With a steam temperature of 500°C and a pressure of 2.5 MPa, a pressure gauge needs to be installed. What type of root valve should be used?
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We need to go to the waste heat boiler, using high-temperature and high-pressure steam to drive the turbine. With a steam temperature of 500°C and a pressure of 2.5 MPa, a pressure gauge needs to be installed. What type of root valve should be used? What is the model and material of the valve, as well as the material of the packing? And if a gasket is used, what type of gasket should be employed? I hope the experts in this forum can give me some advice!
For items within the scope of the equipment, they are provided by the equipment manufacturer itself; for those outside this scope, there are design drawings and order lists prepared by the design institute
15CrMo, Z41H—25R, or other graphite for packing,
For conditions of 500°C and 2.5 MPa, PN25 valves are far from sufficient; 15CrMo valves require at least PN63
I found this type of valve to use as the root valve for the pressure gauge. J61Y-ZT type butt welding stop valve: Inlet: Ф10 mm—Ф34mm (butt weld); Outlet: Ф10 mm—Ф34mm (butt weld). Orifice diameter: DN6 —DN25. Working pressure: 16MPa—41MPa, 3532PSi—6000PSi. Suitable temperature range: -65°F(-54℃)—1200°F(648℃). Materials available: 316L, 316SS, 316H, 304SS, 321SS, 1Cr18Ni9Ti, 20#, A105, 12Cr1MoV, F91, Duplex 2205, Duplex 2507, Monel, Inconel, Hastelloy C. 304 stainless steel is sufficient.
First, it is necessary to determine what type of thread the pressure gauge has; commonly, it is M20X1.5 or NPT1/2. The connection method for the stop valve is determined based on this. For high temperatures, copper gaskets can be used
With such pressure and temperature, it’s better not to use threaded connections; I’m considering using welding instead, as this reduces the risk of leaks. High-temperature copper gaskets at 500 degrees are not suitable; graphite metal wound gaskets or alloy gaskets should be used instead.