Lining Observations
Over-Expansion
Possible cause of damage
Sub-assembly of the lining tube. The resin matrix is displaced into the outer area of the liner. As a result, the fibre portion in the supporting structure may have too little resin.
Assessment
- Reduction of the statically effective wall thickness
- Formation of an annular gap
- Weakening of the CIPP liner
The defect is difficult to detect by qualitative inspection (CCTV) from inside.