NTSB Safety Recommendation Letter P-76-017 through P-76-019

Page 1Official PDFANSPORTATIOO\( SAFETY BO WASHINGTON, D.C. FOR RELEASE: 6:30 A,M,, E,D,T,, MAY 20, 1976 (202) 426-8787 ______-__________________________^______- F o r w a r d e d to: Mr. Keith L. Turley P r e s i d e n t Arizona P u b l i c Service Company P. 0 . Box 21666 Phoenix, Arizona 85036 ISSUED: May 20, 1976 SAFETY RECOMMENDAT I O N ( S ) P-76-17 through 1 9 __ A t 3:18 a . m . on February 8 , 1976, a house i n Phoenix, Arizona, exploded and burned. l/ O f two persons who were h o s p i t a l i z e d as a r e s u l t of t h e a c c i d e n t , one d i e d . The National Transportation Safety Board's i n v e s t i - g a t i o n of t h i s a c c i d e n t d i s c l o s e d t h a t natural gas a t 39-psig p r e s s u r e had leaked from t h e compression coupled connection of a 2-inch p l a s t i c p i p e l o c a t e d 10 feet from t h e house i n an a l l e y . The 2-inch p i p e appeared t o have been i n s e r t e d i n s u f f i c i e n t l y through the gasket and i n t o t h e coupling. Gas which leaked from t h i s j o i n t was trapped from above by h e a v i l y compacted s o i l ; it conse- quently seeped i n t o t h e house, where it was i g n i t e d by an unknown source. The 2-inch p l a s t i c p i p e , which w a s i n s t a l l e d i n 1968 by the Arizona P u b l i c Service Company, was damaged by an excavator i n 1969. The gas company r e p a i r e d t h e leak by i n s t a l l i n g a 6-inch-long compression coupling t o connect each end o f t h e severed 2-inch p l a s t i c pipe. The r e p a i r e d s e c t i o n w a s wrapped with t a p e which extended 3 t o 4 inches over t h e p i p e on each s i d e of t h e coupling. The S a f e t y Board reviewed t h e company's leak experience t o determine i f o t h e r pipes had leaked because of f a u l t y com- - I./ The S a f e t y Board w i l l . n o t i s s u e a formal r e p o r t on t h i s accident. 1808#

Page 2- 2 - pression coupling installations. It learned that an explosion occurred on March 17, 1 were injured as a result. In that when a 2-inch plastic pipe had sep coupling because the plastic pipe ciently into the compression coupling. A review of the gas company's written procedures ind that they did not provide adequate information on the use o this type of compression coupling and that there was no ade training in or monitoring of the installation of this type compression coupling. Therefore, the National Transportation Safety Board recommends that the Arizona Public Service Company: I. Determine the number of similar plastic pipe coupling installations in their facilities, excavate and inspect a statistically representative sample of these to determine if they have been insta remedial action on any deficient the sampling, and based upon the r institute necessary corrective act Urgent Followup) 2. Develop comprehensive construction standards for the installation of cornpressio of pipe for which each type of fit (Class I, Urgent Followup) 3. Train employees who will install compress couplings under the standards developed and monitor the performance by inspecting their work. (P-76-19) (Class Urgent Followup) TODD, Chairman, McADAMS, BURG concurred in the above recommendat By: THESE RECOMMENDATIONS WILL BE RELEASED TO THE PUBLIC INDICATED ABOVE. NO PUBLIC DISSEM CONTAINED HEREIN SHOULD BE MADE BEFORE THAT DATE.#