Data: 2009-08-13 From www.supply-valve.com

1. Minish S to increase work opening and lifetime.
Minish S, which is just to increase system lose without the regulating valves's and reduce the pressure drop allocated on the valves. To guarantee the flow pass the regulating valves, it is necessary to increase the opening of regulating valves. At the same time, the small pressure drop could also weaken the gas etching and erosion. The main methods are followed: make the pore plate after valves to consume pressure drop; close the series-wound hand-operated valves on the pipeline until the regulating valves gets the ideal work opening. This method is especially suitable for the valves that is on small work opening. It is more simple, convenient and effective.

2. Big opening to life-saving
Originally, let the regulating valves work on the biggest opening. Such as 90, so that the cavitation and erosion will only happen on the top of case. Along with the case damages and flow increases, the valves closes a little and the case is damaged a little. Generally, the whole case will be made full use of and can not be used again eventually with the case root and sealing face destroyed. Meanwhile, under the big opening work, the throttle gap is big and erosion is weak. That can raise life span over 1 to 5 times compared with the middle opening and small opening at the start time. For example, a chemical plant has took this measure to increase the valves's life span 2 times.

3. Extend throttle passage to increase life span.
The simplest method to extend throttle passage is thickening seat. That's to say increase the seat holes and then form longer throttle passage. On the one hand, it could delay the sudden enlargement after the throttle of flow closed form and shift the destroyed site to far away from the effect of sealing face; on the other hand, it increase the throttle resistance and reduce the pressure recovery degree so as to weaken cavitation. Someone designs the seat hole into setback type, wave type. That is also for the reason mentioned above. This method is often used on the valves that is high pressure or renewed. It is very effective.

4. Reduce caliber to increase work opening and lifetime.
The main methods are followed: change into a smaller size valves, DN32 into DN25; not change the body, but replace a smaller case seat. For example, a chemical plant replaces the throttle part dg10 into dg8 when repairing and increase the lifetime 1 times.

5. Shift the destroyed site to increase lifetime
Shift the seriously damaged position into backseat, it could protect the sealing face and throttle face of case seat.

6. Use special material to increase lifetime
For resisting cavitation (the destroyed shape like cellular dot) and wash out (clipper-built groove), we could use the special material that is cavitation resistance and wash out resistance to make throttle part. The special material contains 6YC1, A4 steel, satellite, hard alloy, etc. For anticorrosion, we could use the material that is more corrosion-resistant, mechanical property and physical property. This material could divide into non-metal material (rubber, F4, ceramics) and metal material (Monel, hastelloy alloy).

7. Change the flow direction to increase lifetime
Flow open type will flow at the open direction. Cavitation and erosion make mainly effect on the sealing face so that the case root and case seat sealing suffer the destruction quickly; Flow close type will flow at the closed direction, after the cavitation and erosion making mainly effect on the throttle, it protects the sealing face and case root under the seat sealing face and saves the life. So to the flow open valves, if the life-saving issue is prominent, we could only change the flow direction to save the lifetime 1 to 2 times.

8. Change the valves's structure to increase lifetime
Change valves's structure or select longer lifetime valves, which is in order to increase the valves's life. We could select multiple-step type valves, anti- cavitation valves and corrosion-resistant valves, etc.