NTSB Safety Recommendation Letter P-76-006 through P-76-009

Page 1Official PDFNATIONAL TRANSPORTATION SAFETY BOA WASHINGTON, D.C. I S S U E D : February 29, 1976 Forwarded to: Mr. William L. Hutchison President Texas Oil & Gas Corporation 2700 Fidelity Union Tower Dallas, Texas '75201 SAFETY RECOMMENDATION(S) P-76-6 through 9- At 9:45 p.m. on May 21, 1974, a 6-inch gas-gathering pipeline, owned by the Texas Oil and Gas Corporation, ruptured at the edge of a rural road south of Meridian, Mississippi. Three vehicles entered the area which contained the escaping gas and stalled near the rupture. The gas ignited at 10:05 p.m., and five persons died as a result. Three vehicles were destroyed and 40 acres of woodland were burned. Although less than 4 years old, the 6-inch pipe had corroded internally and had been embrittled by hydrogen. The pipeline operator had not detected the corrosion although some corrosion test coupons had been installed. The pipeline had not been scraped internally often enough; consequently, liquids accumulated in the bottom of the pipe. The pipe ruptured at 300 psig - - well below its specified minimum yield strength - - at a weak point thinned by internal corrosion and further weakened by hydrogen embrittlement. Therefore, the National Transportation Safety Board recommends that the Texas Oil and Gas Corporation: (1) (a) Establish a periodic scraper program and install ap- propriate hydrogen probes, test coupons, resistance probes, or other testing equipment at strategic locations to identify and locate internal corrosion problems, (b) examine the test equipment and analyze the scraper residues carefully at regular time inter- vals to monitor the internal condition of the lines, and (c) take necessary action to repair deficiencies found in the pipes and to improve operational proce- dures for the prevention of corrosion and hydrogen embrittlement. (P-76-6) (Class I, Urgent Followup) 1738#

Page 2- 2 - (3) (4) Determine t h e c o r r e c t freque i n h i b i t o r and t h e proper i n j e c t i o n points so t h a t f u r t h e i n t e r n a l corrosion can be deterred. (P-76-71 ( C l a s s I, Urgent Followup) I n s t r u c t i t s employees on t h operation and maintenance of prevent water from entering (Class I, Urgent Followup) I n s t a l l pipe used i n the construction o r r e p a i gathering l i n e s w i t h the lon of the pipe. (P-76-9) (Class 111, Longer Term Fo REED concurred , Acting Chairman, McADAMS, T i n t h e above recommendations. By: Webster B. Todd, Chairman NAIIONAL IRANSPORIAllON SAFEIY BOARD WASHINCION DC 201’11 OFFICIAL IIUSINESS PENALTY FOR PBIVAIE USE, 8300#