Large Diameter Spiral Wound Gasket Behavior, Measured on the Entire Gasket and on Small Gasket Sectors

Gasket manufacturers usually verify the properties of large diameter spiral wound gaskets with a compression test on a very small sector, supposed to behave identically to the global structure. However, full size tests performed at the sealing laboratory of EDF R&D showed high discrepancy between the behavior of a full gasket, and the behavior of a single sector measured by manufacturers. We found out that the preliminary blank tests, consisting in measuring the test rig deformations under compression, are not carried out with the most accurate procedure by the manufacturers, and might yield wrong results. Indeed, the test rig deformations should be measured during a compression test with a rigid metallic ring instead of the gasket, with the same dimensions. Without metallic ring, the test rig deformations can be much underestimated, and consequently the gasket deformations overestimated.