Flanged type: a flanged valve intended for conventional bolt-up to mating pipe flanges. Such valves can be either single flange type, or equipped with body end flanges.
Welding end (buttweld end) type: a valve body intended for installation by full penetration welding.
Wafer or Flangeless type: a flannels valve body (exclusive of the valve bonnet area) that is centered within the pipe flange bolt circle, leaving the bolts exposed to the atmosphere. A wafer valve is held in position only by the compressive forces from mating pipe flanges.