{"operation":"document","citation":"PI-18-0007","title":"Public Service Commission of Wisconsin — Pipeline Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"2018-09-27","effective_on":null,"summary":"PI-18-0007 response to Public Service Commission of Wisconsin concerning 192.557, 192.619.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-18-0007.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-18-0007.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-18-0007","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/docs/standards-rulemaking/pipeline/interpretations/69306/wisconsin-psc-pi-18-0007-09-27-2018-part-192557-and-192619.pdf","body":"<<<PAGE 1>>>\n\nU.S. Department\nofTransportation\nPipeline and Hazardous Materials\nSafety Administration\n1200 New Jersey Avenue SE\nWashington DC 20590\nS E P 2 7 2018\nMr. Thomas M. Stemrich\nPipeline Safety Program Manager\nPublic Service Commission of Wisconsin\n610 N. Whitney Way\nP.O. Box 7854\nMadison, WI 53707\nDear Mr. Stemrich:\nIn a March 7, 2018, letter to the Pipeline and Hazardous Materials Safety Administration\n(PHMSA), you requested an interpretation of 49 Code of Federal Regulations (CFR) Part 192.\nSpecifically, you requested an interpretation to clarify if a pressure test (using natural gas as the\ntest medium) conducted for purpose of uprating maximum allowable operating pressure (MAOP)\nin accordance with 49 CFR Part 192, subpart K could be a flowing gas test, or if the regulations\nrequire a static pressure test. You expressed an opinion that the pressure test required under\n§ 192.619(a)(2)(ii) should be a static pressure test that holds the pressure constant so that all\npotentially hazardous leaks can be detected.\nYou stated that you have a case where an operator, Xcel Energy, is planning to uprate a steel\npipeline from an MAOP of 316 psig to 400 pounds per square inch gauge (psig)1 and provided\nthe following additional information:\n• The operator would like to perform a flowing gas pressure test to 1.5 times the desired\nMAOP (i.e., the test pressure would be 600 psig).\n• The operator would raise the MAOP in four equal increments.\n• The pressure would be held constant for one hour at each interval while a leak survey of the entire\nsystem is conducted.\n• Once the pressure reached 600 psig, a final leak survey would be conducted, and the pressure\nwould be allowed to drop to 400 psig through normal system load demand, or by flaring the gas.\n• A follow-up leak survey would be conducted a week after the line had been running at 400 psig.\nThrough supplemental communication, you provided the following additional information:\n• The pipeline was constructed in 1992.\n• Most of the segment to be uprated is located in class 1 locations, but some portions are in\nclasses 2 and 3.\n1 Xcel Energy requested similar interpretation but withdrew the request.\nThe Pipeline and Hazardous Materials Safety Administration, Office of Pipeline Safety provides written clarifications of the Regulations (49 CFR\nParts 190-199) in the form of interpretation letters. These letters reflect the agency's current application of the regulations to the specific facts\npresented by the person requesting the clarification. Interpretations do not create legally-enforceable rights or obligations and are provided to\nhelp the public understand how to comply with the regulations.\n\n<<<PAGE 2>>>\n\n2\no PHMSA comment: The proposed test pressure would need to be in compliance with\n§ 192.619(a)(2) for class 3 pipe (1.5 times proposed MAOP).\n• The maximum test pressure would be less than 30 percent of the pipe specified minimum\nyield strength (SMYS).\no PHMSA comment: This would be in compliance with§ 192.503(c), although\nPHMSA notes that any test pressure excursion above 30% of SMYS would not\ncomply with§ 192.503(c) and would not be allowed].\n• You stated that the operator might not have pressure test records or complete material\nrecords available to confirm the current MAOP of portions of the pipeline segment to be\nuprated (therefore, there may be specific attributes that were not provided because they\nare unknown).\nFor the circumstance described above, a number of conditions and requirements apply which\nmight preclude the use of a flowing gas test to uprate MAOP, depending on the circumstance.\nThe information provided is insufficient to make a definitive conclusion for the situation you\ndescribe. Some of these requirements and potential impediments to the use of a flowing gas test\nare discussed below. This is not an exhaustive list of requirements that might preclude use of a\nflowing gas test.\nFor a steel pipeline operated at 100 psig or more and below 30% SMYS, the applicable technical\nrequirements of subpart Kare contained in§§ 192.553 and 192.557. Operators must follow all\nrequirements in§§ 192.553 and 192.557. In addition, pressure tests must comply with subpart J\nand§ 192.619(a). With respect to the acceptability of a flowing gas pressure test to uprate\nMAOP, PHMSA points out the following:\nLimitation of §192.553(d)\nSection 192.553(d) has a limitation on uprating. The uprated MAOP may not exceed the MAOP\nthat would be allowed under§§ 192.619 and 192.621 for a new segment of pipeline constructed\nof the same materials in the same location. Thus, the operator would have to ensure that an\nuprated MAOP does not exceed the lowest of the four pressures determined in accordance with\n§192.619(a)(l), (a)(2), (a)(3), and (a)(4). The pressure test itself would satisfy paragraph (a)(2).\nParagraph (a)(3) is not applicable because the pipeline was constructed after 1970. Paragraph\n(a)(4) could be satisfied by the review required in §192.557(b). Section 192.619(a)(l) would\nrequire the following:\n• However, for steel pipe in pipelines being uprated under subpart K, §192.553(d)\nemphasizes that \"if any variable necessary to determine the design pressure under the\ndesign formula (§192.105) is unknown, the MAOP may be increased as provided in\n§192.619(a)(l).\" In accordance with §192.619(a)(l), if any variable necessary to\ndetermine the design pressure of the weakest element in the segment ( determined in\naccordance with subparts C and D) is unknown, 192.619(a)(l) requires that one of the\nfollowing be used as the design pressure:\n(i) Eighty percent of the first test pressure that produces yield under section NS of\nAppendix N of ASME B31.8 (incorporated by reference, see § 192. 7), reduced by\nthe appropriate factor in paragraph (a)(2)(ii) of this section; or\nThe Pipeline and Hazardous Materials Safety Administration, Office of Pipeline Safety provides written clarifications of the Regulations\n(49 CFR Parts 190-199) in the fonn of interpretation letters. These letters reflect the agency's current application of the regulations to the\nspecific facts presented by the person requesting the clarification. Interpretations do not create legally-enforceable rights or obligations and\nare provided to help the public understand how to comply with the regulations.\n\n<<<PAGE 3>>>\n\n3\n(ii) If the pipe is 12¼ inches (324 mm) or less in outside diameter and is not tested\nto yield under this paragraph, 200 p.s.i. (1379 kPa).\nIn order to uprate to a higher MAOP, the operator must know the pipeline material attributes\nrequired in§§ 192.619(a)(l) and 192.105, including diameter, wall thickness, yield strength\n(grade), seam type, and other component pressure ratings (valves, flanges and fittings). For the\ncircumstance described above in which some attributes are not known, a flowing gas test (which\nis limited to 30% of SMYS in accordance with 192.503(c)) would not produce yield and would\nbe insufficient to establish the design pressure for pipe segments with unknown design\nproperties. A hydrostatic test to yield would be required (if the pipe is 12¼ inches or less in\noutside diameter and is not tested to yield, the MAOP would be limited to no more than 200\npsig).\nIn this circumstance (i.e., if any pressure containing material variables necessary to determine the\ndesign pressure under the design formula (§ 192.105) are unknown), a flowing gas pressure test\ncould not be performed because§§ 192.105 and 192.503 requirements would not be verified to\nuprate the MAOP of the segment with natural gas. If material records needed for MAOP\nverification are not available, an operator would need to work with the appropriate 49 CFR Part\n192 Regulating Agency to determine the required material verification activities and any\nrequired special permit (waiver) actions needed to be performed prior to uprating this pipeline\nsegment.\nIsolation of adjacent segments\nAdjacent pipeline segments that are not being updated and/or have an MAOP less than the\nmaximum test pressure must be isolated from the segment being upgraded(§ 192.557(b)(5)).\nTherefore, the operator may not continue to flow gas during the uprating process to a pipeline\nsegment operated at a lower pressure and with an MAOP lower than the maximum test pressure.\nThis requirement might preclude the use of a flowing gas test, depending on the circumstances\nand the effect of isolating adjacent segments.\n• In order to perform a flowing gas pressure test, the adjacent pipeline segment with the\nlower pressure (MAOP) would either need to be isolated or protected by pressure-control\nregulators and with overpressure control and mainline valves for shut-off to prevent over-\npressurization.\nThe Pipeline and Hazardous Materials Safety Administration, Office of Pipeline Safety provides written clarifications of the Regulations\n(49 CFR Parts 190-199) in the form of interpretation letters. These letters reflect the agency's current application of the regulations to the\nspecific facts presented by the person requesting the clarification. Interpretations do not create legally-enforceable rights or obligations and\nare provided to help the public understand how to comply with the regulations.\n\n<<<PAGE 4>>>\n\n4\nIn addition, the operator must take appropriate safety measures to prevent any potential\nhazardous situations should the line leak or fail during the test, including conducting all Code\nrequired leak surveys and repairs. This is especially a concern for uprating segments where the\noperator does not have the pressure test records available to confirm the current MAOP or the\npipeline material properties and component (fittings, flanges or valve) records to confirm the\ndesign pressure of the pipelines' weakest link in accordance with§ 192.619(a)(l).\nIfwe can be of further assistance, please contact Tewabe Asebe at 202-366-5523.\nDirector, Office of Standards\nand Rulemaking\nThe Pipeline and Hazardous Materials Safety Administration, Office of Pipeline Safety provides written clarifications of the Regulations\n(49 CFR Parts 190-199) in the form of interpretation letters. These letters reflect the agency's current application of the regulations to the\nspecific facts presented by the person requesting the clarification. Interpretations do not create legally-enforceable rights or obligations and\nare provided to help the public understand how to comply with the regulations.\n\n<<<PAGE 5>>>\n\nRequest for interpretation- Uprating pressure test.\nGentlemen,\nWe would like your interpretation regarding 192.619(a)(2)(ii) and 192.557. We have a case where an\noperator is planning to uprate a steel pipeline from 316 to 400 psi. The majority of the line was\nconstructed in 1992. In order to meet class 3 design standards, the operator would like to raise the\nMAOP of the pipeline from 316 to 400 PSIG in 4 equal increments to 600 psig (1.5 times the new MAOP).\nGas would be flowing to all the customers along the line in question, during this process. The pressure\nwould be held constant for one hour at each interval while a leak survey of the entire system is\nconducted. Once the pressure has reached 600 psig a final leak survey would be conducted and the\npressure would be allowed to drop to 400 psig through normal system load demand, or by flaring the\ngas. A follow-up leak survey would be conducted a week after the line had been running at 400 psig.\nIt is the contention of PSCW staff that the pressure test required under 192.619(a)(2)(ii) should be a\nstatic pressure test that holds the pressure constant so that all potentially hazardous leaks can be\ndetected. Having gas flowing during the test, in our opinion, would not ensure the discovery of all\npotentially hazardous leaks. We are also concerned that should the line fail during this test it could\ncreate a hazardous situation, depending on where the failure would occur. It should also be noted that\nthe operator does not have the pressure test records available to confirm the current MAOP of portions\nof the pipeline to be uprated.\nWe would appreciate your interpretation on this matter.\nThomas M Stemrich\nPipeline Safety Program Manager\nPublic Service Commission of Wisconsin","truncated":false,"body_characters":12160}