Knife gate valve

Product Overview

The Lug Type Knife Gate Valve is a shut‑off valve with a lug‑type body and a knife‑edge gate. It is designed only for ON‑OFF (open/close) service – not for flow regulation. Unlike flanged knife gate valves, the lug‑type body features threaded lugs around the periphery. Bolts are screwed directly into these lugs to connect with pipeline flanges, requiring no nuts. This design allows the valve to be installed at the end of a pipeline or used as an isolation valve, and facilitates removal from one side for maintenance.

The valve is suitable for media containing particles or fibers, such as sewage, pulp, slurry, and mud. The sharp knife‑edge gate cuts through hanging materials during closure, preventing clogging, while the body flow path has no recesses for self‑cleaning. Available in nominal diameters from DN50 to DN600, pressure ratings PN10/PN16 (Class 150), with body materials including cast iron, carbon steel, and stainless steel. Actuators can be manual, electric, or pneumatic.

Product Structure

The Lug Type Knife Gate Valve mainly consists of the actuator (ON‑OFF type) and the lug‑type valve body assembly.

Actuator (ON‑OFF Type):

1. Available in manual (handwheel), electric, or pneumatic.

2. Electric actuator: motor, gearbox, travel limit switches, torque protection, handwheel.

3. Pneumatic actuator: cylinder, solenoid valve, limit switches.

4. All actuators are ON‑OFF type – not for modulation.

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Lug‑Type Valve Body Assembly:

1. Body: Cast or fabricated body in gray cast iron, ductile iron, carbon steel (WCB), stainless steel (CF8/CF8M), etc. Threaded lugs (Lug type) are provided around the body for bolting directly to pipeline flanges without nuts. Connection dimensions conform to ANSI B16.5, EN 1092‑1, etc. Full‑bore flow path with no recesses.

2. Gate: Stainless steel (304, 316, 310S) knife‑edge gate with a sharp edge to cut through fibers and particles. The gate surface can be hardfaced with Stellite or chrome‑plated.

3. Seats: Available in rubber (EPDM, NBR, FKM), PTFE, or metal sealing; bidirectional sealing optional.

4. Stem: Stainless steel trapezoidal‑thread stem, moving the gate up and down.

5. Packing Box: Contains PTFE or flexible graphite packing, compressed by a packing gland to prevent external leakage.

6. Yoke: Connects the body to the actuator.

The lug‑type connection allows the valve to be installed at the end of a pipeline (as a blind or drain valve) or removed by unbolting from one side, simplifying maintenance.

Function

1. Lug‑Type Connection: The body has threaded lugs; bolts screw directly into the lugs without nuts. The valve can be installed at pipeline ends or used as an isolation valve, allowing easy removal from one side.

2. Knife‑Edge Cutting Function: The sharp edge of the gate cuts through hanging fibers, paper, plastic strips, and other materials during closure, preventing clogging.

3. Self‑Cleaning Flow Path: The body flow path has no recesses. When fully open, the media can flush the interior, preventing solids accumulation.

4. Bidirectional Sealing (optional): A bidirectional floating seat or double‑sided sealing design allows the valve to withstand media pressure from either direction.

5. Full‑Bore Low Flow Resistance: When fully open, the gate is completely out of the flow path, providing minimal pressure loss.

6. Remote ON‑OFF Control: With electric or pneumatic actuators, remote automatic open/close operation is possible.

7. Manual Emergency Operation: Electric/pneumatic actuators are equipped with a handwheel for manual operation during power or air supply failure.

8. End‑of‑Line Installation: The lug‑type valve can be installed directly at the end of a pipeline as a blow‑off or drain valve.

Working Conditions

1. Applicable Media: Sewage, sludge, pulp, slurry, mud, fiber suspensions, particle‑laden liquids, etc.

2. Temperature Range: –20°C to +200°C (PTFE seats); –20°C to +80°C (rubber seats); –29°C to +550°C (metal seats).

3. Pressure Rating: PN10, PN16 (Class 150); higher ratings available on request.

4. Nominal Diameter: DN50 – DN600 (2″ – 24″); larger sizes available on request.

5. Installation: Lug‑type connection – bolts screw directly into body lugs. Can be installed in‑line or at pipeline ends.

6. Typical Applications:

   1. End‑of‑line blow‑off in wastewater treatment plant sludge lines

   2. Isolation and discharge in paper mill pulp lines

   3. End‑of‑line drain in mine tailings pipelines

   4. Chemical slurry lines requiring removal from one side for maintenance

   5. End‑of‑line valves for fruit pulp and sauce lines in the food industry

   6. Branch line isolation in industrial recirculating water systems

Summary

The Lug Type Knife Gate Valve, with its advantages of lug‑type connection, knife‑edge cutting function, self‑cleaning flow path, and easy one‑side removal, is a flexible and reliable shut‑off valve for pipelines handling sewage, pulp, slurry, and similar media. Compared with flanged knife gate valves, the lug‑type can be installed at pipeline ends or removed by unbolting from one side, simplifying maintenance.

Compared with wafer‑type valves, the lug type withstands higher pipe stresses and is suitable for end‑of‑line service. With lug connections, a full‑bore flow path, and optional manual or automated actuators, the Lug Type Knife Gate Valve is an economical and practical solution for automated ON‑OFF pipeline systems that require end‑of‑line installation, frequent maintenance access, or space‑limited layouts.