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When starting a weld in the middle of two sheets,the material must be loaded from the <br /> sides. The machine is to be picked up a few inches, loading the bottom sheet first and <br /> top sheet second. <br /> As soon as the wedge is in position and the nip rollers are engaged, the drive motor <br /> should be energized and the hot wedge moved into position and locked. <br /> Welder alignment and temperature shall be monitored during the seaming process and <br /> any adjustments be made as necessary. <br /> Should the machine tend to bulldoze the subgrade due to soil conditions, the operator <br /> shall take some of the weight off the front of the machine by lifting it slightly. <br /> Alternatively, a base for the machine to travel on could be provided consisting of strips of <br /> geotextile or geomembrane. <br /> To avoid damaging membrane material,once the end of a seam is reached the drive <br /> and/or pressure rollers shall be immediately disengaged before the material runs <br /> completely out of the machine. The machine shall be withdrawn as quickly as possible to <br /> avoid damaging the membrane. <br /> Seaming shall span the full panel length extend well into the anchor trench. <br /> All cross seams or"T intersections are to be extrusion welded where they intersect. The <br /> top flap of geomembrane shall be removed in the area to be extrusion welded and the <br /> weld area is ground prior to welding. <br /> 5.7.0 Extrusion Welder Seaming Procedure <br /> A smooth insulating plate or fabric is shall be placed beneath the hot welding apparatus <br /> both before and after usage. <br /> Using a hot air welders or hand held heat guns with seam rollers the overlapping <br /> materials to be welded must first be pre-bonded to hold the materials in place before <br /> actual extruding. <br /> Welding operations should be observed to assure that the machines are properly aligned <br /> resulting in weld beads that are centered over the edges of the top FML sheets and that <br /> weld bead appearances are smooth and uniform. <br /> PART VI <br /> Non-Destructive Seam Continuity Testing <br /> CLC shall non-destructively test all field seams over their full length using a vacuum test <br /> unit, air pressure testing, or other approved method. The purpose of non-destructive <br /> tests is to check the continuity of seams. It does not provide information on seam <br /> strength. Continuity testing shall be carried out as the seaming work progresses, not at <br /> the completion of all field seaming. <br /> 6.1.0 Vacuum Box Testing <br /> This test method is almost exclusively used for evaluating extrusion weld bead quality. <br /> In areas where vacuum boxes cannot practically be deployed, the welds shall be visually <br /> inspected and manually probed over their full length to check adhesion. <br /> The equipment shall be comprised of the following: <br /> Created by Colorado Lining International 1-800-524-8672 8 <br />