ARK HeatLAG® – Removable Insulation

Conventional Insulation and its Disadvantages

Conventionally for insulation of such high temperature surface, The complexity of the application procedure is very intricate. first studs and C-clamps are welded on the surface of the turbine and mattresses of adequate thickness (up to 250mm) is impelled into the pins and once the insulation is applied, GI netting is the applied on the layer of insulation and then on top of the netting, to provide a finishing surface, Aluminum Cladding is done on the outer side. This is a very complicated procedure to complete, since it requires a lot of on-site welding and on-site labour.
Also, if the external high temperature surface to be insulated has complex geometry, then it is very difficult to complete the Aluminum cladding which especially happens in case of power turbines. And in such cases, when Aluminum cladding is done, it looks very clumsy and unaesthetic.
Power turbines have to go through regular maintenance over regular intervals of 1 to 1.5 years. For this the insulation has to be removed completely. Removing the insulation again is the complicated procedure because the Aluminum cladding has to be removed first which is fixed with bolts. Then the netting and then the insulation has to be removed for initiating the maintenance of the power turbine. Use of HeatLag® avoids this complicated procedure and allows very easy removal of the insulation.
Also, in India, what happens in most of the cases is that, once the insulation is removed, the material which is removed isn’t re-usable and hence is discarded, and the maintenance is completed, for applying the insulation again, labour who is trained to do Aluminum cladding has to be available on site. The insulation and cladding has to be done again which again increases the cost of insulation exponentially.
Due to this, the the high temperature surface is again exposed and the performance and the efficiency of the power turbine also decreases. Therefore, for easy application and removal of the insulation, we have introduced this revolutionary product which allows us very easy application and removal of the thermal insulation which can be completed in several minutes.
In case of conventional insulation which includes Aluminum cladding, advanced technologies that we have developed such as multi-layer multi-reflecting barriers cannot be used and hence the optimum performance is not achieved in case of conventional insulation and the thickness of insulation required increases.

HeatLag® and its Advantages

ARK has introduced this revolutionary product in the field of Power Turbine Removable Heat & Acoustic Insulation. We have developed and successfully implemented our latest technological development of multi-layer multi-reflecting barriers in HeatLag®. Multi-layer technology increases the thermal efficiency of HeatLag® noticeably. For instance, if instead of using a single layer 2 inch thick insulation, if we use 2 layers of 1 inch thick insulation of same material, the later case provides 12% more thermal efficiency because of the intramolecular air film trapped in between the two layers. Also, with addition of each reflecting barrier, due to emissivity of polished aluminum, the efficiency of HeatLag® increases by 28%. HeatLag® uses more than 2 layers of reflecting barriers which increases the thermal efficiency by 144% along with additional 12% increase due to use of multiple layers which adds up to 156% more efficiency compared to conventional insulation methods. According to the temperature on the external surface of the power turbine, we design multiple layers of insulation which are separated by Aluminum perforated sheet which acts as a reflecting barrier for the heat as well as noise coming from the turbine. Perforations on the Aluminum sheet also are useful in diffusing the sound and gives additional Transmission loss of another 4 dB in addition to the 6 dB because of the lagging. HeatLag® provides excellent Heat as well as Acoustic properties because of this technology.
Removable Thermal Insulation Pumps
HeatLAG® can be developed for close-fit application, where as cladding cannot be done for close-fit application and it leaves air pockets which can cause thermal disturbance.
HeatLag® is so easy for installation and even removal that even a 7 year old kid can complete the easy application or removal. After taking the measurements at the site of the turbine, the HeatLag® removable insulation is manufactured at the facility of ARK Noise Control Engineering Center itself and the ready product is sent to the site for ready application which can be very easily completed within a short timespan.
Ebara removable small

Any complex geometry of the external surface of power turbine can be easily covered with HeatLag®. Heatlag consists of multi-layer construction along with Aluminum perforated flexible reflecting barriers which can accommodate any type of complex surface geometry and openings for nozzles, pipes etc. very accurately. HeatLag® provides very smooth finish to any complex surface geometry and is aesthetic as well.
When the power turbine has to go through maintenance at regular intervals of every alternate year, Such checkup usually takes up to 8 weeks, one week for removing the layer of mortar, 5 weeks for the actual check up, and last two weeks for re-establishing the layer of mortar. HeatLag® can be easily removed within a matter of minutes. Therefore it reduces the time which is required for maintenance substantially by up to 3 weeks. Also, once the maintenance of the turbine is complete, HeatLag® can be very easily applied by anyone within a matter of minutes. This avoids the drawback of the conventional insulation entirely and saves important time of removing and installing the insulation entirely.
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HeatLag® eliminates the need of metal cladding entirely. HeatLag® uses special purpose aluminized turbine insulation fiber glass fabric. Its flexibility allows us to design HeatLag® for any complex geometry of the turbine. Its strength allows us to incorporate multiple layers into the design while providing the product with a long life. The special purpose Aluminized Turbine insulation fiber glass fabric used in HeatLag® has excellent heat reflecting properties which helps the design and allows us to limit the temperature of the external surface to 60℃, so that it is safe for people working around it. Also, it improves the thermal efficiency of the turbine vastly.

Bare Heat loss for 500℃ temperature is 28,000 W/m2, But with HeatLag®, the heat loss is reduced to only 165 W/m2. Traditionally, a layer of mortar containing mineral fibers, i.e. a mixture of mineral fibers, cement and water is sprayed onto the outer surface of turbine to obtain a thickness of e.g. 250 mm. Due to vibrations, it is sometimes necessary to reinforce the layer thus formed by wire netting. This need of application of mortar is totally eliminated with use of HeatLag®, and therefore, it is capable of completing the insulation at a reduced thickness of only 75 mm without compromising on heat loss.

In conventional method where box type insulation is provided, insulation is applied at the inner surface of box, and it leaves an air gap between the high temperature surface and the insulation. This air gap is never a closed space and hence it cannot avoid convectional and radiational heat losses and thus surface temperature the surface temperature is usually very high compared to ambient. Thus gradient of temperature is formed and losses are more obvious. Because of this, the surface temperature on the turbine surface is never constant and forms thermal stresses on it. HeatLag® avoids this problem as well.
HeatLag® is designed so that it can withstand a continuous temperature of 600℃ and an intermittent temperature of 800℃. The multiple layers of ceramic blanket inside HeatLag® can withstand a continuous temperature of 1260℃. In case higher temperature is required, we can design HeatLag® to withstand 1425℃ with the use of AZS grade ceramic blanket.

Removable Acoustical Blanket-1

ARK HeatLAG being used on a KSB Multi-Stage Boiler Feed pump

To avoid any sort of sagging or displacement, HeatLag® is fixed with SS stud washer-lockers which are installed at every 6 inches of length. which avoids sagging of insulation over time.
HeatLag® has excellent acoustical properties as well. At ARK Noise Control Engineering Center’s Anechoic Chamber facility, We have performed a detailed FFT (Fast Fourier Transform) analysis for heavy machinery such as power turbines, compressors, motors etc, which typically have lower frequencies of sound involved. We have designed the layers of the insulation to target those frequencies which are typically involved in case of such machinery and hence HeatLag® provides excellent acoustical properties and provides nearly 8 dB of noise reduction at the source itself.
Because of use of perforated sheets in HeatLag®, silencing effect is achieved which works on the same principle as that of a reactive silencer. when the sound waves pass through the perforation holes of the sheet, sound gets diffused and hence sound absorption is seen. Also, when sound waves pass through the fibers of ceramic blankets, air trapped inside the layers of ceramic blanket is disturbed and hence because of friction of air molecules with the fiber material, the sound energy is consumed and hence effective sound absorption is achieved in HeatLag®.

12MW Turbine

ARK HeatLAG being used on a 12MW Steam Turbine


  • HeatLag® is easily removable and easily installable turbine insulation. Removal or Installation of HeatLag® takes less than 10 minutes each and therefore saves important time during the maintenance.
  • HeatLag® is very easy to install, even a 7 year old kid can successfully complete the installation of it within minutes.
  • HeatLag® can be designed for any complex geometry of turbine surface and openings for nozzles, pipes etc.
    HeatLag® eliminates the need of metal cladding entirely. HeatLag® is industry ready and can withstand continuous temperature of 600℃.
  • HeatLag® is capable of maintaining the outer surface temperature within 20℃ above ambient temperature. i.e. if ambient temperature is 40℃, the outside temperature will not exceed 60℃. Because of this, no external metal cladding is required.
  •  HeatLag® Aluminized special purpose turbine fabric is water proof, vapor proof as well as fire proof as defined in BS476 and is O class rated.
  • HeatLag® is Chloride free as well as Sulphur free which are corrosive elements found in mineral wool.
    The necessity of steel jacket or casing is avoided with the use of HeatLag®.
  • HeatLag® avoids formation of thermal stresses on the turbine surface and hence protects it from damage due to thermal stresses.
  • HeatLag® acts as acoustical blanket for the turbine as well. HeatLag® can reduce turbine noise level up to 8 dB at the noise source itself.
  • HeatLag® uses no hazardous materials for the environment and is eco-friendly. All the materials used for 9. HeatLag® are re-usable/re-cyclable.
  •  HeatLag® is completely Asbestos Free and according to OSHA Regulations.
  • HeatLag® has dust ingress level equivalent IP64 and the entire materials are as per the explosion proof ingress levels.
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