NTSB Safety Recommendation Letter P-76-027 through P-76-029

Page 1Official PDFWASHINGTON, D.C. ------------____________________________- Forwarded to: M r . R. J. Lynch President Michigan-Wisconsin Pipe Line Co. One Woodward Avenue Detroit, Michigan 48226 SAFETY RECOMMENDAT I ON (S) Q-76-37 through 29 A t 9:04 a.m., January 7 , 1 9 7 6 , employees a t the Michigan-Wisconsin P i p e 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 n a t u r a l gas liquids a t 70Wpsig 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 n a t u r a l 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 as 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 to 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 f o r 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 t o the 16-inch. All 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 main 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 7OO-psig pressure. "le 12-inch suction line,which w a s already cut i n preparation €or 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 w a s 700 psig; on the other side, the 12-inch suction l i n e pointed s t r a i g h t down t h e 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. 1835#

Page 2Mich-Wis had written comprehensive procedures to control the planning, the preparation, the shutdown, and the reopening of the station to allow the contractor to complete his work. On January 2, 1976, 3 days before the station was to be shutdown, 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 were followed, but the valves were not chained because no chains were on hand. On January 6, the Mich-Wis dispatchers ordered the Cedardale personnel to open the 12-inch loop line to increase the system capacity. This operation was not included in the procedures previously discussed with the contractor nor was the contractor advised as to which valves were to be opened. The station personnel discussed the operation and used a station piping diagram as a guide. The accident occurred when the wrong valve was opened inadvertently, and natural gas liquids deluged the contractor's employees and then ignited. Therefore, the National Transportation Safety Board recommends that the Michigan-Wisconsin Pipe Line Company: Initiate immediate action to conduct periodic training programs, using this accident as an illustration, to impress upon its personnel the importance of following precisely the written procedures covering these situations. (P-76-27)(Class I, Urgent Followup) Examine its procedures and practices for valve and piping changes to assure that each critical action is checked independently by at least two persons, one of whom should be a supervisor. (P-76-28) (Class I, Urgent Followup) Prohibit any valve or piping changes, except under emergency conditions, while construction is being conducted within the area. (P-76- 29) (Class I, Urgent Followup)#

Page 3- 3 - TODD, Chairman, McADAMS, HOGUE, BURGESS, and HALEY, Members, concurred in the above recommendations. By: B. Todd, Jr. Chairman#