The most common type of valve used in fluid control valves in the world is the gate valve - the opening and closing valve in the fluid control process. This type of valve can be found in every refinery, chemical plant, power station, and industrial enterprise manufacturing facility and can be manufactured in sizes ranging from 1/4 inch to 144 inch. The main purpose of the gate valve is to cut off the flow. It is for this reason that gate valves are often referred to as "cutoff" valves or "blocking" valves.
The advantage of using gate valve is that it can provide almost unobstructed media flow in the open position.Among the many common types of valves, only full-opening ball valves can equip with gate valves. Symmetrical design structures and peer-to-peer seals allow the gate valve to intercept the flow of media from either direction. Gate valves can also be made from a variety of materials, small 1/2-inch bright brass taps can be found on the hardware store shelves, and rare high-alloy gate valves can be found in nuclear power station installations.
Due to the potential risk of damage to the seat sealing surface, it is not possible to operate the gate valve in a partially open position or to use the gate valve for regulating purposes.Why this kind of damage occurs because when the gate valve is partially opened, the closing element (gate or wedge) of the gate valve swings between the two valve seats, and scratches may occur, which will affect the sealability of the valve seat.
In appearance, most of the gate valves look very similar. However, the interior of the valve has a variety of different design structures. Most gate valves consist of a valve body and a valve cover, which contain a shut-off element shutter or wedge. The closing element is connected to the valve stem and passes through the valve cover, finally connecting with the hand wheel or other valve stem operating device. The stuffing material inside the stuffing box withstands the pressure around the valve stem.
Although the material of the gate valve can be various metals from aluminum to zirconium, it can be a large number of engineering plastics. However, the most commonly used materials are steel, iron and bronze.
Bronze or brass has excellent machining performance and the lowest cost.It is due to the low strength and softness that the bronze is machinable, and the valve of this material is suitable for low pressure only.Bronze valves are mainly used for water pipes and equipment pipelines of about 300psi or less.
The strength range of the iron valve is between bronze and steel.Iron is harder to process, but cast iron is relatively easy to cast.Iron valves usually have two materials: gray cast iron and malleable iron.The high carbon content and good rust resistance of iron valves make iron valves more suitable for underground use than steel valves.
For industrial valves, the range of steel materials ranges from "WCB" of the lowest number to chromium/molybdenum alloy steel.Unlike brass, bronze and iron, most low alloy steels are weldable, which makes steel valves easy to repair and weld and, in some cases, easier to manufacture.Gate valves can also be made from rare alloys such as titanium to zirconium.