Pipes and tanks
Frost protection of pipes and tanks
Frozen water pipes and -tanks may crack and cause very extensive and costly damage. Remember that a water pipe with ambient temperature below 0°C sooner or later will freeze, no matter how well it is insulated. Drainage pipes can also freeze, with the inconveniences this may cause.
The only way to prevent water from freezing is to add energy in the form of heat. Heating cables installed outside of, or inside, pipes and tanks is a very inexpensive and safe way of doing this. In drainpipes which carry clean water / water from melted ice or snow only, a heating cable can be installed both inside of and on the outside of the pipe. On sewer pipes, the heating cable shall be installed on the outside of the pipe only.
Selection of cable type
For frost protection applications, usually the most affordable solution is to use single conductor cable (also called drum cable). Alternatively, both heating cable elements and self-limiting heating cable can be used. When using single conductor heating cable or heating cable elements, the pipe temperature must not exceed 50°C.
Regardless of choice of cable type, the use of a thermal management system is recommended. Choose a thermostat with external sensor, which will ensure low power consumption and even temperature. In addition, and as an extra precaution, it is often advisable to install a sensor in direct contact with the heating cable, so as to prevent overheating. This requires that the thermal management system has a temperature limiting function.
Calculation of the required power
Calculation of power requirements for pipe heating system is complicated and should be performed by qualified personnel, such as electricians, whether the pipe is above or in the ground, insulated or un-insulated.
In order to calculate the required power and to find the correct heating cable for pipes and tanks, the following data are needed:
• Pipe dimensions, alternatively the tank surface area
• Insulation thickness
• Ambient temperature (buried or in air)
• Desired temperature of the pipe or tank
Uncontrollable or unforeseen conditions suggest that the calculated values should be rounded up to provide a safety margin. A safety factor of 1.2 is not uncommon.
Generally, a pipe installed in air must be insulated. This is also beneficial (if possible) for pipes in the ground. Without insulation, the heat loss in air is very high even for small pipe sizes. For example, an uninsulated 1"pipe will have a power requirement of approximately 45W/m at -30°C.
TXLP heating cable elements
Using heating cable elements makes the installation easier, but the linear power is fixed, which is a limitation in the application of the cable. However, the linear power for the pipe installation can be adjusted by installing multiple loops, or by spiraling the heating cable around the pipe.
TXLP Single conductor heating cable
Provides the most economical installation of frost protections systems for pipes and tanks. Especially when using long lengths, this type of cable is the most economical. At extra long lengths, single conductor heating cable may also be the only option, as heating cable elements are not long enough, and self regulating heating cables cannot be used on account of restraints with respect to power supply (power circuitry) and / or inrush current.
The heating cable will always be installed in “loops” (once or several times) along a pipe, which means the “end" of the cable must come back to the starting point of the installation. This requires a calculation and planning that should be performed by a person having experience with such systems.
A series of self regulating heating cables, very well suited for frost protection of pipes and tanks. It can be cut to length at site, within the length limits set by Nexans, and exact lengths can be customized and installed without complicated calculations. When using self-regulating heating cables, the power supply circuitry must be dimensioned with respect to the inrush current that may occur in such heating cables. Self regulating heating cable systems should be calculated by a person possessing experience with such systems.
A self-regulating heating cable, especially suitable for internal installation in pipes carrying potable water. The material in the cable outer sheath is waterproof and meets the requirements set by the health authorities for this use, i.e. it does not emit harmful substances or add odors or taste to the water. In addition, the cable has a circular cross section, which is optimal with respect to preventing leakages around the nipple. Up to 60 meters of DEROST WATER can be installed inside a water pipe.
A series resistant heating cable for frost protection of pipes longer than 60 meters (up to 295 m). It is intended for installation inside pipes. The outer sheath is made of PE plastic approved for drinking water, and do not emit odors, taste or toxic substances to the water.