A self-sealing power station gate valve is a type of valve that relies on the pressure of the medium to achieve a seal. Its gate moves in a direction perpendicular to the direction of the fluid. The sealing surface of the gate is pressed against the valve seat by the pressure of the medium to complete the seal, without the need for additional external force to force the seal.
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self-sealing power station gate valve Technical parameters
Material:Carbon Steel (WCB, WCC for strength), Stainless Steel (SS304, SS316 for corrosion resistance), Cast Iron
Size Range:DN50-DN800
Connection Options:Flanged, Threaded (NPT, BSP), Butt Weld, Socket Weld
Working Pressure:Class 150 to Class 2500
Working Temperature:-29°C to 425°C
Sealing Options:Metal-to-Metal, Resilient Seat, Graphite, PTFE
Manufacturing Method:Cast, Forged, Machined
Applicable Medium:Water, Oil, Gas, Steam, Chemical Fluids
Manufacturing Standard:API 600, API 602, ASME B16.34
| Nominal pressure(Lb) | Strength test | Water seal test | Gas seal test | |||
| MPa | Lbf/in2 | MPa | Lbf/in2 | MPa | Lbf/in2 | |
| 150 | 3.1 | 450 | 2.2 | 315 | 0.6 | 60 |
| 300 | 7.8 | 1125 | 5.6 | 815 | 0.6 | 60 |
| 600 | 15.3 | 2225 | 11.2 | 1630 | 0.6 | 60 |
The main part material of self-sealing power station gate valve
| Body, bonnet, gate | WCB | 1Cr18Ni9Ti | CF8(304) | CF3(304L) | 1Cr18Ni12Mo2Ti | CF8M(316) |
| Sealing surface | Cr13 or cemented carbide | Body (W) or cemented carbide (Y) | ||||
| Stem and inner parts | 2Cr13 | 1Cr18Ni9Ti | 0Cr19Ni9(304) | 00Cr19Ni11(304L) | 1Cr18Ni12Mo2Ti | 0Cr17Ni12Mo2(316) |
| filler | Flexible graphite | |||||
| Gasket | Stainless steel spiral wound gasket | |||||
| Suitable media | Water, steam, oil and so on | Nitric acid and other corrosive media | Strong oxidizing media | Acetic acid and other corrosive media | ||
| proper temperature | -29~425℃ | -40~500℃ | ||||
The main shape and connection dimensions of self-sealing power station gate valve
| Nominal diameter | The main dimensions and connection dimensions | |||||||
| L | D | D1 | D2 | b | Z-d | H | D0 | |
| 150LB | ||||||||
| 50 | 178 | 150 | 120.5 | 92 | 16 | 4-Φ19 | 323 | 200 |
| 65 | 190 | 180 | 139.5 | 105 | 18 | 4-Φ19 | 347 | 250 |
| 80 | 203 | 190 | 152.5 | 127 | 19 | 4-Φ19 | 383 | 250 |
| 100 | 229 | 230 | 190.5 | 157 | 24 | 8-Φ19 | 457 | 300 |
| 125 | 254 | 255 | 216 | 185.7 | 24 | 8-Φ22 | 632 | 300 |
| 150 | 267 | 280 | 241.5 | 216 | 26 | 8-Φ22 | 635 | 350 |
| 200 | 292 | 345 | 298.5 | 270 | 29 | 8-Φ22 | 762 | 350 |
| 250 | 330 | 405 | 362 | 324 | 31 | 12-Φ25 | 895 | 400 |
| 300 | 356 | 485 | 432 | 381 | 32 | 12-Φ25 | 1080 | 500 |
| 350 | 381 | 535 | 476 | 413 | 35 | 12-Φ29 | 1295 | 600 |
| 400 | 406 | 595 | 540 | 470 | 37 | 16-Φ29 | 1435 | 600 |
| 300LB | ||||||||
| 50 | 216 | 165 | 127 | 92 | 22 | 8-19 | 330 | 250 |
| 65 | 241 | 190 | 149 | 105 | 25 | 8-22 | 368 | 250 |
| 80 | 283 | 210 | 168.5 | 127 | 29 | 8-22 | 394 | 300 |
| 100 | 305 | 255 | 200 | 157 | 32 | 8-22 | 473 | 300 |
| 125 | 381 | 280 | 235 | 186 | 35 | 8-22 | 660 | 350 |
| 150 | 403 | 320 | 270 | 216 | 37 | 12-22 | 711 | 350 |
| 200 | 419 | 380 | 330 | 270 | 41 | 12-25 | 813 | 400 |
| 250 | 457 | 445 | 387.5 | 324 | 48 | 16-29 | 1003 | 500 |
| 300 | 502 | 520 | 451 | 381 | 51 | 16-32 | 1137 | 600 |
| 350 | 762 | 585 | 514.5 | 413 | 54 | 20-32 | 1489 | 600 |
| 400 | 838 | 650 | 571.5 | 470 | 57 | 20-32 | 1581 | 650 |
self-sealing power station gate valve Working principle
The core mechanism of a self-sealing power station gate valve is a self-reinforcing seal based on media pressure. Its structure includes a valve body, valve cover, gate, valve stem, and self-sealing components (such as flexible graphite rings or metal sealing rings):
Closed process: The medium enters from the high-pressure end, and the pressure pushes the gate towards the low-pressure end, simultaneously compressing the self-sealing ring at the connection between the valve cover and the valve body. The greater the pressure, the more significant the deformation of the sealing ring, filling the tiny gaps and forming a highly reliable seal.
Opened process: The valve stem rotates, causing the gate to rise, automatically releasing the media pressure, and the sealing ring returns to its original shape, reducing opening resistance.
Compared to forced-seal gate valves: Traditional power station gate valves require external force (such as a handwheel or electric device) to press the gate against the valve seat, while self-sealing power station gate valves utilize media pressure to achieve a "zero external force" seal, making them particularly suitable for high-pressure conditions.
self-sealing power station gate valve Structural Advantages
- Self-Sealing Design: The valve cover and body use a tapered fit. The self-sealing ring (such as flexible graphite or low-carbon steel) expands under pressure, filling gaps caused by machining errors and thermal deformation.
- Hard Alloy Sealing Surface: The gate and valve seat sealing surfaces are overlaid with cobalt-based hard alloy with a thickness ≥3mm. This provides wear resistance, erosion resistance, and a service life 3-5 times that of ordinary valves.
- Corrosion-Resistant Valve Stem Treatment: The valve stem surface is nitrided, achieving a hardness of HV800 or higher, doubling corrosion resistance and reducing jamming problems caused by rust.
self-sealing power station gate valve Applications
High-Pressure and Harsh Environments:
Power Industry: Main steam pipelines (pressure ≥10MPa), adaptable to temperature fluctuations, preventing valve cover bolt loosening.
Petrochemical Industry: High-Temperature heavy oil pipelines (above 500℃), preventing media leakage and avoiding fire risks.
Nuclear Power Plants: Primary coolant system (radioactive media), metal sealing rings ensure zero leakage and guarantee safety.
Corrosive Media Pipelines:
Chemical Production: Pipelines for highly corrosive media (such as sulfuric acid, chlor-alkali), hard alloy sealing surfaces resist chemical corrosion.
Dust-Containing Media Pipelines:
Blast Furnace Gas Pipelines: High-pressure (0.8-1.2MPa), dust-containing media, imported self-sealing gate valves are wear-resistant, easy to clean, and reduce downtime frequency.
self-sealing power station gate valve factory
