NTSB Safety Recommendation Letter P-76-102

Page 1Official PDFTI FOR RELEASE: (202) 426-8787 WASHINGTON, D.C. 6:30 P 8 M - j E , S , T a j JANUARY 17, 1977 ISSUED: January 17, 1977 ---------.-_ --.. --- F o r w a r d e d to: Lowell L. Elder Chairman American Society of Mechanical SAFETY RECOMMENDAT I O N ( 5 ) Engineers Gas Piping Standards Committee P-76-102 United Engineering Center 345 East 47th Street New York, New York 10017 At 2:40 p.m", on August 13, 1976, a flash fire in the basement of a house at 243 Union Street in Bangor, Maine, killed one gas company employee, burned two other employees, and caused minor damage to the house. The National Trans- portation Safety Board's investigation of the fire disclosed that liquefied petroleum gas (LPG) admixed with air at 7-inches water-column pressure, had escaped from a severely corroded segment of a 1%-inch bare steel service line at the basement wall. The escaping gas migrated underground along the service line and entered the basement through numerous openings in the stone foundation wall. Two Maine Utility Gas Company servicemen had arrived at the house about 2 p.m. to investigate a customer's report of low gas pressure. When they could not locate the source of the problem, two streetcrew personnel were dispatched to assist the service- men. At 2:20 p.m., the streetcrew apened a plug on a Winch tee on the service line in the basement and determined that there was no gas pressure. A rag was used to partially seal the open- ing in the tee while a rod was put through the opening to probe into the service line. This restored gas pressure at the tee. When the rod was removed from the service line, however, the gas pressure returned to zero. The service line was probed again in the same manner until gas pressure was restored; then the plug was replaced in the tee. A serviceman went upstairs and attempted to light the gas range. There was no gas pressure, however, so he returned to the basement and reported this to the streetcrew foreman. He noted that the streetcrew foreman, in the front of the basement, was smoking a cigarette. The other serviceman, in 1 9 5 1#

Page 2P-76-102 the rear of the basem c i g a r e t t e , lit a matc a water heater t o check moment a b a l l of flame foreman and flashed toward the back of crew foreman burned t o death, and t h e severe burns. The gas company's instructions f o r t h i s t servicemen t o vent open o r t o monitor the atmos i n confined locations. o r the introduction of gas f a c i l i t i e s . A contractor had made leakage surveys o mains previously. Thes phere of 18-inch-deep h vals not exceeding the c l o s e s t building) as w e l l as holes probed over nections t o the gas mains. Since service lines the surveys were no the service l i n e s o 73-12 and 49 CFR 1 9 2 . 7 2 the leakage control pro the operations and the liquefied petroleum gas system i s buried more t s o i l , and t h a t t h i s i s a low-pressure g t h a t the surveys were adequate t o detec system. APpendix G - 1 1 o Engineers (ASME) Guide Systems provides f o r ga techniques, describes r e p a i r requirements, Although not s t a t e d t o operators who tr are not equally appli than-air gases. I#

Page 3- 3 - P-76-102 Therefore, the National Transportation Safety Board recommends t h a t the ASME Gas Piping Standards Comittee: Revise the Guide f o r Gas Transmission and Distribution Systems, Appendix G-11, t o include information appropriate t o heavier- than-air gases which w i l l guide operators of systems transporting these gases i n the selection of gas leakage detection technique6 and procedures. (Class 11, P r i o r i t y Followup) (P-76-102) TODD, Chairman, BAILEY, Vice Chairman, McADAMS, HOGUE, and HALEY, Members, concurred i n the above recommendation. By: THIS RECOMMENDATION WILL BE RELEASED TO THE PIJBLIC ON THE ISSUE DATE SHOWN ABOVE. NO PUBLIC DISSEMINATION OF THIS DOCUMENT SHOULD BE MADE PRIOR TO THAT DATE.#