The metal fabrication company whose Minneapolis plant caught fire, leaving two people injured, has been fined tens of thousands of dollars in Minnesota for various safety violations dating back to 2005 and as recently as this June, according to regulatory records.

In the meantime, one of the workers, Robert Feist, remains at HCMC with critical burns from Wednesday's explosion and fire at Metal-Matic, a hospital spokeswoman said Thursday afternoon.

Authorities have not released the identity of the other employee injured at the plant, which sits across the Mississippi River from downtown. Fire department officials said the accidental explosion was caused when a pipe welding torch ignited an aluminum dust and water mixture.

State Occupational Safety and Health Administration (OSHA) records reveal at least six investigations leading to fines, totaling more than $36,000 in fines since 2005.

Violations have included failing to secure loads of materials, lax procedures for controlling potentially hazardous materials, inadequate training, lack of equipment for dust collection, exposure of workers to blades, exposed machinery wheels and chains, among others.

Messages seeking information about the company's safety record were left with management after the blast and again Thursday afternoon.

Smoking rising from Metal-Matic.

At least one of the safety violation cases led to serious injury in 2005, when a worker was burned, said Minnesota OSHA spokesman James Honerman. That case yielded $12,400 in fines.

An "employee started up a tube mill, which produces aluminum dust as part of the process, and a fire started in the aluminizing box," Honerman said, citing agency records. "The mill was shut down, the fire put out, and when the system was restarted, the mill exploded, resulting in burns to an employee's face."

About one-third of the fines in that case were for "not installing and maintaining the arc spray system and associated dust collection system on the tube mills to control the dust and prevent an explosion," Honerman added.

Founded in 1951, Metal-Matic produces tubing for various applications such as automotive, appliance and construction. It has three other locations — another in Minneapolis, and facilities in Bedford Park in suburban Chicago and in Middletown, north of Cincinnati.

Safety regulators have also fined Metal-Matic for two violations at its Ohio facility and for one in Illinois.

Paul Walsh • 612-673-4482