Heat Tracing Cable Stripping, Termination, Splicing & Glanding – Video Training Masterclass
Published 02 Sep 2016
- By Chris Dodds : estimated reading time 8 minutes
This Video Masterclass Blog will demonstrate how to strip, terminate, gland, connect and seal heat tracing cables for pipework frost protection or temperature maintenance applications in safe, industrial and hazardous industries.
T&D working in conjunction with Eltherm have produced the following Video post in order to inform and raise the levels of installation quality for heat tracing cables and systems.
Eltherm is a global leader in the manufacture of electrical heat tracing systems.
Video 1 : Power Termination & Cable Glanding of Eltherm Heat Tracing Cables (ELSR-N-BO)
Prior to stripping and preparing heat tracing cables it is essential to carry out a quick tool check and ensure the correct cable stripping and crimping tools are on-hand for the cutting and removal of the heat tracing cable jacket and insulation.
Treatment of cable braid must be carefully addressed by the heat tracing engineer to ensure safe and reliable termination of tinned copper braid before installing the heat trace cable gland (M25).
Caution : Do Not Damage Copper Buswires. The video demonstrates the importance of heat shrinking the insulation sleeves without scorching or overheating the heat tracing cables. The Video covers the cable glanding of heating cables into junction boxes in order to establish a power connection to the heat trace system.
Note – “Cold-installed” cable glands and connection kits are available for heat tracing systems to be installed in hazardous areas with potentially explosive atmospheres where “hot-working” is forbidden.
Video 2 : End Seal Termination of Eltherm Heat Tracing Cables (ELSR-N-BO)
Once heat tracing cables are installed directly to the pipework to provide frost protection or process temperature maintenance it is essential to prevent moisture ingress into the exposed heating cable end and avoid potential short-circuits.
Here, the heat tracing engineer shows the importance of cutting-out a single cable buswire without damaging the insulation of the separated buswires. The heating cables are then simply terminated using a push-on type insulation sleeve.
Video 3 : Splicing (Jointing) Eltherm Heat Tracing Cables (ELSR-N-AO)
This next Video details the procedure for heat trace cable splicing (jointing). Often heat trace systems require cable re-routing or extension as part of piping renewal, re-direction or upgrade projects.
The Video shows the heat tracing cable preparation steps required before installing heat shrink insulation tubes. In order not to introduce potential cable faults into the heat trace system it is essential to correctly joint the cables.
Self Regulating Heat Tracing
How Does It Work?
Self-regulating heat tracing cables use two parallel bus wires which carry electricity but do not create heat. A semi conductive polymer encases the two bus wires.
As the polymer element heats, it allows less current to flow due to a change in resistance. Different power output heat tracing cables are produced by varying the amount of amount of carbon used to manufacture the cable.
An inner jacket separates the bus wires from the earth braid. An outer jacket is usually applied, especially for cables used in harsh industrial environments or where they may be exposed to chemicals.
Self regulating heat tracing cables can be cut to length in the field and will never overheat. All self regulating heating cables have a maximum exposure temperature.
If the cables are exposed to temperatures above this level, they may become damaged beyond repair. Advances in technology mean cables are now available with exposure temperatures approaching 200ºC.
Frost Protection Heat Tracing Systems for Steel & Copper Pipes
Frost protection of steel and copper pipes is one of the most common applications for heat tracing cables. At low ambient temperatures, pipework is likely to freeze, then burst.
Small diameter pipes will freeze in a matter of hours especially at sub-zero temperatures. It is therefore critical to specify the correct power heating cable and also the correct size thermal insulation.
As a rule of thumb, 10 watts per metre trace heating cable is considered adequate for steel and copper pipe sizes <100mm diameter. That said, this is based on a minimum ambient temperature of -10° Celsius. Temperatures as low as -20° Celsius were recorded in some parts of the UK last winter and this needs to be taken into consideration when designing a frost protection heat tracing system.
Heat loss calculations should be carried out to determine the correct heating requirements for any frost protection system.
Frost Protection Heat Tracing For Plastic Pipes
Additional considerations should be made when using trace heating for frost protection of plastic pipes. Unlike metallic pipes, heat transfer is effected due to the thermal properties of plastic.
Further, users should also be aware of possible chemical migration from the tracing cable to plastic pipe and vice versa.
To help solve both problems, a layer of aluminium tape should be installed to the pipe prior to the installation of the heat tracing cable. This forms a barrier between cable and pipe and also helps with heat transfer and dissipation of surface heating from the cable to the pipe.
Calculations should be made to ensure the correct power output cable is selected.
For example, a 10 watts per metre trace heating cable may provide adequate frost protection for a 100mm metallic pipe but not for a 100mm plastic pipe.
Spiralling the heat tracing cable on plastic pipes increase the w/m ratio or alternatively a higher powered cable could be specified. Consideration must also be given to the maximum surface temperature of any heating cable in case it exceeds the maximum withstand temperature of the plastic pipe.
— Met Office (@metoffice) January 15, 2016
How To Install Heat Tracing
Installation of frost protection heat tracing cables to pipes to prevent freezing is a straightforward task provided that thought has been given to the design of the system.
Once the system components have been selected the following procedures can be followed.
1) Identify the pipes that are to be frost protected
2) Locate the most convenient point to locate the frost protection ambient sensing thermostat
3) Attach the frost protection heat tracing cable to the pipe ensuring it is securely fixed (with glass cloth tape or cable ties) to the pipe between the 4pm and 8pm points.
4) Ensure that the cable is installed in a figure of 8 loop over valves and flanges to allow easy access for maintenance.
5) Make sure you leave enough frost protection cable at the pipe branches and termination points (recommend 0.5m) to comfortably connect into the junction box or thermostat.
6) Once the frost protection cable is fixed to the pipe, mount the junction boxes for each branch (if required) and terminate the cables as shown on the instructions. Ensure that each length of frost protection cable is given an insulation resistance test to confirm no damage has occurred during installation.
7) Make the final connection into the frost protection ambient sensing thermostat and, if a power supply is available, test the thermostat using a pipe freeze spray.
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