NTSB Safety Recommendation Letter P-83-029

Page 1Official PDFNATIONAL TRANSPORTATION SAFETY BOARD WASHINGTON, D.C. ISSUED: N o v e m b e r 4 , 1983 Mr. G. A. Lawrence President American Gas Association 1515 Wilson Boulevard Arlington, Virginia 22209 SAFETY RECOMMENDAT I O N ( S ) P-83-29 - - Mr. Arie M. Verrips Executive Director American Public Gas Association 301 Maple Avenue West Vienna, Virginia 22180 ____-_______________---------------- At 10 a.m., c.s.t., on February 1, 1983, a natural gas explosion and flash fire destroyed a house, killed two persons, and injured three persons at 7 0 5 S.W. First St'reet, in Pryor, Oklahoma, and damaged an adjacent house. Natural gas, escaping from a corroded 1/2-inch residential service line located beneath the house, filled the enclosed crawl space, and migrated through the floor and into the house where it was ignited by one of several appliance pilot lights. The city of Pryor, which owns the gas system, distributes natural gas to its customers by providing service lines to gas meters located at the residential property line. The gas pressure is reduced at the property line regulator from 15 to about 1 / 4 psig, about 'I-inches of water column, for use in various indoor gas appliances. The gas company owns the service lines up to and including the meters. Beyond the meters, the service lines are the property and the responsibility of the building owners. During the investigation, pressure tests were performed from the gas main to about 3 feet inside the crawl space under the house: no leakage was detected. An inspection of the noncompany- owned piping revealed that the 1-inch residenti,al service line entered the crawl space underground and emerged near the center of the crawl space as a 1/2-inch steel pipe. Corrosion was found on the pipe at the point where it emerged from the ground. Examination of the corroded segment revealed a hole located at an 3661-A#

Page 2- 2 - elbow, which was about 5 inches below ground surface. F inspection of the area indicated that the aboveground crawl spac piping and the connecting piping to the indoor appliances were mixture of galvanized and steel piping. Company record indicated that the portion of the service line upstream of th gas meter was installed in 1972. Records did not indicate th installation date of the downstream residential the appliance piping. The provisions of 49 CFR 192, Subpart I -- Corrosion Control, do not extend to noncompany-o the gas company acknowledges no responsibility for the resi dential service lines or the indoor house piping. Consequently, periodic gas leakage surveys or other tests to determine the condition of customer piping similar to those required by 49 CFR Section 192.723, Distribution systems: leaka procedures, for company-owned piping are not performed. The Safety Board is concerned about the similar accidents. Numerous bu i Id i ngs nation with natural gas through buried customer-owned, protected service lines, none of which are required by Federal regulations to have periodic gas leakage surveys or other test to determine their condition and few of which are actual1 surveyed or tested. Therefore, the National Safety Board recommends that the American Gas Association a American Public Gas Association: Notify its member companies of the circumstances of this accident and urge them with respect to custo- mer owned service lines not subject to Federal in- spection requirements (1) to encourage their custo- mers to arrange for periodic inspections of buried gas service lines for corrosion and (2) to encour- age local governments to institute requirements for periodic inspections of buried gas service lines - for corrosion. (Class 11. Prioritv Action) (P-83-29) The National Transportation Safety Board is an Federal agency with the statutory responsibility ". . .to prornot transportation safety by conducting independent accident investi gations and by formulating safety improvement recommendation (P.L. 93-633). The Safety Board is vitally interested in a actions taken as a result of its safety recommendations and wou appreciate a response from you regarding action taken or contem plated with respect to the recommendation in this lett BURNETT, Chairman, GOLDMAN, Vice Chairman, and McADAM BURSLEY, and ENGEN, Members, concurred in t-kjs recommendation. .- BY f -#