Plastics piping systems for non-pressure underground drainage and sewerage. Structured-wall piping systems of unplasticized poly(vinyl chloride) (PVC-U), polypropylene (PP) and polyethylene (PE). Specifications for pipes and fittings with smooth internal and profiled external surface and the system, Type B|Marking, Recycling, Physical properties of materials, Sewers, Polyvinyl chloride, Pipework systems, Sewerage, Underground, Testing conditions, Drainage, Performance, Plastics, Polypropylene, Plastic pipelines, Polyethylene, Pipe fittings, Unplasticized polyvinyl chloride, Pipes