25 Apr No Heat / No Naked Flame Shrink Wrapping – Can It Be Done?
A hot air gun is usually the essential piece of equipment for shrink wrapping, used for welding / joining individual sheets together and of course shrinking the sheeting ‘drum tight’. Although the designs of individual guns can vary a little, for 99% of projects, a hot air gun is used powered by propane gas which is ignited to create a flame. The hot air which this flame produces is used to weld and shrink the plastic.
However, we are sometimes asked if there is an alternative to using a naked flame for shrink wrapping. This is typically because the encapsulation is required in an area where there could be a risk of explosion.
This short article looks at two alternatives to a naked flame heat gun for shrink wrapping. First we will consider the electric heat tool and then we will look at a completely different approach to shrink wrapping which does not use heat at all but rather a tensioning and gluing technique.
Electric Heat Tool
A commonly used alternative to a propane gas hot air gun is an electric heat tool. However, this is not the usual ‘paint stripper’ type of tool you might imagine but rather an industrial grade tool – the Forte S3 manufactured by Leister. To achieve anywhere near the power of the propane gas gun, this electric heat tool must be powered by a 3-phase electric supply (3 x 400V).
Although the Forte S3 is the most powerful hand held electric heat gun available, it can be awkward on scaffolding / construction projects. At 4.4Kg, it is almost 4 x the weight of a propane gas gun and the ergonomics of the device are such that it must be held with two hands. This means that typical shrink wrapping tasks such as creating a welded joint becomes a two person job as one person is needed to hold the heat tool and heat the plastic and another person is needed to press the sheets together.
However, the main challenge with using even a powerful electric heat tool for shrink wrapping such as the Leister Forte S3 is that with an output of 10kW, it has 5-10 times less power than a propane gas heat tool. Whilst this probably does not make much of a difference if you are shrinking a small cover around a pallet, for a large scaffolding or industrial encapsulation which can be many 1000’s of square metres of plastic, this lower power output will greatly add to the installation time and so the cost of the job.
Tensioning & Gluing
An alternative to the gas and electric heat gun, which requires no heat at all is the tensioning and gluing technique. This installation method was first developed for shrink wrap encapsulation projects in oil refineries.
First, the shrink wrap sheet is cut to a sufficient size to cover at least one scaffolding lift with at least 500mm surplus around the top and bottom sheeting rails. This surplus is wrapped around a tensioning bar and a ratchet strap is used so that the tensioning bar is pulled upwards and the shrink wrap sheeting is pulled tightly around the lowest sheeting rail.
When the sheeting is still tensioned, the shrink wrap sheeting is temporarily clipped to the lowest sheeting rail either side of the tensioned area. Then, an adhesive spray is used to glue the shrink wrap sheeting (either side of the tensioned areas) around the lowest sheeting rail and back on to itself.
Once the glued joints have cured, the tensioned areas are released and glued and the entire process is repeated until the first section / run of sheeting is attached, tensioned and glued.
If you would like to see the tensioning and gluing technique in action, we have a very short video, recorded in our test & training facility in Cheshire; https://youtu.be/q8pUlPyAmRE
The main challenge with the tensioning and gluing technique is that it is difficult to tension large areas of sheeting. With traditional scaffold encapsulation, using a gas hot air gun, the sheeting is typically dropped around 3 lifts / 6m vertical drop, before it is fixed back to the scaffolding and heat shrunk. With the gluing and tensioning technique, it is necessary to install the shrink wrap sheeting in much smaller drops. This means that the installation process will be around 3-4 times slower than using a propane gas gun.
So, which approach should you take? Both the electric and the tensioning / gluing technique can be good solutions but the extra time required for these methods (and hence extra costs) should not be underestimated. If you would like a demonstration / trial of either of these no heat / no naked flame shrink wrapping techniques call our team on 01477 532222 own email firstname.lastname@example.org. We look forward to hearing from you.