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<br />confirm the temperature controllers are operating properly and that the <br />welding rod system is operating properly. <br />F. The teflon nozzle should be checked for excessive weaz and replaced if <br />necessary. The teflon Houle must be shaped for proper control of the <br />weld bead configuration. <br />IV. Actual Seaming Process <br />A. FiV(L material to be extrusion welded must have surface oxidation <br />removed by lightly grinding the weld surface with a 60 or 80 grit disk. <br />The grinding is performed parallel to the seam and controlled such that <br />grinding marks do not extend more than 0.2~ inches outside the azea of the <br />~o'eld bead. Grinding should proceed welding by more than one hour. 60 <br />mil or thicker liners should have the edge of the top sheet beveled by <br />grinding to approximately a 4~° angle. <br />B. The FVIL to be extrusion welded must be temporarily bonded to hold the <br />material in place until the extrusion weld bead cools and attains full <br />strength. This is normally accomplished by performing an automatic or <br />hand hot air tack weld. <br />C. The extrusion welder should be purged of all degraded plastics prior to the <br />start of seaming. <br />D. The welding operation should be observed to assure that the weld bead is <br />centered over the edge of the top FML sheet and that weld bead <br />appeazance is smooth and uniform. <br />E. All extrusion welds should be non-destructively tested by vacuum testing <br />as described in the QC Manual. Areas which cannot be cannot be non- <br />destructively tested should be capped. <br />Destructive tests can be conducted when seam lengths aze adequate. <br />56 <br />