State report cites defection weld in deadly Salem power plant blast

SALEM – A defective weld inside a boiler tube played a critical role in the Nov. 6, 2007 explosion at the Salem Harbor generating station that killed three workers, a state report unveiled Thursday.The state Department of Public Safety (DPS) issued its findings relative to the explosion of the boiler at the electricity-generating facility. The blast led to the death of three plant workers – Mark Mansfield, 41, of Peabody; Phillip Robinson, 56, of Beverly; and Matthew Indeglia, 20, of Lawrence and Townsend.The DPS determined that “the primary cause of the failure leading to the fatal explosion was a defective weld in combination with significant external corrosion of the tubes in an area of the boiler known as the dead air space. This caused a tube to spray steam and water onto the adjacent tubes. The collateral damage resulted in the catastrophic failure, which sent steam, water and ash, at approximately 600 degrees Fahrenheit, into the immediate area below the boiler.”According to the report, the law requires a thorough internal and external inspection of the boiler, including the dead air space. DPS investigators were told during interviews of power plant personnel and the insurance inspector that they could not recall this space being opened in at least 10 years.The DPS concluded that “annual inspection of this dead air space would have significantly abated the degree of corrosion in the space and observation of the current level of corrosion should have prompted further examination.”Dominion Resources, the Richmond, Va.-based energy company that owns the power station, said the men were working on the ground floor near the boiler on Tuesday when the steel water pipe ruptured about 20 feet above and blew high-pressure steam on them.As a result of the findings, DPS is pursuing disciplinary actions against the engineer in charge, who by job description is responsible for the operation and maintenance of the boiler. Action is also pending against the insurance inspector responsible for annual inspections.Based on the report, the DPS has taken several actions since the boiler failure. On Nov. 19, only days after the explosion, the certificates of inspection for all four boilers at Salem Harbor Station were revoked. This action prohibited the boilers from restarting until an inspection by DPS inspectors was performed and a new certificate was issued.Before the boilers were placed back in to service, the DPS performed a thorough inspection of each, a process that included non-destructive testing and pressure tests.The DPS also performed an assessment on all solid fuel-fired boilers in the state to ensure that other plants with similarly-fueled boilers were in compliance with existing codes.The DPS is forming a Boiler Task Group to consider and submit proposed changes to the Board of Boiler Rules as a result of the incident, according to Terrel Harris, spokesman for the state Executive Office of Public Safety and Security.The Essex District Attorney’s Office, the Massachusetts State Police, the Salem Police Department, and the U.S. Occupational Safety and Heath Administration also investigated the fatal incident.David Botkins, manager of media relations at Dominion, could not be reached for comment.