Super Duplex Knife Gate Valve Manufacturer in Africa 

Slurry, sludge and solids-bearing chloride service can damage ordinary valve bodies through both abrasion and localised corrosion. A Super Duplex knife gate valve combines a narrow moving gate with corrosion-resistant wetted parts for marine, mining and wastewater duties. African Valve is a prominent Super Duplex Knife Gate Valve Manufacturer in Africa, supplying South Africa, Nigeria, Egypt, Angola, other African countries and export projects.

Knife Gate Working Principle

A thin gate moves vertically through the body and seat area. Its lower edge can pass through or displace fibres, soft deposits and settled slurry that may prevent a conventional wedge gate from closing. It should not be described as cutting through large stones or hard mineral fragments.
The valve is intended mainly for full opening or isolation. Holding the gate partly open can expose the edge, seat and body to concentrated velocity and accelerated wear.

Super Duplex Construction

The body may be cast in ASTM A995 Grade 5A, while the gate, stem and other wrought parts may use ASTM A182 F53 or F55. The selected materials should cover all wetted parts, including scrapers, retainers and exposed fasteners.
Super Duplex provides high strength and strong resistance to chloride pitting, crevice corrosion and stress-corrosion cracking. In abrasive slurry, corrosion resistance alone is not enough. Gate hardness, seat design, velocity, particle size and replaceable wear parts also influence service life.

Seat, Packing and Direction

Resilient seats may provide tighter shutoff in fine slurry or sludge when the elastomer is chemically compatible. Metal seating suits higher temperature and abrasive particles but may allow more leakage. Unidirectional designs have a preferred pressure direction, while bidirectional designs can seal from either side within their documented differential-pressure rating.
Solids carried upward by the gate can collect around the packing gland. Scrapers, flushing ports, purge connections and adjustable packing may be included where build-up is expected.