The gate valve, a valve with switch on-off parts, is perpendicular to the flow of the fluid. Generally being completely on-and-off, it can not used for throttling. The slab gate valve that we are going to talk about today is generally applicable to chemical industry, petroleum, natural gas, environmental protection, city underground pipeline, city gas pipeline and other relevant transmission lines. As for the venting system and the steam storage equipment, it mainly serves as a switch gear.
The features of the slab gate valve :
- 1. The integral sealing structure of the slab gate valve seat shall have an elastic pre-tightening force and be able to seal the upper and lower sealing seats at the same time. The seat is forever face to face with the sealed object.
- 2. The seat is self-cleaning and free from being scoured by the air flow coming from the switch on-and-off. It shall be made of lubricated and abrasion resistant materials.
- 3. The failure of the slab gate valve actuator is isolated from other parts, which enables the repair and replacement to be carried out without taking it apart.
- The Yoke Sleeve: The aluminum bronze toke sleeves are generally equipped with needle thrust bearings so that it can minimize torque during operation.
- The Valve Stem: The screw thread covers the slab gate stem up to the bracket. Its pin is spot welded, which ensures a high stability.
- The Pressure Sealed Seat: The overall design is simple with segmented retaining rings and silver-plated low carbon steel gaskets to facilitate the later disassembly and to achieve an excellent bonnet seal.
- 4. The body of a slab gate valve is usually cast or welded.
- 5. The seat of the slab gate valve is sealed by an O-ring together with the pre-tightening force, which seals both ways in and out of the valve. The stroke in this structure is half that of an ordinary gate valve, therefore it is easy to switch on-and-off.
- 6. For a metal-sealed slab gate valve, outside of the valve body is generally provided with a grease-filling inlet. By the grease injector, the grease gets into the sealing surface through the seat to achieve the zero percent of leakage.
The wedge of the slab gate valve is a rectangular parallel plate with a through-hole of the same diameter as the passage. Once it is fully opened, the passage will be smooth and straight with a relatively low coefficient of flow resistance, which lessen the pressure loss. The wedge is always in contact with the seat in the process of switch on-and-off so that tiny particles clinging on the sealing surface can be wiped away. Moreover, the whole sealing surface is under protect, since it is free form being washed by a variety of media.
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