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6.2.3
Manual Hot-air welding
Use a hand-held welder and silicone covered roller to complete
welds and details where the welding machine is inappropriate.
All hand-held welders, which produce the necessary hot air
temperature of approx. 400 - 450 °C and the necessary air
volume can be used. Hot-air tools with closed loop controlled
temperature (compensation of voltage fluctuations) with display
are recommended.
The hand-held welder is to be inserted at an angle of
• approx. 45° to the membrane edge and
• approx. 30° to the roof area
into the seam overlap.
When the welding parameters are adjusted correctly, there is a
certain development of smoke and the surface of the lower sheet
turns shiny-brilliant when heated correctly. A change of colour,
scorching or the formation of ashes on the nozzle or the welding
zone indicates that the welding temperature is too high.
Membranes are seal-welded in one operation by moving
backwards, whereas small tapes (up to 30 cm) are first tacked
and then seal-welded. When seal-welding, the nozzle must be
inserted between the membranes in a way that the top membrane
edge will also be heated and plastified.
The plastified lap areas will be fused by applying moderate
pressure with a silicone pressure roller, following parallel to the
opening of the nozzle. Due to the backwards movement, the
nozzle always blows against already seal-welded areas of the
seam. The weld must have a consistant width as possible and a
minimum width of 20 mm.
6.3 Welding of T-joints
T-joints are created when 3 membranes meet and must be
formed very carefully, in order to prevent capillary action. T-joints
must be thoroughly manual hot-air welded.
When planning the layout of the sheets cross-joints should be
avoided. When the roof is long or when this should prove to be
too arduous a membrane strip of min. 300 mm width shall be
centered and welded over the overlap. Treatment is similar to that
of T-joints.
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Monarplan
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Installation manual
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