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pressed together. In this case, reactivate by applying another layer of adhesive. Do not leave glued seams on the top of the insulation in external locations. When working outdoors, always turn the glued seams away from the sun.

To avoid tension within the material and prevent the trapped solvent from opening the seam, seams should be held in place with adhesive tape immediately after gluing. Apply the adhesive tape at right angles to the glued seam every 20cm. voices

PIPES WITH CORROSION PROTECTION Check that the adhesive will adhere to any rust-inhibiting primer that has been used to protect pipes. Standard adhesives should be compatible with all coating systems based on epoxy resin or polyurethane. Adhesives may not adhere to asphalt, bitumen or red lead.

When gluing joints under compression, with no gaps present, the wet adhesive method should be used. Pull the seam apart slightly and apply the adhesive thinly and evenly with the brush to both surfaces and press together. No open time is needed in this case.

High atmospheric humidity and high temperatures lead to faster evaporation of the solvent in the adhesive. This means that a film of moisture may appear on the surface of the adhesive. Consequently, the reliability of the adhesive seam cannot be assured as the surfaces to be joined may not bond together.

Under these conditions, the following points may be observed as an alternative: Apply adhesive as normal in a thin, uniform film on both surfaces. Unlike normal bonding, the surfaces to be glued should be held together under pressure while wet. Note: Due to the shorter curing time, adhesive can only be applied to a limited area at a time. Depending on the atmospheric humidity, temperature, material thickness and practical installation conditions, use a tube length of around 1m as a guideline.

WET SEALING ON BUTT JOINTS On all cold refrigerant lines, use adhesive to glue the ends of the insulation tubes to the pipe surface. The adhesive should be applied in a width at least equal to the insulation thickness. For the final wet sealing of the tube / sheet, use fingers to pull the joint apart and apply a thin, even film of adhesive to the two butt joint edges with a small brush. Apply firm and even pressure to the glued joint using fingers and thumbs to finish.

Note: In addition, it is highly recommended that this procedure be followed for all other types of hot pipes located outdoors

Sipho, thank you for your question. I hope that this helps with your installation of insulation over refrigerant piping. Remember, do not compress the insulation more than 10 % of its thickness. We often see this issue when technicians are using cable ties pulled up to tight. RACA

REFERENCES: 1. ACRA 2. ASHRAE 3. Armaflex

LABORATORIES

By Eamonn Ryan

This is the first in a series of two instalments of insights from a SAIRAC Cape Town Centre technical talk. technical