NTSB Safety Recommendation Letter P-79-031

Page 1Official PDFL. TRANSPORTATION SAFETY WASHINGTON, D.C. I S S U E D : October 1 2 , 1979 Forwarded to: M r . G . H . Lawrence President American Gas Association 1515 Wilson Boulevard Arlington, Virginia 22209 SAFETY RECOMMENDAT I ON (S) P-79-31 A t 3:35 a.m., on October 6, 1979, an explosion of l i q u e f i e d n a t u r a l gas (LNG) vapors destroyed a transformer building a t t h e Columbia LNG Corporation F a c i l i t y i n Cove Point, Maryland. One person was k i l l e d i n t h e explosion, one person was c r i t i c a l l y i n j u r e d , and other buildings a t the f a c i l i t y were damaged. The National Transportation Safety Board's continuing i n v e s t i g a t i o n of the accident has found t h a t a high-pressure LNG pump i n t h e high- pressure pump building was discovered leaking about 3:OO a.m., during a routine equipment check by an employee. He n o t i f i e d an employee i n the monitor house about 400 f e e t away by r a d i o of the pump leakage. Because of radio i n t e r f e r e n c e t h e monitor house was able to understand only t h a t a pump was leaking, and t h e employee would phone the monitor house from t h e transformer building. When t h e employee reached t h e transformer building, about 3:30 a.m., he c a l l e d t h e monitor house employee by telephone, advised him of t h e s i t u a t i o n , and s a i d t h a t he was going t o p u l l the c i r c u i t breaker on t h e leaking pump. A t 3:35 a.m., an explosion occurred i n t h e transformer building; one employee was k i l l e d and another was c r i t i c a l l y injured. The Safety Board's inveetigation i n d i c a t e s t h a t LNG leaked through an e l e c t r i c a l termination seal on t h e high-pressure pump, and then vaporized and flowed under pressure through the motor i n l e t conduit s e a l located 1 2 inches below t h e bottom of t h e connection box. LNG and gas vapors then flowed through t h e e l e c t r i c conduit about 225 f e e t from t h e high-pressure pump building to t h e transformer building. There gas vapors leaked through t h e l a s t e l e c t r i c conduit s e a l j u s t below the c i r c u i t breaker. A s t h e employee opened the c i r c u i t breaker a spark ignited t h e gas vapor. 2763#

Page 2- 2 - The Safety Board was informed that because of long lead times and the extent of work necessary to replace the transformers and switch gear, the Cove Point LNG Facility may not be back in full operation for 6 months to 1 year. This LNG facility may be made partially operational in 2 to 4 weeks by making temporary repairs permitting operation of a portion of the gasification equipment. The Safety Board is concerned that other LNG facilities with similar design could experience the same problem. Therefore, the National Transportation Safety Board recommends that the American Gas Association: Notify its member companies operating similar LNG facilities of the known particulars of the Cove Point accident and request that they conduct an inspection of electric conduit seals at their facilities immediately to determine if leaks through the seals could result in similar explosion hazards at their LNG facilities, and that they take appropriate actions to correct any potential hazards found. (Class I, Urgent Action)(P-79-31) KING, Chairman, DRIVER, Vice Ghariman, McADAMS, GOLDMAN, and BURSLEY, Members, concurred in this recommendation.#