Looking forward to hear from you
Call us today!

Wet insulation materials do not insulate!

Wet insulation is as useless as a wet wool sweater in winter. It does not protect the plant from either energy loss or corrosion. A study from the Fraunhofer Institute of Building Physics in Germany, has now confirmed that Armaflex insulation materials are very good protectors against moisture absorption. The cellular rubber insulation with closed cells also ensures long-term energy efficiency in technical systems. The use of mineral wool insulation on cold pipes can lead to an unpredictable risk that can lead to significant follow-up costs.

Condensation is the biggest enemy of insulation

For technical insulation, condensation is number one enemy. If moisture forms on the surface of pipes, or water vapor penetrates into the insulation material from the outside, the insulation system fails. The scary thing about moisture penetration and condensation is that the processes are invisible. Condensation occurs during the insulation on the surface of the pipe. Faults in the insulation system are often only discovered when the material is so moist that it drips from the ceilings or when ice forms on the pipes.

Consequences of wet insulation:

  • Increased energy loss
  • Corrosion during insulation
  • Mold growth
  • High repair and follow-up costs

The insulation effect decreases rapidly and the material eventually loses its function. So when choosing an insulation system, the key question is how well it is protected from moisture absorption.

Insulation materials in an independent test

To study the moisture absorption and condensation properties of various insulation materials, the Fraunhofer Institute of Building Physics (Stuttgart) conducted a scientific test on behalf of Armacell. The materials examined were mineral wool, PUR and cellular rubber (FEF). Cellular rubber insulation with a closed cell structure has an "integrated" steam brake and a diffusion resistor that builds up cell by cell throughout the insulation thickness. For mineral wool and PUR insulation, the steam brake is limited to a thin aluminum or PVC foil. Under normal practical mounting conditions, it is almost impossible to mount this foil in such a way as to obtain a sufficient diffusion barrier. Pipe clamps, bends, elbows, T-pieces, valves, fittings etc. is almost never completely vapor-tight.

To simulate a realistic damage to the insulation system, which is normally the main rule instead of the exception on a construction site, two small 5mm deep holes with a diameter of 5 mm were made into the surface of three of the six samples. The test conditions in the climate chamber were deliberately chosen to be moderate with pipes with an operating temperature of +20 ° C. The ambient temperature was set at +35 ° C and a relative humidity of 55%. The test was performed under these conditions for 33 days.

Condensation on the pipes

During this relatively short test period, considerable moisture had already accumulated during both the PUR and mineral wool insulation. Even under these moderate conditions, the vapor barrier could not prevent moisture absorption. In comparison, no moisture diffused into the cellular rubber insulation and the pipe surface was dry. While the tube insulated with cellular rubber showed no signs of condensation after 33 days, the mineral wool insulation that was with and without damage failed already at the start of the test.

Long-term consequences 

To investigate the long-term effects of moisture absorption, the Fraunhofer Institute performed calculations based on these results and simulated how the insulation materials behave over an estimated period of ten years. Although the thermal conductivity (λ) of the cellular rubber has only increased by around 15% after ten years, the λ value of mineral wool is 77% higher and the PUR insulation is 150% higher. Thermal conductivity increases with each volume% moisture content and the insulation effect deteriorates rapidly. The consequences are not only steadily increasing energy loss over the lifetime, but also a lowering of the surface temperature. If the surface temperature falls below the dew point temperature, condensation occurs and the risk of corrosion increases.

Elastomeric rubber insulation protects against condensation

To avoid condensation on the pipe surface and an increase in thermal conductivity over its service life, it is important that the insulation material is protected against moisture absorption. The thermal conductivity stated for insulation materials must be understood as the thermal conductivity when it is new and dry. Only in combination with the diffusion resistance can it determine which material is selected. In other words, an insulation material with a low “dry λ value” and low diffusion resistance is a poor choice. If the insulation material is completely soaked, the increase in energy consumption is often the least of the problems. Mold, construction damage, such as on ceilings or process disruptions due to maintenance work and downtime can incur large costs.

Take no risk

By using insulation materials with open cell structure on cold systems, consultants and installers take a great risk. This can be expensive. Manufacturers of mineral wool currently emphasize that their insulation materials are suitable for use in cold plants. Although these systems are explicitly marketed as cold insulation materials, these are mineral wool products with an open cell structure coated with a thin aluminum foil. The manufacturer's warranties do not alter the fact that it is the user's complaint that must prove that the product was installed correctly. In some European countries, the use of mineral wool on cooling pipes is severely limited. In Germany, DIN 4140 stipulates that it is only permitted if a double jacket is installed. In Belgium according to standard Type cutlery / 105, mineral wool can only be used on pipes with a temperature higher than +13 ° C. Cooling insulation materials must have a closed cell structure, high diffusion resistance and low thermal conductivity. Only then will possible diffusion processes be permanently reduced to a minimum.

Tip: See also Armacell`s website (www.armacell.no) for more comprehensive information on the topic of the risk of moisture absorption in insulation materials.

(Text: Armacell)