Inspection Detail

Inspection: 123267890 - Phillips Chemical Company

Inspection Information - Office: Houston South Area Office

Investigation Summary

At approximately 11:27 a.m. on June 23, 1999, a reactor was in the process of being brought back into batch-service following a period of downtime for cleaning and servicing. A release of flammable material occurred and the material ignited resulting in a large explosion and fire. On the morning of the accident, the "Inside" or "Board Operator" was informed by his supervisor that the unit's Reactor Engineer wanted to make some changes to the startup process and would be coming down to the control room that morning. The Engineer was responsible for adjusting the chemical formula or recipe for each batch to maintain quality. It was not unusual for her to make minor changes in the chemical ingredients for each batch. However, for this reactor startup, there were several major changes from the usual procedure. Prior to running a regular production batch (approximately 10,000 gallons), a "mini-batch" or series of three charges of chemicals would normally be made. The computer (Distributed Control System or DCS) controlled the full production batches, but the operators manually controlled mini-batches. The employees interviewed said a typical mini-batch would be the first charge would consist of about 2000 gallons of solvent (cyclohexane), 500 pounds of styrene, 500 pounds of BD, and about 10 gallons of coupling agent (CA). The written Operating Procedures conflicted giving the operators differing amounts. On the day of the accident, the Reactor Engineer wanted to avoid the strong odor of unreacted styrene that results when it is dumped to the Reject Tank. She decided to add the catalyst to the mini-batch and to allow the BD and styrene to react before dumping it. She went to her supervisor with the request. The Superintendent authorized the change without an MOC. The Reactor Engineer went to the unit and informed the supervisor what she wanted done, and then gave the recipe to the Board Operator. Although the operators (Inside Operator and Outside Operator (Employee #4)) had never seen a mini-batch reacted before, they added the catalyst to the mini-batch as directed. Due to poor communication and misunderstandings the reactor was charged with 20,000 lbs of butadiene, instead of the 500 lbs intended. When the catalyst was added a runaway reaction quickly resulted. The reactor could not contain the materials in the reaction. The flammable materials escaped at the third level of the structure supporting the reactor, and a BLEVE resulted. Employees #1, #2, and #3 were working on a scaffold along this reactor on the second level. Employees #1 and #2 were burned to death. Employee #3 was able to jump down from the scaffold and escape with his life, and was hospitalized for burns. Employee #4 was also hospitalized for burns. Other employees were burned by the BLEVE and hot polymer, but were not hospitalized. Employees #5 and #8 through #16 suffered from mental stress due to the explosion, and this site's previous history concerning explosions and employee injuries. Other employees received sprains or strains due to the explosions pressure wave knocking them down or falling down in the process of evacuating. In all, 21 employees were involved in this incident. Employees #1 and #2 were killed. Employees #3 and #4 were hospitalized. All other employees were treated but not hospitalized.

Keywords: FLAMMABLE VAPORS, EXPLOSION, BURN, HEAT, FLAMMABLE LIQUID, CHEMICAL REACTION, CHEMICAL, SCAFFOLD