[Header] PHMSA - U.S. Department of Transportation - Pipeline and Hazardous materials Safety Adminis
Pipeline Interpretations

The Pipeline and Hazardous Materials Safety Administration, Office of Pipeline Safety provides written clarifications of the Regulations (49 CFR Parts 190-199) in the form of interpretation letters.  These letters reflect the agency's current application of the regulations to the specific facts presented by the person requesting the clarification.  Interpretations are one form of Guidance provided by this office.

A pipeline safety regulatory interpretation applies a particular rule to a particular set of facts and circumstances, and may be relied upon only by those persons to whom the interpretation is specifically addressed. Interpretation letters are published here to provide the public with a greater awareness and understanding of the regulations.

We welcome feedback from the pipeline safety community to ensure the most recent and accurate letters of interpretation are provided here.  Questions or concerns about a specific letter or topic should be directed to the Office of Pipeline Safety.

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An unsigned text version with a signed PDF of each letter is provided. To view interpretation letters, click the links below the Search box.

In the Search box, you can also enter a word(s) and click Search to locate that term within the letters.

All letters of interpretation posted to the website are fully searchable. This means you can enter a word(s) in the search field and click "Search" to locate that term within a letter.