1 Scope
This part of ISO 4437 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 International Standard.
In conjunction with part of ISO 4437-1, ISO 4437-3, ISO 4437-4, and ISO 4437-5, it is applicable to PE pipes, fittings and valves, their joints, and joints with components of PE and other materials intended to be used under the following conditions:
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a) the maximum operating pressure (MOP) is based on the design stress determined from the compound minimum required strength (MRS) divided by the C factor, and taking into account rapid crack propagation (RCP) requirements;
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b) a temperature of 20 °C as reference temperature for the design basis.
NOTE 1 For other operating temperatures, guidance is given in ISO 4437-5:2014.
For above ground application of pipes conforming to this International Standard, the pipes should be protected by a casing pipe, taking into account any relevant national regulations and installation practices or codes.
This part of ISO 4437 covers three types of pipes:
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— PE pipes (outside diameter dn) including any identification stripes;
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— 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 PE layers have the same MRS rating;
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— PE pipes (outside diameter dn) with a peelable and contiguous thermoplastics additional layer on the outside (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.