Pipe insulation

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Isolation Pipe is the thermal or acoustic insulation used in pipework.

Video Pipe insulation

Apps

Condensation control

Where the pipeline operates at ambient temperature, there is a potential for moisture to condense on the surface of the pipe. Humidity is known to contribute to various types of corrosion, thus preventing the formation of condensation in pipes is usually considered important.

Pipe insulation can prevent the formation of condensation, because the insulating surface temperature will vary from the surface temperature of the pipe. Condensation shall not occur, provided that (a) the insulating surface is above the temperature of the dew point; and (b) the insulation incorporates some form of vapor barrier or retarder which prevents moisture through insulation to form on the surface of the pipe. to prevent corrosion of pipelines, required insulation with appropriate thickness and density.

Pipe freeze

Because some water pipes are outside or in unheated areas where the ambient temperature sometimes falls below freezing water, any water in the pipeline can potentially freeze. As water freezes expands and this expansion can lead to pipe system failure in one of a number of ways.

Pipe insulation can not prevent water clotting in pipes, but it can increase the time required for freezing - thereby reducing the risk of water in a frozen pipe. For this reason, it is advisable to isolate the pipe at risk of freezing, and local water supply regulations may require pipeline insulation applied to pipe work to reduce the risk of pipe freezing.

For a certain length, the smaller pipe has a smaller volume of water than the larger pipe, and therefore the water in the smaller pipe will be easier to freeze (and faster) than the water in the larger-bore pipe equivalent environment). Because small diameter pipes have a greater risk of freezing, insulation is usually used in combination with alternative frost prevention methods (eg, modulated trace heating cables, or ensuring consistent water flow through pipes).

Energy savings

Since pipework can operate at temperatures far from ambient temperature, and the heat flow rate of a pipe is related to the temperature difference between the pipe and the surrounding air, the heat flow from the pipe may become large. In many situations, this heat flow is undesirable. The application of thermal pipe insulation introduces thermal resistance and reduces heat flow.

The heat pipe insulation thickness used to save energy varies, but as a general rule, pipes operating at more extreme temperatures indicate greater heat flow and greater thickness are applied because of greater potential savings.

The location of pipework also affects the selection of insulation thickness. For example, in some circumstances, heating pipes inside well-insulated buildings may not require insulation, since "lost" heat (ie, heat flowing from the pipe into the surrounding air) can be considered "useful" for heating. buildings, such as "lost" heat will be effectively trapped by structural insulation. Conversely, the pipe can be isolated to prevent overheating or unnecessary in the rooms it passes.

Protection against extreme temperatures

Where pipework operates at very high or low temperatures, there is potential for injury to occur if a person comes into physical contact with the pipe surface. The threshold for human pain varies, but some international standards set the recommended touch temperature limit.

Since the insulating surface temperature varies from the surface temperature of the pipe, usually in such a way that the insulating surface has a "less extreme" temperature, pipe insulation can be used to bring the touch surface temperature into a safe range.

Noise control

Pipework can operate as a channel for noise to travel from one part of the building to another (a typical example of this can be seen with the wastewater pipe being poured into the building). Acoustic isolation can prevent this noise transfer by acting to dampen the pipe wall and perform acoustic decoupling functions wherever the pipe passes through fixed walls or floors and wherever the pipe is mechanically repaired.

Pipe work can also emit mechanical noise. In such circumstances, noise penetration from the pipe wall can be achieved by acoustic insulation that incorporates a high-density sound barrier.

Maps Pipe insulation

Factors that affect performance

The relative performance of different pipe insulation on a given application can be influenced by many factors. The main factors are:

• Thermal conductivity ("k" or "?" value)
• Emissivity surface ("?" value)
• Water vapor resistance ("?" value)
• Insulation thickness
• Density

Other factors, such as moisture level and connection opening, may affect the overall performance of pipe insulation. Many of these factors are listed in the international standard EN ISO 23993.

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Materials

Pipe insulation materials come in many forms, but most materials fall into one of the following categories.

Mineral Wool

Mineral wools, including rock and slag wool, are the inorganic strands of mineral fibers that are bonded together using organic binders. Mineral wools are able to operate at high temperatures and show good fire performance ratings when tested.

Mineral wool is used in all types of pipework, especially industrial pipes operating at higher temperatures.

Glass wool

Glass wool is a high-temperature fibrous insulation material, similar to mineral wool, in which the inorganic strands of glass fibers are bonded together using a binder.

As with any mineral wool, glass-wool insulation can be used for thermal and acoustic applications.

Flexible elastomeric foam

It is a flexible, closed cell, rubber foam based on NBR rubber or EPDM. Flexible elastomeric foams exhibit high resistance to vapor pathways that generally require no additional moisture barriers. High steam resistance, combined with high emissivity of the rubber surface, allows flexible elastomeric foams to prevent the formation of surface condensation with relatively small thickness.

As a result, flexible elastomeric foams are widely used in cooling and air conditioning pipes. Flexible elastomeric foams are also used in heating and hot water systems.

Rigid foam

Isolation pipes made of Phenolic, PIR, or PUR foam insulation are common in some countries. Rigid-foam isolation has minimal acoustic performance but can show a low thermal conductivity value of 0.021 W/(mÃ, Â · K) or lower, enabling energy-saving legislation to be fulfilled while using reduced insulation thickness.

Polyethylene

Polyethylene is a flexible plastic foaming insulation widely used to prevent freezing of domestic water supply pipes and to reduce heat loss from household heating pipes.

The performance of fire Polyethylene is usually 25/50 E84 according to the thickness of 1 ".

Mobile Glass

100% Glass is produced mainly from sand, limestone & amp; sodium carbonate..

Airgel

Silica Airgel Insulation has the lowest thermal conductivity of any commercially produced insulation. While no manufacturer currently produces Airgel pipes, it is possible to wrap the Airgel blanket around the pipework, allowing it to function as a pipe insulation.

Airgel usage for pipeline insulation is currently limited.

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Heat flow calculation and R-value

Aliran panas yang melewati isolasi pipa dapat dihitung dengan mengikuti persamaan yang ditetapkan dalam standar ASTM C 680 atau EN ISO 12241. Fluks panas diberikan oleh persamaan berikut:

${\ displaystyle q = {\ frac {\ Theta i} - \ Theta a}} {R_ {T}}}} Â Â$

Dimana:

• ${\ displaystyle \ Theta _ {i}}  ÂÂ$ adalah suhu pipa internal,
• ${\ displaystyle \ Theta _ {a}}  ÂÂ$ adalah suhu lingkungan eksternal, dan
• ${\ displaystyle R_ {T}}  ÂÂ$ adalah total resistansi panas total dari semua lapisan isolasi dan tahanan transfer panas internal dan eksternal permukaan.

To calculate the heat flow, it is first necessary to calculate the thermal resistance ("R-value") for each insulation layer.

For pipeline insulation, R values ​​vary not only with insulation thickness and thermal conductivity ("k-value") but also with outer diameter of pipe and average material temperature. For this reason, it is more common to use thermal conductivity values ​​when comparing the effectiveness of pipe insulation, and the R-value of pipe insulation is not covered by the US FTC value rule.

Ketahanan thermal setiap lapisan isolasi dihitung menggunakan persamaan berikut:

${\ displaystyle R = {\ frac {D_ {x} \ ln (D_ {e}/D_ {i})} {\ lambda}}} Â Â$

Dimana:

• ${\ displaystyle D_ {e}} Â Â$ mewakili diameter luar isolasi,
• ${\ displaystyle D_ {i}} Â Â$ mewakili diameter dalam isolasi,
• ${\ displaystyle \ lambda} Â$ merepresentasikan conducive thermal ("k-value") pada suhu isolasi rata-rata (untuk hasil yang akurat, perhitungan iterasi diperlukan), dan
• ${\ displaystyle D_ {x}} Â$ adalah ${\ displaystyle D_ {e}} Â$ jika perhitungan kehilangan panas akan menggunakan ${\ displaystyle D_ {e}} Â Â$ untuk perhitungan area atau ${\ displaystyle D_ {i}} Â$ jika akan menggunakan ${\ displaystyle D_ {i}} Â Â$ .

Calculating the heat transfer resistance of the outside and inside insulation surfaces is more complicated and requires the calculation of the internal and external heat transfer coefficients. This equation for calculating is based on empirical results and varies from standard to standard (both ASTM C 680 and EN ISO 12241 contain equations for estimating heat transfer coefficients).

A number of organizations such as the North American Insulation Manufacturers Association and Firo Isolation offer free programs that enable the calculation of heat flow through pipeline insulation.

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References

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External links

• Mechanical Insulation Design Guide - National Insulation Association
• Value-R by Isolation Material - InspectAPedia

Source of the article : Wikipedia