NTSB Safety Recommendation Letter P-76-101

Page 1Official PDFTATION SAFETY BOA WASHINGTON, D.C. ISSUED: January 17, 1977 F o r w a r d e d to: Honorable William T . Coleman, Jr. Secretary Department of Transportation Washington, D . C . 20590 Honorable Leslie H . Stanley Cnairiiiari Maine Public U t i l i t i e s Commission State House Augusta, Maine 04333 ................................... SAFETY RECOMMENDAT I ON (5) P-76-101 A t 2:40 p . m . , on August 13, 1 9 7 6 , a f l a s h f i r e i n the basement of a house a t 243 Union Street i n Bangor, Maine, k i l l e d one gas company employee, burned two other employees, and caused minor damage t o the house. The National Trans- portation Safety Board's investigation of the f i r e disclosed that liquefied petroleum gas (LPG) admixed with a i r a t 7-inches water-column pressure, had escaped from a severely corroded segment of a 1%-inch bare s t e e l service l i n e a t the basement wall. The escaping gas migrated underground along the service l i n e and entered the basement through numerous openings i n the stone foundation wall. Two Maine U t i l i t y Gas Company servicemen had arrived a t the house about 2 p , m . t o 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 a s s i s t the service- men. A t 2 : 2 0 p . m . , the streetcrew opened a plug on a 1%-inch tee on the service l i n e i n the basement and determined t h a t there was no gas pressure. A rag was used t o p a r t i a l l y s e a l the open- ing i n the t e e while a rod was put through the opening t o probe i n t o the service l i n e . This restored gas pressure a t the tee. When the rod was removed from the service l i n e , however, the gas pressure returned t o zero. The service l i n e was probed again i n the same manner u n t i l gas pressure was restored; then the plug was replaced i n the tee. A serviceman went upstairs and attempted t o l i g h t the gas range. There was no gas pressure, however, so he returned t o the basement and reported t h i s t o the streetcrew foreman. He noted t h a t the streetcrew foreman, i n the f r o n t of the basement, was smoking a c i g a r e t t e . The other serviceman, i n 1951#

Page 2~ P-76-101 I the rear of the basement, who a l s o w a s aware of the lighted c i g a r e t t e , lit a match t o illuminate h i s way as he s t a r t e d toward a water heater t o check gas pressure i n i t s f u e l l i n e . A t t h i s moment a b a l l of flame appeared around the f e e t of the streetcrew foreman and flashed toward the back of the basement. The s t r e e t - crew foreman burned t o death, and the two servicemen suffered severe burns. The gas company's operating procedures d i d not include instructions f o r t h i s type of operation. They d i d not require servicemen t o vent open service l i n e s t o a safe outside location o r t o monitor the atmosphere f o r combustible gases when working i n confined locations. The procedures d i d not prohibit smoking o r the introduction of other ignition sources while working near gas f a c i l i t i e s . A contractor had made leakage surveys of the company's gas mains previously. These surveys consisted of sampling the atmos- phere of 18-inch-deep holes probed over the gas mains ( a t i n t e r - vals not exceeding the distance between the gas main and the closest building) as well as holes probed over service l i n e con- nections t o the gas mains. Since service l i n e s were not included, the surveys were not adequate t o locate potential gas leakage from the service l i n e s o r meter s e t assemblies. OPSO Advisory Bulletin 73-12 and 49 CFR 192.723(b) require t h a t "The type and scope of the leakage control program must be determined by the nature of the operations and the l o c a l conditions . . . . I ' The f a c t t h a t liquefied petroleum gas i s heavier than a i r , t h a t much of t h i s system i s buried more than 3 f e e t below the surface i n a clay-type s o i l , and t h a t t h i s i s a low-pressure gas system makes it doubtful that the surveys were adequate t o detect gas leakage from t h i s s ys t em. The house's service l i n e evidenced active corrosion as defined i n 49 CFR 192.457(c). Although incomplete, the gas company's records show nine service l i n e leaks from 1974 through July 1 9 7 6 , while Bangor F i r e Department records show three gas service l i n e leaks not recorded by the company from 1973 through July 1976; a l l of the leaks were caused by corrosion a t the foundation wall. The gas company's 1970 through 1975 annual reports t o the Office of Pipeline Safety Operations (OPSO) reported t h a t 77 corrosion leaks were repaired. The annual reports t o OPSO since 1970 show t h a t 1,320 service l i n e s have been r e t i r e d and 30 have been replaced. The Safety Board learne that a t l e a s t one-fourth of the service l i n e s r e t i r e d were corro t o the degree t h a t replacement would have been necessary f o r future use. Many other leak reports t o which the gas company responded a r e recorded by the Bangor Fire Department but do not appea gas company records.#

Page 3- 3 - P-76-101 Title 49 CFR 192.457(b) requires that buried or submerged pipelines installed before August 1, 1971, except those made from cast iron, must be cathodically protected in areas of active corrosion by August 1, 1976. This gas system does not comply with the requirement, but the company has contracted for a sur- vey to determine areas of active corrosion and for development of recommendations for cathodic protection. One of the gas company servicemen stated that the only time the odor of gas was detected at the house was when it came from the service line tee. The other serviceman said he never smelled the odor of gas while at the house. The system received liquefied petroleum gas (LPG) in 30,000-gallon tank cars and the bills of lading indicated that 1% pounds of ethyl mercaptan, an odorant, was added for every 10,000 gallons before it was shipped. The LPG was vaporized and mixed with air as needed. The company's only odor-level check was a monthly sniff test made by an employee without the aid of a device that determined the gas-in- air concentration at which the odor is first perceived. This action was not sufficient to insure that the intensity of the odor would be readily detectable throughout the system. Such assurance is required by 49 CFR 192.625 and OPSO Advisory Bulletin No. 74-1. Therefore, the National Transportation Safety Board recommends that the Department of Transportation in conjunction with its State Agent, the Maine Public Utilities Commission: Monitor the compliance actions taken by Maine Utility Gas Company to insure that it has established operations and maintenance records as required by 49 CFR 192. (Class TI, Priority Followup) (P- 76- 101) TODD, Chairman, BAILEY, Vice Chairman, McADAMS, HOGUE, and HALEY, Members, concurred in the above recommendation. I . Chairman#