The failure analysis of a fire-damaged liquid oxygen gate valve is presented. During start-up operations of a liquid oxygen system, a gate isolation valve experienced an internal ignition that propagated in the valve and breached the extended bonnet under pressure. The resulting fire led to the fatality of two operators. The gate valve was part of a double block with bypass valve configuration, and constructed of stainless steel alloys, a polychlorotrifluoroethylene (PCTFE) bearing and a polytetrafluoroethylene (PTFE)/graphite composite packing. Based on fire patterns, the most probable origin was identified proximate to the bearing location. This was further supported by 13 other similar valves in the same plant demonstrating non-propagating ignitions proximate to their bearings. These bearings, along with unburned exemplars, exhibited contaminants consistent with silicone oil and hydrocarbons. The incident valve remains also exhibited evidence of these contaminants. The gate valve pressure was determined to be between 30 and 60 bar (435–870 psig). Although the exact conditions and operations proximate to the valve at the time of the incident were indeterminable, the most probable ignition mechanism identified was repetitive (vibrational) mechanical impact loading on the oil contaminants and bearing at the bearing location. This paper summarizes the failure analysis and presents contributing factors and recommendations based on findings.