BS EN 448:2009 pdf free download – District heating pipes – Preinsulated bonded pipe systems for directly buried hot water networks一 Fitting assemblies of steel service pipes, polyurethane thermal insulation and outer casing of polyethylene.
4.1.9.4 Inspection of welds
4.1.9.4.1 Detail A — Visual surface examination
When visual surface examination is carried out, it shall be in accordance with 5.3.1. The examinations include a
check of surface, internal, joint geometry and multiple imperfections. The welding shall comply with “quality level B”
of EN-ISO 5817.
4.1.9.4.2 Detail B — Leak tightness test
When a leak-tightness test is carried out in accordance with 5.3.2 or 5.3.3, the welds shall fulfil the conditions
stated there.
4.1.9.4.3 Detail C — Non destructive examination of welds
When non destructive is carried out, it shall be in accordance with 5.3.4. The weld shall comply with “quality level B” of EN-ISO 5817.
4.1.9.5 Competence of the welder
The welder shall be qualified in accordance with EN 287-1 for the techniques, material groups, dimension ranges and welding position concerned. Welding personnel operating mechanized welding equipment shall be qualified in accordance with EN 1418.
NOTE In order to prove this qualification, it is recommended to certify the personnel in accordance with EN 287-1.
4.1.10 Surface condition
In order to ensure proper bonding between the steel service pipe and the PUR-foam insulation, the following procedure shall be followed:
1) prior to insulation, the outer surface of the pipe shall be cleaned so that it is free from rust, mill scale, oil, grease, dust, paint, moisture and other contaminants;
2) before cleaning the pipe, the outer surface of the pipe shall comply with rust grade A, B or C according to ISO 8501-1, without pitting.
4.2 Casing
The casings shall meet the requirements of EN 253:2009, Clause 4.3.
The casing shall be tested in accordance with 5.4 of this European Standard.
4.3 Polyurethane rigid foam insulation (PUR)
The polyurethane rigid foam insulation for fitting assemblies shall meet the requirements of EN 253:2009, Clauses
4.4, 4.5.5 and 4.5.6 and shall be tested in accordance with 5.5 of this European Standard.
Test specimens from fitting assemblies to establish foam properties shall be taken in accordance with 5.2 of this
European Standard.
4.4 Fitting assemblies
4.4.1 Fitting ends
4.4.1.1 Service pipe
The ends of the service pipe shall be prepared for welding in accordance with EN ISO 9692-1:2003 and shall be free from insulation for a minimum length of 150 mm. The tolerance on the declared value shall be ± 10 mm.
4.4.1.2 Centre line deviation
When tested in accordance with 5.6.1 the distance between centre lines of the service pipe and the casing at fitting ends shall not exceed the limits given in EN 253:2009, Table 7.
4.4.1.3 Angular deviation between service pipe and casing
When tested in accordance with 5.6.1, the angular deviation between centre lines of the not insulated end of the service pipe, and the casing at a length of 100 mm from the end, shall not exceed 2°.
4.4.2 Angle between casing segments of bend and minimum length
The maximum angle, a, between two adjacent segments of the casing of a bend shall not exceed 45°, see Figure 4. The length, I, see Figure 4, of the casing at the ends of the fittings shall not be less than 200 mm.