Exxon Gas System, Inc. — Pipeline Safety Interpretation

Page 1Mr. J. Keith McSorley Exxon Gas System, Inc. P. O. Box 3948 Houston, Texas 77253-3948 Dear Mr. McSorley: Thank you for your letter requesting an interpretation of §192.611 as amended (54 FR 24173, June 6, 1989). Your letter indicates that you believe that §192.611(a)(1) should be applicable to a pipeline where, because of a previous class location change, §192.611(a)(2) had been applied and the MAOP reduced. You included as an example data on a pipeline for which the MAOP had been reduced in 1986 from 833 psig to 675 psig. Current application of §192.611(a((1) as amended would permit operation of the pipeline at 801 psig, which, although less than the original MAOP, is considerably higher than the current MAOP. A previous revision to §192.611 was made in 1986 (51 FR 34987, October 1, 1986, Amdt. 192- 53), clarifying that the three MAOP restrictions in this section are options. Prior to that rulemaking, many persons had assumed that the restrictions now designated (a)(1), (2), and (3) were intended to be applied sequentially as circumstances dictated. The most recent revision of this section relies heavily on this interpretation that the restrictions are options. In the Notice of Proposed Rulemaking preceding the 1986 revision (51 FR 1978, June 3, 1986), we stated that, "RSPA does not believe that the 18-month rule blocks operators who choose one compliance option from later selecting the other." This language seems to apply in the situation you have described. The fundamental difference here is that in the intervening time the available compliance options have been changed. This factor, though, should not override the principle established in the previous rulemaking action, that selection and implementation of one option, e.g., lowering pressure, do not preclude later implementation of another option, e.g., retesting. Thus, OPS believes it reasonable to interpret §192.611 to permit an operator who has previously reduced the pressure on a pipeline in response to a class location change to revisit that pipeline and raise the operating pressure within the limits now specified in §192.611(a)(1). We hope that this discussion has answered your questions and made clear the appropriate application of §192.611. If you have any further questions, please do not hesitate to contact us. DB C:\WP51\INTERPRT\192\611\89-09-15 1#

Page 2Sincerely, Richard L. Beam Director Office of Pipeline Safety DB C:\WP51\INTERPRT\192\611\89-09-15 2#