7191 Pipe insulation (0) Insulation and sheathing of water and other liquid, piping, tanks, vessels and components. Excludes mechanical pipe work insulation 7197 Cleaning, repairing and renovating existing liquid supply installations (4) Cleaning, repairing and renovating existing liquid supply systems 7198 Alteration work; demolishing and reconstructing liquid supply installations (0) Demolishing and reconstructing liquid supply installations as part of general demolition, reconstruction, alterations and additions