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Trunnion Mounted Ball Valve Maintenance


Trunnion Mounted Ball Valve Maintenance

Trunnion mounted ball valve should be inspected regularly during operation and any findings should receive immediate attention in order to avoid any further damage to the trunnion mounted ball valve or the system.

Regular inspection and maintenance should be scheduled at a minimum of twice per year, or more often if required.

1.1 In less corrosive environments, it is suggested to check the 
trunnion mounted ball valve body thickness every six months. In more corrosive environments, it should be checked every three months. If the measured wall thickness is less than specified in ASME B16.34, the valve should be replaced immediately.

1.2 The 
trunnion mounted ball valve seat pocket area is a primary area where the operation of the trunnion mounted ball valve can be affected by debris and contaminants within the line. To ensure the seat’s operational movement within the valve, it is recommended that the valve seat pockets be cleaned routinely with a product designed for the valve trim and the service needs. Routine service can vary depending on the severity of the operating service of the valve. Once the trunnion mounted ball valve is in service, it is recommended to use a seat cleaning detergent or light lubricant to clean the seat sealing surface of any debris which may have been introduced into the piping or the trunnion mounted ball valve at the time of installation. Recommended cleaning of the valve seats should be at minimum every six months; valves which are operated more often should be every three months to maintain and ensure the integrity of the seat’s seal. 

1.2.1 In the event your 
trunnion mounted ball valve seats or stem fail, it is possible to restore the seal or to minimize any seat or stem leakage for a temporary or an extended period of time with the injection of a valve sealant in a sufficient amount to create the necessary seal. Valves must be equipped with the seat and or stem injection feature. Injectable seat and seal restoration is for a temporary period of time, until it is convenient to remove the trunnion mounted ball valve from service and replace the seats or seals.

1.2.2 For temporary seat and seal restoration while the valve is under pressure, position the 
trunnion mounted ball valve in the fully closed position. Carefully remove the safety cap from the grease fitting. Never remove the grease fitting when the trunnion mounted ball valve is under pressure. Attach the grease gun connection onto the grease fitting and commence injecting the sealant. CAUTION: Follow all recommended safety and operating instructions from the grease gun and the sealant manufacture. If injection of the sealant is difficult, flush the valve with a valve cleaner and inject sealant again. Always remember to replace the safety caps on the grease fittings.
Trunnion Mounted Ball Valve

1.3 Factory supplied replacement parts should be used any time replacement parts are required. 

1.4 Before removing the
 trunnion mounted ball valve from a pipeline, always mark the connecting flanges for proper fitment and valve flow direction.

1.5 After any 
trunnion mounted ball valve repair,for proper bolt torque to assemble the trunnion mounted ball valve.
1.5.1 Over torquing can cause deformation of the body/bonnet flange causing leakage. Failure to properly follow the tightening sequence will result in the gasket not being compressed evenly, resulting in gasket leakage. 
1.5.2 WARNING: Never use impact devices to tighten the bolting on the body/bonnet connections. Use suitable designed mechanical devices such as hand torque wrenches for tightening .Torque wrenches and standard wrenches may be used in combination when performing tightening sequences.

1.6 To assure the 
trunnion mounted ball valve is sealing properly, perform the required pressure testing per recognized and applicable design standards.
Trunnion Mounted Ball Valve

1.7 During maintenance or servicing of the trunnion mounted ball valve, all replacement parts must be the same as the original specification (parts dimensions and materials). End user may also purchase the spare parts such as packing, gaskets, bolts/nuts etc. when ordering the valve. With the new packing, gasket or bolt/nuts installed, the valve must pass the applicable pressure testing prior to installation and service.

1.8 When the 
trunnion mounted ball valve seat or stem sealing surface is damaged by foreign particles, the emergency sealant injection fittings should be used to first inject the valve cleaner to purge any old grease out, then use proper sealant (suitable to the medium) through a manual pump to fill with sealant. 

1.8.1 Prior to injecting any sealant, lubricant or any other material into the valve, verify that the product is compatible with the valve trim. Emergency Seat Seal Injection 1. Firmly hold the injector base 2. Remove the safety head nut 3. Connect grease gun and pump the sealant Emergency Stem Seal Injection Installation. 

1.9 The gear box requires different grease, suitable for -20°C (-4°F) to 80°C (176°F), contact us for other grease applications.

1.10 If the gear operator is used frequently, the gear box grease should be replaced every three years. If used less frequently, it should be replaced every five years.
Trunnion Mounted Ball Valve

1.11 Gear box position stop calibration:
1.11.1 Install “CLOSE” position travel stop screw and jam nut as shown in illustrations above.
1.11.2 Operate the valve to the fully closed position until it engages with the travel stop screw.
1.11.3 Ensure the valve is completely closed against the stop, loosen the jam nut and turn the stop screw counter-clockwise 3-4 turns.
1.11.4 Open the cavity drain valve.
 Trunnion mounted ball valve body cavity medium will leak from the drain valve. If it continues to leak this may indicate the valve seat is leaking.
1.11.6 If the drain continues to leak, turn the hand wheel clockwise to close the valve further until leaking has completely stopped. Continue turning the hand wheel slightly back and forth to determine the best closed position.
1.11.7 Once the drain valve has completely stopped leaking, turn the CLOSE position stop screw clockwise until it stops, then tighten the jam nut.
1.11.8 If leaking is still experienced after section
1.11.9 above, the seat sealing surface may be damaged and should be repaired or replaced.

5.12 At NO time shall any weld repair be conducted on the valve while in service. Never strike the 
trunnion mounted ball valve with a hammer or other impact device. Ensure that no excess weight is placed on the trunnion mounted ball valve that was not part of the original manufacture design.