How Does high temperature insulation supports Work?
Insulated pipe - Wikipedia
Insulated pipes (called also preinsulated pipes or bonded pipe [1]) are widely used for district heating and hot water supply. They consist of a steel pipe called "service pipe", a thermal insulation layer and an outer casing. The insulation bonds the service pipe and the casing together. The main purpose of such pipes is to maintain the temperature of the fluid inside the service pipes. Insulated pipes are commonly used for transport of hot water from district heating plants to district heating networks and for distribution of hot water inside district heating networks.
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Thermal insulation material usually used is polyurethane foam or similar, with a thermal conductivity λ50 of about 0.024&#;0.033 W/(m·K). While polyurethane has outstanding mechanical and thermal properties, the high toxicity of the [diisocyanates] required for its manufacturing has caused a restriction on their use.[2] This has triggered research on alternative insulating foam fitting the application,[3] which include polyethylene terephthalate (PET) [4] and polybutylene (PB-1).[5] The outer casing is usually made of high-density polyethylene (HDPE). Preinsulated pipes for district heating are described in European standards EN 253 and EN -1. EN 253 describes "District heating pipes - Bonded single pipe systems for directly buried hot water networks - Factory made pipe assembly of steel service pipe, polyurethane thermal insulation and a casing of polyethylene". EN -1 describes "District heating pipes - Bonded twin pipe systems for directly buried hot water networks - Factory made twin pipe assembly of steel service pipes, polyurethane thermal insulation and one casing of polyethylene". Both standards don't give "short names" or abbreviations for described pipes.
According to EN 253: & EN -1:, pipes must be produced to work at constant temperature of 120 °C (248 °F) for 30 years. Thermal conductivity λ50 in unaged condition shall not exceed 0.029 W/(m·K). Both standards describe three insulation thickness levels. Both standards require use of polyurethane foam for thermal insulation and HDPE for casing.
Insulated pipelines are usually assembled from pipes of 6 metres (20 ft), 12 metres (39 ft), or 16 metres (52 ft) in length, directly buried in soil in depths of commonly 0.6&#;1.2 metres (2 ft 0 in &#; 3 ft 11 in).
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An overview of insulated pipes supports - Walraven International
What are insulated pipe supports?
Insulated pipe supports sit in between the pipe itself and the pipe clamp or clips, to maintain thermal performance. One of the main types of insulated pipe supports, phenolic foam blocks, work to prevent thermal conduction which can result in heat loss and an increase in energy usage.
Why do you need them?
Insulated pipe supports isolate the pipework from the pipe clamp to limit heat transfer and thermal bridging. It also allows for a continuous vapour barrier to be carried through the support system.
What are the main types of insulated pipe supports?
There are three main types of insulated pipe supports:
Wood &#; this is the most traditional method of insulating pipe supports.
Phenolic &#; this has become the preferred method of insulating pipe supports.
Calcium silicate &#; this is mainly used in extremely high temperatures.
Wood pipe insulation supports overview:
Wood blocks were the preferred material for insulating supports for a long time. In recent years, however, the use of wooden pipe support inserts has dwindled. This is likely due to the updated British Standard for insulated pipe supports, BS: which now gives the view that &#;wooden pipe supports should not be used&#;.
Wood blocks do not offer a reasonable thermal bridge between the outer works and the pipe. There is an increased risk of condensation forming on wooden blocks and they are ineffective at maintaining vapour barriers.
Phenolic foam pipe insulation overview:
Phenolic foam pipe insulation blocks are a very effective alternative to woodblocks and have rapidly become the number one preferred insulated pipe support material.
Independent thermal analysis has shown that the use of phenolic insulated pipe support inserts can reduce heat loss through the supports of +75°C LTHW systems by up to 10x when compared to woodblock inserts. This is in addition to the benefits of phenolic in maintaining the vapour barrier and limiting heat gain on systems operating below ambient temperature.
Phenolic insulation is also much more cost-effective than wood, calcium silicate or foam glass alternatives due to a higher insulation value.
The image below demonstrates the rate of heat loss on (from left to right) phenolic pipe support, a rubber-lined clip fixed to pipe, a metal clip fixed to pipe, woodblock pipe support.
Calcium silicate pipe insulation overview:
Typically, calcium silicate insulation is used where pipe temperatures exceed 250°F. Therefore, the usual places you&#;ll find this type of insulation include chemical plants, refineries, and steam electric power plants.
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Are there any regulations for insulated pipe supports?
As previously mentioned, there is a British Standard &#; BS &#; which was updated in . This is a code of practice relating to the thermal insulation of pipework, ductwork, associated equipment and other industrial installations. The update included a few significant changes.
One change being that the code of practice no longer permits the use of wooden block pipe supports due to them providing an ineffective vapour barrier and having poorer thermal properties than the alternatives.
In addition, the standard recommends that the pipe support bracket being fixed over the load-bearing insulation is of the same material (or compatible with) the insulation on the pipe.
The benefits of Walraven&#;s insulated pipe supports
Walraven&#;s phenolic foam pipe insulation supports (Phenblox) are CE marked in accordance with EN: + A1:. They are tested and guaranteed compatible with our main unlined clamp ranges (see Walraven Phenblox brochure for compatibility and selection table).
Our blocks are made from high-density phenolic foam with the best available thermal insulation properties. They are CFC and HCFC-free and classified as Zero ODP (ozone depletion products). To guarantee the technical properties of our phenolic, each batch is also tested in accordance with ISO :.
In addition to this, Walraven Phenblox&#; have a special bore coating, which eradicates any possibility of pipe corrosion on copper pipes. They are also manufactured with stepped joint faces to ensure vapour seal and accurate placement.
Our Technical Team has created load tables showing the maximum allowed load for Walraven Phenolic and clip combinations.
&#;We would recommend the use of phenolic foam over the alternatives as it has the best insulation value.&#;
Installing the complete pipe support system
As well as manufacturing phenolic insulation blocks, we also manufacture all of the individual components that, when used together, create the complete pipe support system. This includes parts such as:
Pipe clamps
Fixing rails
Rail/strut accessories
Anchors
Fasteners
Expansion devices
Lightweight fixings
Although Walraven Phenblox&#; can be used in conjunction with other components, there are some advantages to using the complete Walraven system, a couple being:
We have 100% quality control over all of our products since they are all manufactured within our own factories.
Specifying pipe support systems can be complex, as such, our team of Technical Support Advisers provide a FREE project support service to our customers including consultation and problem-solving.
View our phenolic products
Want more information on high temperature insulation supports? Feel free to contact us.