the potential
failure modes of organic reinforcing fibers, stainless steels, copper
alloys and other materials, if the agency is going to permit the use of
these materials. PST stated that the time and the cost involved with
developing adequate performance tests for all of these materials was
high and any resulting economic benefits questionable.
SCI opposed the proposed rule and argued that Standard No. 304's
current performance tests are insufficient to prevent time related
failures resulting from corrosion, stress rupture, viscoelastic
yielding, and aging. SCI stated that the small sample size and short
time period involved with testing made it too difficult and complex to
test for such time related failures. SCI also argued that the history
of CNG fuel containers demonstrated that the standard's current test
requirements were insufficient to prevent catastrophic failures, such
as battery fluid field failures occurring from in-service abuse or
impact damage from roadway debris.
While New York City Transit stated that it did not oppose the
proposed changes, it did express concern that Standard No. 304 is
insufficient to prevent CNG container failures. NYCT's concern is based
on the fact that nearly six percent of one model of CNG fuel containers
produced by a particular manufacturer has experienced failures after
only a few years in service. NYCT stated that 31 of its CNG transit
buses were equipped with these containers and that it was unable to
retrofit the containers because the manufacturer is out of business.
IV. Agency Decision
The agency is deleting the material and manufacturing process
requirements from Standard No. 304 and amending S7.2.1 and S7.2.2 of
the standard to eliminate any reference to those requirements. NHTSA
believes that the deletion of these requirements will facilitate
technological innovation without having an adverse affect on safety.
For the following reasons, the agency is not replacing the deleted
requirements with other requirements, as suggested by some commenters.
First, the agency has concluded that Standard No. 304's current testing
requirements--pressure cycling, burst, and bonfire--are sufficient to
ensure an appropriate level of safety for CNG fuel containers. The
tests indirectly ensure that the containers are manufactured using
appropriate materials and wall thicknesses. The agency believes,
therefore, that the Standard's design and material requirement are
unnecessary and restrict the ability of manufacturers to use the latest
technology in manufacturing CNG fuel containers.
Second, NHTSA has no evidence indicating the existence of a safety
problem that would be addressed by including additional tests, such as
those contained in the proposed NGV2 revision, in the
Standard.1 NHTSA knows of six CNG fuel container ruptures
that have occurred since 1993. According to a safety bulletin published
by the Gas Research Institute in October 1996, all six ruptures could
have been prevented if appropriate precautions had been taken.
Mishandling, misuse, and improper placement and maintenance of the CNG
fuel containers caused the failures. In four of the cases, the CNG fuel
container did not have a shield surrounding it to protect it from
impact damage. A vehicle design change would address this problem. In
the other two cases, the CNG fuel containers ruptured after prolonged
exposure to acidic fluids. In those two cases, the shielding
surrounding the CNG fuel containers lacked adequate drainage.
Consequently, acidic fluids accumulated in the area beneath the
containers and damaged the CNG fuel containers. NHTSA believes that the
proper placement and shielding of the CNG fuel containers along with a
periodic inspection of the container, as directed by the CNG fuel
containers label, could have prevented these failures. None of the
additional testing provisions in the new ANSI/NGV2 industry standard
would have prevented these cylinder failures. The agency, therefore,
does not believe that inclusion of the additional tests is necessary.
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\1\ The agency notes that while several of the commenters stated
that NHTSA should amend Standard No. 304 to require additional tests
to prevent in-service failures of CNG containers, none provided
evidence indicating the existence of a safety problem with in-
service failures that was not addressed by the Standard's current
tests and would be addressed by the inclusion of additional tests.
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Finally, NHTSA agrees with the comments of SCI that testing for
such time related failures as corrosion, stress rupture, viscoelastic
yielding, and aging may be impracticable due to the small sample size
and short time period involved with testing. Thus, even if there were a
safety problem that could not be addressed by the standard's current
testing requirements, NHTSA believes it would be inappropriate to
require these particular tests given the current uncertainty concerning
their effectiveness.
The agency does not believe that manufacturers will fail to
exercise care in selecting appropriate materials to manufacture CNG
containers. NHTSA does, however, stress that any CNG fuel containers
that might be found in the future to have an unanticipated safety
related failure would be subject to recall. NHTSA, therefore, will
continue to monitor the performance of CNG fuel containers closely and
should a safety problem arise, NHTSA will take the appropriate
regulatory or enforcement action.
While NHTSA understands NYCT's concern that one particular model of
CNG containers leaked an excessive amount of gas after only a few years
in service, NHTSA notes that a defective manufacturing process, unique
to the particular manufacturer, rather than a defective design, was the
cause of these failures. No other CNG containers experienced such
failures.2 Neither the Standard as currently drafted nor as
revised by this notice would have prevented the failure of this
particular model of CNG fuel container.
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\2\ The agency notes that the manufacturer of these six
containers went out of business and that other transit fleets who
had purchased the faulty containers retrofitted their buses with new
CNG containers.
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V. Effective Date
The statute under which the agency conducts its vehicle safety
rulemaking requires that each order (i.e., final rule) take effect no
sooner than 180 days from the date the order is issued unless good
cause is shown that an earlier effective date is in the public
interest. In the NPRM, NHTSA tentatively concluded that there was good
cause not to provide the 180 day lead time since the proposed amendment
would delete certain requirements and have no mandatory effect on
manufacturers.
[[Page 66765]]
NHTSA, therefore, proposed a 30 day effective date and sought comment
on whether that date was appropriate or whether more lead time was
necessary. No comments were submitted opposing the proposed effective
date. NHTSA has, therefore, determined that there is good cause for an
effective date 30 days after publication of the final rule.
VI. Rulemaking Analyses and Notices
Executive Order 12866 and DOT Regulatory Policies and Procedures
This final rule was reviewed under E.O. 12866. NHTSA has analyzed
this rule and determined that it is not ``significant'' within the
meaning of the Department of Transportation's regulatory policies and
procedures. This final rule allows manufacturers to use materials other
than those materials currently listed in Standard No. 304. This
rulemaking action will provide manufacturers with the flexibility to
design lighter weight, higher capacity fuel containers. The performance
requirements in Standard No. 304 are met by CNG fuel container
manufacturers, who produce and test containers in accordance with ANSI/
NGV2. A full regulatory evaluation is not required because the rule
will not significantly affect costs or benefits.
Regulatory Flexibility Act
NHTSA has considered the effects of this rulemaking action under
the Regulatory Flexibility Act (5 U.S.C. 601 et seq.). I hereby certify
that the final rule would not have a significant economic impact on a
substantial number of small entities.
The following is NHTSA's statement providing the factual basis for
the certification (5 U.S.C. 605(b)). The final rule primarily affects
manufacturers of CNG containers. The Small Business Administration's
size standards (13 CFR Part 121) are organized according to Standard
Industrial Classification Codes (SIC). SIC Code 3714 ``Motor Vehicle
Parts and Accessories'' has a small business size standard of 750
employees or fewer.
The agency believes that this final rule will not have a
significant economic impact on a substantial number of small businesses
because the manufacturers of CNG containers currently manufacture
according to the ANSI/NGV2 industry standard, and this rulemaking is
consistent with those requirements. NHTSA has stated that this final
rule deletes certain requirements and does not require any CNG
container design changes. The changes will not affect the cost of new
CNG containers.
Paperwork Reduction Act
NHTSA has analyzed this rule under the Paperwork Reduction Act of
1995 (Pub. L. 104-13) and determined that it will not impose any
information collection requirements as that term is defined by the
Office of Management and Budget (OMB) in 5 CFR part 1320.
National Environmental Policy Act
Finally, the agency has considered the environmental implications
of this final rule in accordance with the National Environmental Policy
Act of 1969 and determined that it will not significantly affect the
human environment.
The Unfunded Mandates Reform Act
The Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4) requires
agencies to prepare a written assessment of the costs, benefits and
other effects of proposed or final rules that include a Federal mandate
likely to result in the expenditure by State, local or tribal
governments, in the aggregate, or by the private sector, of more than
$100 million annually. Annual expenditures from this final rule will
not exceed the $100 million threshold.
Executive Order 12612 (Federalism)
The agency has analyzed this rule in accordance with the principles
and criteria set forth in Executive Order 12612. NHTSA has determined
that this rule will not have sufficient federalism implications to
warrant the preparation of a Federalism Assessment.
Civil Justice Reform
This rule has no retroactive effect. NHTSA is not aware of any
state law that would be preempted by this rule. This rule does not
repeal any existing Federal law or regulation. It modifies existing law
only to the extent that it deletes the material and manufacturing
process requirements in Standard No. 304, Compressed natural gas fuel
container integrity. This rule does not require submission of a
petition for reconsideration or the initiation of other administrative
proceedings before a party may file suit in court.
List of Subjects in 49 CFR Part 571
Motor vehicle safety, Reporting and recordkeeping requirements,
Tires.
In consideration of the foregoing, the agency is amending part 571
of title 49 of the Code of Federal Regulations as follows:
PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS
1. The authority citation for part 571 continues to read as
follows:
Authority: 49 U.S.C. 322, 30111, 30115, 30117, and 30166;
delegation of authority at 49 CFR 1.50
2. Section 571.304 is amended by removing S5.2 through S5.7.3 and
by revising S7.2, S7.2.1, and S7.2.2 to read as follows:
Sec. 571.304 Standard No. 304; Compressed natural gas fuel container
integrity.
* * * * *
S7.2 Hydrostatic burst test.
S7.2.1 Each Type 1 CNG fuel container shall not leak when
subjected to burst pressure and tested in accordance with S8.2. Burst
pressure shall not be less than 2.25 times the service pressure for
non-welded containers and shall not be less than 3.5 times the service
pressure for welded containers.
S7.2.2 Each Type 2, Type 3, or Type 4 CNG fuel container shall not
leak when subjected to burst pressure and tested in accordance with
S8.2. Burst pressure shall not be less than the value specified in
Table 1 times the service pressure, as follows:
Table 1.--Stress Ratios
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Material Type 2 Type 3 Type 4
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E-Glass................................. 2.65 3.5 3.5
S-Glass................................. 2.65 3.5 3.5
Aramid.................................. 2.25 3.0 3.0
Carbon.................................. 2.25 2.25 2.25
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[[Page 66766]]
Issued on: November 23, 1998.
Ricardo Martinez,
Administrator.
[FR Doc. 98-31773 Filed 12-2-98; 8:45 am]
BILLING CODE 4910-59-U
