ISO 16486-6:2012 specifies a code of practice dealing with unplasticized polyamide (PA-U) piping systems intended to be buried outside buildings and used for the supply of gaseous fuels. It addresses the common basic principles for gas supply systems.ISO 16486-6:2012 is intended to be applied in association with national standards or codes of practice related to the above-mentioned basic principles.It is applicable to mains and service lines, the components of which are prepared for jointing by scraping and/or machining, and gives instructions for the design, storage, handling, transportation, laying conditions and fusion quality control of PA-U pipes and fittings up to and including 250 mm outside diameter, as well as subsequent joint testing, backfilling, pipe system testing, commissioning and decommissioning.It covers butt fusion jointing and electrofusion jointing.