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 external surface and the system, Type A|Unplasticized polyvinyl chloride, Recycling, Plastics, Polyethylene, Polyvinyl chloride, Physical properties of materials, Sewers, Pipe fittings, Sewerage, Underground, Performance, Drainage, Marking, Pipes, Pipework systems, Testing conditions, Plastic pipelines, Polypropylene