How to Select Industrial High Pressure Valves Based on Temperature and Pressure

By | 2019-8-6 16:34:38 | Hit:0

In addition to considering the corrosion performance, flow characteristics and connection form of medium, the temperature and pressure of medium are important parameters for selecting control valve.


1. Valve service temperature


The service temperature of the valve is determined by the material used to make the valve. The temperature of commonly used materials for valves is as follows:


The service temperature of gray iron valves is - 15 - 250 C.


The service temperature of malleable cast iron valves is - 15 - 250 C.


The service temperature of nodular cast iron valves is - 30 - 350 C.


The maximum service temperature of high nickel cast iron valves is 400 C.


The service temperature of carbon steel valves is - 29 - 450 C. The recommended service temperature T < 425 C in JB / T3595 - 93 standard.


The maximum service temperature of 1Cr5Mo and alloy steel valves is 550 C.


The maximum service temperature of 12Cr1MoVA and alloy steel valves is 570 C.


The service temperature of 1Cr18Ni9Ti and 1Cr18Ni12Mo2Ti stainless steel valves is - 196 - 600 C.


The service temperature of copper alloy valves is - 273 - 250 C.


Maximum service temperature of plastic valves:


Nylon is 100 C.


The chlorinated polyether is 100 C.


The temperature of polyvinyl chloride is 60 C.


Polytrifluorochloroethylene - 60 - 120 C;


Polytetrafluoroethylene - 180 - 150 C.


Rubber diaphragm control valves have different operating temperatures due to different types of rubber.


The natural rubber is 60 C.


Nitrile butadiene rubber and chloroprene rubber are 80 C.


Fluorine rubber is 200 C.


When using rubber and plastics for valve lining, the temperature resistance of rubber and plastics shall prevail.


Ceramic valves, because of their poor temperature resistance and rapid change, are generally used in working conditions below 150 C. Recently, a super performance ceramic valve has appeared, which can withstand the high temperature below 1000 C.


Glass valves, with poor temperature resistance and rapid change, are generally used in working conditions below 90 C.


The temperature resistance of enamel valves is limited by the sealing ring material, and the maximum service temperature is not more than 150 C.





2. Valve pressure


The service pressure of the valve is determined by the material used to make the valve.

The maximum nominal pressure allowed for gray iron valves is 1 MPa.

The maximum nominal pressure allowed for malleable iron valves is 2.5 MPa.

The maximum nominal pressure allowed for ductile iron valves is 4.0 MPa.

The maximum nominal pressure allowed for copper alloy valves is 2.5 MPa.

The maximum nominal pressure allowed for titanium alloy valves is 2.5 MPa.

The maximum nominal pressure allowed for carbon steel valves is 32 MPa.

The maximum nominal pressure allowed for alloy steel valves is 300 MPa.

The maximum nominal pressure allowed for stainless steel valves is 32 MPa.

The maximum nominal pressure allowed for plastic valves is 0.6 MPa.

The maximum nominal pressure allowed for ceramic, glass and enamel valves is 0.6 MPa.

The maximum nominal pressure allowed for FRP valves is 1.6 MPa.


3. Relation between Valve Temperature and Pressure


Valve operating temperature and pressure have a certain internal relationship, but also affect each other. Among them, temperature is the dominant factor. Valves with a certain pressure are only suitable for a certain temperature range. The change of valve temperature can affect the pressure of the valve.


For example, the nominal pressure of a carbon steel valve is 10 MPa, the maximum working pressure P20 is 10 MPa when the working temperature of the medium is 200 C, the maximum working pressure P40 is 5.4 MP when the working temperature of the medium is 400 C, and the maximum working pressure P54 is 4.5 MPa when the working temperature of the medium is 450 C.


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