Abstract: The employer heat treats client-supplied materials with a coating to enhance the physical properties of the material (hot isostatic pressing). At the employer's facility in the production area, they use argon gas under heat and pressure to treat materials. An employee was tasked to perform maintenance on the HIP46 vessel by removing the bottom heat plate on the day of the accident. The employee was positioned to be the attendant for the confined space operation of the HIP46 pit. As the process continued, the employee was found at the bottom of the HIP46 vessel by a production manager. At 1:50 a.m. on October 1, 2021, the employee was found unresponsive in a permit-required confined space (HIP46 vessel). The HIP46 area consists of an underground pit (HIP46 pit) and vessel (HIP46 vessel); both are deemed permit-required confined spaces (PRCS). The HIP46 vessel is approximately 46 inches in diameter and 80 inches deep. On the day of the accident, the employee and the maintenance supervisor were scheduled to perform maintenance on the bottom plate of the HIP46 vessel. The supervisor entered the HIP46 pit as the PRCS entrant to perform the unbolting of the bottom plate of the HIP46 Vessel. The employee was to remain atop as the attendant. No permit was filled out and required PPE was not used during the activity. The employee suffered asphyxiation, was transported to the hospital and later died. Two serious citations and a repeat-serious citation were issued for violations of the permit-required confined space program.