National Tank Truck Carriers, Inc — Hazardous Materials Safety Interpretation

Page 1of Transportation U.S.Department 40s segion, .. 2550 2059 Special Programs Research and . ост & 1998 Administration Mr. Clifford J. Harvison • President Ref. No. 98-0251 National Tank Truck Carriers, Inc. 2200 Mill Road Alexandria, VA 22314-4677 Dear Mr. Harvison: This 1s in response to your letter dated August 25, 1998, • requesting clarification of repair and replacement requirements vehicles under the Hazardous Materials Regulations for reclosing pressure relief valves on MC 306 cargo tank motor Parts 171-180). Your questions are answered as follows: (HMR; 49 CFR Q1. relief valve from a MC 306 cargo tank motor vehicle. The valve After August 31, 1998, we removed a reclosing pressure fails a "bench test" due to a faulty mechanical element within the valve. The mechanical element is repaired and the valve successfully passes the "bench test". May this valve be returned to service on an MC 306 cargo tank motor vehicle? A1. Yes. The HMR permits the return of a refurbished (repaired) reclosing pressure relief valve to the cargo tank from which it was removed. However; if the repaired pressure relief valve no longer meets the performance requirements of the original specification (MC 306), the valve must be replaced. replacement valve must meet the DOT 400-series pressure surge requirements under § 180.405 (h) (2). relief valve from a 22. After August 31, 1998, we removed a reclosing pressure fails a "bench test" and the cause is determined to be the • MC 306 cargo tank motor vehicle. The valve failure of a gasket, external to the valve assembly. We replace the gasket, and the valve successfully passes the "bench test". May this valve be returned to service on an MC 306 cargo tank motor vehicle? A2. Yes. : Regardless of whether the repair or refurbishment is internal or external to the valve assembly (for example, replacement of the valve seats, springs or gaskets), if the pressure relief valve meets the original specification performance criteria discussed in Al above, it may be returned to service on the cargo tank motor vehicle from which it was removed. 180.407#

Page 2I hope this satisfies your inquiry. If you need additional assistance, please do not hesitate to contact us. • Sincerely, R. Ryan tat foR Hattle I. Mitchell, Chief Regulatory Review and Reinventior Office of Hazardous Material Standards#

Page 3-NATIONAL TANK NTTC NATIONAL TANK TRUCK CARRIERS, INC. TRUCK CARRIERS THE NATIONAL ORGANIZATION SERVING THE FOR•HIRE TANK TRUCK INDUSTRY CLIFFORD J HARVISON PRESIDENT 2200 MILL ROAD • ALEXANDRIA, VA 22314-4677 PHONE: 703/838-1960 • FAX: 703/684-5753 August 25, 1998 Mr. Alan I. Roberts Assoc. Admin. for Hazardous Materials Safety U.S. Department of Transportation Research & Special Programs Administration Washington, DC 20590 (Via Fax -- Hard Copy To Follow) Dear Mir. Roberts: Please consider this letter a request for an interpretation of the Administrator's Hazardous Materials Regulations. National Tank Truck Carriers, Inc. (NTTC) is the international trade association of the tank truck industry with over 200 corporate members which specialize in the transportation of hazardous materials in cargo tank motor vehicles. reading of this regulatory language indicates to some that if a reclosing pressure relief valve fails to meet Our concerns center on an apparent ambiguity at 49 CFR 180.407(g)(ii)(A) and (B). A strict "literal" the provisions of "(A)" (during the so-called "bench test') that pressure relief valve cannot be repaired and returned to service. It must be replaced. After August 31, 1998, it must be replaced with a reclosing pressure relief valve that complies with the equivalent "DOT 400" series cargo tank specification. Below, I have outlined two scenarios, followed by a question. SCENARIO "A" -- After August 31, 1998, a reclosing pressure relief valve is removed from an MC 306 of the valve. The mechanical element is repaired and the valve "passes" a subsequent "bench test". May cargo tank. It fails the "bench test", and it is determined that the failure is caused by a mechanical element this valve be returned to service of a cargo tank motor vehicle? Hittie#

Page 4*. SCENARIO "B" - After August 31, 1998, a reclosing pressure relief valve is removed from an MC 306 the valve assembly. The inspector/testor replaces the gasket, and the valve "passes" the "bench test". cargo tank. It fails the "bench test", and it is determined that the failure is caused by a gasket, external to May this valve be returned to service on a cargo tank motor vehicle? Mr. Roberts, given the pendancy of the August 31, 1998 "trigger date", a prompt response would be appreciated. Thank you for your consideration in this matter. truly yours, President - --#