Knife gate valves, built in Longview, Washington.
Cast and fabricated knife gates from 2 in to 120 in, rated up to 600 psi, for water, wastewater, hydropower, mining and industrial service. Engineers get spec help, contractors get bid-ready submittals, owners get valves that can be rebuilt instead of replaced.
Start where your project starts.
Most knife gates get chosen three times: once in the spec, once at bid, and once by the people who run them for decades. We built this site for all three.
Consulting engineers
- Starter spec language you can edit
- Selection help for slurry, sludge and high pressure
- Drawings and data for your design package
Contractors
- Bid pricing for hard bid, CMAR and design-build
- Submittals and domestic content letters
- Ship dates you can put in a schedule
Owners and operators
- Replaceable seats, liners and packing
- Reconditioning and parts
- Retrofits where a valve keeps failing
Which knife gate fits your line?
Answer four questions and get a starting point from the Fabricast line. Then send us the details and an engineer will confirm it.
The knife gate line
Every model is designed and tested to MSS SP-81 with ASME B16.5 drilling. All of them take pneumatic, hydraulic, electric or gear operators without welding. See full specs
| Model | Seat | Shutoff | Body | Rating (CWP) |
|---|---|---|---|---|
| FIG 40 | Metal | Uni-directional | Cast CF8 (304) stainless | 150 psi |
| FIG 50 | Resilient, perimeter | Bi-directional | Cast CF8 (304) stainless | 150 psi |
| FIG 61 | Dual replaceable polymer | Bi-directional, drip-tight | Cast CF8M (316) stainless | 150 psi |
| FIG 145 | Replaceable polymer liners | Bi-directional, drip-tight | Fabricated A36 steel, 2 to 48 in | 150 psi |
| FIG 240 | Metal, bolted bonnet | Uni-directional | Cast 304 or 316 to 36 in, fabricated 42 in and up | 150 psi |
| FIG 345 | Replaceable polymer liners | Bi-directional, drip-tight | Fabricated A36 steel, 2 to 48 in | 300 psi |
| DBB | Dual gates, polymer lined | Double block and bleed | Fabricated A36 steel, to 48 in | 150 psi |
Federally funded project? Start with the paperwork.
AIS, BABA and Buy American are three different rules. We explain which one your job is under and send a signed, project-specific letter with the submittal.
American Iron and Steel
State Revolving Fund water and wastewater projects. Fabricast AIS compliant configurations listed by model.
Build America, Buy America
Infrastructure projects with federal financial assistance since May 2022. Fabricast BABA compliance by model and configuration.
Buy American
Direct federal contracts, such as some federal dams and facilities. Fabricast Buy American compliance by model.
Where Fabricast gates work
Municipal water
Raw water, intakes, filter and process isolation.
Wastewater
Sludge, scum, digesters, grit and pump station isolation.
Hydropower
Large bore and high pressure isolation for penstocks and bypasses.
Mining and oil sands
Tailings and abrasive slurry with replaceable liners. CRN registration for Canada.
Big gates are normal here.
Fabricated knife gates to 120 in, built and tested in the same shop. See project photos
Have a drawing, a spec or a failing valve?
Send it to us. You will hear back from someone who builds knife gates, not a call center.
Knife gate valves
Seven knife gate designs, cast in stainless from 2 in and fabricated to 120 in. Metal, resilient and polymer seats. Uni-directional, bi-directional and double block and bleed. Ratings from 150 psi to 600 psi.
A full port, metal seated knife gate for one-way isolation. The heavy cast body and machined gate shear through solids and seat cleanly. Add a backing ring for reverse flow or horizontal mounting, or an elastomer O-ring seat for tighter shutoff.
- Body, gland, yoke
- Cast CF8 (304) stainless
- Gate
- ASTM A240 304, machined, beveled, surface ground
- Sizes
- Cast through 24 in, fabricated above 24 in
- Rating
- 150 psi CWP (10.3 bar)
- Optional O-ring seats
- Buna-N, EPDM, UHMWPE, FKM
- Standards
- MSS SP-81, ASME B16.5
A rubber seated knife gate with a perimeter seal, so it shuts off in either flow direction. A strong fit for water, wastewater and pump station isolation where flow can reverse.
- Body
- Cast CF8 (304) stainless
- Seat
- Buna-N standard, to 180 °F
- Seat options
- EPDM 300 °F, FKM 400 °F, PTFE 500 °F
- Sizes
- Cast through 24 in, fabricated above 24 in
- Rating
- 150 psi CWP (10.3 bar)
- Standards
- MSS SP-81, ASME B16.5
Two replaceable polymer seals give drip-tight shutoff both ways. The 316 stainless body suits corrosive and chemical service. Seals replace without replacing the valve.
- Body and gland
- Cast CF8M (316) stainless
- Seals
- Dual replaceable, PTFE standard
- Sizes
- Confirm size range
- Rating
- 150 psi CWP (10.3 bar)
- Standards
- MSS SP-81, ASME B16.5
Three replaceable polymer liners and a T-shaped seat insert that locks into them keep the media off the body. Built for abrasive slurry, tailings and sludge, where the wear parts should wear and the body should not.
- Body, gland, yoke
- Fabricated ASTM A36 carbon steel
- Gate
- ASTM A240 304, machined, surface ground
- Liners
- UHMWPE standard, to 180 °F
- Liner options
- Polyurethane, polypropylene, high temp UHMWPE, PTFE
- Sizes
- 2 to 48 in (DN50 to DN1200)
- Rating
- 150 psi CWP (10.3 bar)
A bonneted knife gate that contains the packing and keeps media off the stem. Choose metal-to-metal, metal with O-ring, or dual polymer seats.
- Body
- Cast CF8 (304) or CF8M (316)
- Sizes
- Cast 2 to 36 in, fabricated 42 in and up
- Seat options
- Metal, metal with O-ring, dual polymer
- Shutoff
- Uni-directional, backing ring for reverse flow
- Rating
- 150 psi CWP (10.3 bar)
- Standards
- MSS SP-81, ASME B16.5
The FIG 145 design built for higher pressure. Use it for slurry pipelines, pumped tailings and any lined service above 150 psi. Higher ratings are available on request.
- Body
- Fabricated ASTM A36 carbon steel
- Liners
- UHMWPE standard, T-shaped seat insert
- Sizes
- 2 to 48 in (DN50 to DN1200)
- Rating
- 300 psi CWP (20.7 bar), higher on request
- Standards
- MSS SP-81, ASME B16.5
Two polymer lined gates in one body with a drain and plug between them. It works as a double block and bleed valve and as a line blind, for maintenance isolation where people work downstream. Offered in FIG 145-UHMW, 40-MM and 50-PS configurations.
- Body
- Fabricated ASTM A36 carbon steel
- Seats
- Dual T-shaped inserts locked to polymer liners
- Sizes
- Up to 48 in
- Rating
- 150 psi CWP, higher available
- Standards
- MSS SP-61, ASME B16.5
When the line is too big, too hot, too abrasive or too high pressure for a catalog valve, we fabricate one. Past builds include a 72 in metal seated gate for an industrial facility in Texas and an all-titanium 8 in metal seated gate.
- Sizes
- To 120 in (DN3000)
- Rating
- To 600 psi (41.4 bar)
- Alloys
- 304, 316, 317L, duplex 2205 and 2507, 904L, Hastelloy, titanium
Options that come up on real jobs
Available across the line. Operators mount without welding, so you can change actuation later.
Operation
- Handwheel, with ball bearing yoke bushing on 14 in and larger
- 3:1 and 4:1 bevel gear, chainwheel, lever
- Pneumatic, spring return and hydraulic cylinders
- Electric motor actuators
- Stem extensions
Controls and safety
- Limit and proximity switches
- Solenoid valves, positioners, air sets
- Air tank fail-safe systems
- Mechanical lockouts
- OSHA gate guards
Wear and flow
- V-port inserts for throttling
- Deflector cones and hardsurfacing
- Purge and flushing ports
- Live-loaded packing, PTFE, graphite, Kevlar, food grade
- Specialty gate and exterior coatings
More from the Longview shop
Fabricast also builds the valves that usually sit next to a knife gate.
Slide gate valves
FIG 202 and FIG 215 slide gate valves. Add one line on typical service.
Check valves
Swing checks (FIG 7/27, FV 150-SC) and the FIG 6 tilting disc check in fabricated 304 or 316.
Wedge gate and sampling
FV 150-WG cast CF8M wedge gates, 1/2 in to 12 in. FIG SAM-15/20 sampling valves.
Need drawings or a submittal?
Tell us the model, size and operator. We send dimensional drawings, materials, actuator sizing and test data.
Spec support for consulting engineers
You own the design. We help you get the knife gates right: model selection, materials, actuator sizing, drawings for your package, and spec language that is fair to bidders.
What we do for your design team
No charge, and no obligation to name us sole source.
Selection reviews
Send the valve schedule. We flag gates that will struggle: abrasive slurry on a metal seat, reversing flow on a uni-directional gate, or pressure above a catalog rating.
Drawings and data
Dimensional drawings, weights, materials of construction and actuator data for your plans and models. List CAD formats available: DWG, STEP, Revit.
Actuator sizing
Tell us the differential pressure and media. We size the cylinder, motor or gear so the controls engineer has real numbers.
Domestic content up front
We tell you during design which configurations meet AIS, BABA or Buy American, so the spec and the funding agree. Domestic content guide
Large and special builds
Gates over 48 in, above 300 psi, or in alloys like duplex, 904L, Hastelloy or titanium. We work through the details with you before bid.
Lunch and learn
A one hour session on knife gate selection for slurry, sludge and large bore service. Confirm PDH credit availability.
Starter spec language
Pick a model and options, then copy the text into your spec section and edit it. It names Fabricast or approved equal, so bidders keep competition. The engineer of record verifies every requirement.
How a design assist works
From first question to issued for bid.
Send the schedule
Valve list, P&IDs or a few lines in an email. Size, media, pressure and operator are enough to start.
We review it
A Fabricast engineer marks up selections, materials and actuators and calls out risks.
You get the package
Drawings, data sheets, actuator data and domestic content status for each tag.
Bid day support
We answer contractor questions and quote the same price to every bidder.
Ask an engineer
Include the project name, line size, media, pressure and what is driving the question. We reply within one business day.
Knife gates for contractors
Bid it, submit it, schedule it, install it. You get pricing that matches the spec, submittals that get approved the first time, domestic content letters that hold up at closeout, and ship dates you can plan around.
However the job is delivered
Hard bid
Priced to the spec as written, with exceptions called out in writing before bid day so nothing surprises you at submittal.
Progressive design-build
We join early with the design-builder, price at each design stage, and lock selections before the GMP so the number holds.
CMAR and design-assist
Budget pricing at 30, 60 and 90 percent design, value engineering options with the trade-offs spelled out, and long-lead release when you need it.
Emergency and replacement
A valve failed and the plant is waiting. Send the tag, size and what it mates to. Describe stock and expedite options.
From quote to startup
What you get at each step.
Quote
Line-item pricing by tag, matched to the spec section, with domestic content status and lead time on every line.
Submittal
Drawings, materials, actuator data, test procedures and a signed domestic content letter, organized to the spec. Typical turnaround.
Build and ship
Shop tested before it leaves Longview. Ship dates confirmed in writing and updated if anything moves.
Install and start up
Installation and operation manuals with the shipment. Field service and startup availability.
Things that sink a knife gate submittal
- Wrong flange drilling for the mating pipe or pump
- Uni-directional gate where the flow can reverse
- Actuator sized for normal flow, not shutoff differential
- Domestic content letter that covers the wrong rule
- Bonnet required by spec but not quoted
We check every one of these before we send the submittal.
Lead times
Insert typical lead times by group: cast stainless 2 to 24 in, fabricated 26 to 48 in, fabricated over 48 in, actuated.
Ask about release-for-fabrication on long lead items so your schedule is not waiting on final approval of everything else.
Bidding a job with knife gates?
Send the spec section and the bid date. We confirm what we can supply and send pricing before bid day.
For owners and operators
A knife gate should be a part you maintain, not a part you throw away. Fabricast gates use replaceable seats, liners and packing, and our shop reconditions valves so they go back in service.
Wear parts that come out
Polymer liners, seat inserts, O-rings and polymer seals are replaceable on the models that use them. Packing options include live-loaded sets for less adjustment.
Reconditioning
Send valves back to Longview for teardown, inspection, repair and retest. Confirm whether you recondition other manufacturers' knife gates.
Retrofits for problem valves
If a gate keeps packing out, galling or leaking, we look at why and propose a seat, liner, alloy or operator change that fixes the cause.
Safety on the line
Mechanical lockouts, OSHA gate guards and double block and bleed gates for crews working downstream.
Automation later
Operators mount without welding, so a handwheel gate can take a cylinder or electric actuator when the plant adds controls.
Warranty
Summarize warranty terms from the current warranty page.
When you call about a valve, have these ready
It cuts the back and forth to one call.
- Nameplate photo, or model and serial number
- Line size and flange drilling
- Media, temperature and pressure
- Operator type and control voltage
- What is failing and how often
- Photos of the gate, seat and packing area
AIS, BABA and Buy American, explained for knife gates
Three rules with similar names and different tests. The funding source decides which one applies to your project. Here is how each one treats a valve, and what Fabricast puts in writing.
American Iron and Steel (AIS)
- Where it applies
- Water and wastewater projects funded through the Clean Water and Drinking Water State Revolving Funds.
- What it covers
- Iron and steel products. EPA lists valves among them.
- Fabricast
- Models and configurations that comply, and how castings and plate are sourced.
Build America, Buy America (BABA)
- Where it applies
- Infrastructure projects with federal financial assistance awarded on or after May 14, 2022, including SRF projects.
- What it covers
- Iron and steel, manufactured products and construction materials. EPA guidance says a valve that is predominantly iron or steel is treated as iron and steel, so every step from melting to coating must happen in the United States. Other valves are manufactured products.
- Fabricast
- Models and configurations that comply, by category.
Buy American Act
- Where it applies
- Direct federal purchases and federal construction contracts, such as work let by a federal agency.
- What it covers
- Domestic end products and construction materials, under the clauses written into that contract.
- Fabricast
- Models and configurations that comply.
Summary based on EPA's Build America, Buy America overview (October 2022). Requirements, waivers and agency guidance change. Your contract documents and funding agency govern. This page is general information, not legal advice.
What we send with the submittal
- A signed letter naming the project, the rule it is written to, and the valves it covers
- The basis for compliance: where the valve is manufactured and, for iron and steel, where it was melted and poured or rolled
- Mill test reports and certificates of origin on request
Before you bid, check three things
- The funding source named in the bid documents, and the domestic content clause it brings with it
- Whether the spec asks for a specific certification form
- Whether any project waiver has been granted, and what it covers
Send us the clause and we will tell you which Fabricast configurations meet it, in writing, before bid day.
Need a compliance letter?
Give us the project name, owner, funding source and valve tags.
Knife gates by industry
The same design question shows up everywhere: what is in the pipe, which way can it flow, and how hard does it push. Here is how that plays out in the industries we serve across the United States and Canada.
Raw water intakes, filter isolation, backwash and residuals handling. Resilient seated gates such as the FIG 50 seal in both directions where flow reverses. Many of these jobs are State Revolving Fund projects, so domestic content is settled in design.
Describe Fabricast hydropower work: large bore isolation, bypass and drain lines, pressure ranges, and any federal (Buy American) projects completed.
Hydrotransport and tailings lines in Alberta combine abrasion, pressure and cold. Metric sizing and Canadian registration matter as much as the valve. Confirm CRN registration numbers and provinces, and any oil sands installations to reference.
Pulp and paper, power, chemical and heavy industry. Alloy options from 316 to duplex, 904L, Hastelloy and titanium. Past builds include a 72 in metal seated gate for an industrial facility in Texas. Confirm TAPPI TIS 405 use and pulp and paper references.
Projects
Fabricast gates in the shop, in the yard and in service. Every photo lists the gate, size, application and where it went.
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Have a project like one of these?
Send the size, service and pressure. We will tell you how we would build it.
Knife gate valve questions, answered
Straight answers on selection, standards, sizing and compliance. Do not see yours? Ask us.
What is a knife gate valve?
A knife gate valve closes by driving a thin, sharp-edged gate straight down across the bore. The edge cuts through solids, fibers and rags that would jam other valves, which is why knife gates are used on sludge, slurry, pulp and bulk solids lines. They are isolation valves: fully open or fully closed.
What is the difference between a uni-directional and a bi-directional knife gate?
A uni-directional knife gate seals against pressure from one side, usually with a metal seat. A bi-directional knife gate seals no matter which way the pressure comes from, usually with a resilient perimeter seal or polymer seats. If flow or pressure can ever reverse, specify bi-directional. The Fabricast FIG 50, FIG 61, FIG 145 and FIG 345 are bi-directional.
Which knife gate seat is best for abrasive slurry?
For abrasive slurry and tailings, a polymer lined knife gate with replaceable liners usually outlasts a metal or rubber seated valve, because the liners take the wear and can be replaced without replacing the body. The Fabricast FIG 145 (150 psi) and FIG 345 (300 psi) use replaceable UHMWPE liners, with deflector cones and hardsurfacing available for severe service.
What does MSS SP-81 cover?
MSS SP-81 is the Manufacturers Standardization Society standard for stainless steel, bonnetless, flanged knife gate valves. It covers design, materials, dimensions and testing. Fabricast knife gates are designed and tested to MSS SP-81, with flanges drilled to ASME B16.5.
When should I specify a bonneted knife gate?
Choose a bonneted knife gate when the packing must be contained: enclosed or occupied spaces, odor control areas, hazardous media, or buried and submerged installations. The Fabricast FIG 240 is a bolted bonnet knife gate in cast stainless to 36 in and fabricated from 42 in.
Can a knife gate valve be used for throttling?
Standard knife gates are on/off isolation valves. For limited flow control, a V-port insert shapes the opening so the gate can be positioned partly open. Talk to us about the flow range before using any knife gate to throttle.
What sizes and pressure ratings does Fabricast make?
Fabricast builds knife gates from 2 in to 120 in (DN50 to DN3000) with ratings up to 600 psi (41 bar). Catalog models are rated 150 psi or 300 psi cold working pressure; larger and higher pressure gates are engineered to order.
Are Fabricast knife gates AIS and BABA compliant?
State which Fabricast models and configurations comply with American Iron and Steel, Build America Buy America, and the Buy American Act. Fabricast provides a signed, project-specific compliance letter with the submittal.
Where are Fabricast knife gates made?
Fabricast Valve designs and builds knife gates at its plant in Longview, Washington. Confirm where castings and plate are sourced.
Can I add an actuator to a manual knife gate later?
Yes. Fabricast operators mount without welding, so a handwheel gate can be converted to a pneumatic, hydraulic or electric actuator later. Give us the model, size and differential pressure and we will size the operator.
What is a double block and bleed knife gate?
A double block and bleed knife gate has two gates in one body with a drain between them. With both gates closed and the bleed open, any leakage past the first gate drains away instead of reaching the downstream side, giving positive isolation for maintenance. The Fabricast DBB also works as a line blind.
What information do you need for a quote?
Line size, media, maximum pressure and differential pressure, temperature, flange drilling, operator type and control voltage, quantity, and any domestic content requirement. For bid work, send the spec section and bid date.
Do you supply knife gates in Canada?
Yes, including mining and oil sands projects. Confirm CRN registration status and provinces.
How do I stop a knife gate from leaking at the packing?
Packing leaks usually come from wrong packing material for the media, a worn or scored gate, or packing that needs adjustment. Options include live-loaded packing, a different packing material, flushing ports, or a bonneted design. Send us the details and photos and we will recommend a fix.
Talk to Fabricast
Call the factory, email sales, or find the rep who covers your area.
Factory
- Phone
- (360) 425-0306
- Toll free
- (877) 264-2503
- sales@fabricastvalve.com
- Address
- 1061 Industrial Way
Longview, WA 98632 - Hours
- Monday to Friday, 5 am to 4 pm Pacific