ADB 77-9 — Pipeline Safety Interpretation

Page 1OPSO Advisory Bulletin No. 77-9 September 1977 page 2 The Congress has 60 legislative days in which to pass a joint resolution of approval before the President's decision can take effect. The Alaska Natural Gas Transportation Act provides dates for further executive and legislative review, if necessary. The El Paso Alaska Company had a proposal to pipeline North Slope gas from Prudhoe Bay to Point Gravina, Alaska, liquefy it, and ship the liquefied natural gas by terminal to a California terminal. However, Congress can take no positive action regarding that proposal during its deliberations on the President's Alcan decision. (Note: El Paso announced on September 22 that it was withdrawing its proposal.) Copies of the Decision and Report to Congress on the Alaska Natural Gas Transportation System may be obtained by directing a request to the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402, Stock No. 060-000-00084-1 at $4.00 a copy, telephone number (202) 783-3238. Relates to 49 CFR §195.218 OPSO PROPOSES DELETING REQUIREMENT THAT LONGITUDINAL SEAMS ON ADJACENT PIPE LENGTHS BE OFFSET...On September 21, 1977, the Office of Pipeline Safety Operations (OPSO) issued Notice No. 77-6, Docket No. OPSO-48, in which it proposed revoking the requirements contained in Section 195.218 that longitudinal seams on adjacent pipe lengths be offset. In connection with construction of the Trans-Alaska Pipeline System, the Alyeska Pipeline Service Company (Alyeska) twice requested waivers from compliance with the general requirements of Section 195.218 for a total of eight girth welds. The information furnished by Alyeska in support of their requests and by welding engineering experts outside the government supported the Materials Transportation Bureau's (MTB) granting the requested waivers (41 Fed. Reg. 38202, September 9, 1976, and 42 Fed. Reg. 42943, August 25, 1977; also see August 1977 Advisory Bulletin). In addition to finding that the waivers were not inconsistent with pipeline safety and were in the public interest, MTB concluded that the requirement of Section 195.218 does not appear necessary for safety. Because of the significance of these decisions and their impact on pipelines to be constructed by others, MTB is proposing removing the requirement of Section 195.218 from 49 CFR Part 195. MTB is of the opinion that the advancement of technology for pipe manufacturing and pipe welding has made obsolete the need to offset the longitudinal seam when welding lengths of pipe together. MTB's opinion is based upon the following reasons: 1. The ductility of the pipe and girth weld metals presently in general use provides for localized yielding where high residual stresses may exist and thereby prevents fracture dal\192\147\77-09 1#

Page 2initiation and failure of the weld. (Section 195.218 was adopted when pipe and weld materials in general use were less ductile than materials in general use at present.) 2. The similarity of mechanical properties between the girth weld and pipe metals that are presently in general use minimizes the likelihood of any concentration of residual stresses existing at the intersection of welds and the surrounding heat affected zone. 3. The fact that longitudinal seams are ground flush with the inside pipe circumference at the joint mitigates the likelihood of any concentration of residual stresses caused by excess metal at the intersection of welds. MTB invites all interested persons to participate in this proposed rulemaking by submitting in triplicate such written comments, data, and information as they may desire not later than November 1, 1977. All comments received by the close of the comment period will be considered so far as practicable in developing the final rule. Communications should identify the Docket and Notice numbers and be submitted to: Director, Office of Pipeline Safety Operations, Department of Transportation, Trans Point Building, 2100 Second Street, S.W., Washington, D.C. 20590. Reprints of the Notice were sent to those on the appropriate OPSO mailing lists. TWO FEDERAL/STATE REGIONAL MEETINGS HELD...The Third Annual Southwest (September 7-8) and Western (September 21-22) Regional Meetings of State Agency Pipeline Safety Staff Officials were held in Santa Fe, New Mexico, and Salt Lake City, Utah, respectively. The meetings (continued) dal\192\147\77-09 2#