Butterfly Valves

Lugged, wafer and double flanged butterfly valves of all materials and seat types are easy to use and long lasting as long as they are installed and maintained correctly.

Storage Conditions

  • To protect the seat and seals, do not unpack the valves until they are ready for installation. By doing this you are protecting the valve from dust and debris which may eventually cause seat leakage.
  • Keep in a cool well ventilated space if storing for a longer period of time.

Valve Installation

  • Valves can be installed in any orientation however it is best if it can be installed upright especially in bigger sizes to reduce load on the shaft caused by the actuator or gearbox trying to pull away.
  • It is common for smaller butterfly valves to be mounted in various orientations eg water trucks. This is fine and is common practice.
  • Verify the material of the butterfly valve, seat and disc before installation. Ensure that there are no defects caused by storage or transportation.
  • Verify the pressure rating of the valve vs the application requirement.
  • When installing directly to a pump or another valve be sure to have a pipe spacer between them to allow for the butterfly disc to open.
  • Complete all welding works before valve installation and be sure the flange has cooled to ambient temperature before installing the butterfly valve.
  • Make sure there is no welding residue, waste, rust or other debris in the pipe before installation. Wash with water or a mild detergent if needed.
  • Clean the surface of the flange that will come in contact with the butterfly valve to ensure it is free of rust and debris. Wash with water or a mild detergent if needed.
  • Make sure there is no warpage of the flange or misalignment of the butterfly valve in relation to the flange. This is the most common cause of butterfly valve problems where it is not aligned with the flange/pipe correctly and the disc catches when trying to open/close. Support the valve where necessary to reduce load from the piping assembly.
  • Install spacing bolts taking care not to damage the valve seat and adjust the face to face of the two flanges so there is space when the piping is spread open (enough space to remove the valve or replace it for maintenance).
  • Once the pipes are centred, insert the bolts so that the bottom of the valve can rest upon them to prevent the valve from falling through.
  • Before tightening the bolts operate the valve to ensure it does not catch on the pipework or the flange.
  • Tighten the bolts one at a time doing it in stages so even pressure is applied and a seal is formed between the valve and flanges.
  • Once the installation is complete operate the valve several times to ensure it is free from impingement and it has not moved during installation.

Field Testing

  • Rubber seated butterfly valves are designed to hold rated pressures only. Test pressures above rated working pressure in the closed position can cause damage to the valve.
  • With the disc in the open position the pipeline can be tested up to the valve hydrostatic test pressure.
  • Seat leakage can occur with foreign material between the seat and disc. If this occurs open the valve 10 to 15 degrees to obtain high velocity flushing action. Close and repeat if necessary.
  • Seat leakage can result from a rotational shift in position of the disc in relation to the body. Readjust the closing stop on the actuator/gearbox as necessary.

Operation

  • Do not use the valve at pressures above its working pressure.
  • If the valve is jammed in a position between open and closed check the actuator operation. If necessary remove the actuator and manually operate the valve to fault find. Remove and check valve for foreign objects if required (see maintenance).
  • Excessive torque from the actuator can damage the internal valve parts.

Maintenance

  • Cycle the valve once a month or more if it is not used regularly.
  • Relieve the system pressure before maintaining the valve.
  • To remove from pipework reverse the installation sequence.
  • Replace valve seat (liner) by removing the stem and disc. Press out liner and replace with new part. Reinstall the disc and stem along with seals and clips. Refit into line as in installation sequence.
  • For operational instructions please see each video link under products.

Design Guidance & Product Advantages

  • When sizing the valve always consider available space for the actuator and feedback devices.
  • Consider valve supports to carry excess loads.
  • Extension shafts in SS316 are available upon request. This allows valve to be buried in pits and actuators to be above ground.