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<br />C. Temperature setting will vary according to the FML thickness being <br />installed. In general, the sheet surface temperature as it passes through the <br />nip/drive rollers is about thirty degrees Fahrenheit (fifteen degrees <br />Celsius) lower than the wedge itself. <br />D. .Ambient factors such as clouds, moisture, and hot sun will require the <br />temperature setting of the wedge to vary. A strip of at least five feet in <br />length should be run before welding begins, which will enable the operator <br />to find the proper settings for the particular conditions that day. See <br />:Article 3.35. <br />E. Power for the drive motor should be off when positioning the machine to <br />make a seam. Ivlanually place the machine into the overlapped sheet of <br />material. The sheets should be guided between the idlers and the wedge, <br />and into the drive nip rollers. This procedure is only possible when <br />starting with two new sheets. When starting a weld in the middle of ttvo <br />sheets, the material must be loaded from the sides. The machine is to be <br />picked up a few inches, loading the bottom sheet first, and then the top <br />sheet. As soon as the nip rollers aze engaged and the wedge is in position, <br />the power to the drive motor should be turned on. Once the sheets aze <br />between the nip rollers, they shall be engaged immediately, otherwise a <br />melt-through will occur within a few seconds. The hot wedge should be <br />moved into position and locked. <br />It is necessary that the operator keep constant visual contact with the <br />temperature controls, as well as the completed seam coming out of the <br />machine. Occasional adjustments of temperature controls will be <br />necessary to maintain a consistent weld. Visual inspection and constant <br />hand testing by the peel method or another method as cited in Article <br />3.3.8.2 is also recommended. <br />G. On some soils, the wedge tends to `'bulldoze" into the ground as it travels. <br />This causes soil to enter the weld making the seam weak and <br />unacceptable. To overcome this, it is recommended that the operator take <br />some of the weight off the front of the machine by lifting it slightly. <br />Alternatively, some type of base for the machine to travel on could be <br />provided. Strips of geotextile or geomembrane have proven effective to <br />prevent this bulldozing effect. <br />IV. After Seaming <br />A. A smooth insulating plate or heat insulated fabric is to be placed beneath <br />the hot welding apparatus after usage. <br />49 <br />