Cast iron condition cannot always be judged through a layer of scale. Mechanical preparation and flushing can expose a much different pipe than the first camera pass suggests.
Scale is not the same as wall
Deposits narrow the bore and hide the surface. After preparation, the camera can show whether the invert remains, where corrosion is deepest, and how transitions are behaving.
Lining is geometry-dependent
A liner may isolate flow from a prepared host pipe, but missing sections, severe deformation, inaccessible fittings, or standing water can change the path.
Inspect the transitions
Connections from cast iron to clay, Orangeburg, or plastic are common defect points. A complete scope names how those junctions are treated.
Use the cast iron pipe lining guide for the full decision checklist.
