Texas Trailer Corporation — Hazardous Materials Safety Interpretation

Page 1U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration 1200 New Jersey Avenue, SE Washington, DC 20590 JAN 1 2 2016 Mr. Ray Williams Texas Trailer Corporation 1310 Highway 82 West Gainesville, TX 7 6240 Reference No. 16-0090 Dear Mr. Williams: This letter is in response to your May 19, 2016, email and subsequent emails and phone calls requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to safety relief valves on cargo tanks. Specifically, you ask why the language in § 173 .3 l 5(i)(3) was changed to omit cargo tanks and what setting requirements apply for the start-to-discharge pressure on a safety relief valve for a cargo tank motor vehicle in compressed gas service. Section l 73.315(a) authorizes the use of DOT specification (MC 330 and MC 331) cargo tank motor vehicles for certain compressed gases. Section 173 .315(i) further describes requirements for pressure relief devices on "tanks," applying to both cargo and portable tanks. On June 21, 2001, the Pipeline and Hazardous Materials Safety Administration's (PHMSA) predecessor- Research and Special Programs Administration (RSPA)-published a final rule titled, "Harmonization with the United Nations Recommendations, International Maritime Dangerous Goods Code, and International Civil Aviation Organization's Technical Instructions," in the Federal Register under Docket No. RSP A-2000-7702 (HM-215D). This final rule amended § 173.315(i)(3) to add new requirements for United Nations (UN) portable tanks, which changed the term "tank" to specify a "portable tank, other than a UN portable tank," and omitted cargo tanks from the requirement. In accordance with§ 173.33(d)(3), an MC 330 cargo tank may have pressure relief devices or outlets conforming to the applicable specification to which the tank was constructed, or the pressure relief devices or outlets may be modified to meet the applicable requirement for the specification MC 331. Pressure relief devices for MC 331 cargo tanks are specified in § 178.337-9, which references§ 173.315(i). Section 180.407G)(l)(iv) specifies each self-closing pressure relief valve for an MC 330 or MC 331 cargo tank must open at not less than the required set pressure and not more than 110% of the required set pressure, and must reseat to a leak-tight condition at no less than 90% of the required set pressure. I hope this information is helpful. Please contact us if we can be of further assistance. T. Glenn Foster Chief, Regulatory Review and Reinvention Branch Standards and Rulemaking Division#

Page 2Goodall, Shante CTR (PHMSA) From: Sent: To: Subject: Rivera, Jordan CTR (PHMSA) Monday, May 23, 2016 12:55 PM Hazmat Interps FW: Setting of safety relief valves Hi Shante/Alice, Mr. Williams sent this is as additional information to add to his original interp request (forwarded on Friday 5/20). Please let me know if you have any questions. Thank you, Jordan From: Ray Williams [mailto:ray.williams@texastrailercorp.com] Sent: Monday, May 23, 2016 11:57 AM To: INFOCNTR (PHMSA) Subject: FW: Setting of safety relief valves Hello Info Center, If it is not too late, I would like to make one more request on the inquiry sent May 19, 2016.(See message below) If we cannot apply the setting requirements now listed in 49 CFR 173.315 (3) to a cargo tank, please point out for us where to find the regulation for us to follow in fitting our cargo tanks with relief valves. Best Regards, Ray Williams From: Ray Williams Sent: Thursday, May 19, 2016 3:51 PM To: infocntr@dot.gov Subject: Setting of safety relief valves Hello Info Center,#

Page 3According to 49 CFR 173.315(i)(3), each Safety relief valve on a portable tank must be set to start-to discharge at pressure no higher than 110% of the tank design pressure and no lower than the design pressure specified in paragraph (a) of this section for the gas transported. This section covers compressed gases in cargo tanks and portable tanks. For more than 25 years, this paragraph related to "tank" and not to "portable tank". Can we apply the setting requirements now listed in 49 CFR 173.315 (3) to a cargo tank as well as to a portable tank? Please submit this to any department that can offer a written response to this inquiry. Best Regards, Ray Williams Quality & Technical Services Texas Trailer Corporation 1310 Highway 82 West Gainesville, TX 76240 Phone 940-668-1777 www weldship. com 2#