Documents: The refinery learned of the problems before the 2018 explosion

The explosion, on April 26, 2018, injured 36 refinery employees and contractors, forcing many of the refinery’s 27,000 residents to evacuate due to toxic smoke.

THE PRESIDENT, WI – Officials at an oil refinery in northwest Wisconsin learned about equipment issues years before the 2018 explosion there, according to Occupational Safety and Health Administration documents obtained by Wisconsin Public Radio (WPR).

WPR has secured nearly 1,300 pages of documents from OSHA that shed new light on what these officials knew in the days before the explosion at the refinery at Superior, which was owned by Husky Energy Inc. Years ago. They include problems with a serious valve failure days before the explosion and documented corrosion on that piece of equipment dating back to 2008.

The April 26, 2018 explosion injured 36 refinery employees and contractors, and forced the evacuation of many of the president’s 27,000 residents due to black smoke and concerns that a tank containing the highly toxic chemical hydrogen fluoride might be endangered.

RELATED: Lawsuit filed against Husky Energy, Superior Refining

The refinery was shutting down the fluid catalytic cracking unit when the blast occurred as it prepared for a five-week production break for maintenance. The unit uses heat and a sand-like catalyst to crack or break down large hydrocarbons from crude oil into smaller particles to produce gasoline and other products.

In August 2018, the US Chemical Safety Council said that internal corrosion on the spent catalyst slide valve was likely caused by the explosion due to a failure to separate the air and hydrocarbons between the reactor and the regenerator.

The refinery has known corrosion on this valve during prior turnaround times for at least a decade, according to a 2018 report from OSHA’s Health Response Team.

“According to interviews and records, holes were found in the exhausted sliding valve in two previous cycles (April 2008 and April 2013), and those interviewed indicated that they were aware that this valve could leak due to catalyst wear on the leading edge of the valve gate valve and ring seat,” the report states.

In the week before the explosion, workers noted in the operator’s records that the valve was malfunctioning. Valve problems caused the refinery’s pollution control device to shut down on April 19 and April 22.

Last year, Cenovus Energy became the new owner of the refinery after it bought Husky Energy. Company officials said they have since taken steps to improve safety.

RELATED: Company Will Continue To Use Toxic Chemicals At Wisconsin Refinery

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