The explosion that rocked the Husky Energy Inc. refinery in Superior in April 2018 - and caused the evacuation of thousands of residents - caught everyone by surprise.  Even though many people in the community always 'talked' about the "what if's", no one gave much serious credence to it happening.

But reports recently acquired show that company officials and management at the refinery that was then-owned by Husky did.  The documents that detail the prior knowledge were recently obtained by Wisconsin Public Radio and reported by the Associated Press.

Explosion Reported At Husky Oil Refinery In Superior, Wisconsin
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That report shows that the refinery was going through the daily motions on April 26, 2018 with a "critical valve" that had "problems....and documented erosion...dating back to 2008".  Included in the approximately 1,300 page report are the details about that erosion problem:

"According to interviews and records, holes were found in the spent slide valve on two part turnarounds (in April 2008 and April 2013), and those interviewed indicated that they were aware that this valve could leak because of catalyst erosion on the leading edge of the valve gate and seat ring."

Additionally, operator logs also noted issues.  "In the week leading up to the explosion" those logs included notes from operators "that the valve was malfunctioning."

On the day of the explosion, the refinery was getting ready to be shut down for a "five-week production break for maintenance".  Specifically, workers were shutting down the fluid catalytic cracking unit.  As part of their review of the incident, the U.S. Chemical Safety Board noted in their August 2018 report that "internal wear on the spent catalyst slide valve likely caused the explosion by failing to separate air and hydrocarbons between the reactor and regenerator".

Explosion Reported At Husky Oil Refinery In Superior, Wisconsin
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Since the date of the explosion that caused an evacuation of Superior residents, a lot has happened at the refinery site and with it's operation.  While the rebuilding process started soon afterwards, the refinery has been offline ever since.

Meanwhile, ownership also changed.  Husky Energy Inc. owned the refinery at the time of the explosion and initiated the rebuilding process.  Husky sold the refinery to Cenovus Energy as part of a deal that was finalized in 2021.

Explosion Reported At Husky Oil Refinery In Superior, Wisconsin
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