The procedures for FE testing generally require the test valve be mounted in a device that can firmly hold both the valve and its actuation mechanism. The valve is then cycled from dozens to hundreds of times while pressured up with methane or helium. As an added service simulation, the valve is heated at least twice to around 500° F (260° C) during the test sequence. The heating cycles simulate the temperature variances that might be acting on an installed valve. The temperature spikes also provide prototypical movement in the packing due to the expansion and contraction of the materials of construction. It is usually after a thermal cycle that a valve under test will show leakage.
The two schools of thought on the test media also relate into two schools of thought on the test procedures themselves. The International Organization for Standardization (ISO) has FE testing standards as do the American Petroleum Institute (API) and the International Society of Automation (ISA). The ISO standard 15848-1 is currently under revision to make it more user friendly. API is updating its FE packing qualification standard (API RP622) as well creating a new valve FE test standard (API RP 624).
The most visually exciting of the extreme valve tests is the fire test—when you mix high pressure, water and several gas-fueled “flame throwers” together, the result is certainly not boring. Fire testing is used to simulate a fire in a plant or refinery and determine how well specific valves and components will function during that fire and after it has been extinguished. The procedure involves pressuring the valve with water and then focusing several jets of flame onto the valve. After the test piece has attained the prescribed temperature, the valve is doused with jets of water, simulating the firefighting aspect of the process. The leakage rate of the valve or component is then measured and compared with acceptable leakage rate for the test standard.
Fire testing is performed regularly on soft-seated ball valves to determine if they are fire-safe, meaning that, after the initial polymer seal burns away, a secondary metal-to-metal backup seal can still prevent major flow through. Upstream valve manufacturers use a variety of fire-testing standards to confirm the efficacy of the seals in their products to withstand fires at the wellhead.