# Northwest Pipeline Corporation — Pipeline Safety Interpretation

**Citation:** PI-81-011  
**Type / status:** guidance / guidance  
**Agency:** Pipeline and Hazardous Materials Safety Administration  
**Effective:** Not stated  
**Published:** 1981-05-29

PI-81-011 response to Northwest Pipeline Corporation concerning 192.463.

## Document text

<<<PAGE 1>>>

May 29, 1981
Mr. Lloyd A. Hightower
Director, Operations
Northwest Pipeline Corporation
P.O. Box 1526
Salt Lake City, Utah 84110
Dear Mr. Hightower:
Your letter of May 1, 1981, requests our approval of an aerial survey technique that has been
developed to monitor the level of cathodic protection on a buried pipeline.
We understand the technique would be used to comply with 49 CFR 192.465(a), which requires
that cathodically protected pipelines be tested annually to determine if protection is at the levels
required by §192.463 and Appendix D to Part 192. These regulations do not require the use of
specific testing methods, and any technique may be used that accurately shows the cathodic
protection levels.
This office does not recommend one test method over another, and our approval is not needed for
an operator to use a new method.
Sincerely,
Melvin A. Judah
Acting Associate Director for
Pipeline Safety Regulation
Materials Transportation Bureau
dal\192\463\81-05-29

## Provenance

- Official: Yes
- Source: <https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/Pipeline/1981/PI81011.pdf>
- Source ID: `phmsa`
- SHA-256: `e0e5ad1f6fb7d677d090f6507cf498fd93e33f6e5fcc246dabe1b276b5d4fca8`
- Retrieved: 2026-08-20T00:59:31.977Z
- Exported: 2026-08-24T14:57:01.242Z
- Document slug: `phmsa-interpretation-pi-81-011`

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