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Hot Air Welding
All Sarnafil membranes are joined together by the use of electrically heated hot air.
The resulting joints in the overlapping adjacent sheets create a seam stronger than the membrane itself. The width of the overlap in these seams and the minimum acceptable weld width will vary depending on the system used.
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System
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Minimum Overlap Width
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Minimum Weld Width
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Adhered
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80m
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30mm
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Sarnafast mechanically fastened
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120mm
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30mm
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Sarnabar mechanically fastened
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80mm
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30mm
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Ballasted and Green roof
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80mm
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30mm
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All end and side laps should be at least 80 mm.
Hot air welding of main seams can be carried out with either a Sarnamatic automatic hot air welder, or by a hand welder such as a Leister Triac S or PID, used in conjunction with a pressure roller. At parapet walls and other such junctions, a Perimat semi-automatic hot air welder can also be used. In all cases, the manufacturer‘s instructions and HSE regulations must be followed.
Before work starts, test samples should be taken to determine the correct welding temperature and welding speed. This is particularly important if different types of Sarnafil membrane are being used. When welding, it is important that the welding surfaces are clean and dry. Dirty surfaces of Sarnafil G410-EL, G410-ELF, G476-20TEX, Sarnafil S327-EL or S327-ELF must be cleaned with a damp cloth or, if heavily soiled with Sarnafil Seam Cleaner.
Sarnafil TG66, TG76-Felt and TS77-E must be prepared for welding with Sarnafil T Prep prior to welding, and if heavily soiled, cleaned with Sarnafil T Clean, prior to the application of Sarnafil T Prep.
When working with Sarnafil G410-EL, G410-ELF, G476-20TEX, Sarnafil S327-EL or S327-ELF in thickness’ greater than 1.5 mm, all cross joints need to be chamfered prior to hot air welding. Any chamfered surface still visible after welding should be treated with SarnaLac lacquer.
All thickness’ of Sarnafil TG66, Sarnafil TS77-E or Sarnafil TG76-F must be chamfered at all cross joints, prior to wiping with Sarnafil T Prep and hot air welding.
For more information on Sarnafil G/S and Sarnafil TG/TS, please select from the links below:
For more information on Sarnafil Welding Equipment, please click here.
© 2006 Sarnafil Ltd. Legal Disclaimer
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