In metallic expansion joints, the application of insulation helps to diminish heat loss in the piping system. But in case of rubber expansion joints it is a bad idea. These joints consist of variety of rubber types like (oil based) elastomer , EPDM ( ethylene propelyne ,diene ,monomer) , CMS which is combined with polyster in order to afford pressure restraining capability.
If the user install these expansion joints in typical system, then insulation of hot application need to be considered to avoid failures that results from heat contact.
Coverage Of Insulation
The insulation that covers these joints will infuse up the heat from the fluids that is being pumped into it. While these joints are operated in near temperature limit of the constituent material, these joints may start to loose its oil based properties, causing the elastomer to suit brittle and also dry out.
The pressure restrictive materials can begin to shatter down under the heat. This will lead to catastrophic failure.
Hydration Of These Joints
In order to escape the heat, these joints should be permitted to breathe in the atmosphere. During operation, this will make the joint hydrated. In order to preserve the working temperature below the material restrictions and reduce adverse effects of elevated temperatures atmospheric cooling is necessary.
As heat tracing does not benefit to the structure by maintaining piping system at constant or near constant temperature, one needs to wrap the expansion joint by heat tracing that can concentrate the heat in a restricted contact area.
Thermal Conductivity
Thermal conductivity of Elastomer is less than that of metal and they perform as an insulator. When compared with metal pipe and metal expansion joints, the heat loss is minimal through this type of expansion joint. The requirement for additional external insulation to keep the process of thermal energy may not be essential.
Coverings
Some of the users use metal covers which have metal clips attached to the flange bolt of the rubber expansion joint, which separates them from expansion joints which are made of rubber. The cover protects this expansion joints from harsh elements and provide heat to escape from the expansion.
