The gate valve is a valve that opens by lifting a rectangular gate/wedge out of the path of the fluid. The distinct feature of a gate valve is the sealing surfaces between the gate and seats are planar, so gate valves are often used when a straight-line flow of fluid and minimum restric¬tion is desired. The gate faces can form a wedge shape or they can be parallel. Gate valves are primarily used to permit or prevent the flow of liquids, but typical gate valves shouldn't be used for regulating flow, unless they are specifically designed for that purpose. Because of their ability to cut through liquids, gate valves are often used in the petroleum industry. For extremely thick fluids, a specialty valve often known as a knife valve is used to cut through the liquid. On opening the gate valve, the flow path is enlarged in a highly nonlinear manner with respect to percent of opening. This means that flow rate does not change evenly with stem travel. Also, a partially open gate disk tends to vibrate from the fluid flow. Most of the flow change occurs near shutoff with a relatively high fluid velocity causing disk and seat wear and eventual leakage if used to regulate flow. Typical gate valves are designed to be fully opened or closed. When fully open, the typical gate valve has no obstruction in the flow path, resulting in very low friction loss.
Gate valves are characterized as having either a rising or a nonrising stem. Rising stems provide a visual indication of valve position because the stem is attached to the gate such that the gate and stem rise and lower together as the valve is operated. Nonrising stem valves may have a pointer threaded onto the upper end of the stem to indicate valve position. Nonrising stems are used underground or where vertical space is limited.
Bonnets provide leakproof closure for the valve body. Gate valves may have a screw-in, union, or bolted bonnet. Union bonnet is suitable for applications requiring frequent inspection and cleaning. It also gives the body added strength. Bolted bonnet is used for larger valves and higher pressure applications.
Another type of bonnet construction in a gate valve is pressure seal bonnet. This construction is adopted for valves for high pressure service, typically in excess of 15 MPa (2250 psi). The unique feature about the pressure seal bonnet is that the body - bonnet joints seals improves as the internal pressure in the valve increases, compared to other constructions where the increase in internal pressure tends to create leaks in the body-bonnet joint.
Gate valves may have flanged ends which are drilled according to pipeline compatible flange dimensional standards. Also can be Butt weld and Socket Weld connection.
Gate valves are typically constructed from, cast carbon steel, stainless steel, alloy steels, forged steels, Hastelloy, Monel, Inconel and others.
1. Design and Manufacture of product according to ANSI B16.34, API 600, API 6D, BS, DIN, JIS, GB, etc..
2. Compact structure, small bulk, perfect rigidity, safety and reliable.
3. Blow down part (disc) utilize flexible structure, can automatically compensate distortion of body due to abnormal burden or temperature, so seal credible and prevent wedge being blocked.
4. Manual valve with DN over or equal to NPS 10”, class 400 pounds and DN over or equal to NPS 6”, class 600~2500 pound equip with rolling bearing to operate easily.
5. Material of main body, material to trims, packing, washer, material of fastener can logically combine according to customer’s requirement or actual work status.
6. Exchangeable seat and random combine the material of surface of blow down part to meet the requirement of work status, to prolong service life.