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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Interpretation Response #PI-70-0111 ([United Gas Pipe Line Company] [Mr. W.P. Heineman])

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

Interpretation Response Details

Response Publish Date:

Company Name: United Gas Pipe Line Company

Individual Name: Mr. W.P. Heineman

Location State: LA Country: US

View the Interpretation Document

Response text:


December 2, 1970

Mr. W.P. Heineman
United Gas Pipe Line Company
P.O. Box 1407
Shreveport, Louisiana 71102

Dear Mr. Heineman:

This is in reply to your three letters of October 12, 1970, requesting interpretations of various sections of 49 CFR, Part 192.

In answer to your question concerning requirements for two-phase systems, the statement made in Houston that the most severe regulation (either gas or liquid) be complied within two-phase systems is still correct.

You state that most two-phase systems are designed to transport primarily natural gas. An examination of the "Gas Engineers Handbook", 1966 edition, page 8/11 on two-phase flow indicated that such systems range from gas bubbling in a solid stream of liquid to a fog of liquid in a gas stream. Therefore, to state that all two-phase systems follow either the gas or liquid regulation would not be wise.

You state that the B31.8 should be followed in the future as it has been the Code used in the past for two-phase flow. In the case of stress levels in other than Class 1 locations, the gas regulations would be more severe than the liquid, but in most instances the regulations would be similar for transmission type or trunkline type pipelines. Therefore, you should have no problem in following the most severe regulation, at least at present, with the knowledge we have on two-phase pipelines.

In answer to your question regarding transportation of pipe a change in the language of Section 192.65 is under consideration to apply only to pipe transported after the effective date of the regulations. We recognize that there is a problem with respect to application of our regulation to the original transportation of existing stock of pipe. Therefore, we suggest that you furnish all available information as to the transportation procedures used before RP5L1 was issued and the precise nature and magnitude of the problem.

With regard to your letter on the qualification of steel pipe presently in inventory, our recent amendment to Section 192.55 and Appendix B should have alleviated much, if not all of the problem. If you still find that you have a large inventory that does not qualify under a listed specification or Section 192.55 (d), you may wish to petition for a waiver. Should you elect to follow this course of action, I suggest that your petition contain the following information:

  1. The magnitude of the problem in terms of quantity of pipe and its value.
  2. The reasons why qualification of the pipe under Section 192.55(a)(2) is not appropriate.
  3. The basis upon which the waiver could be found not inconsistent with pipeline safety.
  4. A indication as to whether other companies might also be adversely affected (if the problem is widespread, an amendment might be more appropriate).
  5. Suggested language for an amendment that would alleviate the problem while assuring and equivalent level of safety.

If we can be of further assistance, please do not hesitate to ask.


Original signed by:
Joseph C. Caldwell
Director, Acting
Office of Pipeline Safety

Regulation Sections

Section Subject
192.55 Steel pipe