How To Specify Gonec

How to Specify Gonec High Performance Butterfly Valves

Butterfly valves shall be double flanged and conform generally to BS5155. The valves shall be of the seal in body design principle . Valves with seal in the disc design shall not be accepted.

Sizes DN300 and smaller shall have a solid stainless steel disc. Valves in sizes DN350 and larger shall have a stainless steel replaceable seat secured to the edge of the disc by means of stainless steel countersunk screws. The disc shall be offset in the body to ensure uninterrupted contact around its perimeter and driptight sealing

Body Seal
The replaceable resilient seal shall be secured to the body by means of a stainless steel clamp ring. Design of the seat and seal shall allow replacement without removing the valve from the line. The valve body profile leading to the seal shall be such that any debris located at the bottom of the valve shall be swept away from the sealing area by the high velocity in the final approach to the closing position.

Self-lubricating long lasting sleeve type bearings shall be fitted in the hubs of the valve body and at least one set of thrust bearings will be provided.

Valve shafts shall be continuous or stub shafts and shall be horizontal to the installed valve position.

Internal and external coatings shall be either 250 micron Fusion Bond Epoxy or Copon coating as specified.

Gearbox/ Actuators
Gearboxes and actuators shall be able to operate the valves at the full design pressure of the valves as a differential pressure. The effort on the hand wheel for manually operated valves shall not exceed a total of 400 Newtons. Actuators/gearboxes shall be fitted with mechanical stops to prevent excessive turning and shall be fitted with shear pins. Gearbox design shall allow for conversion to motorized drive at a later stage if required.