{"operation":"document","citation":"PI-15-0004","title":"Alaska LNG — Pipeline Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"2015-09-28","effective_on":null,"summary":"PI-15-0004 response to Alaska LNG concerning 192.112.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-15-0004.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-15-0004.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-15-0004","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/Pipeline/2015/Alaska_LNG_PI_15_0004_09_28_2015_Part_192_112.pdf","body":"<<<PAGE 1>>>\n\nU.S. Department\nof Transportation\nPipeline and Hazardous\nMaterials Safety\nAdministration\n1200 New Jersey Avenue, SE\nWashington, D.C. 20590\nSEP 2 8 2015\nMr. Rick Noecker\nPHMSA Filing Coordinator\nAlaska LNG\n#19025, 237- 4th Ave SW\nCalgary, Alberta T2P OH6, Canada\nDear Mr. Noecker:\nIn a letter to the Pipeline and Hazardous Materials Safety Administration (PHMSA) dated\nApril30, 2015, you requested an interpretation on 49 CFR 192.112(b)(3) and 192.112(b)(2)(iii)\nwith respect to crack arrestor spacing for gas transmission lines.\nYou stated that you performed fracture control calculations in accordance with § 192.112(b )( 1)\nand found that the fracture arrest requirements of§ 192.112(b )(2)(iii) cannot be intrinsically\nobtained with modern X-80 line pipe for an anticipated 2,075 psi design pressure, 42\" diameter\ngas transmission line. You plan to utilize an alternative maximum allowable operating pressure\ndesign with crack arrestor spacing of 8 joints to meet the requirements of§ 192.112(b )(3 ). You\nare seeking guidance regarding fracture control crack arrestor requirements under 49 CFR Part\n192.112(b ). Specifically, you asked how the § 192.112(b )(2)(iii) requirement is applied with the\nuse of mechanical crack arrestors since every crack arrestor is expected to arrest a running\nductile fracture, and you stated that there is no guidance on this in industry consensus standards.\nSection 192.112(b) requires the remediation of potential pipe crack initiation, propagation, and\narrest of fractures to be based upon the full range of gas compositions, operating pressures,\noperating temperatures, pipe grades, and maximum operating stresses including maximum\npressures and minimum temperatures for shut-in conditions that the pipeline will experience\nduring its operating life. The fracture control described in § 192.112(b) limits the maximum\nfracture length to 8 pipe joints with a 99 percent probability of arrest through several possible\nmethods an operator may select, which may include higher pipe toughness, heavier walled pipe,\ncrack arrestors (either mechanical or composite) or a combination of these methods.\nThe Pipeline and Hazardous Materials Safety Administration, Office of Pipeline Safety provides written\nclarifications ofthe Regulations ( 49 CFR Parts 190-199) in the form of interpretation letters. These letters reflect\nthe agency's current application of the regulations to the specific facts presented by the person requesting the\nclarification. Interpretations do not create legally-enforceable rights or obligations and are provided to help the\npublic understand how to comply with the regulations.\n\n<<<PAGE 2>>>\n\n2\nTherefore, it is your responsibility to make sure that the methods chosen are appropriate to the\nrelevant operating factors and§ 192.112 requirements are met. I hope that this information is\nhelpful to you. If we can be of further assistance, please contact Tewabe Asebe of my staff at\n202-366-5523.\nSincerely,\n#//.//v 1/W:TJ.\nJohn A. Gale\nDirector, Office of Standards\n(\nand Rulemaking\nThe Pipeline and Hazardous Materials Safety Administration, Office of Pipeline Safety provides written\nclarifications of the Regulations ( 49 CFR Parts 190-199) in the form of interpretation letters. These letters reflect\nthe agency's current application of the regulations to the specific facts presented by the person requesting the\nclarification. Interpretations do not create legally-enforceable rights or obligations and are provided to help the\npublic understand how to comply with the regulations.\n\n<<<PAGE 3>>>\n\nAlaska LNG\nAlaska LNG Project\nPipeline Engineering\n237 4th Ave SW\nCalgary, AB T2P OH6\nCANADA\n28 April2015\nMr. John A. Gale, Director\nOffice of Standards and Rulemaking (PHP-30)\nPHMSA, U.S. Department of Transportation,\n1200 New Jersey Avenue, SE\nWashington, DC 20590-0001\nUSA\nRe: Request for Interpretation of 49 CFR §192.112(b)(3) and §192.112(b)(2)(iii) with\nrespect to crack arrestor spacing for gas transmission lines\nDear Mr. Gale:\nOur project has performed fracture control calculations in accordance with §194.112(b)(1) and\nfound that the fracture arrest requirements of § 192.112(b )(2)(iii) cannot be intrinsically obtained\nwith modern X80 line pipe given our anticipated 2,075 psi design pressure, 42\" diameter gas\ntransmission line. We plan to utilize an alternative maximum allowable operating pressure\ndesign. Therefore, we plan to design crack arrestors with a spacing of 8 joints to meet the\nrequirements of §192.112(b)(3). We are seeking confirmation in this request for interpretation\nregarding fracture control crack arrestor requirements under 49 CFR Part 192.112(b).\nBackground\nThe regulation at 49 CFR Part 192.112(b )(3) states that\nIf it is not physically possible to achieve the pipeline toughness properties of paragraphs\n(b)(1) and (2) of this section, additional design features, such as mechanical or\ncomposite crack arrestors and/or heavier walled pipe of proper design and spacing,\nmust be used to ensure fracture arrest as described in paragraph (b)(2)(iii) of this\nsection.\n§192.112(b)(2)(iii) goes on to state that fracture control must\nensure at least 99 percent probability of fracture arrest within eight pipe lengths with a\nprobability of not less than 90 percent within five pipe lengths\n\n<<<PAGE 4>>>\n\nThe language in Part 192.112 (b )(2)(iii) is based on the common approach of specifying pipe\ntoughness requirements such that 50% of pipe joints will be capable of arresting a running\nductile fracture. With 50% of pipe joints arresting a crack, the 99% probability in eight joints and\n90% probability in five joints criteria are satisfied. It is not clear how this requirement is applied\nwith the use of mechanical crack arrestors since every crack arrestor is expected to arrest a\nrunning ductile fracture, and there is no guidance on this in consensus standards.\nIn PHMSA's March 8, 2011 letter to the Alaskan Pipeline Project, it communicated the following\nwith respect to \"Crack arrestor spacing\" (emphasis added):\nAs prescribed in 49 CFR § 192.112(b), a pipeline that operates under the alternative\nMAOP provisions of Part 192 must be able to demonstrate that failure cracks will self-\narrest within five (5) pipe joints with 90% probability, Q! within eight (8) pipe joints with\n99% probability.\nThe PHMSA letter to APP, which includes the conjunction \"or'' between the two probabilistic\nrequirements, indicates that ensuring arrest within eight (8) pipe lengths is sufficient to meet the\nregulatory requirements.\nRequest for Interpretation\nAKLNG believes that a crack arrestor spacing of eight joints, with each arrestor designed to\narrest a running ductile fracture, meets the requirements of §192.112(b)(3) and\n§192.112(b)(2)(iii). Confirmation of this interpretation is requested.\nThank you for your consideration of this request for interpretation.\nSincerely,\n;;C/7Lf!\nRick Noecker\nPHMSA Filing Coordinator\nAKLNG Project, Pipeline Engineering\n#19025, 237- 4th Ave SW\nCalgary, Alberta T2P OH6\n587-476-4891 (voice)\n587-582-9666 (mobile)\nrick.noecker@exxonmobil.com","truncated":false,"body_characters":7089}