Types of valve
- Valve is a Mechanical or electromechanical device which is used to control the flow, pressure & temperature of fluid.
- Generally Globe valve, Gate valves, Butterfly valve, diaphragm valve, needle valve, Non return valves etc used in power plant various applications.
- The materials which are directly in contact with high pressure & temperature fluid are called trim materials.
- IBR Valves materials are manufactured according to the ASME class 16.34 B
- “Y” type globe valves have minimum pressure drop as compared to normal globe valves
- WCB indicates cast carbon steel, includes the standard A 216 . Used for fluid temperature up to 425 deg C
- WC-6 indicates Chromium Molybdenum steel, includes the standard A 217. Used for fluid temperature up to 575 deg C
- WC-9 indicates Cast alloy steel, includes the standard A 217. Used for fluid temperature up to 593 deg C
- SA 105 indicates forged & SA 182 indicates forged alloy steels
Equivalent grades of valves:
- SA 216 WCB/WCC: SA 105N
- SA 217 WC6: SA 182 F11
- SA 217 WC9: SA 182 F22
- SA 217 C12A : SA 182 F91
- The MOC of Stud & nut materials of high pressure valves are SA 194 Gr.B7 & SA 194-2H
- Stem nuts of all high pressure valves is of Aluminium bronze materials
- The yoke of all high pressure valves are made up of material A-216 WCB
- Hand wheel of all HP valves are made up of SG iron 400/12
- Stems of all HP valves are made up of A 479-410-2
Comparison between Gate valve & Gate valve
- For a same size of valves, the size & weight of gate valves is more as compared to globe valves
- Time required for operating the gate valve is more as compared to globe valve
- Effort required to operate the gate valve is less as compared to globe valve
- Complicated maintenance procedure for larger size gate valves & simple maintenance procedure for globe valves
- In gate valve pressure drop of fluid is very less as compared to globe valve
- Gate valves cannot be used for flow regulating valves whereas globe valves can be used
- Very less or no turbulence of fluid in gate valves whereas there is much turbulence in globe valves
- Upon prolonged exposure of cast carbon steel or forged carbon steel valves to temperatures above 425°C, the carbide phase of steel may be converted to graphite. Permissible but not recommended for prolonged use above 425°C.
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