Interpretation Response #PI-78-0107

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

Interpretation Response Details

Response Publish Date: 11/08/1978

Company Name:

Individual Name:

Location State: AZ Country: US

View the Interpretation Document

Response text:

November 08, 1978

H.R. Garabrant P.E.
Gas Utilities Safety Engineer
Utilities Division
Southern Arizona O
ffice 415 W. Congress Street
Tucson, Arizona 85701

Dear Mr. Garabrant:
This refers to your letter of August 7, 1978, to Mr. Frank Fulton suggesting that Section
192.321(d) be changed to eliminate the Implication that thermoplastic pipe of 0.090 inch wall
thickness is acceptable for use under Part 192 regardless of pipe diameter.

We have reviewed Section 192.321(d) in light of your suggestion, and do find that the Section may
have the implication you suggest.

The purpose of Section 192.321(d) is to prescribe the minimum wall thickness of thermoplastic pipe
that may be used without encasement. It is not intended to override, and in our opinion does not
conflict with the allowable wall thickness for thermoplastic pipe set forth in ASTM D2513, which is
incorporated by reference in Section 192.59.

Section 192.321(d) could be stated in a better manner to make its purpose clearer. The Section will
be a subject for review during the course of our regulatory reform process, and it may be restated
or otherwise changed as a result of that process. Meanwhile, we plan to publish in the Advisory
Bulletin a clarifying interpretation of Section 192.321(d).
Sincerely, Cesar De Leon Associate Director for
Pipeline Safety Regulation
Materials Transportation Bureau

United States Government
Department of Transportation
Research and Special Programs Administration

Date:                   August 16, 1978

SUBJECT:            Interpretation of Section 192.321(d)

FROM:                Associate Director for Operations and Enforcement, DMT-10

TO:                      Associate Director for Pipeline Safety Regulation, DMT-30

By letter of August 7, 1978 (copy attached), the Arizona Corporation Commission indicates the
existence of a variance between Section 192.321 and ASTM D2513 and requests a correction of Section
192.321.

Thank you for a prompt interpretation of this regulation to facilitate a timely response to the
Arizona Corporation
Commission.

Robert Paullin
Arizona Corporation Commission
2222 West Encanto Blvd. Phoenix, Arizona 85009

August 7, 1978
Mr. Frank Fulton
State Programs
Office of Pipeline Safety Operations Department of Transportation Washington, D.C. 20590

Dear Frank:
I have just noticed, after all these years, what I believe is a very serious and misleading flaw in
Part 192.

Please refer to 192.321 (d), this paragraph would lead one to believe that, except for pipe with an
outside diameter of 0.875", which can have a minimum wall thickness of .062", that any size of
plastic pipe could be used, as long as it had a minimum wall thickness of 0.090" and met the MAOP
requirements.

This, of course, is not true if you refer to ASTM D2513-75b, Paragraph 6,2,1,2 and Table 4, you
will find that
0.090" minimum wall thickness is only acceptable in sizes up to 1 ½ inches. Pipe in sizes greater
than that have progressively greater minimum wall thickness.

I have just finished the investigation of a fatal accident, in which 2" ABS pipe with .090 walls
was involved and one contributing factor I attribute to the high SDR ratio, although other factors
were the primary cause, in my estimation.

Although this pipe was selected before Part 192 was in effect, I believe that paragraph 92.321 (d)
should be deleted or changed to reference ASTM 2513. to prevent someone in the thinking that .090
is ok for all sizes.

Please confirm that my thinking in this matter is correct and turn this request over to the
standards group for correction of Part 192,
Sincerely,
Arizona Corporation Commission
H. R. Garabrant, P.E.
Gas Utilities Safety Engineer
Utilities Division

Regulation Sections