VIZA Valves is one of the China’s leading manufacturers of industrial valves, recognized as a preferred supplier in quality and innovation. Suzhou Viza Valve Co., Ltd is the major subsidiary company and as the headquarter of VIZA group which has been manufacturing trouble-free service valves for more than 10 years. Today, VIZA’s gate, globe, check, ball, butterfly and engineered severe service valves are installed throughout the world, handling diverse applications in oil & gas, petrochemicals, refining, power plants, LNG, pipeline transmission, marine, mining and water industries.

The products have the following design features:

• NACE MR-01-75 Compliance

All materials can be supplied to NACE MR-01-75 compliance. Compliance is ensured during the manufacturing process by strict inspection and material control.

• Anti-static Device

Spring plus graphite type antistatic device is applied between the ball, stem, glad flange, and body, to keep the electrical continuity between all the metallic components and ensure the resistance lower than the most severe service requirement.

• Blow-out Proof Stem

The stem is made separately from the ball with Integral T-type round shoulder; retained by gland, (other designs are available upon request).

•  Single Piston Effect Seats - Cavity Pressure Relief Seat

Standard seat design is primary soft seal, and secondary metal to metal seat. Seat insert is designed as pressed in type which is easy for maintenance. Medium pressure acting in the body cavity creates a resultant thrust to push the seat rings away from the ball. The single piston design permits the automatic release of any over pressure in the body cavity when the valve is in the full open and fully closed position.

• Fire safe design to API607 / API6FA
  
  
• Double Block and Bleed

When the ball is in the closed position, each seat seals off the process medium independently at the same time between the up/down stream and body cavity; it allows bleeding of the trapped cavity pressure (DBB) through drain or vent valve. The double block and bleed function makes it possible to flush the valve under pressure ad verify that the seats are sealing properly.

• ISO 5211 Top Mounting Connection
  
  
• Lockable Design
  
  
• Ball Seat Alignment

Mechanical stops are equipped on all valves to ensure the ball is never to be over rotated.

• AED O-ring

When valves are used under high pressure gas applications, e.g. hydrocarbon gas service under class 600 and above, the gas may be absorbed into the molecular structure of elastomeric O-rings. If the valve is subjected to sudden decompression, the O-rings may be destroyed by the rapidly expanded gas. To avoid this possibility, special AED O-rings, or Lip seals, suitable for such service conditions are available on request.

• Environmental-Friendly Valve

Accurate machining of stem, gland and body sealing surfaces with double sealing (O-ring primary seal plus graphite gasket seal) ensure the low emission which is complying with the most severe pollution-control regulations. The test certifications are available on request.

Optional Features :

• Stainless Steel Overlay on Seat Pocket Area
  
  
• Double Piston Effect Seats

Medium pressure, both upstream and downstream as well as in the body cavity, creates a resultant thrust that pushes the seat rings against the ball. Valves with double piston effect rings require a cavity pressure relief device to reduce the build-up of over pressure in the body cavity.

• Combination Seats

Combination seats design is available on request. That us a standard seat design used for upstream side and double piston effect seats design used for downstream. The advantage is it can reach double piston effect seats design function without cavity pressure relief device to save the cost, meanwhile it only needs a little care to install valve per flow direction arrow.

• Emergency Sealant Injection System

Each valve of size 6" and larger, is equipped with sealant injection located at stem and seats area. The injection is integrated with check valve to provide backup sealing, also a check valve is equipped at front of seat sealant injection to avoid blowing out in case wrong operation. When the soft sealing materials (seat inserts and O-rings) are damaged and leakage happened by fire or other accidents, the sealant can be injected through the injection fittings.

• Vent Valve (Standard for 6” and Larger)
  
  
• Lifting Lugs & Supporting Feet (Standard for 8” and Larger)