This standard specifies general recommendations for the design, construction, testing, commissioning, operation and maintenance of installation pipework; pipework between the delivery point of the gas and the inlet connection to the gas appliance. This standard specifies common basic principles for gas installation pipework. Users of this European standard need to be aware that more detailed national standards and/or codes of practice may exist in the CEN member countries. This standard is intended to be applied in association with these national standards and/or codes of practice setting out the above mentioned basic principles. In the event of conflicts in terms of more restrictive requirements in national legislation/regulation with the requirements of this standard, national legislation/regulation takes precedence as illustrated in CEN /TR 13737. NOTE 1 CEN/TR 13737 contains: clarification of relevant legislation/regulations applicable in a country; if appropriate, more restrictive national requirements; national contact point for the latest information. This standard applies to: gas installations in residential, commercial and public access building having a maximum operating pressure (MOP) less than or equal to 5 bar; industrial gas installations having a maximum operating pressure (MOP) less than or equal to 0,5 bar. NOTE 2 For industrial gas installations having a MOP above 0,5 bar, or installations having a MOP above 5 bar, see prEN 15001-1. This standard is applicable to new installation pipework as well as to replacements of, or extensions to, existing installation pipework. This standard does not contain detailed recommendations relating to the laying of buried pipework. NOTE 3 For more information on buried pipework, see EN 12007-1, EN 12007-2 and EN 12007-3. NOTE 4 For more information on gas pressure regulating installations, see EN 12279. NOTE 5 For more information on gas metering systems, see EN 1776. This standard is applicable to installation pipework supplied from gas distribution systems and from liquefied petroleum gases (LPG) storage vessels. Excluded are: single appliance LPG installations without fixed pipework, achieved by a flexible appliance connector from an adjacent LPG storage cylinder. LPG storage vessels. In this standard the term 'gas' refers to combustible gases, which are gaseous at 15 °C and 1013,25 mbar. These gases, odorized for safety reasons, are commonly referred to as manufactured gas, natural gas or liquefied petroleum gases (LPG). They are also referred to as first, second or third family gases (see EN 437). In this standard, all pressures are gauge pressures, unless otherwise stated.