Interpretation Response #PI-09-0015
Below is the interpretation response detail and a list of regulations sections applicable to this response.
Interpretation Response Details
August 18, 2009
Mr. Paul Cabot
Gas Piping Technology Committee (GPTC)
American Gas Association
400 North Capitol Street, NW
Washington, DC 20001
Dear Mr. Cabot:
In a letter to the Pipeline and Hazardous Materials Safety Administration (PHMSA) dated October 19,2006, you requested an interpretation of the applicability of the Federal pipeline safety regulations in 49 CFR Part 192 to plastic natural gas pipelines. Specifically, you requested an interpretation of 49 CFR §§ 192.513(c), 192.557(c), and 192.619(a)(2)(i) as they relate to uprating polyethylene (PE) pipelines. You used the example of a 4-inch PE pipeline with a design pressure rating of 100 psig, tested to 75 psig at the time of construction, with a maximum allowable operating pressure (MAOP) of 50 psig. You suggested an approach to uprating such a line to 60 psig in increments without testing the pressure and asked whether your approach would be permissible under current regulations.
You correctly noted that § 192.557( c) permits uprating a pipeline by increasing line pressure in increments. You referenced a November 14, 1973, Office of Pipeline Safety interpretation for steel pipelines that permitted incremental uprating of steel pipelines without a pretest. You stated your belief that if this interpretation were applied to plastic pipelines, uprating incrementally in accordance with § 192.557( c) would be acceptable without testing the pressure. You expressed your view that it would be acceptable to incrementally increase the pressure to the new MAOP without testing it to 1.5 times the new MAOP.
As the regulatory agency with primary responsibility. for pipeline safety in the U.S., PHMSA is obligated to ensure the pipeline safety requirements provide an adequate margin of safety. In carrying out our responsibilities, we appreciate receiving input and views from all stakeholders and particularly appreciate the views of the GPTC. In this case, however, we can not agree that the above referenced interpretation can be applied to plastic pipelines. Under § 192.619 the MAOP requirements for steel and plastic pipelines are not the same. For plastic pipelines § 192.619(a)(2)(i) requires the following:
§ 192.619 - (a) Except as provided in paragraph (c) of this section, no person may operate a segment of steel or plastic pipeline at a pressure that exceeds the lowest of the following:
(2) The pressure obtained by dividing the pressure to which the segment was tested after construction as follows: (i) For plastic pipe in all locations, the test pressure is divided by a factor of 1.5.
We agree that § 192.557 allows the uprating ofPE pipelines. However, § 192.619 (a)(2)(i) requires the operator to increase the uprating test pressure to 1.5 times the new MAOP in order to meet the lowest limiting factor for the new MAOP. Therefore, in order for the operator to increase the MAOP from 50 psig to 60 psig, a pressure test to 1.5 times the new MAOP (90 psi g) must be conducted to comply with the § 192.619 (a)(2)(i) requirements. I In addition, other applicable requirements must be met including:
" Following procedures prior to uprating (§ 192.557(b)(1 »;
" Checking rating of applicable appurtenances for the test pressure; and
" Meeting and maintaining operating conditions to ensure pressure increments as required by the uprating (§ 192.553(a».
I hope that this information is helpful to you. If I can be of further assistance, please contact me at (202) 366-4046.
John A. Gale
Director, Office of Regulations
|§ 192.557||Uprating: Steel pipelines to a pressure that will produce a hoop stress less than 30 percent of SMYS: plastic, cast iron, and ductile iron pipelines|