Patch repairs carried out on liners either before or after installation have resulted in leaks and unsightly results. Patch repairs carried out before installation are repairs to the vacuum holes and resin addition holes.
Causes: Consequences of poor patch repairs are unsightly leaks and stains which detract from an otherwise good liner. Making a good patch repair is made more difficult when the air is warm and humid and the liner is cold enough to cause condensation that makes obtaining a dry surface hard to achieve.
Figure 1: A leaking patch repair. (Click photo to view video.)
Figure 2: An unusual and unsightly patch. (Click photo to view video.)
Figure 3: An unsightly leaking patch close to a connection. (Click photo to view video.)
Solutions: Patch repairs will not leak if care is taken to ensure that the liner is clean and dry when the patch is placed. Where solvent adhesion is used, a minimum quantity of solvent should be used preferably applied with a syringe. The syringe should be withdrawn as the patch is “rolled” towards the syringe. After application, use a brush to apply glue to the edges of the patch.
During impregnation and installation ensure that all rollers and elbows (where a bottom inversion is used) are clean and smooth.
Patches should not have square, cut corners-rather the corners should be rounded. This makes them less likely to become dislodged.