A wafer ball valve is a compact valve designed to be inserted between two pipeline flanges. It consists of just the valve body and internal components.
The main parts are the body, ball, stem, seat rings, gland follower, packing, and flange inserts. The valve operates by turning the ball via the stem.
Typical uses are for flow control in pipelines for liquids, gases, and steam. Common industries include chemical, food and beverage, oil and gas, pulp and paper, and pharmaceuticals.
Advantages include compact and lightweight design, ease of maintenance, low torque operation, and reduced installation costs by eliminating flange bolting.
Disadvantages include lower pressure ratings than flanged or threaded valves and the need for specific flange sizes to fit between pipelines.
Size is based on matching the flange inserts to the pipeline flanges. The flow coefficient should match the required flow rate. Pressure rating must be sufficient for the application.
Shutoff is achieved through the spherical ball sealing against resilient seat rings. PTFE seats provide tight shutoff for liquids and gases. Metal seats can be used for high temperature steam.
The end connections are flange inserts made to fit between standard pipeline flanges. Common inserts match ANSI, DIN, BS, and specialty flange standards.
Installation is done by fitting the valve between two flanges with gaskets and bolting the flanges. Removal simply requires unbolting the flanges and lifting out the lightweight wafer valve.
Corrosion resistant coatings are applied to valve bodies and balls. Stainless steel materials are also used for balls, stems, and other components.
Key standards include API 6D, API 608, ASME B16.34, EN ISO 17292, and MSS SP-72 for testing and design. Materials standards also apply.
Maximum pressures range from ANSI 150 lb to 2500 lb ratings. Temperature ranges are -4°F to 750°F, but depend on materials and seat type.
