Maintenance Guide for Pneumatic V-type Ball Control Valves
The pneumatic V-type ball control valve is a uniquely designed valve with a V-shaped ball core that allows for linear adjustment and offers a wide range of control. When the ball control valve is closed, the V-shaped notch creates a snug scissor-like action with the valve seat, providing both self-cleaning functionality and prevention against ball core sticking, making it particularly suitable for pipelines prone to scaling and freezing.
1. Cleaning and Inspection
Valves disassembled from process pipelines must undergo thorough cleaning of all components soaked in process media to prevent corrosion or other damages that could pose risks to personnel and equipment. Additionally, surface rust on exposed components should be removed to ensure integrity.
2. Disassembly
To assess all components for inspection and determine the extent of repair and replacement needed, the actuator and valve must be completely disassembled. During disassembly, care must be taken to protect precision-machined surfaces such as valve cores, seats, stems, ensuring damage prevention to minimize maintenance costs. Special tools should be used for disassembling valve seats.
3. Major Component Overhaul
Inspection of throttle surfaces on valve cores and sealing surfaces between valve cores and seats should be conducted. Minor rust spots or wear can be rectified using general mechanical processing and grinding methods. Severe damage requires replacement of new parts, ensuring coaxial alignment between valve cores and seats. Stem seal surface damage necessitates replacement with new parts. For damage to guide and seal surfaces of the stem, new parts must be replaced for reverse-acting actuators, while appropriate repairs may be undertaken for forward-acting actuators. During spring compression inspection, any defects affecting strength, such as cracks, necessitate replacement with new parts.
4. Replacement of Wear Parts
Wear parts include packing, O-ring seals, gaskets, diaphragms, etc. During each maintenance cycle, disassembled packing, O-rings, and gaskets should be replaced with new ones. Diaphragms should be inspected for any cracks, aging, or signs of wear, with replacement decided based on specific conditions. Generally, these parts should be replaced every 2 to 3 years.
5. Assembly and Commissioning
During assembly, appropriate lubricants should be applied to the positioning, guiding, and threaded connection parts of components to facilitate future disassembly for maintenance. Special attention should be paid to the coaxiality of push rods, valve cores, and valve seats.
In the event of leakage without maintenance and repair, V-type ball control valves often indicate severe damage, which not only increases the difficulty of repair but may also result in repair costs exceeding expectations. Therefore, for effective planning and management of valve maintenance, personnel should possess not only relevant knowledge but also prioritize preventive and maintenance measures, conducting regular inspections of valves including checks on sealing and closure integrity.
