Williams Brothers Engineering Co. — Pipeline Safety Interpretation

Page 1Mr. Clinton McClure Senior Engineer Williams Brothers Engineering Co. Resource Sciences Center Tulsa, Oklahoma 74103 Dear Mr. McClure: This is in reply to your letter of December 4, 1970, requesting an interpretation of 49 CFR, Section 192.611(a). You state: "It has been our practice for a number of years, where the crossing is not cased, to place beneath the road or railroad, pipe of greater wall thickness than the line pipe. There may be a transition pipe of an intermediate wall thickness between the crossing and line pipe in order to comply with welding standards. It has been our practice to test the crossing pipe and the transition pipe with the line pipe and to test it to the same pressure. The test has been 90 percent or more of the SMYS of the line pipe. In most cases this is less than 90 percent SMYS of the crossing pipe and in some cases less than 90 percent SMYS of the transition pipe. There are a number of locations where it will become necessary to changes out pipe on each side of a crossing to comply with the requirements of the new DOT rules and regulations. Will it be necessary to retest the crossing pipe or re-lay new crossing pipe tested to 90 percent of the SMYS of the crossing pipe? I have attached example diagrams." The answer to your question is that it will be necessary either to test as much of the pipe as was not tested to 90% of SMYS or replace such pipe with the pipe meeting the design and testing requirements of Part 192 for new pipe in the location, or the maximum operating pressure may be reduced consistent with the requirements of that Part. Secondly, you ask: "If pipelines designed, constructed and tested in the future become involved in class location changes of this nature, will this subsection of the rule and regulations be applied literally to the "segments" of pipe varying in wall thickness? The answer to your question is that Section 192.611 will be literally applied to segments of pipe such as road crossings. DB C:\WP51\INTERPRT\192\611\71-02-22 1#

Page 2If we can be of further assistance to you, please let us know. Sincerely, Joseph C. Caldwell Director, Acting Office of Pipeline Safety DB C:\WP51\INTERPRT\192\611\71-02-22 2#