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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Interpretation Response #19-0006

Below is the interpretation response detail and a list of regulations sections applicable to this response.

Interpretation Response Details

Response Publish Date:

Company Name: United Petroleum Transport

Individual Name: Randy Decker

Location State: OK Country: US

View the Interpretation Document

Response text:

November 26, 2019

Randy Decker
Director of Maintenance
United Petroleum Transport
4312 S. Georgia Place
Oklahoma City, OK  73129

Reference No. 19-0006

Dear Mr. Decker:

This letter is in response to your February 4, 2019, email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to pressure test requirements for MC 300 series cargo tanks. Specifically, you provide the following scenario:

  • You are the owner of an MC 300 series cargo tank.
  • In accordance with § 180.405(k), the cargo tank is marked with a MAWP of 3 psig.
  • Historically, in accordance with §§ 180.405(k) and 180.407(g)(1)(iv), the cargo tank was pressure tested at 3 psig.

You note that table 1 to § 180.407(g)(iv) was amended following the November 7, 2018, publication of the final rule titled "Hazardous Materials: Response to Petitions from Industry to Modify, Clarify, or Eliminate Regulations" [83 FR 55792; HM 219A]. This rulemaking addressed a petition for rulemaking (P-1615) that revised the table 1 entry for MC 300, 301, 302, 303, 305, and 306 specification cargo tanks to read as: “The test pressure on the name plate or specification plate, or 1.5 times the MAWP, whichever is greater." Previously, the entry had read as: "20.7 kPa (3 psig) or design pressure, whichever is greater."

You ask whether it was the intention of PHMSA to require a MC 300, 301, 302, 303, 305, or 306 specification cargo tank with a marked MAWP or design pressure of 3 psig to be tested to 4.5 psig (1.5 x MAWP of 3 psig) instead of testing it to 3 psig.

The answer is no. In the HM-219A NPRM, PHMSA had originally proposed to revise § 180.407(g)(1)(iv) to read as: "The test pressure on the name plate or specification plate, 20.7 kPa (3 psig) or design pressure, whichever is greater" [81 FR 42609]. While PHMSA received comments to the proposed amendments in § 180.407(g)(1)(iv), these comments did not request a revision to the pressure specification of "20.7 kPa (3 psig) or design pressure."

Following review of your request, PHMSA has identified that this revision was made in error and was not PHMSA's intention. PHMSA is working to address this error soon in an upcoming rulemaking. In the interim, you may continue to requalify the cargo tank at 3 psig.

I hope this information is helpful. Please contact us if we can be of further assistance.


Dirk Der Kinderen
Chief, Standards Development Branch
Standards and Rulemaking Division

180.405(k), 180.407(g)(1)(iv), 180.407(g)(iv)

Regulation Sections

Section Subject
180.405 Qualification of cargo tanks
180.407 Requirements for test and inspection of specification cargo tanks