{"operation":"document","citation":"PI-74-0103","title":"Cathodic Protection Service — Pipeline Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"1974-04-11","effective_on":null,"summary":"PI-74-0103 response to Cathodic Protection Service concerning 192.457.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-74-0103.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-74-0103.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-74-0103","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretations/Pipeline/1974/g74-02-25_Canfield_192.457-nlmx.pdf","body":"<<<PAGE 1>>>\n\nPI-74-0103\nOffice of the Secretary of Transportation\nWashington, D.C. 20590\nOriginal letter before\nInserting last paragraph\nAs requested by TGC-20\nMr. Ted L. Canfield\nCathodic Protection Service\nService Division\nP.O. Box 66387\nHouston, TX 77006\nDear Mr. Canfield:\nThis responds to your letters of February 25 and April 11, 1974, in which you refer to the surface potential survey\nmethod for locating areas of active corrosion on bare Dresser-coupled lines. Your comments related to Advisory Bulletin\nNo. 72-8, dated August 1972, which stated our opinion that the two-electrode “leap-frogging” surface potential survey\nmethod will not provide useful information in determining where active corrosion is taking place on Dresser-coupled\npipelines (insulated joints).\nBasically, you raise the same issues discussed in previous correspondence with Mr. Doremus of your firm. (Enclosed are\na letter from Mr. Doremus dated November 2, 1972, and our response of January 3, 1973.) Our position as stated then\nis that the “leap frogging” surface potential survey method may be sued successfully to located areas of active corrosion\non electrically continuous pipelines.\nYour letter addresses bare Dresser-coupled lines without distinguishing between those which have insulated joints and\nthose which do not. If you can determine beforehand that a Dresser-coupled line does not have insulated joints, then\nwe see no problem with using the “leap-frogging” method to detect active corrosion. However, where a line is known to\ncontain insulated joints or there is insufficient information to determine whether or not the joints are insulated, then we\nhold to our opinion that the “leap-frogging” method would not be useful.\nSincerely,\nJoseph C. Caldwell\nDirector\nOffice of Pipeline Safety\n\n<<<PAGE 2>>>\n\nCathodic Protection Service\nP.O. Box 66387\nHouston, Texas 77006\nApril 11, 1974\nDepartment of Transportation\nOffice of the Secretary\nWashington, D.C. 20590\nAttention: Mr. Joseph C. Caldwell, Director\nOffice of Pipeline Safety\nGentlemen:\nInasmuch as we have not yet received any acknowledgement of our letter dated February 25, 1974 (copy of which is\nattached) we are wondering whether this communication might possibly have gone astray and had not yet been\nreceived by your.\nShould such be the case, please let us know so that we may resubmit this correspondence. In the event you have\nreceived our original correspondence, we are, quite naturally, anxious to hear from you concerning the information and\nsuggestions therein.\nVery truly yours,\nCATHODIC PROTECTION SERVICE\nTed L. Canfield\nPartner\n\n<<<PAGE 3>>>\n\nFebruary 25, 1974\nDepartment of Transportation\nOffice of the Secretary\nWashington, D.C. 20590\nAttention: Mr. Joseph C. Caldwell, Director\nOffice of Pipeline Safety\nGentlemen:\nWe have recently been informed that one of the corrosion service firms has stated to potential clients that , “the surface\npotential survey method is neither valid nor approved by DOT as a means of determining locations for “hot spot”\nprotection on bare Dresser-coupled lines.”\nApparently, this statement is premised on a statement set forth by DOT in Advisory Bulletin No 72-8 dated August 1972,\nas follows:\nOPS Interpretation:…”The Office of Pipeline safety does not feel that the use of the two-electrode “leap-\nfrogging” surface potential survey method will provide any useful information in determining where active\ncorrosion is taking place on Dresser-coupled pipelines (insulated joints).\n“…there are other types of electrical equipment that will do this job…Otherwise, areas of active corrosion on\nDresser-coupled pipelines can only be determined by a study of corrosion and leak history records or leak\ndetection surveys.”\nWe wish to take issue with the general inference or interpretation of this statement to the effect that, “surface potential\nsurvey, when properly conducted, is not a valid survey for determining “hot spots” on Dresser-coupled piping.” We\nfurther submit to you that the surface potential survey, when properly conducted and interpreted and when followed by\naccurate anode installation by location, is indeed the most practical and efficient means of corrosion mitigation in\nconnection with bare Dresser-coupled lines.\nIn support of the above statement, we wish to point out that we have been utilizing our surface potential survey\nprocedure and subsequent “hot spot” protection for corrosion control on bare Dresser-coupled lines for 15+ years. As a\nresult, there is available a considerable amount of substantiative performance date on such lines which indicates that\nthis approach is indeed a highly accurate means of corrosion detection and a highly efficient means of corrosion\nmitigation for bare Dresser-coupled piping. Therefore, we wish to be afforded the opportunity to make this information\nand knowledge available to DOT for evaluation in order to forestall what could be considered as a blanket indictment of\nthis approach. Such an indictment, even though misconstrued would, we feel, be a disservice to the many operators\nwho still number Dresser-coupled lines within their systems.\nIn addition, we offer to conduct a field demonstration of our surface potential survey technique on bare Dresser-\ncoupled piping and then expose representative locations on the line upon completion of the survey to substantiate our\ninterpretation of the data. We would propose to conduct this demonstration, hopefully as soon as possible, at such\nlocation and time that would be convenient for your representative(s) to observe the entire procedure. We could make\navailable, if agreeable with you, arrangements with some of our clients for a segment of line for demonstration\npurposes, or, if you prefer, we would be quite willing to survey a segment of bare Dresser-coupled line which you might\nchoose and for which you would make arrangements with the owner company.\nIf it would be of any assistance in expediting some action along the lines set forth above, we would be quite willing to\npay the transportation and subsistence costs involved with your representative being present at the location of the\nproposed field survey.\n\n<<<PAGE 4>>>\n\nShould you not see fit to become involved with the observance of such a test survey, we would then request the\nopportunity for our personnel to meet with you in the near future in Washington, or at a location of your choosing, for\nthe purpose of discussing with your our surface potential survey procedure and interpretation criteria, as well as\nperformance data on Dresser-coupled systems which have been subjected to the surface potential survey and “hot\nspot” protection approach.\nWe are enclosing for your information a copy of a paper presented by our Mr. LeRoy A. Bash at the South Central\nRegional NACE Conference held in Fort Worth last year. We feel this paper will be of interest to you and to the industry\nwhen it’s published, as it constitutes a very through insight into the theory supporting intelligent use of the refined\nsurface potential survey procedure being used by our firm.\nSince this matter is of extreme importance to us and we feel of importance to the industry as a whole, we are looking\nforward to hearing from you in the very near future.\nVery truly yours,\nCATHODIC PROTECTION SERVICE\nTed L. Canfield\nPartner","truncated":false,"body_characters":7295}