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Interpretation Response #PI-75-0110

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

Interpretation Response Details

Response Publish Date: 09-29-1975
Company Name: Arizona Corporation Commission    Individual Name: Mr. H. R. Garabrant
Location state: AZ    Country: US

View the Interpretation Document

Request text:

June 4, 1975

Arizona Corporation Commission
1688 West Adams
Phoenix, Arizona 85007

June 4, 1975

Mr. Joseph C. Caldwell
Office of Pipeline Safety
Department of Transportation
400 Seventh Street S.W.
Washington, D.C. 20590

Dear Mr. Caldwell:

In regard to Report MRI-2628-TR1, Rapid Shutdown of Failed Pipeline Systems and Limiting of Pressure to Prevent Pipeline Failure Due to Overpressure, Part I, Final Technical Report. On page 28 there is the sentence, "Also, by virtue of the 'grandfather clause' in the federal regulations, such systems are legal."

I would like to point out that at first glance this might appear correct but in Part 192, Subpart L - Operation, and Subpart M - Maintenance, they are not grandfathered. Thus, under 192.621(b) overpressure protection is legally required on all distribution pipeline systems. Also under 192.743(c), if the relieving device is of insufficient capacity, a new or additional device must be legally installed to provide additional capacity as required.

I have convinced quite a few companies to add overprotec­tion control in accordance with the above and have at least three larger companies embarked on an upgrading program in regard to overpressure protection.

I would like to see a correction notice issued in regard to the sentence and change the sentence to inform the public that grandfathering is not applicable in this case.

I am enclosing a copy of some correspondence in my file for your information showing how and why this office has been treating this subject.

If I have mistakenly interpreted the operation and maintenance requirements in regard to this subject, please inform me. I would also be glad to discuss the economic impact of this subject with you at any time.


Gas Utilities Safety Engineer
Utilities Division

Response text:

September 29, 1975

Mr. H. R. Garabrant
Utilities Division
Arizona Corporation Commission
1688 West Adams
Phoenix, AZ 85007

Dear Mr. Garabrant:

This responds to your letter of June 4, 1975, which proposes a correction notice to be used as clarification and information to the public regarding the Office of Pipeline Safety Operations' (OPSO) Contract Study DOT-OS-3000S, "Rapid Shutdown of Failed Pipeline Systems and Limiting of Pressure to Prevent Pipeline Failure Due to Overpressure," and its effect on Part 192, Sections 192.621(b) and 192.743(c).

Conclusions, opinions, or statements made in reports on contract studies performed for OPSO are those of the contractor and do not necessarily state the position of OPSO. OPSO reviews and evaluates these reports and takes action as appropriate.

As you stated in your memorandum, dated May 22, 1974, to all gas operators in the State of Arizona, the grand­father clause is not applicable to the subject sections. A statement in your memorandum that "... old stations that are protected by the grandfather clause be reviewed in light of present day standards and that these stations be replaced with up-to-date stations as money and time permits …” can be considered as advisory only.

Also, in regard to part of paragraph four of the subject memorandum which states "... that changing size or adding a new or additional relief valve (or monitor regulator) was to be classed as maintenance and not new construction, therefore the station did not require entire rebuilding to new code," OPSO would like to call your attention to Section 192.199(g),of the regulations which requires that overpressures-protection devices and pressure-limiting devices be designed and installed to prevent any single incident such as explosion in a vault or damage by a vehicle from affecting the operation of both.. However, the intent of the subject section is separate pressure-limiting devices and overpressure-protection devices by distance, barrier, or separate housing, but the subject interpretation does not rule out other solutions that may be just as good as or better than the mentioned method of separating by distance, barrier, or separate housing. In other words, any new addition of pressure relief or limiting device to these existing facilities must comply with the subject section of the regulation.

I hope that this will clarify the applicability of the sections of Part 192 that apply to the correction of deficiencies of overpressure protection.


Cesar DeLeon
Acting Director
Office of Pipeline
Safety Operations

Regulation Sections

Section Subject
§ 192.743 Pressure limiting and regulating stations: Capacity of relief devices