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.

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.

Welded ends must suit pipe material, wall thickness and the construction procedure. Heat effects, protection of internal seals and post-weld cleanliness are important. Set welding parameters and inspection methods for the actual materials and joint.

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.