Industrial Valve Maintenance and Repair Guide
Repair and Maintenance of Ball Valve
- Check the tightness of bolts and nuts, and if loose, tighten them. Tighten the bolts to attain the torque recommended by the manufacturer. Excess torque will damage the bolts, nuts, and valve flanges.
- Lubrication. Lubricate the valve frequently to prevent abrasion wear on the ball when it closes/opens. Lubrication also enhances the smooth and easier operation of the valve and improves seal effectiveness.
- Grind the valve ball and seat regularly. Grinding will help smooth the ball and seat for a tight seal when the valve closes.
- Open the valve and inspect the valve interior. Replace or Lap the ball valve and/or seat if worn out or damaged. Also, clean the valve interior of materials sticking on the valve body.
- Inspect and replace seals and gaskets if they are worn out or damaged.
Troubleshooting ball valves
- The ball valve is hard to operate.
- Solids clogged in the valve. Open the valve bonnet and clean off the solids.
- Corrosion inside the valve. Clean off corrosion scales inside the valve.
- External fluid leakage
- Loose connection between the valve and the pipe. Tighten the bolts and nuts to the torque recommended by the valve manufacturer.
- Loose connection between the body and the bonnet. Tighten the bolts and nuts.
- Worn-out gasket. Replace the gasket.
- Excess fluid pressure. Ensure the fluid pressure level is as recommended by the valve manufacturer.
- Internal fluid leakage
- Damaged seat. Replace or Lap the valve seat.
- Debris is stuck on the valve seat. Open the valve and clean off the dirt.
- The valve is hard to open/close.
- Foreign materials are stuck in the valve. Open the valve and remove such materials.
- Noisy operation
- High fluid velocity. Reduce the fluid velocity.
- Wrong valve sizing. Replace the valve with a higher-rated valve.
Repair and Maintenance of Check valve/non-return valve
- Perform grinding operation on the valve seat to remove any large or small defect that may impair perfect valve closure.
- Lubrication. Lubricate the moving disc hinge pin to reduce friction, and wear and enhance effectiveness when closing/opening for fluid flow.
- Check and replace the gasket after a particular duration of use. Prolonged use damages the gasket due to the pressure emanating from the body-bonnet connecting bolts.
- Replace or Lap the valve seat. The seat helps to provide a tight seal between the body and the disc, and if it is damaged/worn out, then leakage or backflow will occur.
- Tighten the bolts connecting the body and the bonnet to prevent fluid leakage.
- Tighten bolts connecting the valve to the pipe to prevent fluid leakage at the joint.
Troubleshooting check valve
- The valve disk does not open.
- The valve was installed in the wrong direction. Install the valve such that the fluid flow matches the arrow indicated on the valve body or according to the valve manufacturer's instructions.
- The suction pressure is low. Increase fluid flow pressure to create a higher force that can push the valve disc to open.
- The downstream valve is closed. Open the downstream valve.
- Reverse fluid flow
- The disc is stuck open. Open the valve and remove foreign materials interfering with the disc returning to the valve seat.
- Worn out valve seat. Replace or Lap the valve seat.
- Debris on the valve seat. Open the valve by removing the bonnet and cleaning off the debris.
- Fluid leakage
- Worn-out gasket. Replace the gasket.
- Loose connection. Tighten the bolts and nuts connecting the valve body and bonnet and also those connecting the body and the pipe. However, avoid excessive tightening as it damages the valve gasket, bolts, nuts, and valve flanges.
- The valve vibrates while in use.
- High fluid velocity. Use the valve for the flow velocity recommended by the check valve manufacturer.
Repair and Maintenance of Gate Valve
- Before starting the repair and maintenance, ensure the system is relieved of the pressure to avoid injuries, losses, and environmental damage.
- Valve lapping. Use a Lapping machine to smooth out the valve seat and disc to enhance a tight seal when the valve closes. Using the valve for a long period leads to the formation of scales on the valve, which then interferes with disc closure and, thus, fluid leakage. Also, the build-up of these scales reduces fluid pressure.
- Lubrication. Lubricate the gate valve stem threads and stem nut to reduce friction, wear, and make it easy to open/close. Use a grease gun to do the lubrication.
- Adjust valve packing every month or as recommended by the manufacturer.
- Cleaning. Open the gate valve bonnet component and clean the valve seat, disc, and entry and exit ports to prevent fluid blockage.
- Tighten the bonnet-body bolts and nuts to the torque recommended by the gate valve manufacturer.
- Replace the disc (components that closes fluid flow) if it does not stop the fluid flow effectively. Replacement of the disc would involve opening the valve bonnet to access the valve interior.
Troubleshooting gate valves
- Leakage through the valve-pipe connection.
- Worn-out seals/gasket. Replace the seals/gasket.
- Loose connection of bolts and nuts. Tighten the bolts and nuts.
- Excess fluid pressure. Ensure the fluid pressure is at the level recommended by the gate valve manufacturer.
- Leakage through the bonnet-body connection.
- Loose bolts and nuts. Tighten the bolts and nuts.
- Worn-out seals/gaskets. Replace the gaskets/seals.
- The valve is hard to operate.
- There are clogged materials in the valve or on the valve stem. Disassemble the valve and remove such materials.
- A bend on the valve stem. Replace the stem.
- Extremely tight packing. Loosen the packing.
- No fluid flows through the valve
- The valve is blocked. Disassemble the valve and remove foreign materials from the valve.
- Worn-out gate. Replace the gate.
Repair and Maintenance of Globe Valve
- Valve grinding. Perform Valve grinding regularly to help realise a dense, flat surface. The grinding procedure is performed using a grinding machine. This procedure helps to smoothen seals and seats, allowing perfect and tight seals.
- Lubricate the valve stem frequently to help reduce wear and enhance smooth operation without using high torque to open or close.
- Open the globe valve bonnet and clean off scales or residue accumulating inside the bonnet and valve body to prevent blockage. Also, use this chance to inspect the valve seat and disc and replace them if worn out.
- Replace the gland packing after a certain period of use or as recommended by the globe valve manufacturer to avoid leakage.
- Inspect and replace the seals and O-rings after disassembling the globe valve.
- Replace worn-out bolts and nuts on the bonnet and pipe-body connections. New bolts and nuts will ensure tight connections to prevent leakage and, thus, no fluid losses and environmental damage.
- Clean off any accumulation on the valve body using cleaning solutions.
Troubleshooting globe valve
- Fluid leakage through the bonnet
- Loose bolts and nuts. Tighten the bonnet bolts and nuts to the torque recommended by the manufacturer.
- Worn-out bonnet gasket. Replace the gasket.
- Extreme fluid pressure? Ensure the valve operates at the fluid pressure recommended by the manufacturer. If not so, use a higher-rated globe valve.
- Fluid leakage through the body-pipe connection
- Loose connection. Tighten the bolts and nuts.
- Worn-out gasket? Replace the gasket.
- Extreme fluid pressure? Ensure the fluid pressure matches the value recommended by the manufacturer.
- The handwheel cannot open/close the liquid flow.
- Extremely tightened packing. Loosen packing.
- Worn-out stem threads. Replace the stem.
- Foreign materials clog the valve disk. Open the valve and clean off the materials.
- The handwheel rotates but does not open/close the fluid flow.
- Worn-out disc. Replace the disc.
- Worn-out seat. Replace or Lap the valve seat.
Repair and Maintenance of Pressure Relief Valve
- Inspect the valve for corrosion. Replace corroded components of the valve.
- Cleaning of valve components. Clean internal parts of the valve of foreign materials and moisture that can impair proper functioning. However, avoid aggressive cleaning that may damage delicate parts of the valve.
- Perform lapping regularly. The lapping process will help to remove scales on the valve seat and disc and thus enhance perfect closure when the valve is stopped.
- Overused grease. Clean off overstayed grease since it accumulates dirt and or contaminates the valve.
- Set pressure. The pressure relief valve is made to operate at a certain pressure, and in case of any readjustment or tampering may affect its performance. So, set the pressure to the level recommended by the manufacturer.
- Seat. Replace or Lap the seat if it is causing fluid leakage.
- Rain cap. This cap protects the valve against malfunction due to ice, snow, rain, insects, dirt, debris, and contamination. Replace it if it is missing or damaged.
- The spring on the pressure relief valve deteriorates with time if it is exposed to salty water, industrial pollutants, and chemicals. Replace the spring if the coating becomes chipped or cracked to prevent malfunction and errors.
- Inspect weep holes and remove paint, dirt, ice, or other foreign materials that may interfere with the proper drainage of the valve.
Troubleshooting Pressure Relief Valve
- The piping system cannot attain the required pressure.
- Wrong calibration. Adjust the valve pressure.
- Excess system pressure
- Check the valve for blockage and remove any blocking materials like dirt and contamination.
- The valve is not calibrated to the correct pressure. Adjust the valve pressure.
- Fluid leakage
- Wrongly sized valve. Replace the valve with another that can withstand higher pressure.
- The valve is not tightly closed. Tighten the valve disc through the handwheel. Check for dirt that may interfere with disc closure.
- Damaged seals. Check for worn-out or damaged seals and replace or Lap them.
Repair and Maintenance of Safety valve
- Calibrate the valve regularly to enhance its reliability and sensitivity. Calibration will ensure the valve is within the required set pressure.
- Clean the valve body to remove grease and dirt.
- Check the lead seal to ensure it is intact to prevent the heavy hammer of the safety valve from being moved or becoming loose.
- Lap the valve disc and seat to enhance the perfect and tight seal.
- Replace the valve spring after it becomes corroded due to exposure to industrial chemicals, salty water, and dirt. Corrosion reduces spring strength and may add errors when the valve is set, leading to wrong pressure values.
- Repair the safety valve when it starts leaking. The repair would be in terms of replacing worn-out seals and O-rings.
- Inspect the valve disc and replace it if it is worn out.
- Inspect the bolting torque and adjust the bolts if they are too tight or loose.
Troubleshooting safety valve
- Leakage through the bushing
- Tighten the bushing. Replace the bushing.
- Dirt on the sealing surface. Open the valve and wash away the dirt.
- Damaged sealing surface. Replace the seal or repair it by Lapping.
- Inflexible opening/closing
- Improperly positioned adjusting ring. Adjusting the "adjusting ring" as per the process requirements.
- Moving parts jammed. Inspect the internal parts of the valve for dirt, corrosion, impurities, and improper assembly that may cause this problem and repair it as necessary.
- Safety valve chatter
- High fluid discharge capacity. Use the safety valve for the manufacturer's discharge capacity, or use a higher-rated safety valve.
- The Inlet pipe diameter is too small. Use a larger inlet diameter or reduce the inlet pipe resistance.
- High resistance on the discharge pipe. Lower the discharge pipe resistance.
Repair and Maintenance of Parallel slide valve
- Use a valve grinding machine to grind the valve seats and the two discs to smoothen them so that there is no fluid flow when the valve is stopped.
- Lubricate moving parts such as the yoke sleeve and stem to reduce wear and friction. Lubrication also helps to reduce the energy needed to open/close the valve. Also, lubricate actuator moving parts for actuated valves. Such components are drive sleeves for the motor actuator and sliding surfaces for the hydraulic/pneumatic actuator.
- Clean internal components of the valve, such as the stem, body, bonnet, and packing area. The cleaning helps to remove solids and contamination that may reduce fluid pressure or cause blockage of fluid flow.
- Tighten bolts and nuts connecting the body and bonnet and those connecting valves to the pipe. However, avoid excess torque on the nuts and bolts, as it will damage them. Also, check the valve actuator to ensure it is properly tightened.
- Adjust packing and stuffing box rings to prevent fluid leakage.
Troubleshooting parallel slide valve
- Leakage through the packing chamber
- Loose bolts. Tighten the bolts evenly.
- Insufficient packing. Increase the amount of packing rings.
- The packing chamber is damaged, or the packing is worn-out. Replace with new packing.
- Stem damaged. Replace/repair the stem as necessary.
- Leakage through the sealing
- Worn-out seals. Replace seals.
- Dirt accumulation on the sealing surface. Clean off the dirt. Excess fluid pressure. Reduce fluid pressure.
- The hand wheel is hard to operate
- The packing is too tight. Adjust packing torque.
- Worn out stem threads. Replace stem.
- Dirt accumulation between the stem and gland. Remove the dirt.
- Fluid flow when the valve is closed
- Worn-out disks and/or seats. Replace or Lap the disks and/or seats.
Repair and Maintenance of Wedge valve
- Use a lapping machine to clear scales on the valve seat and disc. Lapping helps to remove defects that interfere with perfect valve closure by making the disc and seat have smooth surfaces.
- Gland adjustment. Adjust the gland regularly to maintain the seal and prevent fluid leakage.
- Lubricate the valve stem to reduce wear through friction and make it easier to open and close the valve.
- Inspect the stuffing box gasket and replace it if damaged or worn out to prevent leakage. Also, tighten the stuffing box nut if it is loose.
- Open the valve and clean internal parts regularly. Such components include seals, O-rings, bonnet, and body. The cleaning helps to remove dirt, corrosion, impurities, and any foreign materials that later cause blockage. Also, check the valve seat and disc and replace them if they are worn out.
- Inspect and replace the bonnet gasket if it is damaged. A good gasket will prevent leakage that may cause losses or environmental damage and thus legal action, especially for hazardous fluids.
- Inspect bolting torque. If the bolts are loose, tighten them but avoid excess torque that may damage the gasket, bolts, and nuts.
Troubleshooting wedge valve
- Internal leakage
- Worn out seat. Replace or Lap the valve seat.
- Worn out seals/O-rings. Replace or Lap the O-rings and seals.
- External leakage
- Loose bolts. Tighten bolts and nuts.
- Worn out gasket. Replace the gasket.
- Excess fluid pressure. Reduce the fluid pressure or use a higher-rated valve.
- Handwheel is hard to rotate
- Dirt on the stem. Open the bonnet and clean off the dirt.
- Damaged stem. Replace the stem.
- The valve does not open/close the fluid flow
- Damaged stem. Replace the stem.
- Worn out/damaged disc. Replace the disc.
Repair and Maintenance of Diaphragm valve
- Perform grinding operation using a lapping/grinding machine to smoothen out the valve diaphragm and weir for perfect closure.
- Cleaning. Clean the diaphragm regularly to prevent the buildup of dirt and contaminants to prevent damage to the diaphragm.
- Inspect the diaphragm and linings for failure and replace them if damaged.
- Check the body, seat, and bolts for tightness. If loose, tighten them to prevent fluid leakage.
- Check the body-bonnet bolts are tightly connected.
- Lubricate the valve stem to reduce the rate of wear and operating torque.
Troubleshooting diaphragm valve
- No fluid flow through the diaphragm valve
- The valve is closed. Open the valve.
- Pipe or strainer clogged. Check the filter or pipe for blockage.
- Leakage between the valve and the pipe
- Loose bolts. Tighten the bolts evenly.
- Worn out gasket or lining. Replace the gasket/lining.
- The valve and pipe are improperly centered. Centre the valve to the pipe.
- Difficult to operate the valve
- Dirt on the stem. Clean off the dirt.
- Worn out stem threads. Replace the stem.
- Foreign materials are trapped between the diaphragm and the body. Remove the foreign materials.
- High fluid pressure. Reduce the fluid pressure or use a higher-rated diaphragm valve.
