Patches are cut with rounded corners and extend past the damaged area by a set margin, commonly 150 mm, then tacked, ground and extrusion welded all the way around. Each patch is numbered, logged on the as-built drawing and tested, usually with a vacuum box or spark test. A cap strip, a long narrow patch, covers a failed length of seam.
Patch every destruct hole with round corners and six inches past the cut, then box it.
Also heard as
- repair
Related terms
Extrusion weld
Geomembrane seam made by laying a bead of molten polymer along the edge of an overlap, used for patches and details.
Vacuum box
Clear-topped box pulled to a vacuum over soapy geomembrane so leaks in seams and patches show up as bubbles.
Destruct
Installer shorthand for a destructive seam sample, and for the job of cutting one out.
Tack
To spot-weld overlapped geomembrane with a hot-air tool so it stays aligned before the final extrusion weld.