Valves are for starting or stopping flow, regulating or throttling flow, preventing back flow or relieving and regulating pressure in fluid or gaseous handling applications like forged steel gate valve. Common valve types include: Ball,Butterfly,Check, Diaphragm, Gate, Globe, Knife Gate, Parallel Slide, Pinch, Piston, Plug, Sluice, etc.

The following forms of valves are employed in a various applications, these descriptions may supply a basic guideline inside selection of valves.Gate valves have one of four forms of bonnets, which offer closure to stop fluids from leaking from the valve. Screw-in bonnets are quite obvious, durable sealing units which use pressure to seal. Union bonnets provide availability to the valve body for applications that will require frequent maintenance or inspection. Bolted bonnets are usually used for larger valves in higher-pressure applications.

Split wedge discs tend to be more flexible and could be used where pipeline strains may distort the valve seats. They were made to overcome sticking on cooling in high-temperature service also to operating torque. This seat is much like two wheels set over a very short axle. Stress analysis is needed to know pipeline stresses and improper installation can increase operating stresses.

Double Disc Parallel Seats Gate ValveIn this kind of a gate valve, there's 2 parallel seats against which a double disc is forced, b y a ‘spreader’. They are utilized for liquids and gases at normal temperatures. As normal gate valves, these are unsuitable for regulation. To prevent jamming, they should be installed vertical with hand wheel up. Due to spreader spring, a strong seal is achieved relating to the disc and seat. In some models fluid pressure is utilized to force the disc up against the seat.

A valve with such a wedge might be installed in any position and it's suitable for virtually all fluids. It is practical for turbulent flow.The flexible wedge gate valve illustrated in below Figure can be a one-piece disk that has a cut across the perimeter to increase the ability to match error or change inside the angle involving the seats. The cut varies in dimensions, shape, and depth.