The Fife LNG plant at Mossmorran, operated by Shell, can provide a challenging environment for any high-pressure valve, but when a need arose for a number of ANSI class 300 DBB valves with a high operating temperature range, few manufacturers could meet the requirements.
The requirement for ANSI 300 class, 2” DBB valves suitable for a temperature range from -50°C up to +350°C would force the designers at Oliver Twinsafe to completely rethink the sealing technology used in their double block and bleed ball valves.
An additional layer of complexity, on top of this already challenging application, came with the requirement to meet the demanding MESC 77/300 design validation test that includes fugitive emission testing
The actual ball sealing was readily achieved as Oliver Twinsafe already manufactures a wide range of metal seated valves, dispensing with any elastomeric seals completely. But even here special attention was needed in relation to the ball and seat materials, especially the tungsten carbide coating required to ensure long service life. For zero and low through seat leakage requirements, such as this application, porosity control of the Tungsten Carbide coating is of paramount importance. Other sealing sites throughout the valve would prove more
Courtesy of Industrial Valve News.