NTSB Safety Recommendation Letter P-76-026

Page 1Official PDFATIONAL TRANSPORTATION SAFETY BOARD WASHINGTON, D.C. I S S U E D : June 23, 1976 F o r w a r d e d to: M r . Walter E . Rogers Pres iden t I n t e r s t a t e Natural Gas Association of America 1660 L S t r e e t , N . W . Washington, D. C . 20036 \ SAFETY RECOMMENDAT ION ( s ) P-76-26 i A t 9:04 a.m., January 7 , 1976, employees a t the Michigan-Wisconsin Pipe Line Company's (Mich-Wis) Cedardale, Oklahoma, compressor s t a t i o n were directed t o open a valve on a shut-in 12-inch gas-gathering pipeline i n an attempt t o increase the flow i n t o the main l i n e . Natural gas and natural gas liquids a t 700-psig pressure roared through the valve, out through the end of an open 12-inch pipe, and i n t o a ditch, where seven men were working near an open flame heater. The natural gas liquids saturated t h e i r clothing and the heater s e t them on f i r e . Five men were k i l l e d and two men were burned seriously a s a r e s u l t of t h i s accident. Mich-Wis had employed an independent contractor t o fabricate the piping and t o i n s t a l l three additional compressors t o increase the capacity of Cedardale s t a t i o n . A l l work was completed except f o r the i n s t a l l a - tion of a 16-inch suction l i n e t o the compressors. The ditch for the 16-inch l i n e had been dug and the 12-inch suction l i n e had been cut i n preparation f o r welding to the 16-inch. A l l piping within the work area had been depressured and gas-freed, and the Cedardale s t a t i o n had been bypassed. The mai.n l i n e carried gas around the s t a t i o n and on t o the transmission l i n e , while the loop l i n e was closed i n a t 700-psig pressure. The 12-inch suction line,which w a s already cut i n preparation f o r welding t o the 16-inch l i n e , was connected t o the main l i n e by a 12-inch valve, which was closed. On one side of t h i s valve, the pressure was 700 psig; on the other side, the 12-inch suction l i n e pointed s t r a i g h t down the ditch. Eight other valves, some open and some closed, cross-connected the two incoming 12-inch pipelines with the s t a t i o n piping. 183 5#

Page 2- 2 - Mich-Wis had written comprehensive procedures to the planning, the preparation, the shutdown, an opening of the station to allow the contractor work. On January 2, 1976, 3 days before the st shut down, all parties concerned with the construction met to discuss the procedures. The discussion included which valves were to remain open and which valves were to be closed and chained to prevent inadvertent reopening; all procedures w followed, but the valves were not chained becau were on hand. On January 6, the Mich-Wis dispatchers ord Cedardale personnel to open the 12-inch loop line to in the system capacity. This o?eration was not included i procedures previously discussed with the contra the contractor advised as to which valves were The station personnel discussed the operation and used a station piping diagram as a guide. The acciden the wrong valve was opened inadvertently, an liquids deluged the contractor's employees Therefore, the National Transportation Safety Board recommends that the Interstate Natural Gas Association of America: Advise their member companies who operate gas-gathering pipeline systems of the importance of fo precise1 the written procedures covering these situat (P-76-26y(Class I, Urgent Followup) TODD, Chairman, McADAMS, HOGUE, BURGESS, and HALEY, M concurred in the above recommendation. By: Webster B. Todd, Jr. Chairman NATIONAL IRANSPORIATION SAFETY BOARD WASHINGTON, D C 2059% OFFICIAL UUSINESS PENALTY FOR PRIVAIE USE. 8300 PRIORITY MAIL#