These design requirements are applicable to valves suitable for use in controlling hot, dirty gas in coal gasification processes. The valves are in service following the gasifier and two cyclones, which remove solid particles above 60 micron size. The hot, dirty gas contains contaminants that are both corrosive and erosive to materials that come in contact with them. In the past, almost all coal-gasification processes have used wet scrubbers directly following the gasifiers to clean and cool the product gases. In the near future, advanced processes, including the COGAS Process, will be constructed. Some of these processes require control valves for throttling hot dirty gas. The commercial development of these advanced processes could be delayed if reliable valves are not available for this severe service. The design and construction of the valves shall comply with commercial standards as defined in ANSI B16.34-1967. It should be noted that the valves will be used in piping systems that conform to the ASME Boiler and Pressure Vessel Code and the ANSI Code for Pressure Piping. Therefore, the valves are also subject to any limitations of those Codes. In the case of a conflict in requirements in these Codes, the more stringent (i.e., more conservative) requirement shall apply. The valves shall be designed to be remote operating type valves.