ISO 6993-4:2006 specifies a code of practice for the design, handling and installation of high-impact poly(vinyl chloride) (PVC-HI) pipes and fittings intended to be used for the supply of gaseous fuels through buried pipelines having an operating temperature range of 0 degrees Celsius up to and including +30 degrees Celsius and a maximum operating pressure of 1 bar (100 kPa).