In a lifting spindle gate valve the valve closes and opens by means of translational or helical movement.
Valves can vary in terms of spindle rotation direction. Depending on these properties, they are divided into 2 types:
• rising spindle. The valve closes and opens by means of translational or helical movement. This type of valves normally has rather big dimensions;
• non-extending rotating spindle. It is smaller in size and is used for transporting petroleum products, water and other media. It does not cause corrosion. All other substances are transported via rising spindle valves.
Steel gate valves with various nominal sizes are commonly used as isolating devices on pipelines. It is widespread for shut-off applications in gas and liquid flows under pressure drop conditions.
The cast iron gate valve is designed to completely switch on or switch off the flowing medium. It can be used at temperatures up to 225 °С. Cast iron gate valve installation position on horizontal pipelines must be with the handwheel upwards, with the spindles positioned vertically.
Non-extending rotating spindle is smaller in size and is used for transporting petroleum products, water and other media. It does not cause corrosion.
If installed on a vertical pipeline, correspondingly, the gate valve must be positioned flat, and the spindles rotate in the horizontal plane. Both steel and cast iron gate valves can be re-used, maintained and refurbished.
Valves of all nominal sizes can have the following control types:
• automatic (using dedicated electrical actuator).
The second option is preferable as it provides the basis for integrating a wide range of functions. Isolating devices can be stopped in any intermediate position by pressing the button. Motors are automatically switched off when the members reach their limit positions. If a trim position sensor is available, a reading can be provided at the control panel to indicate if the passage is open or shut.
Gate valve benefits:
• transported substance can be moved in any direction;
• small total length;
• can be used to shut off both liquid and viscous flows. Also, flow resistance is insignificant.
Gate valve technical data:
• fairly wide range of available nominal diameters: 50 to 1200;
• pressure up to 25 MPa;
• temperature threshold up to 450 °С;
• transported working medium can be steam, lubrication oils, petroleum, water, alkali, acids and many other.