The seamer lightly grinds the area to remove the oxidized skin, preheats it with hot air, then lays a fillet or flat bead from a hand-held extruder fed with rod or pellets of matching resin. Extrusion welds handle patches, pipe boots, corners and repairs where a wedge cannot run. They are checked by vacuum box or spark test rather than air pressure, and destructively like other seams.
Extrusion weld the patch over the destruct hole and get it boxed before cover soil goes down.
Also heard as
- extrusion seam
- extrudate weld
Related terms
Gun
Installer slang for the hand-held extrusion welder used on patches, boots and detail welds.
Grinding
Lightly abrading geomembrane before an extrusion weld to remove the oxidized surface and dirt.
Vacuum box
Clear-topped box pulled to a vacuum over soapy geomembrane so leaks in seams and patches show up as bubbles.
Spark test
Holiday test for extrusion welds in which a high-voltage probe sparks through any gap to a buried conductive wire.
Patch
Piece of geomembrane extrusion-welded over a hole, defect, destructive sample cut-out or failed seam section.