Gate Valve - Extended Bolted Bonnet for Cryogenic Service | Fluitek

Fluitek Extended Bolted Bonnet Gate Valve for Cryogenic Service

The Fluitek Extended Bolted Bonnet for Cryogenic Service is a gate valve designed for flow isolation at low temperatures, below -50 °C. It is suitable for cryogenic liquids and gases, such as liquid nitrogen, oxygen, and air separation media. The valve is used for on/off applications, not throttling.

Construction

• Standard: ANSI
• Connection: butt weld
• Nominal Pressure Rating: Class 600
• Configuration: unidirectional, soft seated, 600#
• Materials: Austenitic steels CF8/CF3, CF8M/CF3M
• Seats: Metal or soft inserts, typically PTFE based

Extended Bonnet

The extended bolted bonnet removes the packing and handwheel from the cold zone. This is critical in LNG, LIN, LOX, and cold box installations, where icing around the stem can affect operational torque and sealing. The valve can be delivered with a mounting plate for installation in a cold box.

Trapped Fluid Control

Documentation mentions equalizing systems to prevent fluid entrapment in body and bonnet extension cavities. In cryogenic fluids, this is a key selection point, as trapped liquid can increase pressure during warming.

Dimensions Class 600

Indicative sizes: 3"–12", bore 76–300 mm, face-to-face 283–502 mm, height from valve center to top 1138–2040 mm, weight 62–565 kg. These factors affect piping support, available space, and handling access.

Oxygen Service

For oxygen applications in air liquefaction plants, special cleaning and purity control are required. Documentation specifies a dedicated process and the ability for quantitative purity verification.

FAQ

When is it selected?
For cryogenic lines Class 600 where extended bonnet and butt weld connection are required.

Why not a standard gate valve?
The packing must remain outside the cold zone.

What should be checked before ordering?
Fluid, temperature, oxygen cleaning, seat type, equalizing system, and cold box requirement.