To determine the gasket's resistance against blowout, due to pressure or temperature.
The gasket is compressed to a defined gasket stress value.
The gasket is left undisturbed for 5 minutes before it is reloaded up to the defined gasket stress. During this period the gasket is left to creep and relax to the defined rigidity of the test rig.
The gasket is left undisturbed for 30 minutes before the test temperature of 400°C (752°F) is applied with an increasing rate of 1.7 K/min. During this period the gasket is left to creep and relax to the defined rigidity of the test rig.
After the 30 minutes waiting period, the specified helium pressure is applied to the test rig. Because of the increasing pressure, the gasket stress is decreasing. For most PTFE-based materials, this may lead to the sudden blowout of the gasket.
The gasket was compressed with gasket stress of 338 MPa. After the initial gasket stress was applied, the gasket was heated up to 400°C. During heating up to this temperature, the gasket stress decreased to 272 MPa. After that, the gasket was pressurized with 52 bar Helium. During this pressurization, the gasket stress decreases again. With an internal pressure of 52 bar, the gasket stress was 148 MPa.
Within a dwell time of 2 x 15 minutes, no pressure drop could be recognized.
The right end of the above graph is magnified to show more details in the graph below.
Pressure, where gasket blowout occurs, shall be > 1.5 x maximum pressure at maximum design temperature.
The DeltaV-Seal has passed the Hot Blowout Test at a temperature of 400°C with initial gasket stress of 338 MPa and internal pressure of 52 bar.