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Interpretation Response #PI-74-0103 ([Cathodic Protection Service] [Ted L. Canfield])

Below is the interpretation response detail and a list of regulations sections applicable to this response.

Interpretation Response Details

Response Publish Date:

Company Name: Cathodic Protection Service

Individual Name: Ted L. Canfield

Location State: TX Country: US

View the Interpretation Document

Response text:

Office of the Secretary of Transportation

Washington, D.C. 20590

Original letter before

Inserting last paragraph

As requested by TGC-20

Mr. Ted L. Canfield
Cathodic Protection Service
Service Division
P.O. Box 66387
Houston, TX 77006

Dear Mr. Canfield:

This responds to your letters of February 25 and April 11, 1974, in which you refer to the surface potential survey method for locating areas of active corrosion on bare Dresser-coupled lines.  Your comments related to Advisory Bulletin No. 72-8, dated August 1972, which stated our opinion that the two-electrode “leap-frogging” surface potential survey method will not provide useful information in determining where active corrosion is taking place on Dresser-coupled pipelines (insulated joints).

Basically, you raise the same issues discussed in previous correspondence with Mr. Doremus of your firm.  (Enclosed are a letter from Mr. Doremus dated November 2, 1972, and our response of January 3, 1973.)  Our position as stated then is that the “leap frogging” surface potential survey method may be sued successfully to located areas of active corrosion on electrically continuous pipelines.

Your letter addresses bare Dresser-coupled lines without distinguishing between those which have insulated joints and those which do not.  If you can determine beforehand that a Dresser-coupled line does not have insulated joints, then we see no problem with using the “leap-frogging” method to detect active corrosion.  However, where a line is known to contain insulated joints or there is insufficient information to determine whether or not the joints are insulated, then we hold to our opinion that the “leap-frogging” method would not be useful.

Sincerely,

Joseph C. Caldwell
Director
Office of Pipeline Safety

Regulation Sections

Section Subject
192.457 External corrosion control: Buried or submerged pipelines installed before August 1, 1971