{"operation":"document","citation":"PI-91-013","title":"Office of Pipeline Safety — Pipeline Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"1991-05-23","effective_on":null,"summary":"PI-91-013 response to Office of Pipeline Safety concerning 192.479, 192.481.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-91-013.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-91-013.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-91-013","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/Pipeline/1991/PI91013.pdf","body":"<<<PAGE 1>>>\n\nMr. Walter Kelly\nDirector\nOffice of Pipeline Safety\n175 Aurora Avenue\nSt. Paul, MN 55103\nDear Mr. Kelly:\nI am responding to Mr. William Barbeau's letter of January 9, 1991. He asked us to comment on\nhis position that passive surface oxidation, or surface rust, comes within the meaning of\n\"atmospheric corrosion\" under §§192.479 and 192.481.\nSurface rust or passive surface oxidation caused by atmospheric corrosion would subject the\npipeline to the requirements of §192.479(b) if the corrosion is deteriorating the pipeline, such as\npitting. Section 192.479(a) requires that a pipeline be cleaned and either coated or jacketed with\na material suitable for the prevention of atmospheric corrosion unless it can be shown that a\ncorrosive atmosphere does not exist; e.g., showing that passive surface oxidation does not\ndeteriorate the pipeline. In any event, §192.481 requires that pipelines that are exposed to the\natmosphere be monitored for atmospheric corrosion.\nWith regard to the assertions by two operators that passive film oxidation protects the pipeline,\nstudies have shown that passive film oxidation inhibits atmospheric corrosion. Therefore, the rate\nof corrosion could be slowed to the point that the corrosion is not deteriorating the pipeline.\nPlease let me know if you need further assistance in this matter.\nSincerely,\nGeorge W. Tenley, Jr\nAssociate Administrator\nfor Pipeline Safety\nDB\nC:\\WP51\\INTERPRT\\192\\479\\91-05-23\n1","truncated":false,"body_characters":1453}