EN 448:2003
(Main)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
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
This European Standard 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 prEN 253.
This standard covers the following fittings: Bends, T-pieces, reducers and anchors.
This standard applies only to insulated fitting assemblies for continuous operation with hot water at various temperatures in accordance with clause 1 of prEN 253:2002.
Guidelines for quality inspection are given in annex A of this standard.
Procedures for PE-welding are given in annex B of this standard.
NOTE This standard does not include rules for calculation of loads and stresses.
Fernwärmerohre - Werkmäßig gedämmte Verbundmantelrohrsysteme für direkt erdverlegte Fernwärmenetze - Verbund-Formstücke, bestehend aus Stahl-Mediumrohr, Polyurethan-Wärmedämmung und Außenmantel aus Polyethylen
Tuyaux de chauffage urbain - Systèmes bloqués de tuyaux pré-isolés pour les réseaux d'eau chaude enterrés directement - Raccords pré-isolés en acier pour tubes de service en acier, isolation thermique en polyuréthane et tube de protection en polyéthylène
La présente Norme européenne définit les prescriptions et les méthodes d'essai applicables aux raccords des systèmes préfabriqués de tubes isolés thermiquement pour les réseaux d'eau chaude enterrés directement, comprenant des raccords de service en acier de DN 20 à DN 1 200, une isolation en mousse rigide de polyuréthane et un tube de protection en polyéthylène
La présente norme couvre les raccords suivants : les coudes, les tés, les réductions et les pièces d'ancrage.
La présente norme s'applique uniquement aux assemblages de raccords isolés par mousse de polyuréthanne utilisés en service continu avec de l'eau chaude à diverses températures conformément à l'article 1 du prEN 253:2002.
Des lignes directrices sur l'inspection de la qualité sont donnés en annexe A de la présente norme.
Des procédures sur le soudage du PE sont données en annexe B de la présente norme.
NOTE La présente norme ne comporte pas les règles de calcul des charges et des contraintes.
Cevi za daljinsko ogrevanje – Izolirani vezani cevni sistemi za podzemeljska toplovodna omrežja – Sestav fitingov jeklenih cevi, poliuretanske toplotne izolacije in zunanjega polietilenskega plašča
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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.RG]HPHOMVNDFernwärmerohre - Werkmäßig gedämmte Verbundmantelrohrsysteme für direkt erdverlegte Fernwärmenetze - Verbund-Formstücke, bestehend aus Stahl-Mediumrohr, Polyurethan-Wärmedämmung und Außenmantel aus PolyethylenTuyaux de chauffage urbain - Systemes bloqués de tuyaux pré-isolés pour les réseaux d'eau chaude enterrés directement - Raccords pré-isolés en acier pour tubes de service en acier, isolation thermique en polyuréthane et tube de protection en polyéthyleneDistrict 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 polyethylene91.140.65Oprema za ogrevanje vodeWater heating equipment23.040.40Kovinski fitingiMetal fittings23.040.10Železne in jeklene ceviIron and steel pipesICS:Ta slovenski standard je istoveten z:EN 448:2003SIST EN 448:2004en01-oktober-2004SIST EN 448:2004SLOVENSKI
STANDARDSIST EN 448:20001DGRPHãþD
SIST EN 448:2004
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 448February 2003ICS 23.040.40Supersedes EN 448:1994English versionDistrict heating pipes - Preinsulated bonded pipe systems fordirectly buried hot water networks - Fitting assemblies of steelservice pipes, polyurethane thermal insulation and outer casingof polyethyleneTuyaux de chauffage urbain - Systèmes bloqués de tuyauxpré-isolés pour les réseaux d'eau chaude enterrésdirectement - Raccords pré-isolés en acier pour tubes deservice en acier, isolation thermique en polyuréthane ettube de protection en polyéthylèneFernwärmerohre - Werkmäßig gedämmteVerbundmantelrohrsysteme für direkt erdverlegteFernwärmenetze - Verbund-Formstücke, bestehend ausStahl-Mediumrohr, Polyurethan-Wärmedämmung undAußenmantel aus PolyethylenThis European Standard was approved by CEN on 28 November 2002.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Management Centre or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovak Republic, Spain, Sweden, Switzerland andUnited Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2003 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 448:2003 ESIST EN 448:2004
EN 448:2003 (E)2ContentspageForeword.4Introduction.51Scope.62Normative references.63Terms and definitions.74Requirements.84.1Steel parts.84.1.1Quality.84.1.2Wall thickness and diameter.84.1.3Bends.84.1.4T-pieces.94.1.5Reducers.94.1.6Anchors.94.1.7Fusion welding of steel fittings.104.1.8Surface condition.124.2Casing.124.3Polyurethane rigid foam insulation (PUR).124.4Fitting assemblies.124.4.1Fitting ends.124.4.2Angle between casing segments of bend and minimum length.134.4.3Requirements of polyethylene welding.134.4.4Leak-tightness of the welded casing pipe.154.4.5Increase in diameter of the casing pipe.164.4.6Minimum insulation thickness in bends.164.4.7Tolerances of the main fitting dimensions.165Test methods.175.1General.175.2Test specimens.175.3Steel parts.175.3.1Visual surface examination of welds.175.3.2Leak-tightness test with water.175.3.3Leak-tightness test with air.175.3.4Radiographic examination of butt welds.185.4Casing.185.5Polyurethane rigid foam insulation (PUR).185.6Fitting assemblies.185.6.1Centre line deviation and angular deviation.185.6.2Visual examination of welds on casing pipes.185.6.3Bending test.185.6.4Increase in diameter of the casing pipe.195.6.5Minimum insulation thickness.195.6.6Leak-tightness of casing pipe fittings.196Marking.206.1General.206.2Steel service pipe.206.3Casing.206.4Fitting assembly.20Annex A (informative)
Guidelines for inspection and testing.21SIST EN 448:2004
EN 448:2003 (E)3A.1Manufacturer’s type test.21A.2Manufacturer’s quality surveillance.21A.3External inspection.21A.4Extent of inspection.21A.5Manufacturer’s responsibility.21Annex B (informative)
Procedures for polyethylene welding.24B.1Introduction.24B.2Requirements for site, machine and equipment.24B.3Items.24B.4Butt fusion welding.25B.4.1Equipment.25B.4.2Welding procedure.26B.5Extrusion welding.26B.5.1Equipment.26B.5.2Welding procedure.27Bibliography.28SIST EN 448:2004
EN 448:2003 (E)4ForewordThis document (EN 448:2003) has been prepared by Technical Committee CEN/TC 107 "Prefabricated districtheating pipe systems", the secretariat of which is held by DS.This European Standard shall be given the status of a national standard, either by publication of an identical text orby endorsement, at the latest by August 2003, and conflicting national standards shall be withdrawn at the latest byAugust 2003.This document supersedes EN 448:1994.Annexes A and B are informative.This document includes a Bibliography.According to the CEN/CENELEC Internal Regulations, the national standards organizations of the followingcountries are bound implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal,Slovakia, Spain, Sweden, Switzerland and the United Kingdom.SIST EN 448:2004
EN 448:2003 (E)5IntroductionThe first edition of EN 448 was approved in 1994. The main areas of the revision are:¾ the title has been amended by ”District heating pipes”;¾ the term ”underground” has been changed to ”directly buried”;¾ the mentioning in the foreword of the production method ”injected (poured)” has been deleted;¾ service pipes with nominal diameters from DN 700 up to and including DN 1200 have been added and therequirements have been amended accordingly;¾ casings with nominal outside diameters from 900 mm up to and including 1 400 mm have been added and therequirements have been amended accordingly;¾ the minimum straight length of the casing at the ends of fittings has been changed to 200 mm;¾ the requirements for polyethylene welding have been changed;¾ annex B has been rewritten;¾ the former annex C has been omitted.This specification is part of the standards for bonded systems using polyurethane foam thermal insulation appliedto bond to a steel service pipe and a polyethylene casing.For information on the minimum expected thermal life with operation at various temperatures with respect to PURfoam performance see EN 253:2003, annex B.The other standards from TC 107 are:EN 253:2003, 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 488:2003, 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 489:2003, 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 13941:2003, Design and installation of preinsulated bonded pipe systems for district heating.NOTEThe following draft in connection with the above mentioned is under development:prEN 14416, District heating pipes – Preinsulated bonded pipe systems for directly buried hot water networks – Surveillancesystems.SIST EN 448:2004
EN 448:2003 (E)61 ScopeThis European Standard specifies requirements and test methods for fittings of prefabricated thermally insulatedpipe-in-pipe assemblies comprising a steel service fitting from DN 20 to DN 1200, rigid polyurethane foaminsulation and an outer casing of polyethylene for use in directly buried hot water networks with preinsulated pipeassemblies in accordance with EN 253.This standard covers the following fittings: bends, T-pieces, reducers and anchors.This standard applies only to insulated fitting assemblies for continuous operation with hot water at varioustemperatures in accordance with clause 1 of EN 253:2003.Guidelines for quality inspection are given in annex A of this standard.Procedures for PE-welding are given in annex B of this standard.NOTEThis standard does not include rules for calculation of loads and stresses.2 Normative referencesThis European Standard incorporates by dated or undated reference, provisions from other publications. Thesenormative references are cited at the appropriate places in the text, and the publications are listed hereafter. Fordated references, subsequent amendments to or revisions of any of these publications apply to this EuropeanStandard only when incorporated in it by amendment or revision. For undated references the latest edition of thepublication referred to applies (including amendments).EN 253:2003, 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 287-1, Approval testing of welders - Fusion welding – Part 1: Steels.EN 288-1:1992, Specification and qualification of welding procedures for metallic materials – Part 1: General rulesfor fusion welding.EN 1418, Welding personnel – Approval testing of welding operators for fusion welding and resistance weld settersfor fully mechanized and automatic welding of metallic materials.EN 10216-2, Seamless steel tubes for pressure purposes - Technical delivery conditions - Part 2: Non-alloy andalloy steel tubes with specified elevated temperature properties.EN 10217-2, Welded steel tubes for pressure purposes - Technical delivery conditions - Part 2: Electric weldednon-alloy and alloy steel tubes with specified elevated temperature properties.EN 10217-5, Welded steel tubes for pressure purposes - Technical delivery conditions - Part 5: Submerged arcwelded non-alloy and alloy steel tubes with specified elevated temperature properties.EN 12814-1, Testing of welded joints of thermoplastics semi-finished products – Part 1: Bend test.EN 25817:1992, Arc-welded joints in steel - Guidance on quality levels for imperfections (ISO 5817:1992).ISO 1106-3, Recommended practice for radiographic examination of fusion welded joints – Part 3: Fusion weldedcircumferential joints in steel pipes of up to 50 mm wall thickness.ISO 3419:1981, Non-alloy and alloy steel butt welding fittings.ISO 6761, Steel tubes - Preparation of ends of tubes and fittings for welding.SIST EN 448:2004
EN 448:2003 (E)73 Terms and definitionsFor the purposes of this European Standard, the terms and definitions given in EN 253:2003 together with thefollowing apply.3.1cold formed bendmanufactured by cold bending of steel pipes3.2butt welding bendmanufactured either by hot bending of steel pipes or by hot forming of steel plates which are subsequently weldedtogether3.3bending angle, adeviation in direction of the steel pipe centre lines3.4forged T-piecemanufactured by hot forming of either steel pipes or steel plates which are subsequently welded together3.5welding saddlebutt welding fitting to be welded into the main pipe for the welded connection between the main pipe and thebranch pipe in a T-piece3.6welded T-piecemanufactured by welding together pieces of steel pipes with or without the use of a welding saddle or a drawncollar on the main pipeKey3.1
Cold formed bend3.2
Butt welding bend3.3
Bending angle, a3.4
Forged T-piece3.5
T-piece with welding saddle3.6a
T-piece with drawn collar3.6b
Directly welded T-pieceFigure 1 — ExamplesSIST EN 448:2004
EN 448:2003 (E)83.7reducerbutt welding fitting to be welded between two steel pipes of different diameters3.8anchorsteel construction used to transfer the axial load from the steel service pipe through the insulation and the casing toa fixed point4 Requirements4.1 Steel parts4.1.1 QualityThe material shall be in accordance with 4.2.1 of EN 253:2003.4.1.2 Wall thickness and diameterThe minimum nominal wall thickness of pipes and butt welding fittings shall prior to processing be at least the sameas for the straight pipes.The nominal diameter, the outside diameter and the minimum nominal wall thickness shall be the same as for thestraight pipes in accordance with Table 1 of EN 253:2003. The tolerances on the outside diameter of the pipe endsshall be in accordance with Table 2 of EN 253:2003.Subject to design considerations other wall thicknesses than those given in Table 1 of EN 253:2003 may be used,but in no case shall these be less than the minima indicated in Table 1 of EN 253:2003.4.1.3 Bends4.1.3.1 Butt welding bendsThe dimensions shall be in accordance with 6.1.2 of ISO 3419:1981 with the exception that the bend radius shallbe ³ 1,5 times the outer diameter. See also prEN 13941.4.1.3.2 Cold formed bendsCold formed bends shall be produced from seamless pipe or longitudinal welded pipes. At cold formed bends madeof longitudinal welded pipes the weld bead shall be positioned in a 45° angle to the bending plane.After bending, the minimum wall thickness of the bent pipe shall be not less than 85 % of the nominal wallthickness of the straight pipe (see Table 1 of EN 253:2003).The maximum ovality o in the bent area shall not exceed 6 %.The formula for the calculation of the ovality is:100´-=sDDDmin smax sowhereDs max is the maximum outside diameter;Ds min is the minimum outside diameter in the same cross section in the bended area;SIST EN 448:2004
EN 448:2003 (E)9Ds is the specified outside diameter.There shall be no folding in the bent area. Waves can be accepted, when the maximum height between trough andcrest of the wave does not exceed 25 % of the nominal wall thickness of the bent pipe.4.1.3.3 Tolerances of bending anglesThe deviation from the nominal bending angle shall not exceed the tolerances given in Table 1.Table 1 — Deviations from nominal bending angleNominal diameter ofservice pipeDeviation£ DN 200± 2,0°> DN 200± 1,0°4.1.4 T-pieces4.1.4.1 Forged T-piecesThe wall thicknesses T and T1 - see Figure 4 of ISO 3419:1981 - shall be at least the same as those for the straightpipes (see Table 1 of EN 253:2003). All other dimensions shall be in accordance with 6.1.4 of ISO 3419:1981.4.1.4.2 Welding saddlesWelding saddles shall be of the type which shall be welded into the wall of the main pipe.The wall thicknesses of the welding saddles shall be at least the same as the wall thicknesses of the main pipesand the branch pipes which shall be welded to the saddles.4.1.4.3 Welded T-piecesWelded T-pieces shall be manufactured either by using welding saddles or by drawing a collar on which the branchpipe is welded or by welding the branch pipe directly to the main pipe. The wall thickness of the collar shall be atleast the same as that for the branch pipe (see Table 1 of EN 253:2003).The collar shall be drawn opposite the welding seam in the main pipe.4.1.4.4 Tolerances of angles between branch pipes and main pipesThe branch pipes shall be perpendicular to the main pipes within a tolerance of ± 2,0°.4.1.5 ReducersReducers shall be in accordance with 6.1.3 of ISO 3419:1981, except for the wall thicknesses T and T1 - seeFigure 3 of ISO 3419:1981 - which shall be at least the same as for the straight pipes (see Table 1 of EN 253:2003)to be welded to the fittings.4.1.6 AnchorsThe wall thickness of the pipe shall be at least the same as for the straight pipe (see Table 1 of EN 253:2003).SIST EN 448:2004
EN 448:2003 (E)104.1.7 Fusion welding of steel fittings4.1.7.1 Filler materialFiller material shall after welding have mechanical characteristics comparable with the parent metal.4.1.7.2 Welding processAll types of fusion welding are acceptable but arc welding with covered electrodes and gas-shielded metal-arcwelding are preferred. The welding process shall be specified in accordance with clause 4 of EN 288-1:1992 andapproved in accordance with 5.1.1 of EN 288-1:1992.The method of approval may be chosen by the manufacturer.Fittings of diameter ³ 300 mm shall be welded in more than one pass.4.1.7.3 Preparation for weldingPipe ends shall be prepared in accordance with the welding procedure used. When using covered electrodes orgas-shielded metal-arc welding, pipe ends and fittings shall be prepared in accordance with ISO 6761 andFigure 2.Figure 2 — Adaptation of inside diameterThe difference between average diameter of the 2 pipe or fittings ends to be welded together shall not exceed avalue of 0,66 times pipe wall thickness; if the pipes and fittings have different wall thicknesses, a value of0,66 times T in accordance with Figure 2 applies.When manufacturing T-pieces with the branch pipe welded directly to the main pipe, preparations shall comply withFigure 3.SIST EN 448:2004
EN 448:2003 (E)11Key1
Section X at crotch of right angle branch.2
Section Y at flank of unequal branch. Ratios ofdiameters £ 2/3.3
Section Y at flank of unequal branch. Ratios ofdiameters > 2/3.4
Section W at flank of equal branch.Figure 3 — Preparation of set-on branches4.1.7.4 Inspection of weldsA.Visual surface examinationWhen visual surface examination is carried out, it shall be in accordance with 5.3.1. The welding shall comply with"quality level B" of EN 25817:1992.B.Leak tightness testWhen a leak-tightness test is carried out in accordance with 5.3.2 or 5.3.3, the welds shall fulfill the conditionsstated there.C.Radiographic examination of butt weldsWhen radiographic examination is carried out, it shall be in accordance with 5.3.4. The weld shall comply with"quality level B” of EN 25817:1992.SIST EN 448:2004
EN 448:2003 (E)124.1.7.5 Competence of the welderThe welder shall be qualified in accordance with EN 287-1 for the techniques, material groups, dimension rangesand welding position concerned. Welding personnel operating mechanized welding equipment shall be qualified inaccordance with EN 1418.NOTEIn order to prove this qualification, it is recommended to certify the personnel in accordance with EN 287-1.4.1.8 Surface conditionThe surface conditions before applying the foam shall be in accordance with 4.2.4 of EN 253:2003.4.2 CasingThe casings shall meet the requirements of 4.3 of EN 253:2003 with the following exception:Prior to foaming, the minimum wall thickness, emin , of the casing pipe shall be in accordance with Table 5 ofEN 253:2003, with a minimum of 3 mm.The casing shall be tested in accordance with 5.4 of this standard.4.3 Polyurethane rigid foam insulation (PUR)The polyurethane rigid foam insulation for fitting assemblies shall meet the requirements of 4.4, 4.5.4 and 4.5.5 ofEN 253:2003 and shall be tested in accordance with 5.5 of this standard.Test specimens from fitting assemblies to establish foam properties shall be taken in accordance with 5.2 of thisstandard.4.4 Fitting assemblies4.4.1 Fitting ends4.4.1.1 Service pipeThe ends of the service pipe shall be prepared for welding in accordance with ISO 6761 and shall be free frominsulation for a minimum length of 150 mm. The tolerance on the declared value shall be ± 10 mm.4.4.1.2 Centre line deviationWhen tested in accordance with 5.6.1 the distance between centre lines of the service pipe and the casing at fittingends shall not exceed the limits given in Table 2.Table 2 — Centre line deviation related to the nominal diametersNominal outside diameter of PE pipemmMaximum centre line deviationmm
75 to 160180 to 400450 to 630710 to 800900 to 1 4003,05,08,010,014,0SIST EN 448:2004
EN 448:2003 (E)134.4.1.3 Angular deviation between service pipe and casingWhen tested in accordance with 5.6.1, the angular deviation between centre lines of the uninsulated end of theservice 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 lengthThe maximum angle, a, between two adjacent segments of the casing of a bend shall not exceed 45°, seeFigure 4.The length, L, see Figure 4, of the casing at the ends of the fittings shall not be less than 200 mm.Key1
a £ 45° with minimum 2 segments2
a £ 45° with minimum 3 segmentsFigure 4 — Segmental casing pipe bends4.4.3 Requirements of polyethylene welding4.4.3.1 GeneralThe quality of a PE weld cannot easily be tested with non-destructive methods.The observation of proper working procedures shall assure that the welds are leak-tight.The welding process should, therefore, be performed according to a documented procedure in accordance withannex B or its equivalent.4.4.3.2 Melt flow rateThe melt flow rate of the pipes to be welded shall not differ more than 0,5 g/10 min when determined in accordancewith 4.3.1.2 of EN 253:2003.SIST EN 448:2004
EN 448:2003 (E)144.4.3.3 Visual appearanceAll welds shall be examined in accordance with 5.6.2. The following requirements shall be fulfilled:Butt fusion welding¾ The valley between the weld beads shall not go beneath the pipe surface.¾ The permitted butt misalignment shall not exceed 20 % of the wall thickness on the entire seam length. Ondifficult fittings such as extruded tees a butt misalignment of up to 30 % and the resul
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