NTSB Safety Recommendation Letter P-78-024

Page 1Official PDFNATIONAL TRANSPORTATION SAFETY BOARD WASHINGTON, D.C. ISSUED: July 6 , 1978 Mr. L. D. Santman Director Materials Transportation Bureau Department of Transportation Washington, D . C . 20590 1 SAFETY l b \T I P-78-24 A t 1 p.m., e . s . t . , on December 1, 1977, a 12-inch, cast-iron high- pressure gas main owned by t h e Atlanta Gas Light Company (AGL) w a s ruptured by an 8-inch steel 1-beam p i l e , which was driven through t h e pipe a t a construction s i t e i n downtown Atlanta, Georgia. - 1/ Within minutes, n a t u r a l gas at 10-psig pressure migrated through t h e ground, entered sewer l i n e s and e l e c t r i c conduit systems, and spread i n t o nearby buildings. The gas did not i g n i t e , but thousands of people were evacuated from nearby o f f i c e buildings. A valve was closed at 2:45 p.m. t o shut off t h e flow of gas t o the ruptured main, and t h e a r e a was declared s a f e a t 4 p.m. The 12-inch g a t e valve t h a t was used t o shut off t h e flow of gas w a s located 1,000 f e e t from t h e rupture. The gas was fed from one d i r e c t i o n and because t h e main was dead-ended, only one valve was required t o shut t h e system. Because t h i s valve was n o t designated an emergency valve, t h e gas company d i d not have t o check and s e r v i c e t h e valve annually as required by Federal regulations f o r emergency valves. The gas company w a s unaware t h a t t h e valve cover had been paved over w i t h 8 inches of asphalt; i f the valve could not have been located or i f t h e valve had f a i l e d t o s t o p t h e flow of gas t o t h e main, 22 emergency valves would have t o have been closed t o i s o l a t e the rupture a r e a . - 1/ For more d e t a i l e d information read "Pipeline Accident Report -- Atlanta Gas Light Company, High-pressure Gas Main Rupture, Atlanta, Georgia, December 1, 1977'' (NTSB-PAR-78-3). 2360#

Page 2If AGL had had t o close the 22 valves, the company would have to have r e l i g h t e d customer services to the e n t i r e downtown business section. It i s apparent from t h i s accident t h a t a d d i t i o n a l emergency valves are needed and should be i n s t a l l e d and located t o make a more rapid shutdown possible. Since emergency valves a r e required t o be inspected annually, t h e c o s t of maintenance influences t h e number of valves s e l e c t e d and, in some existing systems, only a c e r t a i n percentage of e x i s t i n g valves have been designated emergency valves. The Safety Board b e l i e v e s t h a t t h i s i s n o t i n the b e s t i n t e r e s t of public safety. The Safety Board, i n its "Pipeline Accident Report, Northern S t Power Company, Lake City, Minnesota, October 30, 1972," (NTSB-PAR-73- recommended t h a t t h e Office of Pipeline Safety (Operations) of t h e U.S. Department of Transportation: Amend 49 CFR 192.181(a) t o include requirements which express c l e a r l y the i n t e n t of OPS concerning the number and t h e l o c a t i o n of emergency valves i n high pressure gas d i s t r i b u t i o n systems and which t r e a t t h e need f o r keys i n t h e hands of l o c a l a u t h o r i t i e s . (Recommendation P-73-4) On A p r i l 3, 1978, i n a l e t t e r t o the Safety Board, t h e OPSO s t a t e d t h a t because of 'I.. . t h e v a r i e t y of operating conditions and types of systems i n operation throughout the nation, w e do not feel t h a t s p e c i f i c requirements i n t h i s area could be developed t o adequately apply t o a l l operations ." The Safety Board, however, s t i l l believes t h a t a problem e x i s t s i n t h a t t h e r e is a deficiency i n regulation 49 CFR 192.181 as it does not c l e a r l y r e f l e c t t h e requirement f o r location and number of emergency valves. Therefore, t h e National Transportation Safety Board recommends t h a t the Office of P i p e l i n e Safety Operations: Amend 49 CFR 192.181(a) t o s p e c i f i c a l l y define t h e requirement f o r l o c a t i o n and number of emergency valves. (Class 111, Longer Term Action)(P-78-24) K I N G , Chairman, McADAMS, HOGUE, and DRIVER, Members, concurred i n above recommendation.#