NEN EN 448 : 2015
Withdrawn
A Withdrawn Standard is one, which is removed from sale, and its unique number can no longer be used. The Standard can be withdrawn and not replaced, or it can be withdrawn and replaced by a Standard with a different number.
A Withdrawn Standard is one, which is removed from sale, and its unique number can no longer be used. The Standard can be withdrawn and not replaced, or it can be withdrawn and replaced by a Standard with a different number.
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
10-01-2019
01-12-2013
Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 Requirements
4.1 Steel parts
4.1.1 Quality
4.1.2 Wall thickness and diameter
4.1.3 Bends
4.1.4 T-pieces
4.1.5 Reducers
4.1.6 Anchors
4.1.7 Fusion welding of steel fittings
4.1.8 Surface condition
4.2 Casing
4.3 Polyurethane rigid foam insulation (PUR)
4.4 Fitting assemblies
4.4.1 Fitting ends
4.4.2 Angle between casing segments of bend and
minimum length
4.4.3 Requirements of polyethylene welding
4.4.4 Leak-tightness of the welded casing pipe
4.4.5 Increase in diameter of the casing pipe
4.4.6 Minimum insulation thickness in bends
4.4.7 Tolerances of the main fitting dimensions
5 Test methods
5.1 General
5.2 Test specimens
5.3 Steel parts
5.3.1 Visual surface examination of welds
5.3.2 Leak-tightness test with water
5.3.3 Leak-tightness test with air
5.3.4 Radiographic examination of butt welds
5.4 Casing
5.5 Polyurethane rigid foam insulation (PUR)
5.6 Fitting assemblies
5.6.1 Centre line deviation and angular deviation
5.6.2 Visual examination of welds on casing pipes
5.6.3 Bending test
5.6.4 Increase in diameter of the casing pipe
5.6.5 Minimum insulation thickness
5.6.6 Leak-tightness of casing pipe fittings
6 Marking
6.1 General
6.2 Steel service pipe
6.3 Casing
6.4 Fitting assembly
Annexes
A (informative) Guidelines for inspection and testing
A.1 Manufacturer's type test
A.2 Manufacturer's quality surveillance
A.3 External inspection
A.4 Manufacturer's responsibility
B (informative) Procedures for polyethylene welding
B.1 Introduction
B.2 Requirements for site, machine and equipment
B.3 Items
B.4 Butt fusion welding
B.4.1 Equipment
B.4.2 Welding procedure
B.5 Extrusion welding
B.5.1 Equipment
B.5.2 Welding procedure
Bibliography
Access your standards online with a subscription
Features
-
Simple online access to standards, technical information and regulations.
-
Critical updates of standards and customisable alerts and notifications.
-
Multi-user online standards collection: secure, flexible and cost effective.