NTSB Safety Recommendation Letter P-80-074

Page 1Official PDFWASHINGTON, D.C. Forwarded to: \ Honorable Howard Dugoff Administrator Research and Special Programs Administration Washington, D.C. 20590 I P R n 7 4 SAFETY RECOMMENDAT I ON (S) - - About 7:30 a.m., c.d.t., on August 7 , 1978, in Lafayette, Louisiana, natural gas a t 1 5 psig pressure escaped from a corrosion leak in an inactive 1-inch steel service line and migrated beneath a concrete slab and into a building where it ignited. The resulting explosion and fire injured six persons and destroyed the building and its contents. When the service line was installed by t h e Central Louisiana Electric Company, Inc., i n the early 1960's, it was mill-coated with a coal-tar epoxy and the fittings were field-wrapped with tape. Later, a concrete slab was poured over t h e line, possibly depressing it into contact with a 4-inch cast-iron sewerline. In 1973, service to the building was deactivated by removing the meter and capping the line, in compliance with 49 CFR 192.727, which was amended effective November 3, 1972, to exempt service lines from the requirement that they be disconnected at the gas source. Under the amended rule, the service line was required to be maintained under cathodic protection and periodically surveyed for gas leaks. Some time between 1975 and 1976, magnesium anodes were installed on t h e gas piping system, including the service line. The Safety Board's investigation revealed that the coating on the service line had been damaged and that a corrosion hole had developed where t h e service line made contact with the sewerline or was shielded from cathodic protection by the sewerline. Information received from the Louisiana Office of Conservation, Pipeline Division, the State agency that regulates pipeline operations in Louisiana, showed that in March 1978, the Central Louisiana Electric Company, Inc., the pipeline operator, conducted an electrical survey of the line's cathodic protection. The survey showed no abnormality. An engineering consultant, employed by the electric company, inspected the pipe after the accident and reported that the size of the corrosion hole suggested that corrosion could have begun before the installation of anodes. Because of the proximity of the sewerline and/or actual electrical contact with the sewerline, the corrosion probably continued after t h e magnesium anodes were installed. 29668#

Page 2-2- When the post-accident electrical also performed a leak survey, using a co CGI can only detect gas under concrete holes have been drilled through the concr Since the accident, the Safety Board has learned that the electric compa for additional cathodic protection work on the Louisiana Office of Conservation, the units for use as an additional check for company is currently training its personne On June 17, 1975, in a similar acci Stroudsburg, Pennsylvania. The Safety leaking into the basement of the house line that had been capped, but was still under pressure. No gas had been service line for more than 8 years. The Safety Board is concerned that the potential for an’inactiv become a hazard to public safety increas of protection applied. An inactive line should be required to be abandoned after a spec period of time. The Board has been inf for the physical disconnection and purgi period; Michigan specifies 5 years and F time requirement for abandonment of Federal regulations for gas pipelines. Therefore, the National Transportation Safety Board recommen and Special Programs Administration: Initiate rulemaking to prescribe a time l i m i t when service line would be requi disconnected from the main. KING, Chairman, DRIVER, Vice C Members, concurred in this recommenda#