Automatic seal heads

Force free clamping for best test results

  1. Axial hydraulic clamping of control or shut off valves will have a negative effect – in case of control valves, having their seat area (sealing area) in parallel to the clamping axis, the seat will be deformed temporarily by the hydraulic force. Because of the deformed set the valve will deliver significantly higher leakage test results. When mounted force free between two pipeline flanges or when blind flanged the leak results would be a lot better. A typical consequence is good valves being sent back to re overhaul to meet the leak limit requirements.
  2. Leakage tests to appear better than they are – in case of ball valves, having sealing area vertical to the clamping axis, the clamping forces create an additional sealing force that would not be found under normal operational conditions. The seat is “pressed tight” with results appearing better than the valve actually is. The very negative consequence is a valve handed in as “good” failing in the plant and causing trouble to customers.

Because of these aspects most testing standards for control and shut-off valves demand the valve to be free of external forces until the test pressure is charged.

From the very first days back in 1970 METRUS offers the automatic seal head technology for control and shut-off valve test benches to ensure a force free axial clamping. The fully mechanical automatic seal head utilizes the test fluid’s pressure to create the clamping forces sealing the valves inlet and outlet. Consequently the clamping force rises linearly with the test pressure. A PLC or other control logis is not involved. Once under pressure the remaining external clamping force is so small that the valve seems to be floating. Often it is even possible to tilt the valve around the clamping axis just with manual force.

Automatic seal heads

Available for:

Control and Shut-Off Valve test benches:
– CSV 50/200
– CSV 80/300
– CSV 220/300
– CSV 400/600
– CSV 650/800
– CSV 1450/500
– CSV 2000/500

Safety Valve test benches:
– SV 50/400 E

On request for other models and custom solutions