NTSB Safety Recommendation Letter P-79-009 through P-79-012

Page 1Official PDFNATIONAL TRANSPORTATION SAFETY BOARD WASHINGTON, D.C. I S S U E D : June 11, 1979 Mr. H. B. Peet President Delta Natural Gas Co., Inc. Route 1, Box 30A Winchester, Kentucky 40391 \ SAFETY RECOMMENDAT I ON ( s ) i P-79-9 through -12 A t 9:30 p.m., e.s.t., on January 16, 1979, an explosion and f i r e destroyed f i v e commercial buildings and damaged several o t h e r buildings i n London, Kentucky. Two persons were i n j u r e d a s 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 off t h e gas i n t h e s e r v i c e l i n e serving t h e buildings. Twenty-five f i r e companies a s s i s t e d i n extinguishing t h e f i r e . Nitrogen pressure t e s t i n g of t h e 7-inch O.D., s t e e l d i s t r i b u t i o n main, which had had a recent pressure i n c r e a s e to 1 7 psig, revealed a corrosion hole 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 was i g n i t e d by an undetermined source. A t the t i m e of t h e accident, t h e gas company had been i n t h e 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 so t h e main’s operating pressure could be increased to 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., s t e e l , well-casing pipe t h a t had been i n s t a l l e d with mechanical couplings i n 1930 and 1931. The Gas Service Company was not i n compliance with 49 CFR 192.457cb) 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 a t each s e r v i c e 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 t i m e a l l detected l e a k s were reported t o have been repaired, A manhole survey was not included. On Friday, January 1 2 , 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 inspectors walked over the l i n e t o check f o r l e a k s , 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 the weekend. On Sunday, January 1 4 , 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, 1 9 7 9 , customer s e r v i c e was i n t e r r u p t e d when t h e i n s e r t i o n job 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 was 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 was completed on Tuesday a t 5 : 3 0 p.m. The National Transportation Safety Board concludes t h a t applicable portions of 4 9 CFR Subpart K were n o t complied with, and t h a t t h e l e a k 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 Delta Natural Gas Company, Lnc.: Determine t h e condition of o t h e r cathodically unprotected pipe which may be comparable t o t h e f a i l e d pipe, and develop a schedule f o r system improvement based on t h e findings. (Class 11, P r i o r i t y Action) (P-79-9) Develop w r i t t e n uprating procedures s u f f i c i e n t t o comply with requirements of 49 CFR 192 Subpart K and related American Society of Mechanical Engineers guide m a t e r i a l . (Class 11, P r i o r i t y Action) (P-79-10) A s a p a r t o f t h e uprating procedures, provide t h e p r o j e c t foreman with a w r i t t e n plan that w i l l account f o r t h e s p e c i f i c elements and v a r i a b l e s of each case before the commencement of any uprating project. (Class 11, P r i o r i t yAction) (P-79-11]#

Page 3Train a l l personnel involved with uprating procedures t o a s s u r e knowledge of applicable regulations and w r i t t e n company uprating procedures. (Class 11, Action) (P-79-12) P r i o r i t y KING, Chairman, DRIVER, Vice Chairman, McADAMS and BOGUE, Members, concurred i n these recommendations.#