This document gives guidance and requirements for the assessment of conformity of compounds, products, joints and assemblies in accordance with the applicable part(s) of the ISO 16486 series which are intended to be included in the manufacturer s quality plan as part of the quality management system and for the establishment of certification procedures. NOTE 1 A basic test matrix in Annex B provides an overview of the testing scheme. It is recommended that the manufacturer have a management system such as ISO 9001[4] or equivalent. NOTE 2 If certification is involved, certification bodies and inspection bodies operating according to ISO/IEC 17065 and ISO/IEC 17020 are considered to be competent. In conjunction with the other parts of the ISO 16486 series (see Clause 2), this document is applicable to unplasticized polyamide (PA-U) piping systems intended to be buried and used for the supply of gaseous fuels. It is applicable to PA-U pipes, fittings and valves, as well as to their joints and to joints with components of other materials intended to be used under the following conditions: a) a maximum operating pressure (MOP) up to and including 18 bar1) (the MOP is limited to 16 bar for CEN member countries, where ISO 16486-6 is replaced by CEN/TS 12007-6[1]); b) an operating temperature of 20 °C as the reference temperature. NOTE 3 For operating temperatures different to 20 °C, derating coefficients can be used (see ISO 16486-6). CEN member countries use CEN/TS 12007-6[1] and ISO/TS 16486-7 (this document) as a basis, but they can also request additional requirements. For non-CEN member countries, information for dealing with special cases for PA-U can be found in ISO/TS 16486-7 (this document) and PPI TR-3.[7] For mechanical fittings conforming to ISO 17885, guidance for assessment of conformity is not given in this document. When requested, a quality plan based on the tests mentioned can be set up in agreement between user and manufacturer. The ISO 16486 series covers a range of maximum operating pressures and gives requirements concerning colours. NOTE 4 It is the responsibility of the purchaser or specifier to make the appropriate selections from these aspects, taking into account their particular requirements and any relevant national regulations and installation practices or codes.