NTSB Safety Recommendation Letter P-76-096 through P-76-100

Page 1Official PDFFOR RELEASE: (202) 426-8787 TATION SAF TY BOARD WASHINGTON, D.C. 6:30 P,M,, E,s,T,, JANUARY 17, 1977 I S S U E D : January 17, 1977 President Maine Utility Gas Company c/o Utilgas Service Corporation 660 Madison Avenue New York, New York 10021 SAFETY RELOMMENDAT I ON ( S ) P-76-96 through P-76-100 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 opened a plug on a &inch 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 1951#

Page 2the r e a r of the basement, who also 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 a water heater t o check gas pressure i n i t s f u e l l i n e . moment a b a l l of flame appeared around the f e e t of t h e foreman and flashed toward the back of the basement. crew foreman burned t o death, and the two servicemen suffered severe burns. The gas company’s operating procedures did not i n c instructions f o r t h i s type o f operation. They d i d not servicemen t o vent open service l i n e s t o a safe o u t s i o r t o monitor the atmosphere f o r combustible gases whe i n confined locations. The procedures d i d not prohibi or the introduction of other ignition sources while w gas f a c i l i t i e s . A contractor had made leakage surveys of the company’s mains previously. These surveys consisted of sampling the a phere of 18-inch-deep holes probed over the gas mains ( a t i n vals not exceeding the distance between the gas main closest building) as w e l l as holes probed over servic riections t o the gas mains. Since service Lines were the surveys were not adequate t o locate p o t e n t i a l gas the service l i n e s or meter s e t assemblies. OPSO Advisory B 73-12 and 49 CFR 192.723(b) require t h a t “The type and scop the leakage control program must be determined by the natur the operations and the local conditions . . . .” The f a c t liquefied petroleum gas i s heavier than a i r , t h a t much of t system i s buried more than 3 f e e t below the surface i n a clay-t s o i l , and t h a t t h i s i s a low-pressure gas system makes it doub t h a t the surveys were adequate t o detect gas leakage from t h i s - - sys tem. The house’s service l i n e evidenced active corr defined i n 49 CFR 192.457(c). Although incomplete, company’s records show nine service l i n e leaks f r o July 1976, while Bangor F i r e Department records show three service l i n e leaks not recorded by the company f r o July 1976; a l l o f the leaks were caused by corrosion a t t foundation wall. The gas company’s 1970 through 1975 ann reports t o the Office of Pipeline Safety Operatio reported that 77 corrosion leaks were repaired. The reports t o OPSO since 1970 show t h a t 1,320 service li been r e t i r e d and 30 have been replaced. The Safety t h a t a t l e a s t one-fourth of the service l i n e s r e t i r e d t o the degree t h a t replacement would have been necess use. Many other leak reports t o which the gas compan a r e recorded by the Bangor Fire Department but do n - gas company records. ..#

Page 3- 3 - P-76.96 thraugh P-76-100 T i t l e 49 CFR 192.457(b) requires t h a t buried o r submerged pipelines i n s t a l l e d before August 1, 1 9 7 1 , except those made from cast iron, must be cathodically protected i n areas of active corrosion by August 1, 1976. This gas system does not comply with the requirement, but the company has contracted f o r a sur- vey t o determine areas of active corrosion and for development of recommendations f o r cathodic protection. One of the gas company servicemen s t a t e d t h a t the only time the odor of gas was detected a t the house was when it came from the service l i n e tee. The other serviceman said he never smelled the odor of gas while a t the house. The system received liquefied petroleum gas (LPG) i n 30,000-gallon tank cars and the b i l l s of lading indicated t h a t 1% pounds of ethyl mercaptan, an odorant, was added f o r every 10,000 gallons before it was shipped. The LPG w a s vaporized and mixed with a i r as needed. The company's only odor-level check was a monthly s n i f f t e s t made by an employee without the a i d of a device t h a t determined the gas-in- a i r concentration a t which the odor i s f i r s t perceived. This action was not s u f f i c i e n t t o insure that the i n t e n s i t y of the odor would be readily detectable throughout the system. Such assurance i s required by 49 CFR 192.625 and OPSO Advisory s u l l e t i n No. 74-1. Therefore, the National Transportation Safety Board recommends t h a t the Maine l l t i l i t y Gas Company: Develop written procedures t o insure the safety of i t s personnel and the public when work i s performed on active gas f a c i l i t i e s within buildings o r other enclosed locations and t r a i n i t s employees i n the use of the procedures. These procedures should require the use of equipment t o monitor the atmosphere f o r combustible gases and should prohibit smoking, open flames, or other sources of ignition. (Class I , Urgent Followup)(P-76-96) Inspect a sample of the bare s t e e l gas service l i n e s a t foundation walls t o determine the systemwide extent of corrosion and perform a survey capable of detecting gas leakage t h a t includes a l l service l i n e s , meter s e t assemblies,and openings i n foundation walls near gas service l i n e s . Based upon the r e s u l t s of the inspection and survey, take necessary corrective action. (Class I , Urgent Followup)(P-76-97)#

Page 4- P- 76-96 through P- 76- 100 Determine areas of necessary cathodic which could result to public safety. ( P -. 7 6- 9 8 ) (Class I, Urgent Followup) Determine the odor intensity of the gas fifth of its lower explosive limit and p sample the intensity at representative locatio (Class I, Urgent Followup)(P-76-99) Maintain operation and maintenance records a required by 49 CFR 192. (Class I, Urgent Fo (P-76-100) TODD, Chairman, BAILEY, Vice Chairman, McADAMS, HOC Hi iLEY. Members, concurred in the above recommendations. By: THIS RECOMMENDATION WILL BE RELEAS DATE SHOWN ABOVE. NO PUBLIC DISSEMINATION OF THISHOULD BE MADE PRIOR TO THAT DATE.#