Crush Strength

Crush strength is related to gasket thickness, operating (test) temperature, and the inherent properties of the material itself. In the previous issue, we discussed the impact of gasket thickness, so today we will focus on operating (test) temperature.

2、Operating (or Test) Temperature

Gaskets of different structural materials and types naturally have varying compressive strengths. A more representative example is rubber-bonded non-asbestos fiberboard (a commonly used high-temperature resistant non-metallic gasket): under the working condition of 300℃, the crush strength of a 1.5mm-thick sheet is 45MPa, while that of a 3mm-thick sheet is only 30MPa. This is not only lower than that of fiber-reinforced rubber sheets of the same thickness but also much lower than its own performance at room temperature.

BMC expanded polytetrafluoroethylene (PTFE) sheet gaskets offer excellent flexibility.

For another instance, metal materials have significantly higher crush strength than fiber-reinforced rubber sheets. Similarly, oval gaskets made of 316L have higher crush strength than O-rings.

BMC1304: Resistant to high temperature and high pressure, with radial self-tightening sealing function.

The key reason why high temperature impairs crush strength is the "thermal aging effect": For rubber-based gaskets (such as fiber-reinforced rubber sheets), the thermal motion of rubber molecules accelerates at high temperatures, weakening the intermolecular bonding force and causing a transition from an elastic state to a softened state, resulting in reduced load-bearing capacity. The binders (resin-based) in non-asbestos fiberboards will soften, age, or even carbonize, failing to firmly bond the fibers. Under pressure, the fibers are prone to detachment, leading to the collapse of the gasket structure.

BMCORIN: Offers flexible dimensions and is suitable for high-temperature and high-pressure working conditions.

Therefore, for high-temperature working conditions (such as boilers and heat exchangers), priority should be given to gaskets with good thermal aging resistance to avoid crush failure caused by temperature.

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