JACKSON (AP) — International Paper Co. and two brothers who were severely burned when a boiler exploded at a Mississippi plant have until Friday to submit proposals to settle a federal lawsuit.

The family of Terry and Kenneth Townsend sued Ianternational Paper after the explosion killed a contract worker and injured 22 others at its Redwood plant on May 3, 2008.

The plant, about 30 miles west of Jackson, cooks fiber to make liner board, which is used for manufacturing corrugated containers.

The blast killed 28-year-old Marcus Christopher Broome. The Townsends and several others were severely burned when the 12-story boiler exploded during an attempt to restart it after annual maintenance.

In an answer to the lawsuit filed last year, IP acknowledged that the boiler had been shut down for maintenance, there was an explosion and the company knew workers would be present that day.

However, the company argued that workers ‘‘may have failed to exercise reasonable care for their own safety’’ and ‘‘IP is immune from common law liability.’’

International Paper spokeswoman Amy Sawyer said the company works ‘‘very hard to ensure the safety of everyone at our mill every day.’’

‘‘We’ve had a strong track record of that, which made this accident all the more upsetting to all of us, not only at Vicksburg but across the company,’’ she said in an e-mail. ‘‘Our hearts go out to the family of Marcus Broome, and to everyone hurt in the accident.’’

Sawyer said the company does not discuss specifics of cases in litigation.

Kenneth Townsend, who was burned over 60 percent of his body, said in an e-mail that workers should have been cleared from the area before the boiler was restarted.

‘‘If they were going to do this, why not just tell us to stop working until they had the boiler up and running?’’ he asked. ‘‘It doesn’t make any sense.’’

A U.S. Department of Labor’s Occupational Safety and Health Administration report obtained by The Associated Press said an IP manager told investigators that it was ‘‘normal practice for contractors to work during start-up/shut-down.’’

OSHA fined International Paper $77,000 in the months following the explosion for one alleged willful violation and one alleged serious violation.

The willful violation was starting the boiler without adequate steam and not developing safe procedures to start it up when the primary power boiler is offline, according to OSHA.

International Paper is appealing that alleged violation.

The serious violation was failing to have written procedures to determine that an adequate amount of odorant was being added to the natural gas supply line, according to a copy of the OSHA report. Odorant provides an indicator that the highly volatile gas is present.

‘‘There was not gas detection devices inside the furnace nor were there any in the power plant building,’’ the OSHA report said. ‘‘None of the witnesses interviewed recalled smelling any odorized natural gas.’’

OSHA also found that some company officials did not share an internal memo about starting the boiler with workers in the facility’s control room, the report said.

A settlement conference, which is common in such cases but doesn’t necessarily mean a deal will be reached, is scheduled for Sept. 15 in U.S. District Court in Gulfport.