BS EN 253:2009 pdf download – 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

BS EN 253:2009 pdf download – 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 The carbon black shall be finely dispersed in the material. When tested in accordance with 5.2.3,the followingrequirements shall be met: Carbon black agglomerates, bubbles, voids or foreign matter shall not exceed 100 um in diameter. No white orblack stripes or smears may occur. 4.3.1.2 Melt mass-flow rate The melt mass-flow rate(MFR), in g/10 min, of black PE materials used for the manufacturing of casings shall liewithin 0,2≤MFR≤ 1,4 g/10 min determined in accordance with EN ISO1133,condition T(5kg,190 °C). Black coloured PE materials conforming to 4.3.1.1,which do not differ more than 0,5 g/10 min in MFR shall beconsidered fusible to each other. Casings made of PE materials outside this MFR range of 0,5 g/10 min may be fusion welded provided that the pipemanufacturer has demonstrated fusion compatibility by preparing a but fusion joint using the parameters asspecified in Annex A of lS0 11414:1996.The requirement of fusion compatibility is a ductile failure mode of the jointwhen tested at 23 C in accordance with lSo 13953. 4.3.1.3 Thermal stability The thermal stability is determined by oxygen induction time (OIT) of the black coloured PE material and shall be atleast 20 min when tested at 210C according to EN 728. 4.3.1.4 Use of rework material Only clean,not degraded, rework material, generated from the manufacturer’s own production of pipes, shall beused. 4.3.2Casing properties 4.3.2.1 Nominal outside diameter The nominal outside diameter of the casing should be selected from Table 5. The actual outside diameter shall be measured in accordance with EN ISO 3126. 4.3.2.2Wall thickness The wall thickness of the casing shall be in accordance with Table 5. The actual wall thickness shall be measured in accordance with EN ISO 3126. 4.3.2.3 Appearance, surface finish, pipe ends The internal and external surfaces 1) of the casing pipe shall be clean and free from such grooving or other defects that might impair its functional properties (see 5.2.1). The pipe ends shall be cleanly cut and shall be square within 2,5° with the axis of the pipe. 4.3.2.4 Elongation at break The elongation at break determined in accordance with 5.2.2 shall not be less than 350 %. The test is to be applied only on casings that are produced partly or fully...