How are gate valves used in fluid services?
Gate valves are used in almost all fluid services such as air, fuel gas, feedwater, steam, lube oil, hydrocarbon, and all most any services. Pressure drop during operation is very less. It cannot be used to control the flow. A gate valve is slow in operation. Opening and closing take times which is good also as it reduces the chance of hammering.
When is the disk of a gate valve removed?
It is a linear motion valve used to start or stop fluid flow. In service, these valves are either in fully open or fully closed position. When the gate valve is fully open, the disk of a gate valve is completely removed from the flow.
Which is the simplest type of gate valve?
1st is screwed bonnet: This is the simplest design available and it is used for inexpensive valves. 2nd is bolted-bonnet: This is the most popular design and used in a large number of gate valves. This requires a gasket to seal the joint between the body and bonnet.
What are the disadvantages of a flexible valve gate?
The flexible gate allows the gate to flex as the valve seat compresses due to thermal expansion of the steam pipeline and prevents thermal blinding. The disadvantage of flexible gates is that line fluid tends to collect in the disk. These may result in corrosion and ultimately weaken the disk.
What are the different types of valve bonnets?
Valve bonnets are available in many designs and models (the most typical are: bolted, round bolted, welded, pressure seal) and are manufactured in cast steel or forged steel (generally using the same material grade of the body).
What are the different types of valve parts?
Flanged connections are common for larger diameter valves, and they ensure long-lasting, and strong, joints. The flange face may be raised, flat, ring joint, tongue and groove and male & female (the most common finish is the RF type, i.e. raised face), and be finished in any of the available variants (stock, serrated or smooth).
Which is the third most important part of a valve?
After the body and the bonnet, the disc is the third most important element for the proper performance of a valve. Discs are generally manufactured in forged steel and are often reinforced (hard faced) to enhance the mechanical properties of the base material. Seats accommodate the movements of the disc.
What’s the difference between a check and gate valve?
Typical trim combinations for gate, globe and check valves have been standardized by the API trim chart. The disc opens, closes or modulate the flow of the fluid. In the case of a gate valve, the gate (wedge) is the disc of the valve (whereas the disc is called “ball” for ball valves).