Knife Gate Valve Fully Lined with Polyurethane

2" - 24" (DN50 - DN600)

Class 150 - 300 (up to 20 bar / 300 psi)

MSS SP-81, manufacturer-specific (no PU-lined valve API standard exists)

Carbon steel (A216 WCB) body with full internal polyurethane lining

Full-body polyurethane liner (shore hardness 80A-95A), gate coated with PU or hard chrome

Wafer or flanged body, PU liner covers all wetted surfaces—body cavity, seat area, gate channel, bonnet bore. No metal-to-media contact inside the valve.

The Wear Champion For Media That Eats Metal

Mining operations, mineral processing plants, tailings transport pipelines—these aren't gentle on valves. The slurry carries rock fragments, silica, mineral concentrate, and whatever else the process grinds into suspension. That media flows through the valve at 2-3 m/s and abrades every surface it touches.

Standard rubber seats last maybe three to six months on a hard-rock tailings line. Metal seats? Sometimes less, because the slurry doesn't just wear the seat—it scores the gate, erodes the body cavity edges, and turns the bonnet bore into a ragged channel. Polyurethane lining changes the economics entirely. PU's abrasion resistance is 5-10x better than hard rubber. That's not a lab number on a datasheet—it's what you see in actual service on concentrator lines running 18 hours a day.

Full-Body Liner Means Zero Metal Contact

This isn't a seat-pocket liner or a partial coating. The polyurethane liner covers every wetted surface inside the valve: the body cavity, the seat area, the gate channel where the blade travels, and the bonnet bore above the gate. When slurry enters the valve, it touches polyurethane—not carbon steel, not cast iron, not stainless.

That matters for two reasons. First, abrasion resistance is uniform throughout the flow path. There are no exposed metal edges where erosion accelerates because the liner stops short. Second, the liner acts as a chemical barrier. Many mine slurries carry residual process chemicals—flocculants, lime, acid traces—that corrode bare metal over time. PU isolates the body structure from that chemical exposure entirely.

Replace The Liner, Not The Valve

When the liner wears through after two or three years of continuous service, you don't throw away the valve body. You replace the liner. The carbon steel shell is still structurally sound—it hasn't been in contact with the media, so there's no erosion, no corrosion, no fatigue from chemical attack. Liner replacement takes the valve offline for a shift, maybe a day. Replacing the entire valve body would take longer and cost five to ten times more.

This is the economic argument that wins procurement decisions on mine sites. Total cost of ownership over a ten-year service life favors the PU-lined valve by a wide margin, even though the initial purchase price is higher than a bare metal knife gate.

Shore Hardness Selection Depends On Your Slurry

Shore 80A is softer—it flexes more, absorbs impact energy from larger rock particles, and provides better sealing on low-pressure lines. Shore 95A is harder—it resists fine-particle abrasion better and maintains seat geometry under higher pressure. Most mining applications land somewhere in the 85A-90A range. Talk to the manufacturer about your specific slurry composition, particle size distribution, and flow velocity. The right hardness choice extends liner life significantly.

A: No. This product category falls under manufacturer-specific design standards. The body rating follows ASME B16.34 for pressure-temperature limits, but the liner design and performance criteria are established by individual manufacturers.

A: Polyurethane resists most mining process chemicals including mild acid traces, lime, and flocculant residues. For strong acid service (pH below 3 sustained), verify chemical compatibility with the specific PU compound—some formulations degrade under prolonged acid exposure.

A: Standard PU liners operate up to about 80°C continuously. Above that, the material softens and loses abrasion resistance. High-temperature PU formulations reach 100-120°C, but they're harder to source and cost more.

A: Rubber lining works on less abrasive slurries. But on hard-rock and mineral concentrate lines, rubber wears through in months where PU lasts years. The 5-10x abrasion resistance advantage is real on these services.

A: Minimal impact. The liner adds slight friction to gate travel, but the difference is negligible on pneumatically actuated valves. Handwheel-operated valves may feel slightly heavier to stroke on larger sizes.