What valves are used in the petrochemical industry

The gate valve should be preferred under general switching conditions. DN≤40 gate valve should be used open rod support fixed gate structure type; The gate valve with DN≥50 should adopt the open rod support mode elastic gate structure type; For low temperature medium, low temperature gate valve should be selected;

The cut-off valve should be used to replace the gate valve for the switching occasions and the occasions of conveying liquefied petroleum gas and liquid hydrocarbon. For highly toxic media, it is appropriate to choose bellows sealed globe valve instead of gate valve; For occasions with special anti-corrosion requirements, the cut-off valve with non-metallic lining should be selected. Globe valve should use clear rod support type. The globe valve is generally suitable for the size below DN200;

Check valve should be used for automatic protection to prevent medium backflow. Under normal circumstances, DN≤40 should be used when the lift type check valve (only allowed to be installed on the horizontal pipeline); DN= 50-400, should be used swing check valve (not allowed in the medium from the top to the bottom of the vertical pipe); DN=100 to 400, can also be used to clamp check valve, its installation position is not limited;

The butterfly valve can replace the gate valve under the following conditions: the design pressure is less than 1.0MPa, the design temperature is less than 100℃, the pipe diameter is DN400mm-1200mm, the medium is industrial water or compressed air, and the double eccentric or three eccentric soft seal type can be used; The design pressure is less than 1.0MPa, the design temperature is less than 300℃, and the medium is compressed air. At this time, double eccentric or three eccentric metal hard seal type should be used. The design pressure is less than 1.0MPa, the design temperature is less than 300℃, the diameter is D400MU-1000mm, the medium is oil and gas, and the double eccentric or three eccentric gold housing hard seal type should be used: The design pressure is less than 2.0MPa, the design temperature is less than 300℃, the diameter is DN200mm-500Mn, and the medium is oil and gas. At this time, the three eccentric metal hard seal type should be used: the double eccentric type must have the metal elastic seal ring structure; Double eccentric or three eccentric butterfly valve should have bidirectional sealing function, at least its reverse sealing pressure should not be less than 80% of the forward; Design and selection should be carried out in conjunction with the manufacturer.

The ball valve can replace the gate valve under the following conditions: the design pressure is less than 10MPa, the design temperature is less than 100℃, DN≤200, the medium is industrial water, compressed air, non-metal seal can also be used to choose metal seal ball valve; The design pressure is less than 2.0MPa, the design temperature is less than 300℃, DN≤200, the medium is oil and gas, the metal seal ball valve should be selected: the design pressure is less than 4.0MPa, the design temperature is less than 426℃, DN≤800, the medium is saturated water or superheated steam, the metal seal ball valve should be selected; Metal seal ball valve must have wear compensation and thermal expansion compensation structure, design selection should be combined with the manufacturer.