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Interpretation Response #PI-72-046

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

Interpretation Response Details

Response Publish Date: 10-13-1972
Company Name: Equitable Gas    Individual Name: Charles M. Rutter, Jr.
Location state: PA    Country: US

View the Interpretation Document

Request text:

September 29, 1972

Mr. Lance F. Heverly
Assistant Chief
Technical Division
Office of Pipeline Safety
Department of Transportation
Washington, D.C. 20590

Dear Lance:

As stated in the D.O.T. Requirements for Corrosion Control in Section 192.461(1) External corrosion control: protective coatings, it is required that protective coatings must be applied on a properly prepared surface. It is my interpretation or belief that the criteria for a properly prepared surface is that obtained by grit blast cleaning (or equal) to parent metal of the structure to be coated. Further preparation of the surface would be to apply a primer, if required,
that is manufactured and required by the manufacture of the coating to be used, or an equal primer that is approved by the coating manufacturer.

Does this describe a properly prepared surface for the application of insulating coatings? If this is a proper description and as you know so as to facilitate and/or to assure proper surface preparation of steel pipe such pipe is normally purchased without oils, lacquers, varnishes, paints, etc., applied to the pipe surfaces, when such pipe is to coated for below ground installation.

In your opinion, should this also be a requisite for the use of appurtenances that are to be installed below ground and are to be hand coated at the time of installation, thereby eliminating paints, enamels, and specially aluminum paints that are normally and regularly applied to appurtenances such as valves by certain valve manufacturers?


Charles M. Rutter, Jr.

Superintendent - Corrosion

Response text:

October 31, 1972

Mr. Charles M. Rutter, Jr.
Equitable Gas
420 Boulevard of the Allies
Pittsburgh, Pennsylvania 15219

Dear Mr. Rutter:

This is in response to your letter of September 29, 1972, in which you described a procedure for preparing a surface to receive a protective coating for the purpose of external corrosion control. You ask if your procedure meets the requirements of Section 192.461(a)(1) and, if so, whether such a procedure is required for appurtenances that are to be installed below ground and are to be hand coated at the time of installation.

As we understand your procedure, the properly prepared surface is obtained by grit blast cleaning (or equal) down to the parent structure of the metal, followed by application of a primer that is approved or recommended by the coating manufacturer. From the information presented, this procedure appears to meet the requirements of Section 192.461(a)(1).

With respect to your question on the application of such a procedure to underground appurtenances, there is no requirement that Section 192.461(a)(1) be met solely in this manner. The regulation is stated as a performance type standard and the method of compliance is left to the operator. Because of the odd shapes of pipeline appurtenances and the penetrating effect of some coatings and primers, the decision as to what constitutes a "properly prepared surface" in a particular case is left to the operator.

Your continued interest in the pipeline safety program is appreciated.


Joseph C. Caldwell
Office of Pipeline Safety

Regulation Sections

Section Subject
§ 192.461 External corrosion control: Protective coating