The heating cable is applied against the pipe inside the insulation.
At this type of application it is very important that the heating cable is applied close to the pipe that is to be frost protected in order to get a good heat transfer.
When the cable is attached to the pipe, a method to get a good heat transfer is to put an aluminium tape above the cable and against the pipe along the cable.
It is recommended to use glass fibre tape when the cable is to be attached to the pipe, as this tape is heat resistant and at the same time it is good to the cable.
If the required power per meter pipe is corresponding or it is somewhat lower than the power per meter heating cable, the cable is applied to the pipe and attached with a glass fibre tape across the pipe with a c/c-distance of 250-350mm.
If the required power per meter pipe is larger than the power per meter heating cable you have to do a so called “spiral application”.
Required power 15 W/m pipe, heating cable 10 W/m.
If 1.5m heating cable is applied on 1m pipe you will get 15 W/m pipe.
The heating cable is applied inside the pipe in direct contact with the medium.
An easy way to frost protect existing and already insulated pipes and at new applications is to apply heating cables inside the pipes.
The advantage with this method is that the cable will get in direct contact with the medium that is to be heated, which gives a fast melting and less working expenses, as more difficult conditions are solved with a lower output.
A heating cable with higher output than 12 W/m should not be applied in direct contact with a plastic pipe as the cables sheath temperature might damage the pipe.
At a higher required power the heating cable can be applied in sand with a distance of some centimetres in order to produce a heat barrier between the cable and the pipe.