Super Duplex Butterfly Valve

Large seawater and chloride-bearing pipelines often need a lightweight isolation valve that fits between existing flanges. A Super Duplex butterfly valve provides compact quarter-turn operation while protecting the body, disc and shaft from localised corrosion. African Valve is a leading Super Duplex Butterfly Valve Manufacturer in Africa, supplying South Africa, Nigeria, Egypt, Angola, other African markets and international projects.

Super Duplex Wetted Materials

Cast bodies and discs may use ASTM A995 Grade 5A, while shafts, pins and wrought components may use ASTM A182 F53 or F55. The body, disc, shaft and retainers should be reviewed as one wetted assembly.
Super Duplex provides high strength and strong resistance to chloride pitting, crevice corrosion and stress-corrosion cracking. Warm seawater, stagnant crevices and fabrication quality still influence performance.

Offset and Seat Selection

Concentric wafer valves commonly use resilient or fluoropolymer seats for moderate-temperature water and chemical service. Double-offset construction reduces seat rubbing during opening. Triple-offset valves use metal sealing geometry for higher temperature, frequent cycling or more demanding shutoff.
The seat and offset arrangement should be selected independently from the body alloy. A Super Duplex body does not automatically make a resilient seat suitable for high temperature, abrasive solids or aggressive chemicals.

Technical Specifications

Size Range: DN50 to DN1200
Pressure Ratings: ASME Class 150 to Class 600
Design Standards: API 609 and ASME B16.34 where applicable
Testing Standard: API 598
End Connections: Wafer, installed between specified flanges
Operation: Lever, gearbox, pneumatic, hydraulic or electric actuator
Body Materials: ASTM A995 Grade 5A or compatible Super Duplex grade
Disc and Shaft Materials: Super Duplex or project-specified compatible alloys
Offset Options: Concentric, double offset or triple offset
Seat Options: EPDM, NBR, PTFE, laminated or metal seat
Actuator Mounting: ISO 5211

Installation and Torque

The adjoining pipe bore must provide enough clearance for the disc at every angle. Separate gaskets should only be used when permitted by the seat design.
Actuator torque depends on size, differential pressure, seat material and temperature. Maximum seating and unseating torque should be used when selecting the operator. The valve is normally installed where both mating flanges remain connected during maintenance. Bolt tightening should be gradual and cross-patterned to avoid uneven seat compression or body distortion.

Compact Valve Supply

African Valve supplies Super Duplex butterfly valves for marine, water and process projects across Africa. The enquiry should include fluid chemistry, chlorides, pressure, temperature, flange standard, offset geometry, seat material, shaft grade, actuator and inspection requirements.