BS EN 448:2015 pdf download.District heating pipes – Preinsulated bonded pipe systems for directly buried hot water networks – Fitting assemblies of steel service pipes, polyurethane thermal insulation and outer casing of polyethylene.
EN 448 has been aligned with EN 488 and other relevant European Standards. Other standards from CEN/TC 107 are:
— EN 253, District heating pipes — Preinsulated bonded pipe systems for directly buried hot water networks — Pipe assembly of steel service pipe, polyurethane thermal insulation and outer casing of polyethylene;
— EN 488, District heating pipes — Preinsulated bonded pipe systems for directly buried hot water networks — Steel valve assembly for steel service pipes, polyurethane thermal insulation and outer casing of polyethylene;
— EN 489, District heating pipes — Preinsulated bonded pipe systems for directly buried hot water networks —Joint assembly for steel service pipes, polyurethane thermal insulation and outer casing of polyethylene;
— EN 13941, Design and installation of preinsulated bonded pipe systems for district heating;
— EN 14419, District heating pipes — Preinsulated bonded pipe systems for directly buried hot water networks — Surveillance systems;
— EN 15632 (all parts), District heating pipes — Pre-insulated flexible pipe systems;
BS EN 448 specifies requirements and test methods for fittings of prefabricated thermally insulated pipe-in-pipe assemblies comprising a steel service fitting from DN 20 to DN 1200, rigid polyurethane foam insulation and an outer casing of polyethylene for use in directly buried hot water networks with preinsulated pipe assemblies in accordance with EN 253.
BS EN 448 covers the following fittings: bend, tee, reducer, single use compensator and anchor.
BS EN 448 applies only to factory made prefabricated fitting assemblies and single use corn pensators for continuous operation with hot water at various temperatures in accordance with EN 253.
This European Standard applies to fitting assemblies with a minimum design pressure of 16 bar (overpressure) complying with EN 13941.
This European Standard does not include calculation rules for loads and stresses. The design and installation rules, for the system, are given in EN 13941.
4 Requirements
4.1 Steel parts
4.1.1 General
The material of the fitting steel parts shall be certified in accordance with EN 10204. If traceability on material is required by the end user it shall be specified at the time of ordering. Corresponding material certificates shall be delivered to the end user if specified at the time of ordering.
4.1.2 Quality
The quality of pipe material used for the assembly of fittings shall be in accordance with
EN 253:2009+A2:2015, Table 1. The quality of butt welding pipe fittings shall be in accordance with
EN 10253-2.
NOTE For Sweden, a deviating situation is applicable for EN 253:2009+A2:2015, Table 1 (see the A-deviation in EN 253:2009+A2:2015, Annex G).
4.1.3 Wall thickness and diameter
According to the scope of this European Standard, all components shall be designed for a minimum of 16 bar.
NOTE: If the fitting assemblies have to be used in situations with pressures higher than 16 bar, extra calculations will be necessary.
The minimum nominal wall thickness of all components shall prior to processing be at least the same as for the straight pipes.
The nominal diameter, the outside diameter and the minimum nominal wall thickness shall be the same as for the straight pipes in accordance with EN 2S3:2009+A2:2015, Table 2. The tolerances on the outside diameter of the pipe ends shall be in accordance with EN 253:2009+A2:2015, Table 3.
Subject to design considerations other wall thicknesses than those given in EN 253:2009+A2:2015, Table 2 may be used, but in no case shaLl these be less than the minima indicated in EN 253:2009+A2:2015, Table 2.
All components shall be designed in accordance with EN 13941, for the actions and stresses that normally occur during a system’s entire service life.
4.1.4 Bends
4.14.1 Butt welding bends
The dimensions shall be in accordance with EN 10253-2 with the exception that the bend radius shall be  1,5 times the outer diameter.
4.1.4.2 Cold formed bends
Cold formed bends shall be produced from seamless pipe or longitudinal welded pipes. At cold formed bends made of longitudinal welded pipes the weld bead shall be welded to factor V = 1 (calculation stress = 100 %). After bending, the minimum wall thickness of the bent pipe shall be not less than 85 % of the nominal wall thickness of the straight pipe (see EN 253:2009+A2:2015, Table 2).
The maximum ovality In the bent area shall not exceed 6 %.