Cryogenic Top-Entry Ball Valves

A Cryogenic Top-Entry Ball Valve is a quarter-turn isolation valve specifically designed for extremely low-temperature service.
It features a one-piece body with a removable top bonnet that allows full access to the ball, seats, and stem for in-line maintenance without removing the valve from the pipeline.
An extended bonnet and stem keep the packing and actuator away from the cryogenic fluid.
When the ball is rotated 90 degrees to the open position, flow is unrestricted with minimal pressure drop; when closed, the ball seals tightly against the seats to provide reliable bidirectional shut-off for fluids such as LNG, liquid nitrogen, oxygen, argon, and hydrogen at temperatures down to –196°C (–320°F) or lower.

How a Cryogenic Top-Entry Ball Valve Works

The valve contains a floating or trunnion-mounted ball that rotates 90 degrees inside the one-piece body.
Turning the handwheel, gear operator, or actuator rotates the stem, which is connected to the ball.
In the fully open position the ball bore aligns with the pipeline, creating a straight-through flow path with very low pressure drop.
In the closed position the solid ball face seals tightly against spring-loaded or pressure-assisted seats.
An extended bonnet raises the packing box well above the cold zone so the packing does not freeze.
A cavity-relief hole (usually upstream) or self-relieving seats vent pressure that builds when trapped cryogenic liquid warms and expands, protecting the valve body from over-pressurization.
The top-entry design allows the entire internal assembly to be removed vertically through the bonnet for inspection or repair while the valve remains installed in the line.