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Interpretation Response #24-0012

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

Interpretation Response Details

Response Publish Date:

Company Name: Kwik Trip

Individual Name: Mr. Carl Suhr

Location State: WI Country: US

View the Interpretation Document

Response text:

May 9, 2024

Mr. Carl Suhr
Kwik Trip
1626 Oak Street
P.O. Box 2107
La Crosse, WI  54602

Reference No. 24-0012

Dear Mr. Suhr:

This letter is in response to your February 22, 2024, email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to cargo tanks. In your email, you reference § 180.411(c)—which lists examples of welds and structural defections requiring cargo tanks be taken out of hazardous materials service until repaired. You note that when discussing this issue with a cargo tank manufacturer, they assert that since "pinhole" is not defined in the HMR they—the cargo tank manufacturer—default to the American Society for Mechanical Engineers (ASME) Code which states that if pinholes are present but do not leak during hydrostatic testing they are acceptable.

We have paraphrased and answered your questions as follows:

Q1. You ask whether there is a standard for "pinholes" in welds that are part of a cargo tank.

A1. For a cargo tank, § 180.411(c) states that "any cargo tank with a weld defect such as a crack, pinhole, or incomplete fusion, or a structural defect must be taken out of hazardous materials service until repaired." Although "pinhole" is not defined in the HMR, a manufacturer or cargo tank owner may not choose to revert to the American Society of Mechanical Engineering (ASME) Code for a definition of a pinhole or for guidance. PHMSA asserts that the word "pinhole" as referenced in the HMR is being used to elaborate what a weld defect could be on a cargo tank. The determination of whether a weld defect exists and/or warrants taking a cargo tank out of service under § 180.411(c) would be determined during the inspection processes required under the HMR.

Q2. You ask whether there is a standard for "pinholes" in welds that attach appurtenances to the barrel of a cargo tank (i.e., pads).

A2. In § 171.8, a cargo tank is defined as "a tank intended primarily for the carriage of liquids or gases and includes appurtenances, reinforcements, fittings, and closures." Therefore, appurtenances are considered as part of the cargo tank and their respective welds are subject to the same requirements for pinholes in § 180.411(c).

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


Steven Andrews
Acting Chief, Regulatory Review and Reinvention Branch
Standards and Rulemaking Division

171.8, 180.411(c)

Regulation Sections

Section Subject
171.8 Definitions and abbreviations
180.411 Acceptable results of tests and inspections