Tutorial on Adjustment and Leak Repair Before Installing Bellows Globe Valve
Release date:
2021-01-05
Adjustment and Leak Repair Tutorial for Bellows Globe Valve Before Installation
Bellows globe valves must be adjusted before installation and use, so everyone knows how to adjust bellows globe valves! What should be noted during adjustment?
Opening pressure adjustment
Before leaving the factory, the opening pressure of the bellows globe valve should be adjusted one by one to the set value required by the user. If the user recommends the working pressure level of the spring, it is usually adjusted according to the lower limit of the pressure level. Before installing the bellows globe valve on the protected equipment or before installation, the user must readjust it on site to ensure that the set pressure value of the bellows globe valve meets the requirements. The opening pressure can be adjusted by rotating the adjustment screw within the spring working pressure range indicated on the nameplate to change the compression amount of the spring. Before rotating the adjustment screw, the valve inlet pressure should be reduced to below 90% of the opening pressure to prevent the valve disc from rotating when turning the adjustment screw, which may damage the sealing surface.
To ensure the accuracy of the opening pressure value, the medium conditions during the adjustment of the bellows globe valve should be as close as possible to the actual operating conditions. The type of medium changes, especially when the cumulative state of the medium is different, the opening pressure often varies. When the working temperature rises, the opening pressure usually decreases. Therefore, when adjusting at high temperature under room temperature, the set pressure value at room temperature should be slightly higher than the required opening pressure. The structure and material selection of the valve depend on its application and should be based on the manufacturer's instructions. Traditional bellows globe valves are used to fix additional back pressure. If the opening pressure is adjusted after inspection, its set value should be the required opening pressure minus the additional back pressure value.
Causes of bellows globe valve leakage
1. Loose sealing ring connection threads, screws, and pressure rings.
2. Sealing ring not tightened.
3. Sealing ring connected and corroded.
4. Sealing ring welded to the valve body with poor overlay welding quality.
Bellows globe valve maintenance methods
1. Remove screws and pressure rings for cleaning, replace damaged parts, grind sealing surfaces and connection seats, then reassemble. For parts with severe corrosion damage, repair methods such as welding and bonding can be used.
2. Leakage areas in the sealing rolling region should be filled with adhesive and then fixed by rolling.
3. If the sealing ring's connection surface is corroded, it can be repaired by grinding, bonding, etc. If it cannot be repaired, the sealing ring should be replaced.
4. The sealing ring should be repaired according to welding specifications. When surface parts cannot be repaired, the original surface treatment should be removed.
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