{"operation":"document","citation":"PI-78-034","title":"Gas Pipeline Safety Division — Pipeline Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"1978-12-14","effective_on":null,"summary":"PI-78-034 response to Gas Pipeline Safety Division concerning 192.457.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-78-034.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-78-034.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-78-034","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/Pipeline/1978/PI78034.pdf","body":"<<<PAGE 1>>>\n\nMr. T. K. Spalding\nDirector\nGas Pipeline Safety Division\nWest Virginia Public Service Commission\nCharleston, WV 25305\nDear Mr. Spalding:\nIn your letter of November 29, 1973, you forwarded questions submitted to you by a local\noperator. These questions with our comments are as follows:\nQuestion 1\nDo the minimum standards require the cathodic protection of the section of a bare, welded\ntransmission line where it crosses a public highway, or makes a parallel encroachment on the\nright-of-way, if both the transmission line and the highway are in a Class 1 location?\nOPS Comment\nRegardless of Class or location (such as at a highway crossing), a transmission operator must\ncomply with Section 192.457(b)(1) which requires cathodic protection in areas in which active\ncorrosion is found. As required by Section 192.457(b), the operator shall determine areas of\nactive corrosion by electrical survey, or where electrical survey is impractical, by the study of\ncorrosion and leak history records, by leak detection survey, or by other means. Specifically, if\ntests do not indicate the presence of active corrosion at a highway crossing, then cathodic\nprotection is not necessary.\nQuestion 2\nOn a bare transmission or distribution line do you consider a soil resistivity survey to be an\nelectrical survey, as required by 192.457(b), for determining hot spot protection?\nOPS Comment\nA soil resistivity survey consists of electrical measurements which are helpful in determining those\nportions of a pipeline system in which corrosion is more likely to occur than in other portions.\nFollowing this survey, an electrical survey, such as pipe-to-soil potential measurements or surface\npotential measurements, is normally made in areas of low resistivity so that cathodic protection\ncan be provided first in those areas that need it most.\nDB\nC:\\WP51\\INTERPRT\\192\\457\\78-12-14\n1\n\n<<<PAGE 2>>>\n\nOn a transmission pipeline, an electromagnetic survey could be made in lieu of soil resistivity and\npie-to-soil potential surveys.\nIf an operator plans to cathodically protect an entire portion of bare transmission pipeline or\ndistribution system, a soil resistivity survey is sufficient. If the operator plans to provide cathodic\nprotection only in areas of active corrosion as required by Section 192.457(b), a soil resistivity\nsurvey by itself will not pinpoint areas of active corrosion. For this reason, a combination of soil\nresistivity survey and, for example, pipe-to-soil potential survey is necessary.\nI trust this answers your questions. If not, please let us know.\nSincerely,\nJoseph C. Caldwell\nDirector\nOffice of Pipeline Safety\nDB\nC:\\WP51\\INTERPRT\\192\\457\\78-12-14\n2","truncated":false,"body_characters":2677}