{"operation":"document","citation":"PI-93-039","title":"Airborne Environmental Surveys — Pipeline Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"1993-07-16","effective_on":null,"summary":"PI-93-039 response to Airborne Environmental Surveys concerning 192.463.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-93-039.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-93-039.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-93-039","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/Pipeline/1993/PI93039.pdf","body":"<<<PAGE 1>>>\n\nJuly 16, 1993 (?)\nMr. Dave Mitchel\nDirector\nAirborne Environmental Surveys\nSuite 108\n3130 Skyway Drive\nSanta Maria, CA 93455\nDear Mr. Mitchel:\nThis responds to your letter of April 12, 1993, to George W. Tenley, Jr. regarding the use\nof airborne cathodic monitoring equipment to detect and measure the impressed cathodic\ncurrents in pipelines. Your letter states that your technology involves the determination of\ncurrent and current density at any point on an impressed-current pipeline by direct\nmeasurement of electromagnetics, specifically the magnetic field associated with the\nimpressed current. Your letter further states that these measurements may be made from\nground surface, or from airborne platforms.\nProperly applied, electromagnetic can yield continuous measurements and plots of current\nalong a pipeline, including interference from foreign pipelines, bonds, taps, casing shorts,\ncoupling separations, coating conductivity changes and holidays. It is very important that\nan existing baseline pipe-to-soil potential be established by conventional methods. The\nelectromagnetic techniques can be employed to establish baseline data that can be overlaid\non the original baseline pipe-to-soil to accurately portray the performance of the cathodic\nprotection system. This technique would provide an approach to assess the performance\nof the cathodic protection system to determine compliance with the requirements of 49\nCFR 192.463(a) and §192.465(b) and (c).\nAs set forth in my letter of November 7, 1991, an operator has the freedom to conduct its\ninspections utilizing whatever appropriate technology or means it chooses, including your\nairborne cathodic monitoring equipment, to comply with the inspections under 49 CFR\n192.463(a) and §192.465(b) and (c) of rectifiers or other impressed current power source.\nIf the airborne cathodic monitoring equipment provides reliable data, your airborne remote\nsensing technique is an acceptable means of inspection under the above rules.\nSincerely,\nCesar De Leon\nDirector, Regulatory Programs\nOffice of Pipeline Safety\ndal\\192.463\\93-07-16","truncated":false,"body_characters":2108}