D.J.'s Truck Repair, Inc. — Hazardous Materials Safety Interpretation

Page 1U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration 1200 New Jersey Avenue, SE Washington, D.C. 20590 FEB 2 5 2008 Mr. David Jones Owner D.J.'s Truck Repair, Inc. 7202 Herter Industrial Drive Godfrey, IL 62035 Ref. No. 06-0260 Dear Mr. Jones: This responds to your letter requesting clarification of the rejection criteria when performing a leakage test on a cargo tank motor vehicle that is used primarily for the transportation of compressed gases, such as anhydrous ammonia and propane, under the Hazardous materials Regulations (HMR; 49 CFR Parts 171 -1 80). Specifically, you ask if the back flow check valve installed on a product inlet opening (spray fill line) is considered a self-closing stop valve and, therefore, must be leak tight when leak tested under 9 180.407(h). You state that when the liquid valve is opened while testing the product piping system under pressure, the back flow check valve will often leak. I apologize for the delay in responding and hope it has not caused any inconvenience. Under 9 178.337-8(a)(3), each product inlet opening must be fitted with a back flow check valve or an internal self-closing stop valve located inside the cargo tank or inside a welded nozzle that is an integral part of the cargo tank. Under the leakage test requirements in tj 180.407(h), only internal or external self-closing stop valves and product piping and delivery hoses are required to be tested for leak tightness under pressure. Therefore, a back flow check valve is not required to be leak tight and would need not be considered under the rejection criteria under 4 180.407(h)(3). I trust this satisfies your inquiry. Please contact us if we can be of further assistance. Sincerely, Hattie L. Mitchell Chief, Regulatory Review and Reinvention Office of Hazardous Materials Standards#

Page 2D. J. 's Truck Repair, Inc. 7202 Herter Industrial Drive + Godfrey, IL 62035 Phone (618) 466-9346 +Fax (618) 466-6634 06-1>zbO November 8,2006 Office of Hazardous Materials Standards Research and Special Programs Administration ATTN: DHM- 10 U. S . Department of Transportation 400 7th Street SW Washington, DC 205 90-000 1 My question concerns the back check valve installed on the spray fill line of NH3 and LP bulk transports. Specifically, is the back check valve considered a self-closing stop valve that should seal leak tight. When conducting a leakage test per Title 49 CFR, 180.407 (h) quite often the back check valve will leak after opening the liquid valve to flood and test the product piping system. Some industry personnel claim that the back check valve should leak to stabilize the internal prcssure. Others feel that if it leaks it should be replaced. Since there is the cost of relieving the internal pressure, to replace the leaking valve, the cost of the valve and the re-pressurization of the bulk transport, I am requesting your interpretation of the condition. Thank you for your consideration and I await vour reply. David ones' Owner#