12″-150LB-Wafer Knife Gate Valve
Description
12″-150LB Wafer Knife Gate Valve – Technical Data Sheet
1. General Description
Product Name: Wafer Type Knife Gate Valve
Model: 12″-150LB
Nominal Diameter: 12 inches (NPS 12, DN 300)
Pressure Class: Class 150 (ANSI 150LB)
Connection Type: Wafer type
Product Introduction:
The knife gate valve is a shut‑off valve specifically designed for slurries, granular materials and fibrous media. Its key closure member is a gate with a sharp knife edge. When fully open, the gate is completely lifted above the valve body, allowing the medium to pass straight through with a smooth, unobstructed flow path, minimizing sediment accumulation. During closing, the sharp lower edge of the gate easily cuts through solid particles and fibrous debris in the flow channel, ensuring a tight shut‑off. The 12″-150LB wafer knife gate valve is suitable for low to medium pressure applications and is widely used in mining, metallurgy, papermaking, chemical industry, power generation, wastewater treatment and food processing.
2. Design Standards
| Item | Standard |
|---|---|
| Design & Manufacture | MSS SP‑81, JB/T 8691 |
| Face‑to‑Face (Structure Length) | MSS SP‑81, TAPPI TIS 405.8, GB/T 15188.2 |
| Flange Connection Dimensions | ANSI B16.5 Class 150 |
| Inspection & Testing | MSS SP‑81, API 598, GB/T 13927 |
| Pressure‑Temperature Rating | ASME B16.34 |
MSS SP‑81 applies to bonnetless, metal‑seated knife gate valves from NPS 2 to NPS 36 and specifies pressure limits and material requirements. For sizes 2″ to 24″, the maximum working pressure is 150 psi.
3. Main Technical Parameters
| Parameter | Value |
|---|---|
| Nominal Pipe Size (NPS) | 12″ (DN 300) |
| Pressure Class | Class 150 (150 LB) |
| Maximum Working Pressure | 150 psi (10.3 bar) |
| Face‑to‑Face Dimension L | 8″ (approx. 203 mm)* |
| Flange Standard | ASME B16.5 Class 150 |
| Flange Facing | RF (Raised Face) / FF (Flat Face) |
| Connection Type | Wafer type |
| Actuation | Handwheel (manual) / Pneumatic / Electric / Electro‑hydraulic |
| Temperature Range | -29°C to +425°C (depending on seat material) |
| Suitable Media | Pulp, sewage, coal slurry, ash, gypsum slurry, powder, etc. |
| Valve Type | Bonnetless, rising stem |
*Note: Face‑to‑face dimensions may vary slightly. For 12″ size, typical dimension is 8″ (203 mm). Full open height approx. 45″ (1143 mm), handwheel diameter approx. 18″ (457 mm).
4. Dimensional Data (Reference for 12″ Class 150 Wafer Knife Gate Valve)
| NPS | Face‑to‑Face L (mm) | Flange OD D (mm) | Bolt Circle D1 (mm) | No. of Bolt Holes | Bolt Hole Dia. (mm) |
|---|---|---|---|---|---|
| 12″ | approx. 203 | approx. 505 | approx. 470 | 12 | approx. 25 |
Note: Flange dimensions strictly conform to ASME B16.5 Class 150.
5. Main Component Materials
| Component | Available Materials |
|---|---|
| Body | Carbon steel WCB, CF8 (304 SS), CF8M (316 SS), Ductile iron, Duplex stainless steel |
| Gate | 304 SS, 316 SS, 2205 Duplex SS, 17‑4 PH SS |
| Stem | 304 SS, 316 SS, 17‑4 PH SS |
| Seat | EPDM (-50°C ~ +150°C), NBR (-40°C ~ +100°C), PTFE, Polyurethane (PU), Metal hard‑seat |
| Packing Gland | 304 SS, 316 SS, Ductile iron |
| Packing | PTFE, Graphite, Lubricated packing |
| Fasteners | Stainless steel A4‑70 / A2‑70 |
Material Notes:
-
Body material: MSS SP‑81 requires ASTM A216 WCB cast steel for corrosion resistance and pressure integrity.
-
Seat material: Resilient seats (EPDM, NBR, polyurethane) are suitable for slurry media and provide bubble‑tight shut‑off; metal seats are for high temperature or dry media with better wear resistance.
-
Gate material: Stainless steel gate is polished on both sides to prevent clogging and protect the seat.
6. Structural Features & Advantages
| No. | Feature | Description |
|---|---|---|
| 1 | Wafer design | Compact, lightweight, space‑saving – the valve body has no integral flanges and is clamped between pipeline flanges. |
| 2 | Bonnetless design | The gate lifts completely above the body, preventing media accumulation and clogging. |
| 3 | Sharp knife edge | The gate bottom has a blade that cuts through solids and fibers during closing, ensuring reliable shut‑off. |
| 4 | U‑cup seal | Newly developed U‑cup seal design provides excellent sealing performance. |
| 5 | Replaceable seat | Resilient seats can be easily replaced on‑site, reducing maintenance cost. |
| 6 | Bidirectional sealing | Optional bidirectional sealing design meets different pressure requirements. |
| 7 | Body guide | Guides in the body ensure accurate and stable gate movement. |
| 8 | Self‑adjusting packing | Self‑adjusting packing gland provides effective stem sealing while also cleaning the gate. |
7. Performance Data
| Test | Test Pressure | Acceptance Criteria |
|---|---|---|
| Shell (Strength) Test | 1.5 × rated pressure (225 psi) | No visible leakage per MSS SP‑81 / API 598 |
| High‑Pressure Seat Test | 1.1 × rated pressure (165 psi) | No visible leakage per MSS SP‑81 / API 598 |
| Low‑Pressure Seat Test | As per standard | API 598 |
| Stem Seal Test | As per standard | No visible leakage |
Leakage Class:
-
Resilient seats (EPDM/NBR/PU): Bubble‑tight shut‑off (zero leakage)
-
Metal hard seat: ANSI/FCI 70‑2 Class III or Class IV
MSS SP‑81 requires a hydrostatic test at 1.5 times the rated working pressure to verify pressure‑containing integrity and sealing performance.
8. Applications & Industries
| Industry | Typical Media | Remarks |
|---|---|---|
| Mining / Metallurgy | Ore slurry, tailings, coal slurry, ash | Knife edge cuts solid particles; wear‑resistant |
| Paper & Pulp | Pulp, white water, black liquor | Gate easily cuts fibrous pulp without wrapping |
| Wastewater Treatment | Raw sewage, sludge, sand | Handles fibrous and solid‑laden wastewater |
| Power Generation | Fly ash, bottom ash, limestone slurry (FGD systems) | Wear‑resistant, suitable for FGD slurry |
| Chemical Industry | Corrosive slurries, powders | Option of stainless steel, duplex or special alloys |
| Food Industry | Food slurries, syrups | Hygienic design, easy to clean |
9. Actuation Options
| Actuation | Description | Typical Application |
|---|---|---|
| Manual (Handwheel) | Rising stem handwheel, low torque, easy operation | General service, no automation |
| Manual (Chainwheel) | Chain operation for high or hard‑to‑reach locations | Overhead installations |
| Pneumatic Actuator | Double‑acting or spring‑return, fast stroke | Automated lines, explosion‑proof areas |
| Electric Actuator | Remote control capability | Centralized control, intelligent systems |
| Electro‑hydraulic Actuator | Smooth operation, low impact | High‑pressure service, precise positioning |
10. Installation & Maintenance Instructions
-
Installation direction: For uni‑directional valves, follow the flow arrow on the body. Bi‑directional valves have no orientation restriction.
-
Flange alignment: Ensure the pipe flanges are precisely aligned to avoid uneven loading and leakage.
-
Bolting: Use long bolts passing through the valve body and both pipe flanges. Tighten diagonally and evenly.
-
Packing maintenance: If packing leaks, tighten the packing gland bolts. Replace packing if worn out.
-
Seat maintenance: Clean the sealing area or replace the seat if damaged or contaminated.
-
Not for throttling: Knife gate valves are designed for fully open or fully closed service only – not for flow regulation.
-
Regular lubrication: Lubricate the actuation mechanism and stem periodically to ensure smooth operation.
11. Quality Assurance & Inspection
| Inspection Item | Details |
|---|---|
| Shell (Strength) Test | 100% at 1.5× rated pressure, no visible leakage |
| Seat Leakage Test | 100% at 1.1× rated pressure, leakage meets standard requirements |
| Material Verification | Material certificate provided (EN 10204 3.1 or 3.2) |
| Visual Inspection | 100% – no defects, uniform coating |
| Dimensional Check | 100% inspection per drawing |
| Functional Test | Smooth opening/closing, no sticking or binding |
All tests are performed in accordance with MSS SP‑81 and API 598.
