All gasket materials have a temperature range they work over. Going outside of this range is a recipe for leakage, but buying one with a wider range than is necessary can be unnecessarily expensive. Why buy a silicone gasket when a nitrile gasket will do the job? The key lies in understanding the expected in-service temperatures.
Effects on the joint
Temperature, and especially temperature cycling, affects sealing in three ways:
- Expansion/contraction of the joint and fasteners alters clamping loads and gaps.
- High/low temperatures can result in material cracking of extruding out of the joint.
- Cycling demands the material recovers to maintain the seal at all times.
The external thermal environment
Gaskets placed outdoors can experience large temperature swings, but ambient temperature is only part of the story. Piping running above a desert floor will absorb solar energy, getting well above 100F. Likewise, a brisk north wind in a Minnesota winter can produce effective temperatures far below zero.
Extreme temperatures are not uncommon indoors either. Foundries and frozen food distribution centers are both examples of where gaskets could see very high or very low temperatures, (although swings between the two are less likely.)
Media temperature
Knowing the mean temperature of the media being transported or sealed isn’t enough. Abnormal operating conditions could lead to unexpected peaks or dips, as can shut-downs and start-ups. Steam cleaning in particular can lead to higher than normal temperatures.
For enclosures it’s important to estimate the worst-case thermal load. Electrical equipment like drives and transformers produce significant heat and while a cabinet might have ventilation, consider the possibility of a blocked filter or failed fan.
Thermal gradients
Temperature differentials across a sealed joint can also challenge gasket materials, especially when that gradient changes. Piping cryogenically-cooled liquids through the desert, or hot gases in the arctic can make joints move and needs materials that recover quickly without taking a compression set.
Consider the worst-case
When selecting gasket material, know what temperatures to anticipate and choose accordingly. For information on gasket materials, contact a product specialist at Hennig Gasket.
