Double Disc Slab Gate Valves
These are slab gate valves specifically designed for delayed coking, ethylene an FCC cracking service.
The double disc gate valve has two separate stellited discs and two removable stellited seats rings; these discs are moving between two guides plates; when the two discs are in closed position, a flexible wedges system which is located and fixed on the side of the cavity body applies the necessary seating forces on the two discs to obtain the necessary tightness against the seats. This design feature offers the solution to other designs that are known to become jammed due to high temperatures and the “sticking” of the discs. These discs are then “dragged” along the seats without the proper release damaging the seats and making it very problematic to seat again without using excessive amounts of steam.
A superior purging system has also been implemented with additional steam paths around the wedges system to eliminate possible coke build-up. Additional purging ports can be designed as recommended during the design phase for maximum purging efficiency.
When the valve is in open position the flexible bellow located on the pipe is reinforced by 3 outside graphite rings which push the 2 parts of the pipe against the body seats creating a tight seal. This design improvement solves
the common problem with other designs having the body cavity filled with coke blocking the discs in half position.
- Two independent sealing discs for true “Block and Bleed” functionality
- Steam purged for 100% positive shut-off and inability for particles to enter the valve body or atmosphere
- Capable of remote operation for complete personnel safety
- Low maintenance design for uninterrupted operations between turnarounds
- Mechanical spreading mechanism that requires no additional force for long-term sealing capability
- Capable of manual operation for immediate operation
- Standard sizes to 48"
Strahman serves a wide variety of industries and process applications, and we understand there are needs for custom designs to fit in custom applications.