5 Jan 2018
Often times, electrical conduit systems are subject to extreme temperatures.
From oil & gas drilling in the Arctic to high-temperature underground steam tunnels, Calbond® specializes in manufacturing PVC Coated products for use in the harshest environments.
Due to the physics of thermal expansion, the metal will expand as the ambient temperature cycles. The amount and rate of expansion depend on the temperature and the type of metal. This is important to consider when installing long runs of the conduit in environments with extreme/fluctuating temperatures. When dealing with PVC Coated conduit, one may question whether the coating will expand with the conduit. The short answer is yes, the coating does expand (and contract) with the base metal.
The expansion rate of PVC is greater than the base metal, so technically, it is trying to expand more than the metal when there is a temperature swing. PVC, however, has more elasticity than the base metal, so it conforms to the metal within reasonable tolerances.
Damage to your installation caused by expansion or contraction indicates that expansion fittings are needed to compensate for the movement. These fittings allow relief for the tension of the conduit system caused by expansion or contraction. In regards to the PVC coating, it is not mechanically connected from one length of conduit to the next, as is the base metal via threaded couplings. By virtue of the slip-fit design of each PVC joint, every coupling becomes an expansion fitting for the PVC coating.