Alloy 20 Wafer Butterfly Valve Manufacturer  in Africa

Equipment skids and large chemical lines often leave little room for a heavy double-flanged isolation valve. An Alloy 20 wafer butterfly valve fits directly between two flanges and uses a rotating disc to control or stop corrosive flow. Its compact body reduces installation weight, while Alloy 20 resists many sulphuric acid and chloride-containing media. African Valve is a prominent Alloy 20 Wafer Butterfly Valve Manufacturer  in Africa, serving Nigeria, Egypt, South Africa, Kenya and Ghana and supplying the Middle East, Europe and other international markets.

How Is the Wafer Body Retained?

The body is positioned between the mating pipe flanges. Long bolts or studs pass around the valve and draw the flanges together. The valve does not contain its own full flange ends.

This construction reduces face-to-face length, but it also makes alignment important. The flanges must be parallel, and the pipeline must be supported independently. A wafer valve should never be used to correct pipe misalignment.

The flange bore and gasket must also provide disc clearance. A gasket projecting into the bore can interfere with the disc and damage the seat.

Disc Position and Flow Behaviour

When the shaft rotates, the disc turns through approximately 90 degrees. In the open position, the disc remains inside the flow stream. This causes more obstruction than a full-bore ball valve, although the butterfly valve is much lighter in larger sizes.

The valve can be used for isolation and limited flow adjustment. It should not be assumed to provide precise control unless the disc geometry, actuator and operating range have been selected for that duty.

Which Offset Design Is Suitable?

A concentric valve has the shaft centred through the disc and seat. It normally uses a resilient or PTFE seat and is suited to moderate pressure-temperature service.

Double-offset construction separates the shaft from both the disc centre and pipe centreline. The disc lifts away from the seat earlier during opening, reducing friction.

Triple-offset valves use an additional angular offset and a conical metal-sealing arrangement. They are selected for elevated temperature, higher pressure or services requiring reduced seat rubbing.

Alloy 20 and Seat Compatibility

ASTM A351 CN7M is commonly used for cast bodies and discs. ASTM A182 F20 may be used for forged shafts or other machined components.

PTFE and reinforced PTFE are common in clean chemical duty. Elastomer seats may be used only after checking compatibility with the fluid concentration and temperature. Metal seating is considered where soft materials would erode, soften or burn.

Technical Specifications

Size Range: DN40 to DN1200
Pressure Ratings: Class 150 to Class 300; PN10 to PN40
Design Standards: API 609 and ASME B16.34
Testing Standard: API 598
End Connections: Wafer type for ASME B16.5 or EN flanges
Operation: Lever, gearbox, electric, pneumatic or hydraulic actuator

Product Benefits

• The wafer body reduces installation length.

• Low valve weight limits pipe support loads.

• Quarter-turn operation provides rapid response.

• Alloy 20 supports aggressive chemical service.

• Offset designs reduce seat rubbing and operating torque.

• ISO 5211 mounting permits standard actuator installation.

Applications

The valve is used in sulphuric acid lines, fertilizer plants, pickling systems, chemical utilities and corrosive water treatment. It is particularly suitable for medium and large pipes where space and total installed weight are important.

Final Inspection

Disc alignment, shaft runout, seat compression and body dimensions are checked before testing. Shell and seat leakage tests verify pressure containment. Actuation torque is measured through repeated cycles. PMI, MTCs and NDT reports can be supplied according to the project inspection plan.