NTSB Safety Recommendation Letter P-79-026

Page 1Official PDFANSPORTA pd SAFETY D WASHINGTON, D.C. ISSUED: September 4, 1979 Mr. L.D. Santman Director Materials Transportation Bureau Department of Transportation Washington, D.C. 20590 \ SAFETY RECOMMENDAT ION (SI P-79-26 __ 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 s e v e r a l other buildings i n London, Kentucky. Two persons were injured 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 f i r s t 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 extin- guishing t h e fire.&/ Nitrogen pressure t e s t i 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 a recent pressure increase t o 1 7 p s i g , revealed a corrosion hole i n the 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 possibly by a spark from an e l e c t r i c motor i n a beverage cooler. A t t h e time of t h e accident, t h e gas company had been i n t h e process of modifying some 1,500 f e e t 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 t o serve a l a r g e r load. Most of t h e e x i s t i n g Line being uprated was used, bare, 7-inch O.D., steel, w e l l 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 - 1/ For more d e t a i l e d information read "Pipeline Accident Report--Gas Service Company, Explosion and F i r e , London, Kentucky, January 16, 1979" (NTSB-PAR-79-2). 2660A#

Page 2- 2 - was not in compliance with 49 CFR 192.457(b) because there was no cathodic protection provided for this type of pipe throughout the system. Corrosion holes could exist elsewhere in the system. The uprating was accomplished by installing regulators at each service and conducting a flame ionization survey. This survey had been conducted in August 1978. At that time all detected leaks were reported to have been repaired. A manhole survey was not included. On Friday, January 12, 1979, pressure on the line, which normally operated at 4 ounces, was increased to 17 psig; inspectors walked over the line to check for leaks, by smell only, while pilots lights were being relighted. The higher pressure was left on the line throughout the weekend. On Sunday, January 14, 1979, three more walking surveys were completed over this sector of pipeline. As before, no manhole inspection was undertaken, and the walk-over surveys were accomplished through smell. only. On Monday, January 15, 1979, customer service was interrupted when the insertion job was commenced. The pilot lights were relighted on Monday evening, and this procedure was repeated on Tuesday, January 16, 1979, and the insertion work continued throughout the day of the accident. The relight was completed on Tuesday at 5:30 p.m. The National Transportation Safety Board concludes that applicable portions of 49 CFR Subpart K were not complied with, and that the leak could have been detected and the accident prevented if proper uprating procedures had been followed. Therefore, the National Transportation recommends that the Materials Transportation Bureau of the U.S. Department of Transportation: Monitor, through its State agent, the Kentucky Public Service Commission, the activity of the Gas Service Company, Inc., to uprate its gas distribution system in London, Kentucky, in compliance with the Federal regulations. Priority Action) (P-79-26) (Class 11, KING, Chairman, DRIVER, Vice Chairman, GOLDMAN, and BURSLN, Members, concurred in the above recommendation. McADAMS, Member, did not participate.#