Absperrschieber

Product Overview

The Hard Seal Knife Gate Valve is a knife‑edge gate valve with both the seat and gate sealing faces made of metal (hardfaced with Stellite or other hard alloys). It is designed only for ON‑OFF (open/close) service – not for flow regulation. Compared with soft‑seated (rubber, PTFE) knife gate valves, the hard seal version offers high temperature resistance, high wear resistance, erosion resistance, and long service life.

It is particularly suitable for high‑temperature media, slurries containing hard particles, and other severe services requiring metal‑to‑metal sealing. The sharp knife‑edge gate cuts through fibers, particles, and other materials during closure, preventing clogging. The body flow path has no recesses to avoid material buildup. The valve has flanged connections, with nominal diameters from DN50 to DN800, pressure ratings PN10/PN16 (Class 150) – higher ratings available on request – and body materials including carbon steel and stainless steel. Actuators can be manual, electric, or pneumatic.

Produktstruktur

The Hard Seal Knife Gate Valve mainly consists of the dem Antrieb (EIN‑AUS‑Typ) und hard‑seated valve body assembly.

Antrieb (EIN‑AUS‑Typ):

1. Verfügbar in manueller (Handrad), elektrischer oder pneumatischer Ausführung.

2. Elektrischer Antrieb: Motor, Getriebe, Endlagenschalter, Drehmomentschutz, Handrad.

3. Pneumatischer Antrieb: Zylinder, Magnetventil, Endlagenschalter.

4. Alle Antriebe sind vom EIN‑AUS‑Typ – nicht zur Regelung geeignet.

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Hard‑Seated Valve Body Assembly:

1. Gehäuse: Cast or fabricated body in carbon steel (WCB), stainless steel (CF8/CF8M), duplex, etc. Flanged ends conforming to GB/T 9113, ANSI B16.5, EN 1092‑1, etc. Full‑bore flow path with no recesses.

2. Schieber: Stainless steel (304, 316, 310S) knife‑edge gate with a sharp edge. The sealing face (contact area with the seat) is hardfaced with Stellite 6, Stellite 21, or other hard alloy, then ground to provide high hardness and excellent wear resistance.

3. Seat: One‑piece or removable metal seat with a hardfaced (Stellite) sealing surface, lapped with the gate to achieve a metal‑to‑metal seal. Bidirectional sealing construction is optional.

4. Spindel: Edelstahl-Spindel mit Trapezgewinde, die den Schieber auf- und abbewegt.

5. Stopfbuchse: Contains PTFE or flexible graphite packing, compressed by a packing gland to prevent external leakage. High‑temperature graphite packing is optional.

6. Joch: Verbindet das Gehäuse mit dem Antrieb.

7. Optional Bonnet: Available with an enclosed bonnet (for hazardous media) or open‑frame (bonnetless) construction.

The sealing pair of the Hard Seal Knife Gate Valve is metal‑to‑metal, with no soft materials such as rubber or PTFE, providing high temperature and wear resistance.

 Funktion

1. Metal Hard Seal: The seat and gate sealing faces are hardfaced with Stellite or equivalent, offering high hardness (HRC 35–45), wear resistance, and erosion resistance – ideal for highly abrasive media containing hard particles.

2. High Temperature Capability: The metal seal withstands temperatures up to 550°C, making it suitable for high‑temperature slurries, hot ash slag, hot dust, and similar media.

3. Schneidfunktion mit scharfer Kante: Die scharfe Kante des Schiebers durchtrennt beim Schließen hängende Fasern, Papier, Kunststoffstreifen und andere Materialien und verhindert so Verstopfungen.

4. Selbstreinigender Strömungsweg: Der Strömungsweg im Gehäuse weist keine Hinterschneidungen auf. Bei voller Öffnung kann das Medium das Innere spülen und so die Ansammlung von Feststoffen verhindern.

5. Bidirektionale Abdichtung (optional): A bidirectional metal sealing design allows the valve to withstand media pressure from either direction.

6. Vollerdurchgang mit geringem Strömungswiderstand: Bei voller Öffnung befindet sich der Schieber vollständig außerhalb des Strömungswegs, was einen minimalen Druckverlust gewährleistet.

7. Fernbedienung EIN‑AUS: Mit elektrischen oder pneumatischen Antrieben, ist eine ferngesteuerte automatische Öffnungs-/Schließfunktion möglich.

8. Manuelle Notbetätigung: Elektrische/pneumatischen Antrieben pneumatische Antriebe sind mit einem Handrad für den manuellen Betrieb bei Strom- oder Druckluftausfall ausgestattet.

Arbeitsbedingungen

1. Anwendbare Medien: High‑temperature slurry, coal slurry, ash slag, hot dust, tar, slurries containing hard particles, corrosive slurries (stainless steel body required), etc.

2. Temperaturbereich: –29°C to +550°C (depending on hardfacing material).

3. Druckstufe: PN10, PN16 (Class 150); höhere Druckstufen auf Anfrage.

4. Nenndurchmesser: DN50 – DN800 (2″ – 32″); larger sizes available on request.

5. Installation Orientation: Vertical stem‑up recommended.

6. Not Suitable For: Applications requiring zero‑leakage soft sealing (metal seal leakage is higher than soft seal, typically ANSI Class IV–V).

7. Typische Anwendungen:

   1. High‑temperature ash and slag discharge in coal‑fired power plants

   2. High‑temperature slurry transport in metallurgy

   3. Tar and asphalt lines in coking plants

   4. High‑temperature catalyst slurry shut‑off

   5. Fly ash discharge in waste‑to‑energy plants

   6. High‑temperature raw material slurries in glass and ceramic industries

   7. High‑temperature reactor discharge in chemical plants

Zusammenfassung

The Hard Seal Knife Gate Valve, with its advantages of metal‑to‑metal hard sealing, high temperature resistance, high wear resistance, and knife‑edge cutting function, is an ideal shut‑off valve for high‑temperature, highly abrasive, and hard‑particle‑laden media. Compared with soft‑seated knife gate valves, the hard seal version operates continuously at temperatures up to 550°C, resists erosion, and offers a long service life, making it suitable for ash slag, high‑temperature slurry, tar, and other severe services.

However, note that the leakage rate of a metal seal is higher than that of a soft seal; it is not suitable for applications requiring absolute zero leakage. With flanged connections, a full‑bore flow path, and optional manual or automated actuators, the Hard Seal Knife Gate Valve is a reliable and durable solution for automated ON‑OFF pipeline systems handling high‑temperature, hard‑particle‑laden media where zero‑leakage soft sealing is not required.