Interpretation Response #PI-01-0110 ([Washington Utilities and Transportation Commission] [Mr. Douglas Kilpatrick, P.E.])
Below is the interpretation response detail and a list of regulations sections applicable to this response.
Interpretation Response Details
Response Publish Date:
Company Name: Washington Utilities and Transportation Commission
Individual Name: Mr. Douglas Kilpatrick, P.E.
Location State: WA Country: US
View the Interpretation Document
Response text:
U.S. Department of Transportation
Research and Special Programs Administration
400 Seventh St. S.W.
Washington, D.C. 20590
May 31, 2001
Mr. Douglas Kilpatrick, P.E.
Pipeline Safety Director
Washington Utilities and Transportation Commission
P.O. Box 47250
Olympia, WA 98504-7250
Dear Mr. Kilpatrick:
This letter is in response to your letter of March 15, 2001, requesting an interpretation of the pipeline pressure up rating requirements in 49 CFR Part 192, Subpart K.
You note that a local distribution company (LDC) wants to up rate a steel pipeline in a Class 3 location to a pressure that will produce a hoop stress of less than 30 percent of specified minimum yield strength (SMYS). In 1957, the pipe was pressure tested to 465 psig and the LDC established a maximum allowable operating pressure (MAOP) of 190 psig based on the highest operating pressure during the five-years prior to July 1, 1970. The LDC proposes to raise the pressure from 190 psig to 250 psig in four increments of 15 psig.
You assert that the up rating procedure described above does not meet the minimum requirement of 49 CFR § 192.553(d), which states that
... a new maximum allowable operating pressure established under this subpart may not exceed the maximum that would be allowed under this part for a new segment of pipeline constructed of the same materials in the same location.
We agree that the word "part" as used in 192.553(d) refers to 49 CFR Part 192, rather than just to Subpart K. Therefore, any up rating is limited by the provisions of § 192.619, Maximum allowable operating pressure; Steel or plastic pipelines.
The up rating regulations in Subpart K do not require that a new pressure test be conducted at the time of up rating. And, § 192.555(c), which covers up rating to a pressure that will produce a hoop stress 30 percent or more of SMYS, explicitly allows the use of a previous pressure test as the basis for MAOP, even if the pipeline was not operated to the MAOP during the five years prior to July 1, 1970. Although the use of a previous pressure test is not mentioned in § 192.557, which covers up rating to a pressure that will produce a hoop stress less than 30 percent of SMYS, it makes no sense to rely on a previous pressure test for high-stress pipe and to disallow it for low-stress pipe. And, in any case, § 192.553(d) clearly states that the new MAOP may not exceed the maximum that we would allow for new pipe of the same material at the same location. Therefore, reliance on a previous pressure test is allowable for up rating to a higher MAOP, providing that the pressure test, de-rated for class location as specified in § 192.619, allows for a maximum allowable operating pressure equal to or greater than the proposed up rated pressure.
In response to your specific questions:
- Do you agree with our interpretation that the LDC must up rate to a pressure using the table and factors found in 49 CFR § 192.619(a)(2)(ii)?
Answer: No. The LDC may follow the up rating procedure in 49 CFR Part 192, Subpart K. The up rated pressure will be limited to the maximum pressure that can be supported by a current or previous pressure test, as de-rated for class location using the factors found in 49 CFR § 192.619(a)(2)(ii).
- If you agree, is the factor used based on date installed, or date up rated. In this case would the LDC need to up rate to 375 psig (250 x 1.5 - date updated) or 350 psig (250 x 1.4 -- date installed) to establish an MAOP of 250 psig?
Answer: Not applicable.
- According to § 192.555(c), can a pipeline installed and tested prior to the start of the five-year window ending July 1, 1970, be up rated to a pressure that will produce a hoop stress of 30 percent or more of SMYS, using the original pressure test as the basis of the MAOP?
Answer: Yes. 49 CFR § 192.555(c) states that ". . . an operator may increase the MAOP of a segment of pipeline constructed by September 12, 1970, to the highest pressure that is permitted under § 192.619, using as test pressure the highest pressure to which the segment of the pipeline was previously subjected." A new pressure test is not required, unless the old pressure test cannot justify the up rated pressure.
If you need further assistance, please call me at (202) 366-4565.
Sincerely yours,
Richard D. Huriaux, P.E.
Manager, Regulations
Office of Pipeline Safety
Regulation Sections
| Section | Subject |
|---|---|
| 192.553 | General requirements |