# DOT Training Solutions — Hazardous Materials Safety Interpretation - **operation:** document - **citation:** 22-0028 - **title:** DOT Training Solutions — Hazardous Materials Safety Interpretation - **source type:** guidance - **agency:** Pipeline and Hazardous Materials Safety Administration - **status:** guidance - **official:** true - **published on:** 2023-01-24 - **effective on:** Not available - **summary:** 22-0028 response to DOT Training Solutions concerning 178.345, 180.407. - **machine formats:** - **json:** https://regulus.evalyn.ai/document/phmsa-interpretation-22-0028.json - **markdown:** https://regulus.evalyn.ai/document/phmsa-interpretation-22-0028.md - **app url:** https://regulus.evalyn.ai/document/phmsa-interpretation-22-0028 - **source url:** https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/docs/standards-rulemaking/hazmat/interpretations/77216/220028.pdf **body:** <<>> U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration 1200 New Jersey Avenue, SE Washington, DC 20590 January 24, 2023 Mr. Randy Decker Safety Consultant DOT Training Solutions P.O. Box 25311 Overland Park, KS 66225 Reference No. 22-0028 Dear Mr. Decker: This letter is in response to your March 17, 2022, email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to the testing and inspection requirements for multi-compartment Department of Transportation (DOT) specification cargo tanks. In your email, you state that §§ 180.407(g)(1)(vi) and 180.407(h)(1) of the HMR require that each cargo tank of a multi-tank cargo tank motor vehicle be pressure-tested and leakage- tested respectively, with the adjacent cargo tanks empty and at atmospheric pressure. Furthermore, you ask whether a void at atmospheric pressure between double bulkheads—as described in your email—may be considered an adjacent compartment for the purposes of pressure and leakage testing under § 180.407. The answer is no. Sections 180.407(g)(1)(vi) and (h)(1) both state that “each cargo tank of a multi-tank cargo tank motor vehicle must be tested with the adjacent cargo tanks empty and at atmospheric pressure.” Under § 178.345-1(c), the HMR define a “void” as “the space between tank heads or bulkheads and a connecting structure.” Therefore, a “void” does not meet the definition of a cargo tank. I hope this information is helpful. Please contact us if we can be of further assistance. Sincerely, T. Glenn Foster Chief, Regulatory Review and Reinvention Branch Standards and Rulemaking Division <<>> Pollack From: INFOCNTR (PHMSA) To: Dodd, Alice (PHMSA) Cc: Hazmat Interps Subject: FW: Request for a letter of clarification Date: Wednesday, April 13, 2022 4:45:05 PM Attachments: image002.png image003.png 22-0028 Hi Alice, Please see the below interpretation request. Should you have any questions, do not hesitate to reach out. Regards, -Breanna From: Randy Decker Sent: Thursday, March 17, 2022 3:59 PM To: INFOCNTR (PHMSA) Subject: Request for a letter of clarification CAUTION: This email originated from outside of the Department of Transportation (DOT). Do not click on links or open attachments unless you recognize the sender and know the content is safe. Need clarification on voids on multi-compartment cargo tanks. In 180.407 (g)(1)(vi) and 180.407 (h)(1), the regulations state that a tank of multi-compartments must be tested with the adjacent tank empty and open to atmosphere. If the tank has double bulkheads, therefore a void would be between the compartments. Would the void be considered the adjacent compartment? The void is never to be plugged on the bottom and open to atmosphere at all times. Randy Decker Safety Consultant Mobile: (913) 350-0373|Toll Free: (866) 296-7394 Email: randydecker@dottrainingsolutions.com Website: https://dottrainingsolutions.com <<>> PO Box 25311 Overland Park, Kansas 66225 - **truncated:** false - **body characters:** 3097