NTSB Safety Recommendation Letter P-75-001 through P-75-004

Page 1Official PDF- 1 6 - 3 . If c a r r i e r pipe with heavier walls had been installed a t this road crossing instead of casing pipe, this failure might not have occurred. PROBABLE CAUSE I_- -- The National Transportation Safety Board determines that the probable cause of the accident was the failure of a substandard girth weld due to repeated soil s t r e s s e s . Contributing to the imposed s t r e s s e s w e r e the position of the pipe inside the casing and the heavy clay soil surrounding the pipe a t each end of the casing. RECOMMENDAT lONS ---.__- The National Transportation Saiety Board recommends that the Office of Pipeline Sitety of the Department of Transportation: 1. 2. Conduct an industrywide survey on the value of casing pipelines beneath roads and railroads. This survey should be undertaken in cooperation with the American Association of State Highway an3 Transportation Officials, T h e F e d e r a l Highway Administration, appro;, riate industry associations and engineering societies; a n d 49 CFR 192. 323, Casing, should be amended, if necessary. (Recommendation P-75-sl) Require the Michigan-Wisconsin P i p e Line Company to: Recalibrate the pressure-dro? settings on their existing a:ito.ma:ic valves to better i n s u r e their actuation on p r e s s u r e drops caused by line failure, a s required under 49 CFR 192. 745, Valve Maintenance: Transmission lines. (Recornsmendation P-75-2) Conduct t e s t s along its pipeline s y s t e m (including casing locations) in a r e a s of s e v e r e soil swell potential and take a;,propriate corrective mt’asures to prevent s i m i l a r failures f r o m vccurring, a s required under 49 CFK 192. 705 Transportation lines: Patrolling. (R-corn neiidation P-75-5)#

Page 2-17- T h e Safety Board f u r t h e r recommends that the ASME Gas Piping Standards Committee: 3 . Develop guidelines for the use, setting, and maintenance of automatic valves on g a s transmission pipeline systems. (Recommendation P- 75-4) BY T H E NATIONAL TRANSPORTATION SAFETY BOARD JOHNH. REED TXGirman FRANCIS H. McADAMS M e m b e r LOUIS M. THAYER Member ISABEL A . BURGESS Member WILLIAM R. HALEY Me n b e r April 2, 1975#