This part of EN 1555 specifies the characteristics of pipes made from polyethylene (PE) for piping systems in the field of the supply of gaseous fuels. It also specifies the test parameters for the test methods referred to in this standard. In conjunction with Parts 1 and 3 to 5 of EN 1555, it is applicable to PE pipes, their joints and to joints with components of PE and other materials intended to be used under the following conditions: a) a maximum operating pressure, MOP, up to and including 10 bar 1); b) an operating temperature of 20 °C as reference temperature. NOTE 1 For other operating temperatures, derating coefficients should be used, see FprEN 1555-5. EN 1555 covers a range of maximum operating pressures and gives requirements concerning colours and additives. It covers three types of pipe: PE pipes (outside diameter dn) including any identification stripes; PE pipes with co-extruded layers on either or both the outside and/or inside of the pipe (total outside diameter dn) as specified in Annex A, where all layers have the same MRS rating; PE pipes (outside diameter dn) with a peelable, contiguous thermoplastics additional layer on the outside of the pipe (`coated pipe') as specified in Annex B. NOTE 2 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.