NEN EN 13941 : 2009 + A1 2010

Foreword
1 Scope
2 Normative references
3 Units and symbols
  3.1 Units
  3.2 Symbol
4 Terms and definitions
5 General considerations for system design
  5.1 General requirements
  5.2 Service life
  5.3 Preliminary investigations
  5.4 Determination of project class
       5.4.1 Risk assessment
       5.4.2 Project classes
  5.5 Design documentation
       5.5.1 General
       5.5.2 Operational data
       5.5.3 Data related to the pipeline
       5.5.4 Specifications for quality control
6 Components and materials
  6.1 Basic requirements
       6.1.1 Non standardised components
  6.2 Steel pipe components
       6.2.1 General
       6.2.2 Documentation
       6.2.3 Characteristic values for steel
       6.2.4 Specific requirements for bends and tees
       6.2.5 Specific requirements for reducers and extensions
       6.2.6 Specific requirements for other components
  6.3 Polyurethane foam insulation
  6.4 PE casing
  6.5 Expansion cushions
  6.6 Valves and accessories
       6.6.1 General requirements
       6.6.2 Marking and documentation
7 Action and limit states
  7.1 General
  7.2 Simplified analysis procedure
  7.3 Actions
       7.3.1 General
       7.3.2 Classification of actions
  7.4 Limit states
       7.4.1 General
       7.4.2 Limit states for service pipes of steel
       7.4.3 Composite stress conditions
       7.4.4 Limit states for PUR and PE
8 Installation
  8.1 General
  8.2 Transportation and storage
  8.3 Excavation of pipe trench
  8.4 Installation of pipes and components
       8.4.1 General
       8.4.2 Steel pipes
       8.4.3 PUR-PE Joints
       8.4.4 Accessories
       8.4.5 Expansion zones
  8.5 Welding of the steel pipe and testing of the steel welds
       8.5.1 General
       8.5.2 Quality system for the different project classes
       8.5.3 Qualification of the welding procedures
       8.5.4 Welding consumables
       8.5.5 Place and position of the weld
       8.5.6 Performance of welding work
       8.5.7 Special procedures
       8.5.8 Inspection of the weld joint
       8.5.9 Documentation
  8.6 Strength pressure test and leak tightness test
  8.7 Assembly of casing pipes, joint installation and site insulation
  8.8 Backfilling of trench
  8.9 Pipe bends and other components
       8.9.1 Pipe bends
       8.9.2 Branches
       8.9.3 Valves and accessories
  8.10 Setting into operation
       8.10.1 General
       8.10.2 Filling with water for initial operation
       8.10.3 Surveillance system
  8.11 Special constructions
       8.11.1 Special components
       8.11.2 Above-ground pipelines with preinsulated pipes
       8.11.3 Insertion into casing pipe
  8.12 Construction work during the operation stage
Annex A (normative) Design of piping components under internal pressure
        A.1 General
        A.2 Symbols
        A.3 Straight pipe and bends
        A.4 Tees and branch connections
        A.5 Reducers and extensions
        A.6 Dished ends
Annex B (informative) Geotechnics and pipe-soil interaction
        B.1 Scope
        B.2 Symbols and units
        B.3 Soil parameters for global analysis (pipe-soil interaction)
        B.4 Characteristic values for soil loads and soil parameters
        B.5 Specific requirements for stability
        B.6 Specific requirements for parallel excavations
        B.7 Requirements for soft soils and settlement areas
Annex C (informative) Global- and cross sectional analysis
        C.1 General
        C.2 Symbols
        C.3 Survey of limit states for steel
        C.4 Locations to be assessed
        C.5 Actions
        C.6 Global analysis
        C.7 Calculation of stresses
        C.8 Fatigue analysis
        C.9 Further actions
Annex D (informative) Calculation of heat losses
        D.1 General
        D.2 Heat loss per pipe pair
        D.3 Insulance of the soil
        D.4 Insulance of the insulation material
        D.5 Insulance of the heat exchange between flow and return pipe
Bibliography

Defines rules for design, calculation and installation for preinsulated bonded pipe systems for buried hot water distribution and transmission networks with pipe assemblies in accordance with EN 253, for continuous operation with hot water at various temperatures up to 120 degrees C and occasionally with peak temperatures up to 140 degrees C and maximum internal pressure 25 bar (overpressure).