What is a valve?

Gate valve is one of the most common opening and closing valves, which uses gate (i.e. opening and closing parts, in which the opening and closing parts are called gate or gate, and the gate seat is called gate seat) to connect (fully open) or cut off (fully closed) the medium in the pipeline. It is not allowed to be used as interception, so it should be avoided to open the gate slightly in use, because the erosion of high-speed flowing media will accelerate the damage of the sealing surface. Shuangde gate is called gate valve because it acts as lifting motion on one side perpendicular to the center line of gate pedestal passage and cuts off the medium in pipeline like a gate.

Gate valve [1] refers to a valve whose closure (gate) moves vertically along the central line of the passage. Gate valves are mainly used for cutting off in pipelines. Forged steel gate valve is a kind of valve widely used. It is usually used for cutting device with diameter DN (> 50mm), and sometimes for cutting device with very small diameter. Gate valves, as a kind of lower grade valves, are more common.

Stem structure

1) Open stem gate valve: The stem nut is on the cover or bracket. When opening and closing the gate plate, the stem nut is rotated to achieve the lifting of the valve stem. This structure is beneficial to the lubrication of the valve stem and has obvious degree of opening and closing, so it is widely used.

2) Dark stem gate valve: stem nut in the body of the valve, in direct contact with the medium. When opening and closing the gate, it is realized by rotating the valve stem. The advantage of this structure is that the height of the gate valve is always unchanged, so the installation space is small. It is suitable for large caliber or limited installation space of the gate valve. The structure should be equipped with an opening and closing indicator to indicate the degree of opening and closing. The disadvantage of this structure is that the valve stem threads are not only unable to lubricate, but also easily damaged by medium erosion.

2.3 Main Classifications

In addition, according to material classification: 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.

According to the standards of different countries, it can be divided into national standard gate valve, American standard gate valve, German standard gate valve and Japanese standard gate valve.

According to the connection mode of the valve, it can be divided into flange gate valve, welding gate valve and threaded gate valve (also divided into internal thread and external thread).

According to the pressure level of the valve, it can be divided into high-pressure gate valve and low (medium) pressure gate valve.

According to the driving mode of the valve, it can be divided into electric gate valve, pneumatic gate valve and manual gate valve.

In addition, it can also be classified according to the use, valve isolation mode, etc., which will not be cited here. To facilitate procurement, valves can be divided into 46 categories, as follows:

Electric gate valve, pneumatic gate valve, manual gate valve, high temperature gate valve, low temperature gate valve, thermal insulation gate valve, high pressure gate valve, low pressure gate valve, flat gate valve, knife gate valve, wedge gate valve, soft sealing gate valve, stainless steel gate valve, forged steel gate valve, cast steel gate valve, cast iron gate valve, copper gate valve, corrugated pipe gate valve, lining fluoride gate valve, API gate valve, power station gate valve, flange gate valve Welded gate valve, threaded gate valve, seat seal valve, wire gate valve, water seal gate valve, open bar gate valve, concealed bar gate valve, spiral gate, bevel gear gate valve, butt welding gate valve, gas gate valve, slag discharge gate valve, plunger gate valve, distribution gate valve, pound gate valve, vacuum isolation gate valve, seal gate valve, national standard gate valve, American standard gate valve, German standard gate valve, daily standard gate valve, import gate valve and others Gate valves.