# Pipeline Safety Interpretation PI-79-0100

**Citation:** PI-79-0100  
**Type / status:** guidance / guidance  
**Agency:** Pipeline and Hazardous Materials Safety Administration  
**Effective:** Not stated  
**Published:** 1979-02-06

PI-79-0100 concerning 192.625.

## Document text

<<<PAGE 1>>>

PI-79-0100
February 06, 1979
DEPARTMENT OF TRANSPORTATION
RESEARCH AND SPECIAL PROGRAMS ADMINISTRATION
WASHINGTON, D. C. 20590
Mr. Donald E. McCoy
Transportation Safety Institute
6500 S. MacArthur Boulevard
Oklahoma City, Oklahoma 73125
Dear Mr. McCoy:
This is in response to your recent letter asking how much time is permitted under Part 192 to
make system changes (in particular odorization) necessitated by class location changes.
While §192.613(a) requires an operator to make necessary changes, no time period for
compliance is specified. However, a similar provision under §192.611(c) requires confirmation
or revision of MAOP within 18 months after a change in class location. In view of this
similarity, it appears that an 18-month compliance period is appropriate to apply under
§192.613(a). In a previous interpretation, we have stated that the 18-month period begins to run
upon completion of a structure which results in a new class location (see May 12, 1978 memo to
DMT-213.)
Sincerely,
Cesar De Leon
Associate Director for
Pipeline Safety Regulation
Materials Transportation Bureau

<<<PAGE 2>>>

Mr. Cesar DeLeon, Associate Director
Office of Pipeline Safety Regulations
Materials Transportation Bureau
Washington, D. C. 20590
Dear Mr. DeLeon:
The purpose of this letter is to request your office's interpretation concerning CFR 49, paragraph
192.625(b) regarding the odorization of natural gas in transmission lines.
The question is as follows:
Suppose a transmission operator is not odorizing the gas in a segment of his pipeline
system because the segment met the class location exemption allowed by either paragraph
192.625(b)(1) or 192.625(b)(3). If the operator were to detect a class location change (i.e., from
Class 1 or 2 to Class 3 or 4) when performing the surveillance procedures required by paragraph
192.613(a), what period of time is he allowed under the regulations to accomplish the physical
system changes necessary to now odorize the gas? Moreover, is this period of time measured
from when the class locations actually changed or from when the operator detected the change in
class location?
Your assistance in clarifying this question is appreciated.
Your very truly,
Donald E. McCoy
Pipeline Safety Specialist

## Provenance

- Official: Yes
- Source: <https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/Pipeline/1979/g79-02-06_McCoy_192.625-msfx.pdf>
- Source ID: `phmsa`
- SHA-256: `92271e52dcd680976e89c37f622f30e0c138f0310c6ac8fa87a2a8717ba190ba`
- Retrieved: 2026-08-20T00:59:31.977Z
- Exported: 2026-08-22T22:00:11.393Z
- Document slug: `phmsa-interpretation-pi-79-0100`

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