{"operation":"document","citation":"PI-18-0003","title":"Enstar Natural Gas Company — Pipeline Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"2019-03-11","effective_on":null,"summary":"PI-18-0003 response to Enstar Natural Gas Company concerning 192.467.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-18-0003.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-18-0003.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-18-0003","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/docs/standards-rulemaking/pipeline/interpretations/70716/enstar-pi-18-0003-03-11-2019-part-192467.pdf","body":"<<<PAGE 1>>>\n\nU.S. Department\nofTransportation\nPipeline and Hazardous Materials\nS afety Administration\n1200 New Jersey Avenue SE\nWashington DC 20590\nHAR TT28 1 9\nMr. Steve Cooper\nDirector of Operations\nEnstar Natural Gas Company\n3000 Spenard Road\nP.O. Box 190288\nAnchorage, AK 99519-0288\nDear Mr. Cooper:\nIn a letter to the Pipeline and Hazardous Materials Safety Administration (PHMSA), you\nrequested an interpretation of 49 Code of Federal Regulations (CFR) Part 192. Specifically, you\nrequested interpretation for external corrosion control under § 192.467.\nYou stated that in cases where a casing is shorted with a pipeline, electrical isolation of the\npipeline would not be practical, and as an alternative solution to compliance with the\nrequirement, Enstar Natural Gas Co. (Enstar) has been performing increased interval leak\nsurveys to ensure integrity of the pipeline system. You stated that the inspection process has\nbeen completed annually. You stated, in the past, PHMSA issued an interpretation\n(Interpretation PI-86-004) that allowed this compliance method. You asked PHMSA to provide\nEnstar a similar interpretation.\nAs to the referenced interpretation (PI-86-004) compliance alternative, the tests under\n§ 192.465(a) is for a pipeline that is under cathodic protection and the test is conducted once\neach calendar year. Section 192.465 governs how often external corrosion must be monitored,\nwhereas§ 192.467 provides the requirements for achieving electrical isolation of buried or\nsubmerged pipelines. The § 192.467 requirements apply to pipelines that must be electrically\nisolated from other underground metallic structures (in this case, casing) and, therefore, each\npipeline must be electrically isolated from metallic casings that are a part of the underground\nsystem. Therefore, an operator must comply with the monitoring requirements under\n§ 192.465(a), as well as following the§ 192.467 requirements for casings shorted to the\npipelines.\nAs you know, a pipeline system is not cathodically protected if it is not protected in its entirety.\nAs in this case, a pipeline inside a casing is not cathodically protected where the casing is shorted\nto the pipeline. Paragraph 192.467(c) states that \"if isolation is not achieved because it is\nimpractical, other measures must be taken to minimize corrosion of the pipeline inside the\ncasing.\"\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\nPerforming annual leak surveys identifies where corrosion has already occurred to such a degree\non Enstar's pipeline that it is leaking. Depending upon the pipeline maximwn allowable\noperating pressures (MAOP), diameter, operating stress levels, gas odorization, and pipe material\nproperties, leak detection may not be effective for maintaining safety. As such, Enstar's usage of\nannual leak surveys for casings shorted to the casing may not be an acceptable \"other measure to\nminimize corrosion of the pipeline inside the casing\" as required by§ 192.467.\nIn the case of a casing shorted to the pipeline, Enstar must develop and implement procedures for\nperforming inspections and tests, implementing remedial measures, and docwnenting the\nfindings in accordance with§ 192.467(c) and (d) to determine the adequacy of electrical\nisolation. If there is a short to the casing, Enstar must perform remedial actions to attempt to\nclear the short. PHMSA would expect Enstar, at a minimwn, to clear any shorts that are\npractical to clear such as through the excavation of both ends of the casing, performing\ninspections, re-centering- the carrier pipe inside the casing pipe, and removing or repairing\nmaterials that may cause the short such as: metallic shorts and damaged casing insulator spacers\nat the casing end points and any electrolytes between the casing and pipeline. If after attempting\nto clear the short, it is determined impractical to achieve electrical isolation, Enstar must take\nother preventive measures to mitigate corrosion of the pipeline inside the casing and to maintain\nsafety.\nThe following are examples of other preventive methods that may be used when isolation\nmeasures to clear the short are impractical, if the operator determines they will minimize\ncorrosion of the pipeline inside the casing. These examples clarify and supersede the 1986\ninterpretation (PI-86-004) referenced by Enstar:\n1) filling \"high dielectric fill or corrosion inhibiting materials\" between the casing/carrier\npipe that the operator can demonstrate will minimize corrosion of the carrier pipe and\nmonitoring of the dielectric fill or corrosion inhibiting materials at a minimum in\naccordance with the timing and during the patrolling and leakage surveys required in\n§§ 192.705(b) and 192.706;\n2) monitoring corrosion with in-line inspection (ILi) tools that have demonstrated that they\ncan properly detect and assess corrosion over the shorted locations and including\nconcentrated pinhole corrosion areas along the carrier pipe. When assessing the shorted\nlocations, the operator must use the proper application of ILi tool tolerance, class location\nsafety factor in determining the safe operating pressure for any shorted corrosion area,\nand corrosion growth rate, and at intervals that meet either§ 192.939 or at a more often\nreassessment interval if required based upon corrosion growth rate. If the shorted casing\nmasks a proper inline inspection tool assessment, this would not be an applicable method;\n3) utilizing leak detection monitoring and intervals in combination with Items 1 or 2 above,\nif leak monitoring can maintain safety based upon parameters such as assessments of risk\nand the consequences to the public. The risk assessment must be based upon the pipeline\nMAOP, diameter, operating stress levels, odorization of the gas, usage of remote or\nautomatic closure valves for isolation, the pipeline material properties, whether the\npipeline would only leak at operating pressures, and that leak detection monitoring\n(periodic or ongoing) would reduce the impact of an in-service leak to safety;\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 3>>>\n\n3\n4) 5) implementing remedial measures to maintain the carrier pipe MAOP based upon suitable\nremaining strength calculation methods(§ 192.933(d)(l)(i)) and using the class location\ndesign factor (§ 192.111) of the pipeline whether it is in a high consequence area or non-\nhigh consequence area for any assessment findings, and whether through findings in\nconducting Items 1, 2, or 3 above or other findings; or\napplying for a special permit in accordance with§ 191.341 that is applicable to the\npipeline operating, safety, and environmental conditions.\nIn the case of casing shorted to the pipeline, Enstar must perform inspection, tests, and\nremediation with procedures that are in accordance with§ 192.467. lfwe can be of further\nassistance, please contact Tewabe Asebe at 202-366-5523 .\n. Gale\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 tlie 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\nEN STAR\n.....\nNatural Gas Company\n3000 Spenard Road\nP.O. Box 190288\nAnchorage, AK 99519-0288\nwww.enstarnaturalgas.com\nNovember 14, 2016\nU.S. DOT\nPHMSA Office of Hazardous Materials Standards\nAttn: Pllli-10\nEast Building\n1200 New Jersey A venue, SE.\nWashington, DC 20590-0001\nRE: Interpretation Request, Title 49 Code of Federal Regulations §192.467\nPipeline Safety Officer,\nWith this letter ENST AR Natural Gas Company (ENST AR) requests an interpretation of\n§192.467 External corrosion control: electrical isolation (c) as it pertains to the conditions present at\nspecific locations on its natural gas system. In cases where a casing is shorted with a pipeline, electrical\nisolation of the pipeline as contemplated in 49 C.F.R. 192.467, and as strictly construed, would not be\npractical. Challenges posed by difficulty of construction in areas where maintaining continuity of service\nto end-of-the-road communities during the work have made resolving isolation issues difficult.\nAs an alternative solution to date ENST AR has been performing increased interval leak surveys\nto ensure integrity of the system. This process has been completed annually in accordance with a\nprevious PHMSA interpretation, PI-86-004, which was given to the Public Service Commission of\nKentucky in 1986. ENST AR requests that PHMSA grant the same guidance to ENST AR as described in\nthe interpretation PI-86-004, specifically part 3. Reasonable time allowance and methods for operator\ncorrection of shorted casings.\nShould you have any questions regarding this request for interpretation, please feel free to call me\nat 907-334-7730 between 8:00 AM and 5:00 PM AST.\nSincerely\nENST AR Natural Gas Company\nSteve Cooper, P.E.\nDirector of Operations\nSteve.Cooper@EnstarNaturalGas.com\nAnchorage: 907-277-5551 • Kenai Peninsula Office: 907-262-9334 • Mat-Su Office: 907 376-7979","truncated":false,"body_characters":10227}