Steel gate valves are used to completely shut off or open the flow of medium in a pipeline system. The working medium can be water, steam, oil, oil, alkali, acid and others. The maximum pressure is up to 25 bar, and the temperature is up to + 450 ° C. The nominal diameter varies from 50 to 1200 mm, but there are companies that produce gate valves of both larger and smaller diameters on request. All valves of this type can be conditionally divided into groups depending on the following characteristics:
1. By the type of the valve, there are wedge and parallel valves, which are also distinguished by the location of the sealing rings. Wedge gate valves are also divided into rigid and split gate valves. In rigid ones, a solid-cast wedge is used, which ensures good tightness, however, at high fluctuations in the temperature of the medium, due to the thermal expansion of the alloy, jamming can occur, in order to avoid which gate valves with a composite two-disc locking element were created. Parallel gates are available in single-disc (gate) and double-disc (spring or wedge-shaped spacer between discs).
2. The running unit can be retractable and rotary (non-retractable). Gate valves with a rising spindle are considered more durable, since their working body does not come into contact with the medium, while in modifications with a non-rising spindle, the opposite happens. However, there is an advantage of the latter over the retractable mechanism, they are more compact and can be used in a limited space.
3. Steel gate valves are operated by means of a handle, reducer, electric or pneumatic actuator.
4. The gate valves are connected to the pipeline using bolted flanges or by welding.
5. According to the manufacturing method, steel valves are:
- solid steel,
- steel welded,
- stamped steel.
When assembling pipelines, the most common in use are cast valves, as one of the most reliable pipeline elements.
Steel gate valve has both advantages and disadvantages over other types of gate valves, such as cast iron gate valve, for example. Steel requires additional time to open or close, the height of the product is greater than that of other types of valves, and it is also impossible to adjust the flow rate of the working medium. However, despite all this, valves and today remain quite popular pipeline products.
