Selection of sealing surfaces for high-alloy gate valve seats and discs
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For Alloy 20 valves used in sulfuric acid service, is Stellite alloy welded on the seat and disc sealing surfaces? If the sealing surface is not cladded, isn’t it more prone to wear and thus lead to internal leakage? But can Stellite material used for cladding resist sulfuric acid corrosion?
Cobalt-based alloys are resistant to sulfuric acid (the appropriate type depends on the temperature)
The sulfuric acid operating conditions I dealt with were encountered in storage and transportation projects; the temperature of the sulfuric acid was at room temperature (during operation), and the design temperature did not exceed 60 degrees℃； The pressure is not high either; it does not exceed the range of PN25 or CL300. Alloy 20 valves are used, and the valve seat and valve disc sealing surfaces are also made of Alloy 20; no STL alloy is welded on them. Whether abrasion occurs is related to factors such as the presence of solid particles in sulfuric acid, the hardness of the particles, their size, and the flow rate – it depends on the specific circumstances.