The opening and closing part of the gate valve is the gate, and the movement direction of the gate is perpendicular to the direction of the fluid. The gate valve can only be fully opened and fully closed, and cannot be adjusted or throttled. The gate has two sealing surfaces. The two sealing surfaces of the most commonly used pattern gate valve form a wedge shape. The wedge angle varies with the valve parameters, usually 5°, and 2°52' when the medium temperature is not high. The gate of the wedge gate valve can be made into a whole, called a rigid gate; it can also be made into a gate that can produce a small amount of deformation to improve its manufacturability and compensate for the deviation of the sealing surface angle during processing. The plate is called the elastic gate. When the gate valve is closed, the sealing surface can be sealed only by the medium pressure, that is, relying on the medium pressure to press the sealing surface of the gate plate to the valve seat on the other side to ensure the sealing of the sealing surface, which is self-sealing. Most of the gate valve is forced seal, that is to say, when the valve is closed, the gate should be pressed to the valve seat by external force, so as to ensure the sealing surface sealing. The gate valve of the gate valve moves in a straight line with the valve stem, which is called a lifting stem gate valve, also called a rising stem gate valve. Usually there is a trapezoidal thread on the lifter, and through the nut at the top of the valve and the guide groove on the valve body, the rotating motion is changed into a straight line motion, that is to say, the operating torque is changed into the operation thrust. When the valve is opened, when the lift height of the gate is equal to 1:1 times the diameter of the valve, the passage of the fluid is completely unblocked, but this position cannot be monitored during operation. In actual use, the apex of the valve stem is used as a sign, that is, the position where the valve stem does not move is taken as its fully open position. In order to consider the locking phenomenon of temperature changes, usually open to the top position, and then return to 1/2-1 turn, as the fully open valve position. Therefore, the fully open position of the valve is determined by the position of the gate, that is, the stroke. In some gate valves, the stem nut is set on the gate plate, and the rotation of the hand wheel drives the valve stem to rotate, so that the gate plate is lifted.

 

Gate valves are divided into wedge type and parallel type according to the structure of the gate plate. There are three structures of wedge gates: single gate, double gate and elastic gate.

Gate valves are divided into flat gate valves and knife gate valves according to different structural types.

Gate valves are divided into rising stem gate valves and dark stem gate valves according to different bonnet forms.

The working principle of the manual gate valve: Turn the handwheel, and through the advance and retreat of the thread of the handwheel and the valve stem, the valve plate connected to the valve stem is lifted or lowered to achieve the opening and closing effect.

According to the classification of shell/body material, gate valves can be divided into:

Metal material valves: such as carbon steel valves, alloy steel valves, stainless steel valves, cast iron valves, titanium alloy valves, Monel valves, copper alloy valves, lead alloy valves, etc.

Metal body lined valves: such as rubber-lined valves, fluorine-lined valves, lead-lined valves, plastic-lined valves, and enamel-lined valves.

Main criteria:

(1) GB/T 12232-2005 General Valve Flange Connection Iron Gate Valve

(2) GB/T 12234-2007 Steel gate valve with stud connection bonnet for petroleum and natural gas industry

(3) GB8464-87 "General Technical Regulations for Internal Thread Connection Gate Valves, Globe Valves, Ball Valves, and Check Valves"

(4) GB8465.1-87 "Internal thread connection gate valve, globe valve, ball valve, check valve basic size iron gate valve"

(5) JB/T53162-1999 "Gate Valve Product Quality Classification"

(6) JB/T5298-91 "Steel Flat Gate Valve for Pipeline"

(7) JB/Z243-85 "Gate valve static pressure life test procedures"

(8) JB/TQ648-8 "Iron Wafer Type Flat Gate Valve"

(9) JB/T53200-94 "Product Quality Classification of Iron Consideration Flat Gate Valves"

(10) JB/T53242-94 "Quality Classification of Steel Plate Gate Valves"

 

Product advantages:

1. Small flow resistance. The medium channel inside the valve body is straight through, the medium flows in a straight line, and the flow resistance is small.

2. It is less labor-saving when opening and closing. Compared with the globe valve, because whether it is open or closed, the direction of movement of the gate is perpendicular to the direction of medium flow.

3. Large height and long opening and closing time. The opening and closing stroke of the gate is relatively large, and the lifting is carried out by the screw.

4. The phenomenon of water hammer is not easy to occur. The reason is the long shutdown time.

5. The medium can flow in any direction on both sides, which is easy to install. The two sides of the gate valve channel are symmetrical.

6. The structural length (the distance between the two connecting end faces of the housing) is relatively small.

7. The shape is simple, the structure length is short, the manufacturing process is good, and the application range is wide.

8. Compact structure, good valve rigidity, smooth passage, small flow resistance, stainless steel and hard alloy sealing surface, long service life, PTFE packing, reliable sealing, easy and flexible operation.