NTSB Safety Recommendation Letter P-78-012 through P-78-014

Page 1Official PDFiG?J f-Y ST NATIONAL TRANSPORTATION SAFETY BOARD WASHINGTON, D.C. ISSUED: February 8 , 1978 ______---_-_-_-__-__________________I___- Forwarded to: \ Mr. Frank N . Ikard President American Petroleum 2101 L Street, N . W. Washington, D.C. 20037 I n s t i t u t e SAFETY R E C O M M E N D A T I O N ( S ) P-78-12 through P-78-14 A t 4:30 a.m., e . d . t . , on J u l y 20, 1977, a 12-inch propane p i p e l i n e , owned by t h e Consolidated Gas Supply Corporation, ruptured near t h e town of Ruff Creek, Pennsylvania. The l i q u i d , under 450-psig pressure, escaped from the p i p e l i n e , vaporized, and propane vapors s e t t l e d l i k e a fog over t h e bottom of a valley. 1/ - Ahout 6 a.m., two men i n a pickup truck entered t h e propane cloud; t h e truck s t a l l e d and the propane gas ignited when a n attempt w a s made to r e s t a r t t h e truck. A f l a s h f i r e , approximately 100 yards wide, followed a streambed located along the bottom of t h e v a l l e y and burned everything i n i t s path f o r a distance of 1 m i l e . The flames were over 100 f e e t high a t t h e point of t h e rupture and burned f o r 1 4 hours u n t i l t h e remaining propane l i q u i d i n t h e p i p e l i n e could be i s o l a t e d i n t h e p i p e l i n e by the use of valves and stopples. A s a r e s u l t of t h i s accident, t h e 2 persons i n the truck were k i l l e d , t h e truck was destroyed, 57 head of c a t t l e were k i l l e d , overhead power and telephone l i n e s were destroyed, a hay storage shed containing 450 b a l e s of hay was burned, 1,800 b a r r e l s of propane burned, and a meadow and wooded a r e a 1 m i l e long by 100 yards wide was burned. - 1/ F o r more d e t a i l e d information about t h i s accident, read "Pipeline Accident Report -- Consolidated Gas Supply Corporation, Propane P i p e l i n e Rupture and F i r e , Ruff Creek, Pennsylvania, J u l y 20, 1977" (NTSB-PAX-78-1) 2260#

Page 2- 2 - The n a t u r a l gas p i p e l i n e industry w a s not generally aware of t h e phenomenon of stress-corrosion cracking (SCC) i n p i p e l i n e s u n t i l 1965 when a p i p e l i n e i n Natchitoches, Louisiana, f a i l e d and k i l l e d 1 7 persons Since then, t h e American Gas Association has been involved i n s e v e r a l research programs t o determine t h e cause and c o r r e c t i o n of SCC i n g a s pipelines. Although SCC of l i q u i d p i p e l i n e s may be a t t h e same s t a g e t h a t it w a s i n the gas i n d u s t r y 13 years ago, t h i s accident should be a warnin s i g n t h a t t h i s type of accident could happen again unless more is kno about t h e prevention of SCC i n a l l kinds of pipelines. The Safety Board is p a r t i c u l a r l y concerned about t h e conversion o n a t u r a l gas p i p e l i n e s t o l i q u i d s e r v i c e where some i n c i p i e n t SCC could be present i n a s u s c e p t i b l e s t e e l . It would be d e s i r a b l e t o nondestructively test (NDT) t h e n a t u r a l gas p i p e l i n e before conversion. One NDT technique which has been used i n t h e gas i n d u s t r y r e q u i r e s t h a t t h e p i p e l i n e be s t r e s s e d t o e m i t a d e t e c t a b l e sound when p l a s t i c deformation occurs a t crack t i p s . Because t h e elements of s t r e s s and cracking for a c o u s t i c emission t e s t i n g are present i n SCC, t h i s t e s t i n g technique could possibly be used i n t h e conversion of gas l i n e s t o l i q u i d lines. A common propane odorant w a s not required by r e g u l a t i o n o r used i n t h i s p i p e l i n e because i t could contaminate t h e product or make it unsuitable f o r use with a processing c a t a l y s t . However, i f a n acceptab odorant or a n i r r i t a n t had been developed f o r this p i p e l i n e product, t h men burned i n t h i s accident might not have t r i e d t o restart t h e i r t r u c k and might have walked o u t of the propane vapors t o c l e a r air, less than 100 f e e t away. . - .. . - t h e Therefore, the National Transportation S a f e t y Board recommends t h a t American Petroleum I n s t i t u t e : P a r t i c i p a t e i n and encourage research i n t o stress- corrosion cracking, e s p e c i a l l y on o l d e r steel gas p i p e l i n e s t h a t have been converted t o l i q u i d s e r v i c e . (Class 111, Longer Term Action) (P-78-12) Conduct f i e l d tests, using acoustic emission t e s t i n g techniques developed by t h e gas industry, t o determine i f highly s t r e s s e d p o r t i o n s of l i q u i d p i p e l i n e s can be located, and stress-corrosion cracking can be detected by t h i s means before f a i l u r e . (Class 111, Longer TermAction) (P-78-13)#

Page 3- 3 - Conduct research to develop some form of d e t e c t o r , e i t h e r a s a n odorant o r i r r i t a n t , of t h e presence of l i q u e f i e d petroleum gas. The detector should be one t h a t w i l l not contaminate t h e product or make it unsuitable f o r use with processing c a t a l y s t s . (Class 111, Longer Term Action) (P-76-14) McADAMS, HOGUE, and KING, Members, concurred i n the above recommendations. BAILEY, Acting Chairman, did not participa_'e_. &% By: Ray Bailey Acting Chairman 2260#