ISO 16631:2016 specifies the requirements and test methods applicable to ductile iron pipes, fittings, accessories and their joints with dimensions compatible with plastic (PVC or PE) piping systems:

- to replace or repair existing plastic pipelines;

- to convey water (e.g. for human consumption, raw water, etc.);

- operated with or without pressure;

- installed below or above ground;

- defined according to their external diameter (DN/OD series);

- classified according to pressure (C class).

The pressure class specified in this International Standard is C25. This pressure resistance level will meet or exceed those of plastic pipes. These ductile iron pipes, fittings, accessories and joints can be used along with plastic pipelines, where they are needed (for example, with higher pressure rating sections, higher traffic load, etc.), for the construction of water pipelines.

The dimensions of the products according to this International Standard, in the size range DN/OD 50 to DN/OD 225, are compatible with those of plastic pipes (ISO 1452‑2 for PVC and ISO 4427‑2 for PE). The spigots of plastic pipes used for water applications can be inserted into sockets of pipes manufactured according to this International Standard. The spigots and sockets of products defined in this International Standard are not dimensionally compatible with the products defined in ISO 2531.

ISO 16631:2016 gives specifications for materials, dimensions and tolerances, mechanical properties and standard coatings and linings of pipes, fittings and accessories. It also gives performance requirements for all components including joints.

ISO 16631:2016 covers pipes, fittings and accessories cast by any type of foundry process or manufactured by fabrication of cast components, as well as corresponding joints in the size range DN/OD 50 to DN/OD 225 inclusive.

ISO 16631:2016 is applicable to pipes, fittings and accessories which are

- manufactured with socketed or spigot ends for jointing by means of various types of gaskets (which are not within the scope of this International Standard), and

- compulsory delivered internally and externally coated.

ISO 16631:2016 is also applicable to socketed fittings which include flanged connections.

NOTE In this International Standard, all pressures are relative pressures expressed in bar[1].

[1] 100 kPa = 1 bar.