Installing elastomeric foam sheet

Before you start, make sure you have a tape measure for measuring centre lengths and diameters, a fillet knife for long straight cuts, a small paring knife or ceramic knife for finer work, a hole punch in various sizes for round cut-outs and a short-haired brush for applying adhesive. Also use a paint marker (e.g. Pilot B1) for marking out on the material.

Always wear an active carbon filter mask when working with adhesive and elastomeric foam. Check that the filter has not expired, as the activated carbon must prevent inhalation of volatile substances from the adhesive and the thinner. Also wear safety glasses to protect your eyes from adhesive splashes, which may require rinsing for a long time and possibly medical attention.

Never rely solely on a tape measure to calculate the circumference of a pipe. Instead, cut a strip of the sheet material you are working with — e.g. 13 mm wide if you are using 13 mm sheet — and wrap it round the pipe. Mark where the two ends meet. The method compensates for the outside of the material stretching while the inside compresses, and gives a more accurate circumference measurement than a calculation using pi.

Always measure the circumference with a strip of the same sheet — not with a tape measure and pi.

To draw a sheet-metal bend you need to know the pipe diameter and the small radius, which is calculated from the welded bend's factory radius. Example: a diameter of 60 mm has a factory radius of 76 mm; subtract half the sheet thickness (e.g. 30 mm) and you get the small radius of 46 mm. Also halve the measured circumference, as you draw two mirror-image halves that are glued together. Remember to allow a quarter of the pipe diameter as compensation for the material's movement, so the bend does not end up more than 90 degrees.

First draw a 90-degree angle on sheet material or a piece of cardboard as a template. Mark the insulation thickness (e.g. 13 mm) from the edge, and mark the small radius at the intersection. Draw the two arcs using the centre point, and mark out half the circumference along the arc. Also mark a quarter of the pipe diameter from the corner. Cut out the two mirror-image halves with a filleting knife for the cleanest edges, and glue the halves together at the back and at the throat.

If the bend needs an extra straight piece, simply add the desired length (e.g. 50 mm) at right angles to the end of the bend before you cut. It is a good idea to make a template with several different extension lengths so you can easily choose the right one for the current project.

Always cut slightly too long, and trim afterwards.

An S-bend is made by placing two bend templates directly against each other and gluing them together. Note that in this construction the two bends cannot rotate 90 degrees relative to each other — the result is purely an S-shape in the same plane.

Measure the circumference of the pipe with a material strip. Draw a template with the full circumference as the width and the desired length of the main pipe (recommended approx. 300 mm with spacing marks every 30 mm). The tee's branch is drawn with half the circumference as the width and the centre length as the height. Both halves of the branch are glued on either side. Use a hole punch (e.g. 28 mm) to make rounded corner cuts, giving tight and neat joints.

Use the same template as for a 90-degree T-piece. Make a 45-degree cut on the two sheets that represent the T-piece's legs before they are glued on. In the upper part, cut along the visible pattern, while in the crotch you should use the smallest possible hole punch to minimise air pockets. The most important thing is to achieve good adhesive contact with the pipe to prevent condensation.

If the centre length and pipe length are very short, the cut edges will pull in towards the joint. Compensate by taking a sheet with half a circumference plus 100 mm in one direction and a full circumference plus 100 mm in the other. Mark out a radius of 60 mm in all cases. Then correct with an arc equal to half the insulation thickness on one side and a full insulation thickness on the other side, so that you end up with straight edges.

Measure the flange diameter (e.g. 165 mm) with a tape measure, and cut an end cap approx. 10 mm larger (e.g. 175 mm) to leave a little clearance all round. Then measure the circumference of the end cap with a material strip to determine the width of the wrap. Glue the end cap inside the wrap rather than on top — this gives a considerably neater edge and hides any irregularities in the edge of the end cap. Measure the spindle height and subtract the insulation thickness to find the correct length of the wrap.

Measure the large and the small diameter including insulation with a material strip. Draw a base line, and mark the large diameter (e.g. 150 mm for a 114 mm pipe with 13 mm sheet) and the small diameter (e.g. 86 mm for a 60 mm pipe with 13 mm sheet) at the correct distance corresponding to the length of the reducer (typically 100 mm). Join the end points with a ruler, and extend the lines to a common centre point. Draw two arcs from this point. Mark the large circumference along the outer arc using the strip method, and cut out.

Apply adhesive with a short-haired brush and let it dry sufficiently. Test the drying stage with the fingernail test: touch the surface with a fingernail — if the nail does not stick and the surface does not feel tacky, it is the right time to press the joint. Surfaces to be joined are held under pressure while the adhesive is still slightly moist. If the adhesive is too dry, it will not bond.

Always apply adhesive from the inside out over the edge, so excess adhesive ends up on the back and is not visible on the finished surface.

Elastomeric foam is not UV-resistant and must always be painted, covered or otherwise clad when installed outdoors. Apply the first coat of paint immediately after the insulation has been fitted, and the second coat before seven days have passed. Use only the paint recommended by the supplier. Also remember that pipes and tanks must be protected against corrosion before elastomeric foam is fitted, and when insulating stainless steel, contact the manufacturer's customer service to clarify material compatibility.