- Material
- Cast iron
- Possible locations
- Soil stacks and drainage runs
- Separate assessments
- Deposits inside the pipe and remaining structural condition
- Useful records
- Route, joints, supports and access
Cast iron drainage and soil systems
An above-ground cast iron soil stack and a buried drain have different access and support arrangements. The assessment needs the route, joints, branches and supports as well as the pipe material.
A leak may come from a connection, physical damage or deterioration of the pipe. Internal inspection can show the visible inside surface, but not every concealed external surface or support. Any such survey limits should be recorded.
Deposits and remaining pipe condition
Deposits may have to be removed before the remaining pipe wall can be assessed. Cleaning can improve access to the bore, but it cannot replace material already lost through corrosion or other deterioration.
The cleaning method must suit the condition of the pipe. Where the remaining wall or joint condition is uncertain, the preparation method should reflect that uncertainty.
Internal repair systems
A coating, a local patch and a structural liner do different jobs even though each creates a new internal surface. The repair specification should state what the selected system is intended to achieve.
Branch openings, changes of direction and the ability to prepare the pipe all affect whether an internal system can be installed. If a joint, support or badly deteriorated section needs replacement, internal treatment alone may not resolve the problem.
Repair specification and completion checks
The repair specification should record the preparation, repaired length, selected system and post-work inspection. Any known limitations should also be recorded so the extent of the completed repair is clear.