Our Parallel Slide Gate Valve design offers many advantages over double disc wedge gate valves in providing tight reliable shut-off in water and steam service.
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The seating principle of the Parallel Slide Gate Valve makes it far superior to the double-disc wedge gate valve; with a more forgiving seating method that compensates for minor seat variations and uses internal forces to provide reliable tight sealing.
1. Does not require torque force to shut off
• Our Parallel Slide Gate Valve uses position seating allowing the line force in the system to assist in the sealing of the valve seat by holding the downstream disc firmly against the downstream seat.
Vs
- A double-disc wedge gate valve relies upon torque force to wedge the disc into the valve body to provide shut off. This requires the valve seat in a double disc wedge gate to actually deform to provide seating. Over a short period of time, this can lead to permanent deformation of the seat allowing a leak path to occur.
2. Less Torque requirement
• Position seating also requires less torque to open and close than torque seating. This allows for use of a smaller actuator to operate our valve, thereby reducing operational cost.
3. Wider seating surface
• The wide flat seating surface of our valve offers an advantage in sealing surface area. Our valve has a seating surface width of up to two inches. This prevents minor scratches or seat deformation from becoming a leak path.
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- A double-disc wedge gate valve relies upon a line contact seating surface, it has a very thin seating surface area. A line contact seat increases the probability that a minor seat inconsistency will become a leak path.
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4. Reduction in seat wear
The greater seating surface of our valve provides for the distribution of bearing stresses over a large area thus reducing seat wear caused by the everyday operation.
5. No reseating of disc
Due to its wide flat seats and position seated design, a parallel slide gate does not require reseating of the disc after a valve closed hot cools down.
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A double-disc wedge gate, due to its torque seated design, may require that you reseat it after cooling due to contraction which may loosen a previously adequate seal.
6. Protection against thermally locking a valve in the closed position
• Thermally locking a valve in the closed position can occur when a hot valve in the closed position begins to cool. This will then require increased torque to break the disc away from its seat.
• The two independent discs of the Parallel Slide Gate Valve, along with the position seated design, allows for compensation for varying rates of thermal contraction, thereby preventing thermal binding from occurring.
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- Double disc wedge gate’s seating principle calls for wedging the disc into the body it cannot compensate for varying rates of contraction and the valve then can become jammed closed, requiring more torque than available to open the valve.
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