NTSB Safety Recommendation Letter P-78-053 through P-78-055

Page 1Official PDFNATIONAL TRANSPORTATION SAFETY BOARD WASHINGTON, D.C. Mr. J.E. Tyree President Oklahoma Natural Gas Company 624 South Boston Tulsa, Oklahoma 74119 SAFETY R E C O M M E N D A T I O N ( S ) P-78-53 through 55 --_. On March 251, 1978, the Oklahoma Natural Gas Company ( O N G ) dispatched a crew t o shut off gas service t o a shopping center in Oklahoma City a t a regulator vault so t h a t customer service lines could be repaired. The crew was unable t o close a valve, inside the vault, t h a t was under water upstream of the regulator, so they disconnected the l i n e on the low-pressure side of the regulator a t a 2-inch union and plugged the line without f i r s t stopping the flow of gas. There was another valve o u t s i d e the vault; however, i t was paved over with asphalt, and the crew did not attempt to uncover i t . On April 24, 1578, ONG assigned a different crew to restore g a s service t o the shopping center. A t 3:50 p.m., c.s.t., two employees were overcome by gas while attempting t o reconnect the 2-inch union w i t h o u t f i r s t stopping the flow of gas inside the vault. T h i s crew also had n o t been able t o close the valve inside the vault upstream of the regulator, and the.y d i d not tr,y t o uncover the valve outside the vault. Instead, the men had removed the plug and stuffed the l i n e with a rag. When the rag was pulled out, however, they were unable to align the union properly to s t a r t the threads. The escaping gas f i l l e d the 3- by 4- by 6-foot vault within minutes and the men were overcome. Three other ONG employees entered the vault through the 19-inch opening t o rescue the men and were also overcome; the crew d i d not have a respirator a t the job s i t e . One man was p u l l e d out of the vault n y other ONG workers and was revived a t the scene; however, the other four men died of asphyxiation. A mainline valve f i n a l l y was turned o f f , and rescue personnel with a i r packs arrived and removed the asphyxiated men from the vault. The five men involved in connecting the line in the vault had each been employed by ONG an average of 20 years, and three of them were supervisors. Although ONG has trained its men on the use o f air-breathing masks, ventilators, and l i f e b e l t s , the company does not have written instructions about where t h i s safety equipment shall be used. 2422#

Page 2The Safety Board concludes that if the ONG workmen had pumped the water out of the vault and made the valve operable, o r if they had uncovered the valve outside the vault so t h a t i t could be used to stop the flow of gas before connecting the 2-inch union, this accident would not have occurred. The Safety Board has investigated similar accidents involving gas company employees who were overcome by gas while working i n a vault. 1/ In many cases, senior gas men who were acquainted w i t h the hazaras of natural gas were involved in these accidents. Therefore, the National Transportation Safety Board recommends t h a t the Oklahoma Natural Gas Company: Requlre its employees t o use valves or other means t o stop the flow of gas before disconnecting or reconnecting active gas lines. (Class I , Urgent Action) (P-78-53) In training b o t h new and long term employees, emphasize the need t o have available safety equipment while performing certain hazardous work in confined spaces and the importance of testing the atmosphere, the use of safety devices, and the use of safe procedures. Urgent Action) (P-78-54) (Class I , Revise i t s safety manual t o include written instructions on where and how t o use safety equipment as an on-the-job complement t o existing training a c t i v i t i e s . (Class I , Urgent Action)(P-78-55) KING, Chairman, t k A D A M S , HOGUE, and DRIVER, IAembers, conciirred i n the above recommendations. - - 1/ "Pipeline Accident Report -- Equitable Gas Company, Pittsburg Pennsylvania, November 17, 1971," (NTSB-PAR-72-2); National Fue Gas Company accident, Buffalo, New York, March 26, 1977.#