How to Rebuild Tri-Clover Valves
Tri-clover valves are air actuated – they are opened and closed with pneumatic power. They are common in factories and on systems where there are pneumatic lines for some other reason. When there is a problem, or when the valves are inspected for routine maintenance, the valves should only be serviced by a trained expert. Even opening the bonnet – the housing of a valve – can be dangerous. Pneumatic systems often trap compressed air, which can impel metallic parts into the body when the air pressure is suddenly released.
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Instructions
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Shut off the pneumatic system before you start working on valves. Open any bleeding valves near the tri-clover valve to make sure the pressure is neutral. Open the valve slowly, keeping your face and body as far from the bonnet as possible.
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Examine the rubber or PTFE grommets, gaskets and valve seats. If they are cracked, torn or deformed, they should be replaced. Check the valve, bonnet and other parts for galling, which is abrasion caused when metal pieces come in contact with each other. If there is galling, the parts should be replaced.
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Inspect the valve seats – below the rubber cushions – to see if there is any damage or irregularities such as scratches or nicks. If the valve seat is damaged, it should be replaced. Check the coupler to make sure that the three balls in the coupler move freely. And if they do not, they should be replaced.
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Tips & Warnings
Valves that are bound up and difficult to open can usually be opened with the help of air pressure, but this should only be done if necessarily, For types 210, 215 and 280 normally open actuators, remove the body clamp, the gasket and the lower body. Apply air to the actuator until the valve extends. Lift the sleeve and remove the valve stem through the bonnet. Remove the actuator clamp and separate the actuator from the yoke. Cut off the air supply. For types 220 and 225 normally closed actuators, apply air until the stem retracts. Remove the body clamp, gasket, and lower body. Extinguish the air supply. Lift the sleeve and remove the valve stem through the bonnet. Remove the actuator clamp and separate the actuator from the yoke.
The air supply should be off whenever you are working on air actuated valves, but if you have the air supply on to loosen a valve, be sure to keep hands, face and tools away from the valve as much as possible.
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