Union Carbide Corporation Discloses Results Of Prentiss Plant Study

Company Has Identified Technical Causes of Force Majeure Shutdown Last Year

Midland, MI - Union Carbide Corporation, a subsidiary of The Dow Chemical Company, announced that it has identified the technical causes for the force majeure shut-down of an ethylene oxide unit in Prentiss, Alberta, late last year. The unit is owned by Alberta & Orient Glycol Company Limited and operated using METEOR ethylene oxide (EO) technology licensed from Union Carbide.

According to the results of the plant study, welds in the high strength steel that were used in the water-cooled EO reactor were determined to be susceptible to stress corrosion cracking under the typical operating conditions in the EO reactor water jacket. Based on the findings, Union Carbide has modified the design standards for future water-cooled EO reactors and is preparing a technical paper to share the details of the observed cracking with others who may experience similar issues.

"We took the force majeure shutdown of our EO unit in Prentiss very seriously and have been extremely diligent about investigating the underlying causes for the technical failure," said Joseph A. Bromley, business director, Licensing & Catalyst, METEOR EO/EG & LPOxo at Dow. "Not only were we able to identify the exact cause of the EO reactor water jacket crack and repair it, but by publishing our findings we are hopeful that we can help others in the industry avoid facing this same issue in the future."

According to the findings, the cracks appeared only in sections of the reactor that handled water and, therefore, did not pose the risk of a reactive chemical release. Different materials were used in the reactive section of the vessel. The cracks were repaired during the shut-down, and the unit was restarted in February 2004. Alberta & Orient has instituted a regular inspection and repair procedure to ensure the integrity of the EO unit and is evaluating long-term alternatives.

Union Carbide has modified the design standards for future water-cooled EO reactors based on the understanding of the susceptibility to stress-corrosion cracking and on design standards that have been commercially demonstrated to eliminate the cracking. Additionally, a review of other water-cooled reactors in operation has been conducted. Union Carbide plans to make a technical paper available sometime in 2006, pending formal review.

SOURCE: Union Carbide