Wafer Hard-Seated Butterfly Valve

Service conditions

A butterfly valve changes the available flow area as its disc rotates about the stem. Its compact rotary arrangement is widely used for pipeline isolation. Flow-control duty also requires assessment of disc position, differential pressure, flow response and actuator control capability.

Hard-seated butterfly valve behavior depends on contact geometry, material pairing and surface condition. Temperature cycling makes thermal expansion, differential pressure and operating torque important. Select offset geometry, preferred flow direction and leakage class for the actual arrangement.

Construction and description

Match the operator to the valve load and site operating method. Manual operation needs accessible clearance. Frequent cycling or remote control also calls for assessment of output capability, duty and position feedback.

Wafer installation places the valve between mating flanges. Check flange standard, pipe bore, bolt arrangement and clearance for moving internal parts. Additional gasket requirements depend on the seat and connection design.

Define fluid composition and continuous and start-stop operating conditions, then assess body, internals and seals as a combination. Particles, deposits and cleaning affect sealing surfaces and mechanisms; plan maintenance for the actual service.

Service conditions

Triple-offset construction combines offsets of the stem relative to the sealing plane and flow axis with an angled conical sealing surface. This geometry reduces sealing-surface contact through much of the stroke and develops sealing load near closure. Required torque, preferred flow direction and reverse-pressure capability depend on the actual seal construction. Metal and nonmetallic layers in a laminated seal require separate compatibility and temperature review.