Certification and inspection documents

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.

Construction and description

Powder service differs from liquid flow: particles may accumulate, become trapped or cause wear around the disc. Consider particle size, bulk density, moisture and conveying method when assessing seats, shaft dust sealing and operating torque.

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.

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.