The Features and Performance of Butterfly Valve
Jan 18,2023Read More
The installation position of butterfly valves is usually between flanges. Butterfly valves should be installed at least four to six pipe diameters away from discharge nozzles, elbows or branches to minimize the impacts of turbulent flow. Before installation, clean the pipeline and check the smoothness/flatness of the flanges. Ensure that the pipes align. When installing the valve, keep the disc in a partially open position. It may be necessary to spread the flanges to avoid damages to the seat faces. Use locating holes or a sling around the body when lifting or moving the valve. Avoid lifting the valve at the actuator or its operator.
Storage and handling of butterfly valves
The seat, disc, stem and bushing of the butterfly valve should be coated with a silicone lubricant. The disc should be positioned at 10° open. Where applicable, the faces of each valve should be covered with cardboard, plywood or similar sturdy material to prevent damage to the seat face, disc edge or butterfly valve interior.
Valves should be stored indoors with face protectors intact. Storage temperature ideally should remain in a range from +40°F to 85°F. When valves have been stored for more than 3 months, open and close the valves. Repeat for every 3 months of storage. Store valves so that no heavy loads are applied to the bodies. Use caution when handling the valve or valve package. Never lift by the valve handle, gear operator, hand wheel, or actuator. Securely place a rope or hoist around the valve body while handling.
Valve location and orientation in piping
Valve location: Whenever possible, butterfly valves should be installed 6 pipe diameters from other elements in the pipeline, such as joints, elbows, etc. This might not always be possible, but it is important to achieve as much distance as possible. Where the valve is connected to a check valve or pump, use an expansion joint to ensure that the disc does not interfere with the adjacent equipment.
For slurries, sludge, pulp, dry cement or any other media with sediment or particles, manufacturer recommends the valve be installed with the stem in the horizontal position with the lower disc edge opening in the downstream direction.
Butterfly Valve Installation Procedure
Make sure the pipeline and pipe flanges are clean. Any foreign material such as pipe scale, metal chips, welding slag, welding rods, etc. can obstruct disc movement or damage the valve. Align the piping and then spread the pipe flanges so that the valve body can be easily placed between the flanges without contacting the pipe flanges.
Check to see that the valve disc has been positioned to a partially open position with the disc edge approximately 1/4" to 3/8" from the face of the seat. (Approximately 10° open.)Insert the valve between the flanges taking care not to damage the seat faces. Always pick the valve up by locating holes or by using a nylon sling around the valve neck. IMPORTANT: Never pick the valve up by the actuator or operator as damage may occur. Place the valve between the flanges, center it, and then span the valve body with all flange bolts.
DO NOT TIGHTEN THE BOLTS AT THIS TIME. Carefully open the disc to the full open position, ensuring that the disc does not make contact with the pipe I.D. Systematically remove any jack bolts on flange spreaders and hand tighten the flange bolts. Very slowly close the valve disc to ensure disc edge clearance from the adjacent pipe flange I.D. Open the disc to full open and tighten all flange bolts per specifications. Repeat a full open to close rotation of the disc to ensure proper clearances.
Butterfly valve Installation Procedure with flange welding
When butterfly valves are installed between ANSI welding type flanges, care should be taken to abide by the following procedures to ensure no damage will occur to the seat: Place the valve between the flanges with the flange bores and valve body bore aligned properly. The disc should be in the 10° open position. Span the body with flange bolts. Take the flange-valve-flange assembly and properly align in the pipe. Tack weld the flanges to the pipe.
When tack welding is complete, remove the bolts and the valve from the pipe flanges and complete the welding. Be sure to let the pipe and flanges cool before installing the valve.
CAUTION: Never complete the welding process (after tacking) with the valve between the pipe flanges. This causes severe seat damage due to heat transfer.
Good Practices for butterfly valve installation
Pipework opened to allow free valve entry with the disc in a semi-closed position. NOTE: Best practice is to have the disc in the 10% open position while installing.
Valve in semi-closed (10% open) position to:
Protect disc edge;
Reduce rubber interference during installation and start-up;
Help reduce initial torque build-up.
Disc should be returned to the full open position after flange alignment and before evenly pulling up the flange bolts. Tighten flange bolts according to the bolt torques and as per the given diagrams.
Bad Practices for butterfly valve installation
Pipework not spread sufficiently could tear rubber seat. Disc in open position will hit flange and score disc edge.
Disc in fully closed position causes seat distortion. When flanges are drawn up, rubber will close around disc edge creating excessive torque in initial operation.
Incorrect pipe alignment will cause interference between the disc edge and flange face, creating leakage and excessive torque for opening valve.
Do NOT use flange gaskets. All BI-TORQ butterfly valve seats have a molded-in o-ring that creates a positive seal when used in conjunction with standard ANSI flange faces. The use of gaskets unnecessarily might cause leakage or misalignment.
Do not over torque or improperly tighten bolts in any other pattern than that listed below.
Daily maintenance of industrial butterfly valve
Maintenance of valves involves the lubrication of mechanical components, inspection and repair of actuators. Valves with requirements for regular lubrication contain fittings from where grease is applied. Sufficient lithium-based grease should be applied at recommended intervals to minimize rusting and corrosion.
Inspection of the actuators at regular intervals to identify any signs of wear or loose electrical, pneumatic or hydraulic connections that may affect valve operation is also important.
In addition, users should clean all parts of the butterfly valve using a silicon-based lubricant. The valve seats should be inspected for any signs of wear and replaced whenever necessary. The discs of butterfly valves used for dry applications like compressed air service need to be lubricated. Butterfly valves that are not frequently cycled should be operated at least once monthly.
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