ISO/TR 4191:2014 gives recommended practices for installation of unplasticized poly(vinyl chloride) (PVC-U) and oriented unplasticized poly(vinyl chloride) (PVC-O) pipes, fittings, valves, and ancillaries when used in piping systems conveying water under pressure.

The recommendations are intended to give practical guidance of design and installation of piping systems incorporating pipes, fittings, valves, and ancillary equipment made from PVC materials and used for the following purposes: water mains and services buried in ground, waste water under pressure, and conveyance of water above ground for both outside and inside buildings, for the supply of water under pressure at approximately 20 °C (cold water) intended for human consumption and for general purposes.

ISO/TR 4191:2014 is also applicable to components for the conveyance of water up to and including 45 °C. For temperatures between 25 °C and 45 °C, Figure 1 of ISO 1452‑2:2009 applies.

In addition, recommendations are given for the connection to fittings, valves, and ancillary equipment made from materials other than PVC.