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THERMOPLASTIC MEMBRANE ROOFING - ADHERED Section 07541 15-1207 roof membrane. The substrate shall be clean, dry, free from debris and smooth with no surface roughness or contamination. Broken, delaminated, wet or damaged insulation boards shall be removed and replaced. Sarnacol 2121 Adhesive: Follow manufacturer's current recommendations for proper installation. 3.10 HOT-AIR WELDING OF SEAM OVERLAPS A. General 1. All seams shall be hot-air welded. Seam overlaps should be 3 inches (76 mm) wide when automatic machine -welding and 4 inches (100 mm) wide when hand -welding, except for certain details. 2. Welding equipment shall be provided by or approved by Sika Sarnafil. All mechanics intending to use the equipment shall have successfully completed a training course provided by a Sika Sarnafil Technical Service Representative prior to welding. 3. All membrane to be welded shall be clean and dry. B. Hand -Welding Hand -welded seams shall be completed in two stages. Hot-air welding equipment shall be allowed to warm up for at least one minute prior to welding. 1. The back edge of the seam shall be welded with a narrow but continuous weld to prevent loss of hot air during the final welding. 2. The nozzle shall be inserted into the seam at a 45 degree angle to the edge of the membrane. Once the proper welding temperature has been reached and the membrane begins to "flow", the hand roller is positioned perpendicular to the nozzle and rolled lightly. For straight seams, the 1-1/2 inch (40 mm) wide nozzle is recommended for use. For corners and compound connections, the 3/4 inch (20 mm) wide nozzle shall be used. C. Machine Welding 1. Machine welded seams are achieved by the use of Sika Sarnafil's automatic welding equipment. When using this equipment, Sika Sarnafil's instructions shall be followed and local codes for electric supply, grounding and over current protection observed. Dedicated circuit house power or a dedicated portable generator is recommended. No other equipment shall be operated simultaneously off the generator. 2. Metal tracks may be used over the deck membrane and under the machine welder to minimize or eliminate wrinkles. D. Quality Control of Welded Seams The Applicator shall check all welded seams for continuity using a rounded screwdriver. Visible evidence that welding is proceeding correctly is smoke during the welding operation, shiny membrane surfaces, and an uninterrupted flow of dark gray material from the underside of the top membrane. On-site evaluation of welded seams shall be made daily by the Applicator at locations as directed by the Owner's Representative or Sika 21