 September 21, 2020, the Evergreen packaging paper mill in Canton, North Carolina. Two contract workers were fatally injured by a fire that erupted in a confined space when a heat gun fell into a bucket of flammable resin. During September 2020, the Evergreen packaging paper mill was undergoing a planned shutdown during which maintenance work was occurring throughout the facility. In one of the mill's units, a contract company known as BLASTCO was performing repairs in a vessel called an upflow tower. Another contract company, RIMCORE, was working in a different vessel called a downflow tower. The two vessels were connected at the top by a large diameter pipe. BLASTCO was tasked with repairing approximately 30 feet of the inside surface of the upflow tower, which was made of a material comprised of fiberglass matting and epoxy vinyl ester resin, otherwise known as fiber reinforced plastic, or FRP. To repair the tower, the contractors would grind away the old damaged material, then apply alternating sheets of new fiberglass with layers of resin. The rate at which the resin hardens depends on several factors, including ambient temperature. The resin hardens faster in warmer temperatures. On the other hand, the resin takes longer to harden in cooler weather. And this is what BLASTCO workers experienced on the night of September 20. On the particularly cool night, the resin and fiberglass matting slid down the walls of the upflow tower before the resin could harden. BLASTCO workers attempted several means of troubleshooting the resin, but were ultimately unsuccessful and continued to struggle. Sometime after 2 AM on September 21, two BLASTCO workers resorted to using an electric heat gun to warm the resin, causing it to harden faster. The BLASTCO crew did not communicate to Evergreen or the RIMCORE contractors working in the connected tower that they were using the heat gun. At approximately 5.15 AM, the heat gun fell into a five-gallon bucket of the flammable resin. A fire erupted inside the upflow tower. The BLASTCO workers inside the tower did not have a fire extinguisher or other means to put out the fire. They quickly evacuated. Smoke and flames from the fire traveled rapidly through the connecting pipe to the downflow tower, where two RIMCORE contractors were working. They were overcome by the smoke and unable to escape. Both workers were fatally injured. During its investigation, the CSB identified four safety issues that led to the incident at Evergreen packaging. Hot work safety, pre-job planning, confined space safety, and combustible materials of vessel construction. The CSB found that the heat gun could produce temperatures in excess of the resin's flashpoint and auto-ignition temperatures. Therefore, it should have been recognized as an ignition source, and its use should have been considered hot work under both Evergreens and BLASTCO's definitions. But BLASTCO workers did not recognize the use of the heat gun as a hot work hazard because it did not produce a flame or spark, and they did not inform Evergreen or RIMCORE of its use. Had BLASTCO recognized the use of the heat gun as hot work, their own procedures would not have allowed its use in a confined space in the presence of flammable resin. Another safety issue identified by the CSB was a lack of pre-job planning. BLASTCO workers were not sufficiently prepared to apply resin during cold weather and did not have a plan to safely troubleshoot the problem of the resin hardening too slowly. For example, the CSB found that BLASTCO had two drum heating bands available at the time of the incident that could have safely warmed the resin in a drum outside the upflow tower, negating the need for the heat gun. But because these drum heating bands were not identified during pre-job planning as equipment workers might need, they were not staged for use, and BLASTCO workers could not locate them. As a result, workers resorted to using a heat gun instead, which ultimately ignited the resin inside the upflow tower. Hot work should be avoided if a safer alternative is available. Effective pre-job planning could have prevented this incident. BLASTCO could have used a troubleshooting guide to address the cold weather or may have been able to delay the work until ambient temperatures were warmer. A third safety issue identified by the CSB was confined space safety. The upflow and downflow towers at Evergreen Packaging were permit-required confined spaces. OSHA requires that a confined space entry be terminated whenever, among other conditions, a condition that is not allowed under the entry permit arises in or near the permit space. BLASTCO's confined space policy contained a similar requirement. The heat gun, an ignition source, constituted a condition that was not allowed under the entry permit, but BLASTCO did not recognize the ignition hazard. Therefore, BLASTCO did not terminate its confined space entry when the heat gun was introduced into the space. And the CSB found that Evergreen BLASTCO and RIMCORE treated the upflow and downflow towers as separate and independent confined spaces, even though the towers were connected by a crossover pipe. Interviews with each contracting company revealed both companies separately conducted safety analyses for the vessel in which they were completing work and were only minimally aware of the work being done in the other vessel. But the CSB found that since the two towers constituted a single confined space and BLASTCO's and RIMCORE's entries were simultaneous, the two maintenance tasks constituted simultaneous operations, or SIMOPS. SIMOPS can be defined as operations occurring close together in time and place, which might interfere or clash with one another, increasing the risks of the activities or introducing new risks altogether. But Evergreen did not have a SIMOPS program in place at the time of the incident, which would have facilitated coordination between the two contractors who were performing work close together in time and place. The last safety issue identified by the CSB was the use of combustible materials of construction in the upflow tower and crossover line. The five-gallon bucket of resin that the heat gun fell into did not contain enough fuel to create a fire of the size and duration that occurred during the incident. The CSB found that the upflow tower and crossover line, which were constructed of combustible FRP, both caught fire. This contributed to the quick spread of smoke and flames to the downflow tower, where the two RIMCORE employees were fatally injured. As a result of its investigation into the incident at Evergreen packaging, the CSB made a recommendation to OSHA to issue a safety information product addressing the analysis and control of hazards that are not pre-existing, but which result from work activities inside permit-required confined spaces. The agency also recommended OSHA require owner operators to ensure the coordination of simultaneous operations involving multiple work groups, including contractors. And the CSB reiterated a previous recommendation to OSHA to publish a safety and health information bulletin addressing the hazards and controls when using flammable materials in confined spaces.