NTSB Safety Recommendation Letter P-79-008

Page 1Official PDFNATIONAL TRANSPORTATION SAFETY BOARD WASHINGTON, D.C. I S S U E D : May 18, 1979 - " , - - - - _ - - _ - " , - _ _ - I _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - Forwarded to: \ J \ Mr. Robert B. Peabody President American Iron and Steel I n s t i t u t e 1000 16th S t r e e t , N . W . Washington, D . C . 20036 Mr. Charles 3 . DiBona I Pres i d en t American Petroleum I n s t i t u t e 2101 L S t r e e t , N.W. Washington, D.C. 20037 --__-_-_--_____-_______________I________ S A F E T Y RECOMMENDAT I O N ( S ) A t 12:02 a . m . , c . d . t . , on August 4 , 1978, propane t h a t had vaporized and spread widely fron: a ruptured 8-inch l i q u e f i e d petroleum gas (LPG) pipeline owned by t h e .i:id-America Pipeline System (MAPCO) ':as i g n i t e d by an unknown source i n a r u r a l area near Donnellson, Iowa. The intense f i r e k i l l e d two persons and c r i t i c a l l y burned t h r e e o t h e r s : one of the c r i t i c a l l y burned persons later died. A farmhouse and s i x outbuildings were destroyed, and two adjacent homes were damaged.l/ The s e c t i o n of p i p e l i n e involved i n t h i s accident was constructed of 8 5/8-inch O.D., 0.156-inch w a l l , API 5LX, Grade 52 l i n e pipe which was manufactured by t h e e l e c t r i c - t e s i s t a n c e welding process. The industry piping code lists 0.104 inch a s the l e a s t wall thickness recommended f o r 8 5/8-inch O.D. line.Z/ The pipe was coated and wrapped, cathodically protected by r e c t i f i e r s , and had 4 f e e t of cover a t t h e point of rupture. The l i n e was constructed i n 1962, i n accordance wi.th the American Standard Code f o r Pressure Piplng (ASA B31.4-1959). S t e e l m i l l s commonly manu- f a c t u r e 8 5/8-inch O.D. l i n e pipe i n wall thicknesses up to 0.500 inch; some m i l l s quote s p e c i f i c a t i o n s up t o 0.875 inch. I n the range of wall thicknesses from 0.104 to 0.500 inch, 0.156-inch w a l l pipe lies i n the f i r s t 20 percent--on the t h i n side--of t h e t o t a l range. - - 1/ For more d e t a i l e d information read "Pipeline Accident Report-- M i d America P i p e l i n e System Liquefied Petroleum Gas Pipeline Rupture and F i r e , Donnellson, Iowa, August 4, 1979" (NTSB-PAR-79-1). - 2 / Table 404.1.1, "Least Nominal Wall Thickness f o r S t e e l Pipe," American National Standards Code f o r Pressure Piping, Liquid Petroleum Transportation Piping Systems, ANSI, B31.4-1974. 2460-B#

Page 2- 2 - A m e t a l l u r g i c a l examination of the f a i l e d section of pipe concluded t h a t the f a i l u r e was caused by e x t e r n a l mechanical damage i n the form of a dent and a gouge. The 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 t h e naked eye. P i p e l i n e s handling LPG, which t h e Safety Board has repeatedly shown t o be a hazardous product t h a t cannot be contained, controlled, or dispersed s a f e l y a f t e r escaping from a p i p e l i n e rupture, a r e not required by OPSO regulations t o have e i t h e r heavier walled pipe, tougher pipe, stronger p i p e , or b e t t e r pipe than other p i p e l i n e s . M e t a l l u r g i s t s can debate whether heavier w a l l pipe o r tougher pipe may be more rupture- f r e e than t h e pipe i n t h i s accident, b u t u n t i l some formal e f f o r t is made i n t h i s d i r e c t i o n , accidents l i k e t h i s one, caused by previous damage t o t h e pipe, w i l l probably continue. The Safety Board b e l i e v e s t h a t pipe can be manufactured t o transport LPG more s a f e l y . Therefore t h e National Transportation Safety Board recommends t h a t the American Iron and S t e e l I n s t i t u t e and t h e American Petroleum I n s t i t u t e : Undertake research f o r more s t r i n g e n t s p e c i f i c a t i o n s f o r l i n e pipe manufactured f o r LPG p i p e l i n e s e r v i c e t o minimize o r m i t i g a t e the e f f e c t s of dents and gouges. Consideration should be given t o t h e research c u r r e n t l y being conducted by the American Gas Association on t h i s problem. (Class 11, P r i o r i t y Action)(P-79-8) K I N G , Chairman, DRIVER, Vice Chairman, McADAMS and HOGUE, Members, concurred i n t h i s recommendation.#