Breaking the Paradigm of Fire Safe Valves

Abstract API initiatives for fire test for valves used on the Oil & Gas industry started back in 1978, with API RP 6F 1st Edition "Tentative API Recommended Practice for Fire Test for Valves", from October 1978. This Tentative Recommended Practice was intended to cover the requirements for testing and evaluating the performance of API Spec 6A "Specification for Wellhead Equipment" 11th Edition from Oct/1977 and API 6D "Specification for Pipeline Valves" 17th Edition from Oct/1977, when the valves were exposed to specifically defined fire conditions. This tentative standard was planned to be reviewed after two years, to consider the test experience gained during that time. Between 1973 and 1983, period of time that covers the existence of API RP 6F, it is noticed an intense development of features related to fire safe valves within the O&G industry, leading to many patents being filed during this time – 22 relevant identified US patents, averaging 2.2 patents per year. Most of these patents describe the utilization and different configurations of fusible materials that melts and allows the stem to move to close a backseat, stem packings for low and high temperatures using compressed graphite, solutions for reducing the external leakage after stem packing failure due to fire, utilization of shrouds to protect the stem packing and bolting materials, among other solutions. After API 6FA 1st Edition from May/1985, relatively fewer US patents related to fire safe valves were filed, with a total of 10 relevant US patents filed between 1983 and 2018, averaging 0.3 patents per year, indicating that the O&G industry had already a relatively very matured product for this purpose. These patents indicated different features, but still using eutectic rings, heat shields and stem packings with graphite fillers to control external leakage. The current paper describes a system and method that breaks the paradigm of keeping lower temperatures around the stuffing box to protect the sealing system of fire safe valves, by using the high temperature of the flames to degrade the stuffing box, while restricting external leakage through the valve to acceptable levels per O&G industry standards, along with a system to disconnect the backseat to reduce the operational torque when opening the valve under differential pressure after the fire exposure.