Pipe insulation
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{{Short description|Thermal or acoustic insulation used on pipework}} |
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[[Image:Hallway insulation.jpg|thumb|right|300px|Pipe insulation and building insulation shown together during construction and once finished in an apartment building in [[Ontario]], [[Canada]].]] |
[[Image:Hallway insulation.jpg|thumb|right|300px|Pipe insulation and building insulation shown together during construction and once finished in an apartment building in [[Ontario]], [[Canada]].]] |
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'''Pipe Insulation''' is [[thermal insulation|thermal]] or [[acoustic insulation|acoustic]] insulation used on pipework. |
'''Pipe Insulation''' is [[thermal insulation|thermal]] or [[acoustic insulation|acoustic]] insulation used on pipework. |
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===Condensation control=== |
===Condensation control=== |
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Where pipes operate at below-ambient temperatures, the potential exists for |
Where pipes operate at below-ambient temperatures, the potential exists for water vapour to [[condensation|condense]] on the pipe surface. Moisture is known to contribute towards many different types of [[corrosion]], so preventing the formation of condensation on pipework is usually considered important. |
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Pipe insulation can prevent condensation forming, as the surface temperature of the insulation will vary from the surface temperature of the pipe. Condensation will not occur, provided that (a) the insulation surface is above the dewpoint temperature of the air; and (b) the insulation incorporates some form of water-vapour barrier or retarder that prevents water vapour from passing through the insulation to form on the pipe surface. |
Pipe insulation can prevent condensation forming, as the surface temperature of the insulation will vary from the surface temperature of the pipe. Condensation will not occur, provided that (a) the insulation surface is above the dewpoint temperature of the air; and (b) the insulation incorporates some form of water-vapour barrier or retarder that prevents water vapour from passing through the insulation to form on the pipe surface. |
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===Pipe freezing=== |
===Pipe freezing=== |
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Since some water pipes are located either outside or in unheated areas where the |
Since some water pipes are located either outside or in unheated areas where the ambient temperature may occasionally drop below the freezing point of water, any water in the pipework may potentially freeze. When water freezes it [[Properties of water|expands]] and this expansion can cause failure of a pipe system in any one of a number of ways. |
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Pipe insulation cannot prevent the freezing of standing water in pipework, but it can increase the time required for freezing to occur—thereby reducing the risk of the water in the pipes freezing. For this reason, it is recommended to insulate pipework at risk of freezing, and local water-supply regulations may require pipe insulation be applied to pipework to reduce the risk of pipe freezing."UK Water bylaw pipe insulation requirements", UK Copper Board, {{cite web |url=http://copperplumbing.org.uk/sites/default/files/content_attachments/insulation-and-bylaw-requirements.pdf |title=Archived copy |accessdate=2015-06-28 |url-status=dead |archiveurl=https://web.archive.org/web/20150630230642/http://copperplumbing.org.uk/sites/default/files/content_attachments/insulation-and-bylaw-requirements.pdf |archivedate=2015-06-30 }}{{cite web|url=https://clevelandplumbguy.com/tips-to-keep-pipes-from-freezing/|title=Tips to Keep Pipes from Freezing|date=9 August 2022 }} |
Pipe insulation cannot prevent the freezing of standing water in pipework, but it can increase the time required for freezing to occur—thereby reducing the risk of the water in the pipes freezing. For this reason, it is recommended to insulate pipework at risk of freezing, and local water-supply regulations may require pipe insulation be applied to pipework to reduce the risk of pipe freezing."UK Water bylaw pipe insulation requirements", UK Copper Board, {{cite web |url=http://copperplumbing.org.uk/sites/default/files/content_attachments/insulation-and-bylaw-requirements.pdf |title=Archived copy |accessdate=2015-06-28 |url-status=dead |archiveurl=https://web.archive.org/web/20150630230642/http://copperplumbing.org.uk/sites/default/files/content_attachments/insulation-and-bylaw-requirements.pdf |archivedate=2015-06-30 }}{{cite web|url=https://clevelandplumbguy.com/tips-to-keep-pipes-from-freezing/|title=Tips to Keep Pipes from Freezing|date=9 August 2022 }} |
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===Mineral wool=== |
===Mineral wool=== |
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[[Mineral wool]]s, including rock and slag wools, are inorganic strands of mineral |
[[Mineral wool]]s, including rock and slag wools, are inorganic strands of mineral fibre bonded together using organic binders. Mineral wools are capable of operating at high temperatures and exhibit good fire performance ratings when tested."Rock wool technical description", Rockwool, http://guide.rockwool.co.uk/products/industrial-(rti)/pipe-section-mat.aspx {{Webarchive|url=https://web.archive.org/web/20120722034409/http://guide.rockwool.co.uk/products/industrial-(rti)/pipe-section-mat.aspx |date=2012-07-22 }} |
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Mineral wools are used on all types of pipework, particularly industrial pipework operating at higher temperatures."Industrial Rockwool insulation", Rockwool, http://guide.rockwool.co.uk/products/industrial-(rti)/process-pipe.aspx {{Webarchive|url=https://web.archive.org/web/20120618162209/http://guide.rockwool.co.uk/products/industrial-(rti)/process-pipe.aspx |date=2012-06-18 }} |
Mineral wools are used on all types of pipework, particularly industrial pipework operating at higher temperatures."Industrial Rockwool insulation", Rockwool, http://guide.rockwool.co.uk/products/industrial-(rti)/process-pipe.aspx {{Webarchive|url=https://web.archive.org/web/20120618162209/http://guide.rockwool.co.uk/products/industrial-(rti)/process-pipe.aspx |date=2012-06-18 }} |
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These are flexible, closed-cell, rubber foams based on [[Nitrile rubber|NBR]] or [[EPDM rubber]]. Flexible [[elastomeric foam]]s exhibit such a high resistance to the passage of water vapour that they do not generally require additional water-vapour barriers. Such high vapour resistance, combined with the high surface emissivity of rubber, allows flexible elastomeric foams to prevent surface condensation formation with comparatively small thicknesses. |
These are flexible, closed-cell, rubber foams based on [[Nitrile rubber|NBR]] or [[EPDM rubber]]. Flexible [[elastomeric foam]]s exhibit such a high resistance to the passage of water vapour that they do not generally require additional water-vapour barriers. Such high vapour resistance, combined with the high surface emissivity of rubber, allows flexible elastomeric foams to prevent surface condensation formation with comparatively small thicknesses. |
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As a result, flexible elastomeric foams are widely used on |
As a result, flexible elastomeric foams are widely used on refrigeration and air-conditioning pipework. Flexible elastomeric foams are also used on heating and hot-water systems. |
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===Rigid foam=== |
===Rigid foam=== |
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===Cellular Glass=== |
===Cellular Glass=== |
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100% Glass manufactured primarily from sand, |
100% Glass manufactured primarily from sand, limestone & soda ash. |
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Cellular insulations are composed of small individual cells either interconnecting or sealed from each other to form a cellular structure. Glass, plastics, and rubber may comprise the base material and a variety of foaming agents are used. Cellular insulations are often further classified as either open cell (cells are interconnecting) or closed cell (cells sealed from each other). Generally, materials that have greater than 90% closed cell content are considered to be closed cell materials. |
Cellular insulations are composed of small individual cells either interconnecting or sealed from each other to form a cellular structure. Glass, plastics, and rubber may comprise the base material and a variety of foaming agents are used. Cellular insulations are often further classified as either open cell (cells are interconnecting) or closed cell (cells sealed from each other). Generally, materials that have greater than 90% closed cell content are considered to be closed cell materials. |
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==Heat flow calculations and R-value== |
==Heat flow calculations and R-value== |
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Heat flow passing through pipe insulation can be calculated by following the equations set out in either the |
Heat flow passing through pipe insulation can be calculated by following the equations set out in either the ASTM C 680{{cite web |title=ASTM C 680 calculation standard | publisher=American Society for Testing and Materials | url=http://www.astm.org/Standards/C680.htm }} or EN ISO 12241{{cite web | title=EN ISO 12241 calculation standard | publisher=International Organization for Standardization | url=http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=41703 }} standards. Heat flux is given by the following equation: |
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In order to calculate heat flow, it is first necessary to calculate the thermal resistance ("[[R-value (insulation)|R-value]]") for each layer of insulation. |
In order to calculate heat flow, it is first necessary to calculate the thermal resistance ("[[R-value (insulation)|R-value]]") for each layer of insulation. |
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For pipe insulation, the [[R-value (insulation)|R-value]] varies not only with the insulation thickness and thermal conductivity ("k-value") but also with the pipe outer diameter and the average material temperature. For this reason, it is more common to use the thermal conductivity value when comparing the effectiveness of pipe insulation, and [[R-value (insulation)|R-values]] of pipe insulation are not covered by the US FTC [ |
For pipe insulation, the [[R-value (insulation)|R-value]] varies not only with the insulation thickness and thermal conductivity ("k-value") but also with the pipe outer diameter and the average material temperature. For this reason, it is more common to use the thermal conductivity value when comparing the effectiveness of pipe insulation, and [[R-value (insulation)|R-values]] of pipe insulation are not covered by the US FTC [http://www.ftc.gov/bcp/rulemaking/rvalue/16cfr460.shtm R-value rule] {{Webarchive|url=https://web.archive.org/web/20071231035220/http://www.ftc.gov/bcp/rulemaking/rvalue/16cfr460.shtm |date=2007-12-31 }}. |
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The thermal resistance of each insulation layer is calculated using the following equation: |
The thermal resistance of each insulation layer is calculated using the following equation: |
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Calculating the heat transfer resistance of the inner- and outer-insulation surfaces is more complex and requires the calculation of the internal- and external-surface coefficients of heat transfer. Equations for calculating this are based on empirical results and vary from standard to standard (both ASTM C 680 and EN ISO 12241 contain equations for estimating surface coefficients of heat transfer). |
Calculating the heat transfer resistance of the inner- and outer-insulation surfaces is more complex and requires the calculation of the internal- and external-surface coefficients of heat transfer. Equations for calculating this are based on empirical results and vary from standard to standard (both ASTM C 680 and EN ISO 12241 contain equations for estimating surface coefficients of heat transfer). |
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A number of organisations such as the [http://www.pipeinsulation.org North American Insulation Manufacturers Association] and [ |
A number of organisations such as the [http://www.pipeinsulation.org North American Insulation Manufacturers Association] and [http://www.firoflex.co.uk/KnowHow/FiroCalculation.html Firo Insulation]{{dead link|date=May 2025|bot=medic}}{{cbignore|bot=medic}} offer free programs that allow the calculation of heat flow through pipe insulation. |
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==References== |
==References== |
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==External links== |
==External links== |
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{{Commons category|Pipe covering}} |
{{Commons category|Pipe covering}} |
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* [http://www.insulation.org/midg/ Mechanical Insulation Design Guide] |
* [http://www.insulation.org/midg/ Mechanical Insulation Design Guide] - National Insulation Association |
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* [http://www.inspectapedia.com/interiors/Insulation-Values-Table.htm R-Values by Insulation Material] - InspectAPedia |
* [http://www.inspectapedia.com/interiors/Insulation-Values-Table.htm R-Values by Insulation Material] - InspectAPedia |
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