# Missouri Public Service Commission — Pipeline Safety Interpretation

**Citation:** PI-81-015  
**Type / status:** guidance / guidance  
**Agency:** Pipeline and Hazardous Materials Safety Administration  
**Effective:** Not stated  
**Published:** 1981-07-28

PI-81-015 response to Missouri Public Service Commission concerning 192.355.

## Document text

<<<PAGE 1>>>

July 28, 1981
Mr. Dale W. Johansen
Assistant Director, Gas Department
Engineering Section
Missouri Public Service Commission
P. O. Box 360
Jefferson City, Missouri 65102
Dear Mr. Johansen:
We apologize for the lateness of our response to your letter of April 14, 1981, asking whether
§192.357(d) requires nonrelief type service regulators, which would release gas only upon failure
to have their breather vents vented to the outside atmosphere.
As indicated by the enclosed interpretations (dated October 12, 1973, and November 1, 1976),
§192.357(d) does not apply to nonrelief type service regulators because they do not release gas
during operation. Nevertheless, nonrelief type service regulators that have breather vents are
subject to the requirements of §192.355(b)(2) and must be installed so that gas escaping from the
vents in the events of diaphragm or other failure is released into the outside atmosphere.
We trust that this response will satisfy your concerns.
Sincerely,
/signed/
Melvin A. Judah
Acting Associate Director for
Pipeline Safety Regulation
Materials Transportation Bureau
dal\192\355\81-07-28
1

<<<PAGE 2>>>

October 12, 1973
Mr. A. C. Singer
Vice President of Operations
The Gas Service Company
700 Scarritt Building
Kansas City, Mo. 64142
Dear Mr. Singer:
In your letter of September 24, 1973, you requested an interpretation of Paragraph 192.357(d),
Title 49, Code of Federal Regulations, which reads as follows:
"Each regulator that might release gas in its operation must be vented to the outside
atmosphere."
Your specific question was whether the above paragraph requires an outside vent on service
regulators which are installed inside, and which are not equipped with relief facilities. Since they
do not release gas in their operation, you have considered such regulators as constituting a closed
system.
Your interpretation is correct. Since there is no release of gas in the operation of such a service
regulator, that regulator need not be vented to the outside atmosphere.
If we may assist further, please let us know.
Sincerely,
/signed/
Joseph C. Caldwell
Director
Office of Pipeline Safety
dal\192\355\81-07-28
2

<<<PAGE 3>>>

November 1, 1976
Mr. Leonard M. Coffelt
Missouri Public Service Commission
P. O. Box 360
Jefferson City, Missouri 65101
Dear Mr. Coffelt:
This responds to your letter dated September 21, 1976, asking that we review a previous
interpretation dated October 12, 1973, regarding 49 CFR 192.357(d). You ask whether that
interpretation permits "service regulators to be installed within a building without venting the
diaphragm breather vent to the outside atmosphere."
Section 192.357(d) reads:
"Each regulator that might release gas in its
operation must be vented to the outside atmosphere."
The October 12, 1973, interpretation essentially provides that Section 192.357(d) does not apply
to a regulator which does not release gas in its operation.
That interpretation was not intended to permit installation of a regulator with a diaphragm
breather vent inside a building without placing the discharge end of the vent outside the building.
Sections 192.199(e) and 192.355(b)(2) are clear that the outlet of each regulator vent must be
located outside.
Sincerely,
/signed/
Cesar DeLeon
Acting Director
Office of Pipeline
Safety Operations
dal\192\355\81-07-28
3

## Provenance

- Official: Yes
- Source: <https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/Pipeline/1981/PI81015.pdf>
- Source ID: `phmsa`
- SHA-256: `a9d0c65c9925eaa6caabdc78fa442e69a36246f8784b6c3f07c845a7ae493f72`
- Retrieved: 2026-08-20T00:59:31.977Z
- Exported: 2026-08-22T05:23:57.913Z
- Document slug: `phmsa-interpretation-pi-81-015`

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