Federal Motor Vehicle Safety Standards; Compressed Natural Gas Fuel Container Integrity

Summary:

In response to petitions for reconsideration, this agency is amending the bonfire test procedures in the Federal motor vehicle safety standard concerning compressed natural gas fuel container integrity. The amendments will facilitate the testing of compressed natural gas containers without adversely affecting safety.

Table of Contents

Dates:

Effective date: The amendment in this document becomes effective November 29, 2000.

Petitions for reconsideration: Any petition for reconsideration of this rule must be received by NHTSA no later than December 14, 2000.

Addresses:

Petitions for reconsideration of this rule should refer to the above mentioned docket number 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. Charles Hott, National Highway Traffic Safety Administration, 400 Seventh Street, SW., Washington, DC 20590 (Telephone 202-366-0247).

For legal issues: Mr. Steve Wood, NCC-20, Assistant Chief Counsel for Rulemaking, National Highway Traffic Safety Administration, 400 Seventh Street, SW., Washington, DC 20590 (202-366-2992).

Supplementary information:

I. Regulatory Background

On September 26, 1994, NHTSA published a final rule establishing Standard No. 304, Compressed Natural Gas Fuel Container Integrity, which specifies tests and performance requirements regarding the durability, strength, and pressure relief of compressed natural gas (CNG) fuel containers. (59 FR 49010) The September 1994 final rule also specified labeling requirements for CNG fuel containers. The CNG fuel container requirements are based on specifications in ANSI/NGV2, a voluntary industry standard addressing CNG fuel containers which was adopted by the American National Standards Institute (ANSI). [1] One of the performance tests involves subjecting containers to a bonfire test to evaluate their pressure relief characteristics.

NHTSA decided in the September 1994 final rule to specify that No. 2 diesel fuel be used to generate the fire in the bonfire test. The agency indicated that it was specifying No. 2 diesel fuel on an interim basis because of its awareness that environmental problems result from use of this fuel. The agency stated that it would study whether other fuels could be used for the bonfire test.

On December 19, 1994, NHTSA published a supplemental notice of proposed rulemaking (SNPRM) that proposed, among other things, to amend the bonfire test procedures and conditions to allow alternative fuel types. (59 FR 65299) Specifically, the agency proposed that the bonfire test be conducted with any fuel that generates a flame temperature equivalent to that of No. 2 diesel fuel (i.e., any fuel that generates a flame temperature of 850 to 900 degrees Celcius (C)). NHTSA requested comments about the appropriateness of using flame temperature to define equivalence among fuel types.

Commenters addressing the issue of bonfire fuel generally supported the proposal. EDO Corporation and Brunswick Composites favored allowing any fuel as long as the specified temperature is maintained. Ford Motor Company commented that the proposal was appropriate, provided the flame characteristics of different fuels are similar. AGA/NGVC also supported the proposal.

On November 24, 1995, NHTSA published a final rule that amended the bonfire test procedures and announced its decision to terminate rulemaking on additional performance requirements for CNG containers that the agency had previously proposed. (60 FR 57943) Specifically, section S8.3.6 was amended to allow the bonfire test to be conducted using any fuel that generates a flame temperature between 850 and 900 degrees C for the duration of the test. The agency stated that the amendment provided greater flexibility in conducting the bonfire test. It further stated that the amendment eliminated a provision that specified the use of a fuel that posed environmental problems.

II. Petitions for Reconsideration

NHTSA received petitions for reconsideration from the American Automobile Manufacturers Association (AAMA), Ford, Consumers Gas, Powertech (a research and development laboratory), and CNG container manufacturers, including NGV Systems, Pressed Steel Tank (PST), and Lincoln Composites (Lincoln). The petitioners requested that NHTSA amend Standard No. 304 with respect to the requirements for labeling CNG containers and the bonfire test procedures. In a final rule published September 6, 1996, the agency responded to issues associated with the labeling of CNG containers. (61 FR 47086) In today's notice, NHTSA responds to the issues associated with the bonfire test.

Lincoln, Powertech, and NGV Systems stated that the bonfire test procedures in S8.3.6 are not feasible. Section S8.3.6 states that “The fire is generated by any fuel that maintains a flame temperature between 850 and 900 degrees C for the duration of the test, as verified by each of the three thermocouples in S8.3.2 or S8.3.3.” NGV Systems provided test data that indicate that the thermocouple temperatures reached during a bonfire test cannot be verified under the procedures specified in the final rule because of variability in the testing. Lincoln recommended that the agency adopt the 1996 edition of NGV2, which requires that two of the three thermocouples average 590 degrees C (1100 degrees F) over any one-minute interval (except that there would be no temperature requirements if the container vents within five minutes of igniting the fire). Lincoln did not explain why this temperature, which is much lower than the initial requirement of 850-900 degrees, would be sufficient. PST stated that because thermocouples on the container do not register temperatures as high as 850 C and are not constant within the 50 C range during the test, diesel fuel should be specified.

Powertech requested that NHTSA harmonize its requirement with the International Standards Organization's (ISO) proposed standard (CD 11439) and the Canadian Standards Associations' proposed standard (B51-95 (part 2)). Both proposed standards are consistent with the 1996 edition of NGV2 which specifies a minimum fire temperature of 590 degrees C using a thermocouple that is placed directly below the container and is shielded from direct flame impingement. These organizations did not establish a maximum test temperature because of the difficulty in precisely controlling the large-scale fire test conditions. In addition to recommending the adoption of NGV2's bonfire temperature, Lincoln recommended rewording the entire bonfire test procedure in FMVSS No. 304 to make it consistent with the 1996 edition of NGV2. That company further stated that if its recommendation were not accepted, then the bonfire test procedures of the standard should be withdrawn and that the issue of the bonfire procedures should be revisited after NGV2 is completed.

III. NHTSA Decision

After reviewing the petitions and other available information, NHTSA has decided to amend the bonfire test procedures to be consistent with the ANSI/NGV2 industry standard published in June 1998. That standard specifies that, within five minutes of ignition, the average temperature of two of the thermocouples must be not less than 430 degrees C over each one minute interval for the duration of the test, beginning 5 minutes after the ignition of the fire and ending 20 minutes after ignition. It also calls for placement of three thermocouples one inch below the CNG container, and specifies that temperatures be recorded every 30 seconds after the ignition of the fire. In other words, any two of the three thermocouples must have an average temperature of not less than 430 degrees C over a 60-second interval, i.e.,

ER30oc00.008

These test procedures will facilitate the testing of CNG containers in several ways, while maintaining the level of safety currently required by Standard No. 304. First, eliminating the current narrow 50 degree C temperature range will make it easier to conduct compliance tests consistent with the temperature specifications of the standard. Data submitted by the petitioners that indicate that the final rule's bonfire test procedures were not feasible because the petitioners could not maintain the temperature specified in the 1995 final rule. Second, specifying that the thermocouples will be placed so that they are suspended below the CNG containers, instead of attached to them as is currently specified in the standard, will increase their accuracy in measuring the flame temperature. Third, specifying a minimum average temperature for the thermocouples will facilitate the use of any type of fuel that can be used to generate the needed heat for the bonfire tests. The temperature specified in the1995 final rule is the flame temperature for diesel fuel, 850-900 degrees C. This is not practical because the container must reach the flame temperature of the fuel that is burning. At such high temperatures, the CNG container material may be destroyed.

NHTSA's decision to pattern the bonfire test procedures after ANSI/NGV2 is consistent with the National Technology Transfer and Advancement Act (NTTAA), which generally requires Federal agencies to evaluate and use existing voluntary consensus standards [2] in their regulatory activities unless doing so would be inconsistent with applicable law (e.g., the statutory provisions regarding NHTSA's vehicle safety authority) or otherwise impractical;see section 12(d) of Pub. L. 104-113. The agency believes that NGV2 is suitable and consistent with the agency's own statutory mandate to be practicable and meet the need for safety. Accordingly, NHTSA has revised the bonfire test procedures to be consistent with the June 1998 version of the ANSI standard.

Technical Amendment

In addition, NHTSA is making a technical amendment to the Application section (S3) to state explicitly that Standard No. 304 applies to “each passenger car, multipurpose passenger vehicle, truck, and bus that uses CNG as a motor fuel and to each container designed to store CNG as motor fuel on-board any motor vehicle.” While the standard's applicability is stated in S6.1 and S6.2, it was not fully stated in S3.

IV. Rulemaking Analyses and Notices

A. Executive Order 12866 (Federal Regulation) and DOT Regulatory Policies and Procedures

NHTSA has considered the impact of this rulemaking action under Executive Order 12866 and the Department of Transportation's regulatory policies and procedures. This rulemaking document was not reviewed under E.O. 12866, “Regulatory Planning and Review.” Further, this action has been determined to be “nonsignificant” under the Department of Transportation's regulatory policies and procedures. The agency has decided not to prepare a Final Regulatory Evaluation (FRE) because the impacts of these amendments are so minimal as not to warrant preparation of a full regulatory evaluation. The amendments in today's final rule make the bonfire test conditions consistent with a voluntary industry standard. Since the industry is already following that standard, this change does not result in any changes in costs.

B. Regulatory Flexibility Act

NHTSA has also considered the effects of this rulemaking action under the Regulatory Flexibility Act. Based upon the agency's evaluation, I certify that this rule will not have a significant economic impact on a substantial number of small entities. The rationale for this certification is that the amendments will not result in any cost increase or decrease for CNG container manufacturers. NHTSA is aware of approximately ten companies that manufacture CNG containers. Because each CNG container manufacturer is affiliated with a Fortune 500 or other large business, none of them would be considered a small business under the U.S. Small Business Administration's affiliation rule (13 CFR 121.401).

C. Executive Order 13132 (Federalism)

The agency has analyzed this rulemaking in accordance with the principles and criteria contained in Executive Order 13132 and has determined that it does not have sufficient federalism implications to warrant consultation with State and local officials or the preparation of a federalism summary impact statement. The final rule has no substantial effects on the States, or on the current Federal-State relationship, or on the current distribution of power and responsibilities among the various local officials.

D. National Environmental Policy Act

In accordance with the National Environmental Policy Act of 1969, NHTSA has considered the environmental impacts of this rule. The agency has determined that this rule will not have any adverse impact on the quality of the human environment.

E. Civil Justice Reform

This rulemaking does not have any retroactive effect. Under 49 U.S.C. 30103, whenever a Federal motor vehicle safety standard is in effect, a State may not adopt or maintain a safety standard applicable to the same aspect of performance which is not identical to the Federal standard, except to the extent that the State requirement imposes a higher level of performance and applies only to vehicles procured for the State's use. 49 U.S.C. 30161 sets forth a procedure for judicial review of final rules establishing, amending or revoking Federal motor vehicle safety standards. That section does not require submission of a petition for reconsideration or other administrative proceedings before parties may file suit in court.

List of subjects in 49 cfr part 571

Imports, Motor vehicle safety, Motor vehicles, Rubber and rubber products, Tires.

In consideration of the foregoing, the agency is amending Standard No. 304;Compressed Natural Gas Fuel Container Integrity, Part 571 at Title 49 of the Code of Federal Regulations as follows:

Part 571—[amended]

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 revising S3 and S8.3 through S8.3.9 to read as follows: § 571.304

S3. Application. This standard applies to each passenger car, multipurpose passenger vehicle, truck, and bus that uses CNG as a motor fuel and to each container designed to store CNG as motor fuel on-board any motor vehicle.

* * * * *

S8.3Bonfire test. The requirements of S7.3 shall be met under the conditions of S8.3.1 through S8.3.7.

S8.3.1Fill the CNG fuel container with compressed natural gas and test it at:

(a) 100 percent of service pressure; and

(b) 25 percent of service pressure.

S8.3.2Container positioning.

(a) Position the CNG fuel container in accordance with paragraphs (b) and (c) of S8.3.2.

(b) Position the CNG fuel container so that its longitudinal axis is horizontal and its bottom is 100 mm (4 inches) above the fire source.

(c)(1) Position a CNG fuel container that is 1.65 meters (65 inches) in length or less and is fitted with one pressure relief device so that the center of the container is over the center of the fire source.

(2) Position a CNG fuel container that is greater than 1.65 meters (65 inches) in length and is fitted with one pressure relief device at one end of the container so that the center of the fire source is0.825 meters (32.5 inches) from the other end of the container, measured horizontally along a line parallel to the longitudinal axis of the container.

(3) Position a CNG fuel container that is fitted with pressure relief devices at more than one location along its length so that the portion of container over the center of the fire source is the portion midway between the two pressure relief devices that are separated by the greatest distance, measured horizontally along a line parallel to the longitudinal axis of the container.

(4) Test a CNG fuel container that is greater than 1.65 meters (65 inches) in length, is protected by thermal insulation, and does not have pressure relief devices, twice at 100 percent of service pressure. In one test, position the center of the container over the center of the fire source. In another test, position one end of the container so that the fire source is centered 0.825 meters (32.5 inches) from one end of the container, measured horizontally along a line parallel to the longitudinal axis of the container.

S8.3.3Number and placement of thermocouples. To monitor flame temperature, place three thermocouples so that they are suspended 25 mm (one inch) below the bottom of the CNG fuel container. Position thermocouples so that they are equally spaced over the length of the fire source or length of the container, whichever is shorter.

S8.3.4Shielding.

(a) Use shielding to prevent the flame from directly contacting the CNG fuel container valves, fittings, or pressure relief devices.

(b) To provide the shielding, use steel with 0.6 mm (.025 in) minimum nominal thickness.

(c) Position the shielding so that it does not directly contact the CNG fuel container valves, fittings, or pressure relief devices.

S8.3.5Fire source. Use a uniform fire source that is 1.65 meters long (65 inches). Beginning five minutes after the fire is ignited, maintain an average flame temperature of not less than 430 degrees Celsius (800 degrees Fahrenheit) as determined by the average of the two thermocouples recording the highest temperatures over a 60 second interval:

ER30OC00.009

If the pressure relief device releases before the end of the fifth minute after ignition, then the minimum temperature requirement does not apply.

S8.3.6Recording data. Record time, temperature, and pressure readings at 30 second intervals, beginning when the fire is ignited and continuing until the pressure release device releases.

S8.3.7Duration of exposure to fire source. The CNG fuel container is exposed to the fire source for 20 minutes after ignition or until the pressure release device releases, whichever period is shorter.

S8.3.8Number of tests per container. A single CNG fuel container is not subjected to more than one bonfire test.

S8.3.9Wind velocity. The average ambient wind velocity at the CNG fuel container during the period specified in S8.3.6 of this standard is not to exceed 2.24 meters/second (5 mph).

* * * * *
Issued on: October 24, 2000. Sue Bailey,

Administrator.

Footnotes

1. NGV2 was developed by an industry working group that included container manufacturers, CNG users, and utilities.

2. Voluntary consensus standards are technical standards developed or adopted by voluntary consensus standards bodies. Technical standards are defined by the NTTAA as “performance-based or design-specific technical specifications and related management systems practices.” They pertain to “products and processes, such as size, strength, or technical performance of a product, process or material.”

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