NTSB Safety Recommendation Letter P-79-013

Page 1Official PDFNATIONAL TRANSPORTATION SAFETY BOARD WASHINGTON, D.C. I S S U E D : June 11, 1979 President American Gas Association \ SAFETY RECOMMENDAT I O N ( S ) P-79-13 Arlington, Virginia 22209 i 1515 Wilson Boulevard ----------------------------------------,- A t 9:3O p.m., e.s.t., a n January 16, 1979, an explosion and f i r e destroyed f i v e commercial buildings and damaged s e v e r a l o t h e r buildings i n London, Kentucky. Two persons were i n j u r e d as a r e s u l t of t h e accident. F i r e f i g h t e r s , t h e first emergency personnel on t h e scene, evacuated t h e buildings. The l o c a l manager and a gas serviceman from t h e Gas Service Company, Inc., (a subsidiary of t h e Delta Natural Gas Co., Inc.) a r r i v e d about 5 minutes a f t e r t h e explosion. By 9:40 p.m. they had closed a valve which shut o f f t h e gas i n the s e r v i c e l i n e serving t h e buildings. Twenty-five f i r e companies assisted i n extinguishing t h e fire. Nitrogen pressure t e s t l n g of t h e 7-inch O.D., steel d i s t r i b u t i o n main, which had had a recent pressure increase t o 1 7 psig, revealed a corrosion h o l e i n t h e pipe. Further i n v e s t i g a t i o n indicated t h a t t h e gas which had escaped from t h e corrosion hole had migrated through a break i n an adjacent s a n i t a r y sewer and then i n t o t h e buildings where it w a s i g n i t e d by an undetermined source. A t t h e t i m e of the accident, t h e gas company had been i n the process of modifying some 1,500 feet of t h e steel gas main by i n s e r t i n g a 2-inch p l a s t i c pipe 60 t h e main's operating pressure could be increased t o serve a l a r g e r load. Most of t h e e x i s t i n g l i n e being uprated was used, bare, 7-inch O.D., steel, well-casing pipe t h a t had been i n s t a l l e d w i t h mechanical couplings i n 19.30 and 1931. The Gas Service Company w a s not i n compliance with 49 CFR 192.457(b) i n t h a t t h e r e was no cathodic p r o t e c t i o n provided f o r t h i s type of pipe throughout t h e system. Corrosion holes could exist elsewhere i n t h e system. 2660#

Page 2- 2 - The uprating was accomplished by i n s t a l l i n g r e g u l a t o r s at each service and conducting a flame i o n i z a t i o n survey. This survey had been conducted i n August 1978. A t t h a t time a l l detected l e a k s were reported t o have been repaired. A manhole survey was n o t included. On Friday, January 12, 1979, pressure on t h e l i n e , which normally operated at 4 ounces, w a s increased t o 1 7 psig;and i n s p e c t o r s walked over t h e l i n e t o check f o r leaks, by smell only, while p i l o t l i g h t s were being r e l i g h t e d . The higher pressure was l e f t on t h e l i n e throughout t h e weekend. On Sunday, January 14, 1979, t h r e e more walking surveys were completed over t h i s s e c t o r of pipeline. A s before, no manhole inspection was undertaken, and t h e walk-over surveys were accomplished through smell only. On Monday, January 15, 1979, customer s e r v i c e was i n t e r r u p t e d when the i n s e r t i o n j o b was commenced. The p i l o t l i g h t s were r e l i g h t e d on Monday evening,and t h i s procedure w a s repeated on Tuesday, January 16, 1979, and t h e i n s e r t i o n work continued throughout t h e day of t h e accident. The r e l i g h t w a s completed on Tuesday at 5 : 3 O p.m. The National Transportation Safety Board concludes t h a t applicable p o r t i o n s of 49 CFR Subpart K were not complied with, and that t h e leak could have been detected and t h e accident prevented i f proper uprating procedures had been followed. Therefore, t h e National Transportation Safety Board recommends t h a t t h e American Gas Association: Advise its member companies of t h e circumstances of this accident and urge them t o review t h e i r a c t u a l operating p r a c t i c e s f o r uprating p i p e l i n e s to assure t h a t they conform t o e s t a b l i s h e d company procedure, r e l a t e d i n d u s t r y guidelines, and Federal regulations. (Class I, Urgent Action) (P-79-13) KING, Chairman, DRIVER, Vice Chairman, McAI)AMS and HOGUE, Members, concurred i n this recommendation.#