Fort Edward Express Co., Inc. — Hazardous Materials Safety Interpretation

Page 1of Transportation U.S. Department Washington, SiC Washington, D.C. Research and Administration Special Programs JUN 3 1998 Mr. Douglas J. Varney Service Manager Fort Edward Express Co., Inc. Fort Edward, NỸ 12828 Dear Mr. Varney: This is in response to your letter regarding the pressure relief devices for an MC-331 cargo tank operated in dedicated chlorosilane service under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). Specifically, you ask if it is allowable to install a pressure relief device rated at 250 psig in a cargo tank that is in dedicated chlorosilane service having design pressure of 312.5 psig stamped on the tank specification plate. I apologize for the delay in responding and hope it has not caused any inconvenience. The specifications for a pressure relief device in an MC-331 cargo tank are found in 49 CFR 178.337-9(a). Section 178.337-9(a)(3) states that each valve must be designed, constructed, and marked for a rated pressure not less than the cargo tank design pressure at the temperature to be encountered. Therefore, it is not allowable to install a pressure relief device rated at 250 psig in a cargo tank in dedicated chlorosilane service having a 312.5 psig design pressure marked on the cargo tank specification plate. I hope this satisfies your request. Sincerely, Delmer F. Billings Office of Hazardous Materials Standards#

Page 2Operators of Gall File: 118.337 RANSPORTATIOM SPECIALISTS Fort Edward Express Co., Inc. 113.315 TRANSPORTERS OF PETROLEUM PRODUCTS se: 333 FORT EDWARD, N. Y. 12828 PHONE: 518 792-6571 October 20, 1997 U.S. Department of Transportation The Research and Special Programs Administration Washington, DC 20591 Dear Sir, - Recently a question arose regarding the emergency venting requirements for an MC-331 cargo tank, tank was uninsulated and had a design pressure of 312.5 psi @ 150°F. The tank operates in dedicated that was undergoing a Pressure test in accordance with Part 180.407(g), in our repair shop. This cargo Chlorosilane service: Specifically, my question is; Is it allowable to install 250 psi relief valves into this cargo tank, having a 312.5 psi design pressure stamped on the tank specification plate? The owner's representative stated that the cargo tank was annually leak tested at 100 psi [per 180.407(h)(1)(i)]. He also referenced section 173.315(i)(3) in his effort to convince me that installing tank relief valves set lower than the tank design pressure in this case was allowable. Through my research, I concluded that the tank pressure relief valves must be not less than the design pressure as stamped on the specification plate based on the following: • Section 178.337-9(a)(1) references section 173.315(1)? Section 173.315(1)I (3) specifically] does not apply, since Chlorosilane is not listed in paragraph (a) of that section. • Section 178.337-9(a)(3) states "Each valve must be designed, constructed, and marked for a rated pressure not less than the tank design pressure ..." • Finally, I feel that the pressure that the owner uses for the annual leakage test is irrelevant to the intended purpose of 178.337-9(3). speciücation, and any exceptions or restrictions that may apply as outlined in the "Hazardous Materials Since the goal of all parties involved is to verify that this cargo tank complies with the original Regulations", I am requesting your written interpretation of the rules as they apply to this situation. To send your response, or if you require any additional information, please contact me at: Fort Edward Express Co., Inc., Route 9, Saratoga Road, Fort Edward, NY 12828. Thank you. Service Manager#