NTSB Safety Recommendation Letter P-79-014 through P-79-015

Page 1Official PDFNATIONAL TRANSPORTATION SAFETY BOARD WASHINGTON, D.C. ISSUED: July 13, 1979 ......................................... Forwarded to: Honorable Cecil D. Andrus Secretary U.S. Department of t h e I n t e r i o r Washington, D.C. 20240 SAFETY RECOMMENDAT ION (S) p-79-14 and 15 A t 8:45 a.m., Alaska daylight time, on June 10, 1979, t h e p i l o t of a h e l i c o p t e r reported s i g h t i n g o i l on t h e surface of t h e Atigun River near t h e r o u t e of t h e Alyeska P i p e l i n e Service Company's 48-inch crude o i l pipeline. The o i l was seen on t h e n o r t h s i d e of Atigun Pass, 166 m i l e s south of t h e p i p e l i n e terminal at Prudhoe Bay, Alaska. Alyeska was n o t i f i e d and began shutdown procedures a t 9 a.m. By 9:28 a.m. t h e n o r t h section of the l i n e between pump s t a t i o n s Nos. 1 and 4 w a s shut down. By 10:46 a.m. t h e e n t i r e line had been shut down. The p i p e between pump s t a t i o n s Nos. 4 and 5 was drained. The l e a k was uncovered a t 2:00 p.m. on June 11. The p i p e l i n e at t h i s l o c a t i o n was buried in bedrock with 1 2 feet of cover on a slope of approximately 15 t o 18 degrees. The l e a k was approximately 1,300 f e e t n o r t h of t h e summit of Atigun Pass about 200 f e e t u p h i l l from an i n - sulated box. The l e a k was through a 7-inch-long, 1/64-inch-wide crack, which passed through a longitudinal weld. The crack was one of several small cracks on and near a wrinkle in t h e pipe. Only one crack went a l l the way through the 0.462-inch-thick wall of t h e pipe. The pipe at t h i s l o c a t i o n had wrinkled in two sections. Looking south, t h e wrinkles were between 9 and 11 o'clock and between 1 and 3 o'clock. The wrinkles were approximately 7 inches from peak t o valley. Company work crews completed a temporary r e p a i r weld at 2 p.m. on June 1 2 , so t h a t t h e t r a n s p o r t a t i o n of t h e crude o i l could be resumed. The wrinkle i n the p i p e l i n e w a s of such a configuration t h a t temporary r e p a i r clamps could not be used. Line start-up was i n i t i a t e d imme- d i a t e l y . The r e p a i r was confirmed as holding a t 3:30 p.m. Flow was increased gradually u n t i l normal f-low, 1.2 m i l l i o n b a r r e l s per day, was reached at 8:OO a.m. on June 14. The p i p e l i n e had been shut down f o r about 62 hours. 2701#

Page 2Honorable Cecil D. Andrus - 2 - Alyeska fabricated a permanent s p l i t - s l e e v e r e p a i r clamp and moved it t o t h e l e a k site. This clamp was welded over t h e wrinkled area on June 15 and 16. Alyeska does keep l e a k r e p a i r clamps i n s t o c k f o r emergency u s e but not of a configuration t o f i t over wrinkled pipe. I f t h e temporary weld could not have been made strong enough t o hold, t h e line could have been shut down f o r a period longer than 62 hours. Five days a f t e r t h e f i r s t leak, at 3:15 p.m. on June 15, the p i l o t of an Alyeska h e l i c o p t e r on a r o u t i n e surveillance f l i g h t reported a l e a k n o r t h of pump s t a t i o n No. 12 near t h e L i t t l e Tonsina River, but no o i l had entered t h e river. Because of t h e apparent small s i z e of t h e l e a k and because no o i l had entered t h e river, Alyeska decided that t h e system would not have t o be shut down. Alyeska began excavating during the evening of June 15 and uncovered t h e l e a k a t 4:00 a.m. on June 16. O i l was leaking through a 3-inch c r a c k along t h e heat-affected zone of a longitudinal weld, not in the weld metal proper. This crack was a l s o near a wrinkle in the pipe. The l e a k was approximately 2,000 f e e t n o r t h of pump s t a t i o n No, 12, and t h e p i p e l i n e in t h i s area i s on a r e l a t i v e l y f l a t slope. The pipe is buried i n what was considered t o be thaw-stable silts and g r a v e l w i t h 4 f e e t of cover. The ground had apparently s e t t l e d on each s i d e of the leak. The wrinkle a t t h i s l o c a t i o n was a t 9 o'clock looking north. The s i z e of t h e wrinkle and t h e width of t h e crack was d i f f i c u l t t o determine because of o i l spraying from t h e crack. By 4 2 3 p.m., Alyeska completed a temporary r e p a i r by placing t W o Smith clamps a c r o s s t h e crack. Another s p l i t - s l e e v e r e p a i r clamp de- signed t o fit over t h e temporary r e p a i r clamps had t o be f a b r i c a t e d i n Anchorage. The r e p a i r work was completed on June 18. The June 10 s p i l l r e s u l t e d i n a r e l e a s e of approximately 1,500 b a r r e l s (63,000 gallons) o f crude o i l ; t h e June 15 s p i l l r e s u l t e d in a r e l e a s e of approximately 300 b a r r e l s (12,600 gallons) of crude o i l ; t h e s e l o s s e s were estimated by Alyeska personnel at t h e l e a k site. The s p i l l s were too small t o be v e r i f i e d by t h e Alyeska metering system. Metallurgical tests w i l l be made on samples of pipe from both leaks. During construction of t h e p i p e l q e , buried s e c t i o n s of the system were required to be insulated, except when buried i n bedrock or thaw- s t a b l e ground. The first l e a k was i n a buried s e c t i o n considered t o be - - I/ Thaw-stable ground is frozen bedrock o r s o i l s containing l i t t l e or no ice. Thaw settlement is not a problem i n thaw-stable earth.#

Page 3Honorable Cecil D. Andrus - 3 - i n bedrock, and t h e second l e a k was considered t o be i n thaw-stable ground. Therefore, n e i t h e r section was insulated. Both l e a k s were a t wrinkles i n t h e pipe. The p i p e l i n e at t h e second l e a k appeaxed t o have s e t t l e d . Before beginning construction of t h i s f a c i l i t y , Alyeska entered i n t o a formal agreement with t h e U.S. Department of t h e I n t e r i o r , which o u t l i n e d construction and operating p r a c t i c e s t h a t Alyeska was t o follow to i n s u r e t h e s a f e operation of t h e f a c i l i t y . One of t h e operating requirements c a l l e d f o r the development and use of a curvature moni- t o r i n g program t o d e t e c t , record, and analyze a b e r r a t i o n s in t h e v e r t i c a l and horizontal curvature of t h e pipe a t c r i t i c a l l o c a t i o n s along the pipeline. Alyeska developed a "super-pig" t o r u n through t h e pipe t o perform t h i s measurement requirement. Curvature monitoring runs were t o be completed p e r i o d i c a l l y accord- ing t o t h e agreement. The p i p e l i n e has been carrying o i l s i n c e June 1977. Baseline data d e f i n i t i o n was completed f o r t h e super-pig i n May 1978. A confirmation run t o a u t h e n t i c a t e t h e baseline was completed i n December 1978, but no monitoring runs have y e t been undertaken. The confirmation run showed no s i g n i f i c a n t curvature d i f f e r e n c e s when com- pared t o t h e baseline. I n order t o maintain proper s u r v e i l l a n c e , the Safety Board b e l i e v e s that Alyeska should be performing t h e s e monitoring a c t i v i t i e s r e g u l a r l y , a t l e a s t q u a r t e r l y , before and a f t e r each freeze/thaw cycle. The wrinkles in t h e pipe near each of t h e l e a k s probably could have been detected by t h e monitoring system i f it had been operational. The next run of t h e super-pig is scheduled f o r J u l y 1979. Based on the p a s t performance of Alyeska in following through on curvature monitoring runs, t h e Safety Board is concerned about p o s s i b l e delay i n completing t h e scheduled run. Therefore, t h e National Transportation Safety Board recommends that t h e U.S. Department of t h e I n t e r i o r : Enforce t h e operational requirements of t h e agree- ment between Alyeska and I n t e r i o r , e s p e c i a l l y those related t o system i n t e r i t y surveillance. (Class I, Urgent Action) (P-79-1 f+ f#

Page 4Honorable Cecil D. Andrus - 4 - Monitor t h e Alyeska reevaluation of ground s t a b i l i z a - t i o n i n a l l areas where t h e p i p e l i n e is buried without i n s u l a t i o n in bedrock o r ground considered t o be thaw s t a b i l i z e d . (Class I, Urgent Action) (P-79-15) KING, Chairman, DRIVER, Vice Chairman, and McADAMS, Member, concurred i n these recommendations. GOLDMAN, Member, did not p a r t l c i p a t e . /&bc+ By: James B. King M Chairman#