NTSB Safety Recommendation Letter P-79-016 through P-79-019

Page 1Official PDFNATIONAL TRANSPORTATION SAFETY BOARD WASHINGTON, D.C. ---_-,--------_--_,.----------------------- Forwarded to: Mr. F. G. Turpin President Alyeska P i p e l i n e Service Company 1835 South Bragaw Anchorage, Alaska 99504 SAFETY RECOMMENDAT I ON (S) p-79- 1 6 through -19 A t 8:45 a . m . , Alaska daylight time, on June 10, 1979, t h e pi,lot of a helicopter 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 Pipeline Service Company's 48-inch crude o i l pipeline. The o i l was seen on t h e north 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. the n o r t h s e c t i o n of t h e line between pump s t a t i o n s Nos. 1 and 4 was shut down. By 10:46 a.m. t h e e n t i r e line had been shut down. The pipe 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 feet 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 in- sulated box. The l e a k was through a 7-inch-long, 1/64-inch-wide crack, whi.ch passed through a longitudinal weld. The crack w a s one of several small cracks on and near a wrinkle in t h e pipe. Only one crack went a l l t h e way through t h e 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 n i n k l e d in two sections. Looking south, the 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 12, so that 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 was of SUCH a configuration t h a t temporary r e p a i r clamps could not be used. L i n e start-up was i n i t i a t e d h e - d i a t e l y . The r e p a i r was confirmed as holding at 3:30 p.m. Flow w s increased gradually u n t i l normal faow, 1 . 2 million b a r r e l s per day, was reached a t 8 : D O 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 2Mr. F. G. Turpin - 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 the leak s i t e . This clamp was welded over t h e w r i n k l e d area on June 15 and 16. Alyeska does keep l e a k r e p a i r clamps in s t o c k f o r emergency use but not of a configuration t o f i t over w r i n k l e d pipe. I f t h e temporary w e l d could not have been made strong enough t o hold, t h e l i n e could have been shut down f o r a period longer than 62 hours. Five days after t h e f i r s t leak, a t 3:15 p.m. on June 15, t h e 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 s u r v e i l l a n c e 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 r i v e r . Because of t h e apparent small size of the l e a k and because no o i l had entered t h e r i v e r , Alyeska decided t h a t t h e system would not have t o be shut down. Alyeska began excavating during t h e evening of June 15 and uncovered t h e l e a k a t 4:OO a.m. on June 16. O i l was leaking through a 3-inch crack along t h e heat-affected zone of a Longitudinal weld, not i n t h e weld metal proper. The This crack was a l s o near a wrinkle in the pipe. l e a k was approximately 2,000 feet north of pump s t a t i o n No. 1 2 , and the p i p e l i n e i n 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 w h a t was considered t o be thaw-stable 1! silts and gravel with 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 t h e Leak. The wrinkle a t t h i s l o c a t i o n was at 9 o'clock looking north. The size of the wrinkle and t h e width of the 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 4:23 p.m., Alyeska completed a temporary r e p a i r by placing two 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 f i t 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 in Anchorage. The r e p a i r work was completed on June 18. The June 1 0 s p i l l r e s u l t e d i n a release of approximately 1,500 b a r r e l s (63,000 gallons) of crude o i l ; the June 15 s p i l l r e s u l t e d i n a release of approximately 300 b a r r e l s (12,600 gallons) of crude o i l ; these l o s s e s were estimated by Alyeska personnel at the 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 pipeline, buried s e c t i o n s of t h e system were required t o be insulated, except when buried in bedrock or thaw- s t a b l e ground. The first l e a k was in 4 buried s e c t i o n considered t o be 1/ Thaw-stable ground is frozen bedrock o r s o i l s containing l i t t l e or - Thaw settlement is not a problem i n thaw-stable earth. no ice. '#

Page 3M r . F. G. Turpin - 3 - in bedrock, and t h e second l e a k was considered t o be in 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 pipeline at t h e second l e a k appeared t o have settled. 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 outlined construction and operating p r a c t i c e s that Alyeska was t o follow t o insure 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 called f o r t h e 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 vertical and horizontal curvature of t h e pipe at c r i t i c a l l o c a t i o n s along t h e pipeline. Alyeska developed a "super-pig" t o run 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 according t o t h e agreement. The pipeline has been carrying oil since June 1977. Baseline d a t a d e f i n i t i o n was completed f o r t h e super-pig in May 1978. A confirmation run t o authenticate t h e baseline was completed in December 1978, but no monitoring runs have yet been undertaken. The confirmation r u n 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 compared t o t h e baseline. I n order to maintain proper surveillance, t h e Safety Board b e l i e v e s that Alyeska should be performing t h e s e monitoring pctivities r e g u l a r l y , at least quarterly, before and after each freeze/thaw cycle. The wrinkles i n 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 r u n of t h e super-pig is scheduled f o r July 1979. Based on t h e p a s t performance of Alyeska in following through on curvature monitoring runs, t h e Safety Board i s concerned about possible delay in completing t h e scheduled run. Therefore, t h e National Transportation Safety Board recommends t h a t Alyeska P i p e l i n e Service Company: Complete t h e scheduled run of t h e curvature monitoring device expeditiously t o determine other l o c a t i o n s w i t h abnormal buckles or bends. (Class I, Urgent Action) (P- 7 9- 16) Develop and implement an inspection program adequate t o d e t e c t curvature aberration. Xnspections should be completed at least quarterly. (Class I, Urgent Action) (P-79-17j * Reevaluate t h e ground s t a b i l i z a t i o n in 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#

Page 4MT. F. G. Turpin - 4 - OT ground considered t o be t h a w s t a b i l i z e d . Take c o r r e c t i v e action where ground movement has occurred due t o thawing. (Class I, Urgent Action) (P-79-18) Fabricate a v a r i e t y of s p e c i a l split-sleeve r e p a i r c l a m p s l a r g e enough t o encompass pipe wrinkles similar t o those encountered in t h e Latest f a i l u r e s . These r e p a i r sleeves should be stored t o provide f o r rapid d i s p o s i t i o n t o leak sites. (Class I, Urgent Action) (P-7 9-19 ) KING, Chairman, DRIVER, Vice Chairman, and McADAMS, Member, concurred in these recommendations. GOLDMAN, Member, did not p a r t i c i p a t e .#