NTSB Safety Recommendation Letter P-79-007

Page 1Official PDFNATIONAL TRANSPORTATION SAFETY BOARD J/ / 2;' WASHINGTON, D.C. ISSUED: May 18, 1979 Elr. Charles J. DiBona P r e s i d e n t \ SAFETY RECOMMENDAT I O N ( s ) American Petroleum I n s t i t u t e P-19-7 i 2101 L Street, N . W . Washington, D . C . 20037 A t 12:02 a . m . , c . d . t . , on August 4 , 1978, propane t h a t had vaporized and spread widely from a ruptured 8-inch l i q u e f i e d petroleum gas (LPG) p i p e l i n e owned by t h e Mid-America P i p e l i n e System (MAPCO) was i g n i t e d by an unknown source i n a rural a r e a near Donnellson, Iowa. The i n t e n s e f i r e k i l l e d two persons and c r i t i c a l l y burned three o t h e r s ; one of t h e c r i t i c a l l y burned persons l a t e r died. A farmhouse and s i x o u t b u i l d i n g s were destroyed, and two a d j a c e n t homes were damaged.11 - The r u p t u r e i n t h e p i p e l i n e was approximately 33 inches long and o r i g i n a t e d on t h e west s i d e of the l i n e . It propagated l o n g i t u d i n a l l y about 1 7 inches and then s p i r a l l e d over 360 degrees a t each end and stopped. Close examination of the o u t s i d e s u r f a c e showed gouge marks along and on e i t h e r s i d e of the f r a c t u r e . The most severe gouge w a s approximately 7 1 / 2 inches l o n g and 1 / 4 inch wide and was located along t h e bottom s i d e of t h e f r a c t u r e . The depth of t h e gouge was approximately 0.005 t o 0.007 inch. Metallographic examination a l s o i n d i c a t e d t h a t t h e p i p e h a d been dented. MAPCO records and o t h e r d a t a showed t h a t no excavation a c t i v i t i e s o t h e r than the lowering of t h e p i p e l i n e had been undertaken by e i t h e r t h e company or by o t h e r s a t t h e r u p t u r e a r e a . This i n d i c a t e s t h a t t h e damage was done between t h e time t h e p i p e was manufactured and the time t h e p i p e l i n e was constructed. Even though t h e damaged s e c t i o n was r e l a t i v e l y small and would have been d i f f i c u l t t o d e t e c t with the naked eye, t h e p i p e was inspected four times. The p i p e was inspected a t t h e s t e e l m i l l , again when it was unloaded and s t o c k p i l e d near the right-of- way, again when i t was being coated, and f i n a l l y when t h e coating was - 1/ For more d e t a i l e d information read "Pipeline Accident Report-- Mid-America P i p e l i n e System Liquefied Petroleum Gas P i p e l i n e Rupture and F i r e , Donnellson, Iowa, August 4 , 1978" (NTSB-PAR-79-1). 2460-B#

Page 2- 2 - being i n s p e c t e d b e f o r e t h e p i p e was lowered i n t o t h e d i t c h . Although t h e s m a l l s i z e of t h e damage and its l o c a t i o n toward t h e bottom of the pipe would have made d e t e c t i o n d i f f i c u l t , t h e S a f e t y Board b e l i e v e s a c a r e f u l , thorough i n s p e c t i o n of t h e p i p e during c o n s t r u c t i o n might have revealed t h e damage. t h a t Three months before t h e a c c i d e n t , W C 0 completed lowering a s e c t i o n of t h e Farmington l a t e r a l under Highway 2 a d j a c e n t t o t h e a c c i d e n t s i t e . Because of the widening of t h e highway and the depth of t h e d r a i n a g e d i t c h e s on each s i d e of the road, it was necessary t o lower t h e p i p e l i n e more than 11 f e e t . I n o r d e r t o o b t a i n enough s l a c k i n t h e p i p e l i n e t o lower i t t h i s much, t h e company's " r u l e of thumb" p r a c t i c e r e q u i r e d t h a t f o r every f o o t t h e 8-inch s t e e l p i p e w a s t o be lowered, a 35-foot-long s e c t i o n had t o be exposed. MAX0 and c o n t r a c t o r personnel excavated a trench 237 f e e t from t h e n o r t h s i d e of t h e highway along t h e p i p e l i n e . Approximately every 30 f e e t , the crew l e f t a column of d i r t under the p i p e l i n e f o r s u p p o r t . It was l a t e r determined t h a t MAPCO had started lowering the p i p e l i n e 15 f e e t from where the r u p t u r e occurred and t h e p i p e e l e v a t i o n had changed 10 f e e t along 170 f e e t of pipe from t h a t p o i n t . The crew then c u t south a c r o s s the highway and dug a t r e n c h exposing the p i p e l i n e f o r another 290 f e e t . The p i p e l i n e w a s then r e p o r t e d l y lowered slowly and allowed t o follow t h e contour of the trench. The t r e n c h was then b a c k f i l l e d and compacted. A d d i t i o n a l casing w a s added t o the o r i g i n a l c a s i n g on t h e s e c t i o n of p i p e l i n e a c r o s s the highway b e f o r e b a c k f i l l . The p i p e l i n e was not o p e r a t i n g a t the time t h e l i n e was lowered; however, it d i d have a s t a t i c p r e s s u r e of 200 t o 250 p s i g . t h e Therefore, American t h e Petroleum N a t i o n a l T r a n s p o r t a t i o n I n s t i t u t e : S a f e t y Board recommends t h a t Advise its member companies who o p e r a t e similar LPG p i p e l i n e s of t h e importance of c a r e f u l , thorough i n s p e c t i o n during p i p e l i n e c o n s t r u c t i o n t o minimize the incidence of d e n t s and gouges which could r e s u l t i n similar a c c i d e n t s , and b r i n g t o t h e i r a t t e n t i o n t h e need t o use proper engineering techniques when it is necessary t o r e l o c a t e or lower a s e c t i o n of p i p e l i n e . (Class 11, P r i o r i t y Action) (P-79-7) K I N G , Chairman, DRIVER, Vice Chairman, McADAMS and HOGUE, Members, concurred in t h i s recommendation.#