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Type and classification of gate valves
Source: | Author:hkw239488 | Publish time: 343 days ago | 317 Views | Share:

Gate valve mainly composed of body, bonnet, gate, stem, seat and sealing packing, is one of the most common valve types in isolation valve. The primary purpose of a gate valve is to intercept fluid, and for this reason it is often referred to as a "shut off" or "blocking" valve. Gate valve has many kinds of different structure forms and use different types of sealing elements. According to the structure of the sealing element, it can be divided into several different types.

Gate valve type

Classified by valve stem:

According to the type of valve stem, it can be divided into rising stem gate valve and non-rising stem gate valve. The valve stem is an operating component of the gate valve, and its function is to transmit the opening and closing force to the opening and closing parts.

1, the rising stem gate valve stem trapezoidal thread is placed outside the body, located in the upper part of the stem, by rotating the stem nut, make the stem drive the gate up and down synchronously to achieve the valve opening and closing, so it is easy to identify the valve opening and closing state to avoid wrong operation. The stem nut is widely used because it is easy to lubricate and open and close visually outside the body cavity. But in harsh environment, the valve stem exposed thread is vulnerable to damage and corrosion, and even affect the operation. The disadvantage is that the opening height of the valve is large, usually in addition to the original height of the valve to add a stroke, which requires a lot of space for operation.

2, Non-rising stem gate valve also known as rotary stem gate valve (also known as dark rod wedge gate valve), stem nut is placed inside the body, in direct contact with the medium, often fixed on the gate. The valve stem nut drives the gate to move up and down through the rotation of the valve stem to complete the opening and closing. Usually there is a trapezoidal thread at the bottom of the stem, through the thread at the bottom of the valve and through the guide groove on the disc, to change the rotation motion into a straight line, that is, to change the operating torque into operating thrust. Because the trapezoidal thread for transmission is located inside the valve body, it is easy to be corroded by medium and cannot be lubricated. But its valve stem does not do lifting movement, the need for operation space is small, so it is suitable for the limited location of the place of dense pipeline.

Classified by structure:

According to the structure type, it can be divided into wedge gate valve and parallel gate valve. That is, wedge type gate valve is called wedge type gate valve, and plate type gate valve is called parallel type gate valve.

1. Plate gate valve means that the sealing surface is parallel to the vertical center line, so the sealing surface on the valve body and gate is also parallel to each other. The most common type of gate valve is the double gate type, in order to close the valve body and ram double seal surface contact tight, often used in two gate clip with double thrust wedge. It is mostly used in low-pressure pipelines such as small pipelines. Parallel gate valves with single gate are also available but are very rare.

2. Wedge gate valve is a gate valve whose sealing face is at a certain Angle from the vertical center line, or whose two sealing faces are wedge-shaped. Wedge gate valve single, double are available. Double ram type has the advantages of sealing and Angle accuracy is low, temperature change is not easy to wedge the ram, sealing surface wear can be compensated by gasket. The disadvantage is that the structure is complex, easy to stick in dry medium, the main is that the upper and lower baffle is easy to fall off after years of corrosion.

Other categories:

According to different standards: national standard gate valve, American standard gate valve, German standard gate valve, Japanese standard gate valve

Connection mode: flange gate valve, welding gate valve, threaded gate valve (also divided into internal thread and external thread)

Pressure class: high pressure gate valve, low (middle) pressure gate valve

Drive mode: electric gate valve, pneumatic gate valve, manual gate valve

Classification by material: stainless steel gate valve, forged steel gate valve, cast steel gate valve, carbon steel gate valve, cast iron gate valve, copper gate valve (also divided into bronze gate valve, brass gate valve), ceramic gate valve, plastic gate valve.