A Phillips investigation team mobilized to determine what caused the explosion at the company's K-Resin plant in Pasadena, Texas on March 27 has been focusing on a storage tank .
The storage taken, which has been taken off line, may have played a role in the incident, according to Phillips officials.
"The most plausible scenario at this point is that a dry butadiene tank, believed to be empty and in a purge mode, had sufficient 'popcorn' polymer and butadiene in the tank to react," said Jim Ross, general manager of the Phillips Houston Chemical Complex (HCC), which houses the K-Resin facility.
"We also believe the popcorn polymer plugged the purge lines so that an effective purge was not taking place. Under those circumstances, it appears that a reaction of residual popcorn polymer and butadiene could provide enough heat to overpressure the vessel, resulting in vessel failure."
The investigation into the incident at the K-Resin plant is not yet complete and will not be complete until a review and analysis of the tank, residues and blast damage can be accomplished.
However, Phillips has shared these preliminary findings with OSHA, which is also conducting an investigation.
"We are working closely with the investigating agencies, local officials, union leadership and our employees to fully understand what happened and take corrective actions," said Ross.
Meanwhile, the company continues to offer a wide range of assistance to employees, contractors and family members.
"Our primary concern is for the well-being of those who were affected by the incident," said Ross. "We are continuing to provide support in the form of financial assistance, counseling, communications and, where needed, temporary accommodations for family members of those who remain the hospital.
Of the 69 people who received medical attention following the accident, four Phillips employees and one contract worker remain hospitalized and all are listed in stable condition.
The Phillips investigation team consists of corporate personnel, representatives from HCC's unions (PACE and IBEW), its contractors, Brock and Zachry, and ECRC, a firm specializing in safety audits and services.
"We remain absolutely committed to operating this facility safely," said Ross. "We will not restart the K-Resin plant until we are certain that it is safe to do so."