{"operation":"document","citation":"PI-81-014","title":"Memo: Internal — Pipeline Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"1981-07-09","effective_on":null,"summary":"PI-81-014 response to Memo: Internal concerning 192.455.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-81-014.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-81-014.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-81-014","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/Pipeline/1981/PI81014.pdf","body":"<<<PAGE 1>>>\n\nACTION: Request for Interpretation of\nSection 192.455(a) Relative to the Use\nof Metallic Sleeve Crack Arrestors on\nLarge Diameter Pipelines\nMelvin A. Judah\nActing Associate Director Gas Pipeline Project\nLloyd W. Ulrich\nDirector, Alaska Natural Gas Pipeline Project, DMT-50\nYour memorandum of March 17, 1981, asks whether the crack arrestor sleeves designed for the\nNorthern Border Pipeline Company would affect compliance with sections 192.455(a) and\n192.463(a) for segments of pipeline underneath the sleeves.\nYou have raised a proposition, based on pipeline casings, that once the sleeves are in place, they\nmay shield the pipeline from cathodic protection needed to comply with section 192.455(a) and\nmake it difficult to determine whether protection is at the level required by section 192.463(a).\nRegarding pipeline casings, experience shows that if casings are properly installed in a manner\nwhich assures that the casing is electrically isolated from the pipeline, and will remain so, and the\npipeline in the casing is effectively coated and free of holidays, the pipeline will be protected\nagainst corrosion by standard corrosion protection methods. Of course, if casings become\nelectrically shorted, the pipeline beneath the casing will not be cathodically protected as required.\nWe do not know any reason why a crack arrestor sleeve would not behave in this same way.\nIt seems, therefore, the problem facing Northern Border is verification of electrical isolation\nthrough inspection during construction and subsequent operation of the pipeline.\nDB\nC:\\WP51\\INTERPRT\\192\\455\\81-07-09\n1\n\n<<<PAGE 2>>>\n\nACTION: Request for Interpretation of §192.455(a) relative to the use of metallic sleeve\ncrack arrestors on large diameter pipelines.\nLloyd W. Ulrich, Director\nAlaska Natural Gas Pipeline Project\nDMT-50\nMelvin A. Judah, Acting Associate Director\nfor Pipeline Safety Regulation, DMT-30\nIn May 1981, Northern Border Pipeline Company is planning to begin construction of 823 miles\nof 42-inch pipeline from Phillips County, Montana, to Hancock County, Iowa. This will be part\nof the eastern leg of the Alaska Natural Gas Transportation System. The line is designed to\noperate at 1435 psig.\nIn an effort to minimize the effects of a potential pipeline failure by a longitudinal propagating\nductile fracture, Northern Border is planning to install at an even spacing along the pipeline, steel\nsleeve type crack arrestors loosely fit around the outside of the pipeline. These sleeves are grade\nX-70 steel, two feet long, with 44.250 inch O.D. and 0.598 inch wall thickness, giving a 43.050\nnominal I.D. The crack arrestor will be installed on a precoated nominal 40 feet length of 42-inch\nO.D. grade X-70 pipe.\nThe sleeve will be installed by centering the sleeve over one end of the 42-inch line pipe and\nadvancing it until a minimum distance of 10 feet exists from the end of the pipe to the crack\narrestor. The sleeve will be supported by five urethene supports at each end and spaced at equal\ndistances around its circumference.\nAfter installation of the centering supports, a seven-inch wide pipeline coating tape will be\ncentered at each end of the crack arrestor sleeve for an end seal. Temporary sealing straps will be\ninstalled around the circumference of the tape as a reinforcement.\nA 3/8-inch zerk fitting is to be installed in a hole previously taped at the bottom of the sleeve. An\nasphalt extended urethane will be pumped through the zerk fitting into the annulus between the\npipe and the crack arrestor sleeve until liquid urethane vents from a 1/4-inch vent at the top of the\ncrack arrestor.\nAfter the urethane cures to a solid, the temporary end seal straps and the zerk fittings are to be\nremoved. In addition, the vent hole and the fill hole will be filled. Pipeline coating tape will be\napplied over the entire sleeve extending sufficiently onto the pipeline to a positive seal.\nDB\nC:\\WP51\\INTERPRT\\192\\455\\81-07-09\n2\n\n<<<PAGE 3>>>\n\nFrom the above description, it can be seen that the crack arrestor sleeves are similar to pipeline\ncasings that are regularly used on pipelines at road and railroad crossings. It has been well-\nestablished that despite the possible shielding of cathodic protection by pipeline casings, they do\nnot cause a corrosion problem provided they are well insulated from the carrier pipe and water is\nkept out of the casing. However, we are not aware of any studies that have shown that cathodic\nprotection on a pipeline will be effective inside of a casing. As a result, it appears that a segment\nof a pipeline inside of a casing or crack arrestor sleeve on a pipeline that has a cathodic\nprotection system installed to comply with §192.455(a) may not be \"protected in its entirety\" as\nrequired by §192.455(a)(2).\nFrom a practical standpoint, we believe that there would be no corrosion problem with the crack\narrestor sleeves when installed as described above. The mainline pipe coating, in addition to the\nasphalt extended urethane, and the pipeline coating tape over the entire unit are all high dialectic\nstrength materials and excellent moisture barriers which would virtually eliminate the possibility of\ncorrosion.\nCasings and crack arrestor sleeves also make it very difficult to determine the level of cathodic\nprotection as required by §192.463(a).\nIn view of the above discussion, it is requested that an interpretation be made as to whether the\nuse of the crack arrestor sleeves described would be in compliance with §192.455(a) and\n192.463(a).\nBecause of the short time before construction begins on this pipeline and the possible need for a\nwaiver, it is requested that this interpretation be expedited in compliance with the requirements of\nSection 9(b) of the Alaska Natural Gas Transportation Act of 1976.\n#\nDB\nC:\\WP51\\INTERPRT\\192\\455\\81-07-09\n3","truncated":false,"body_characters":5825}