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BS EN 13941-1:2019+A1:2021 District heating pipes. Design and installation of thermal insulated bonded single and twin pipe systems for directly buried hot water networks - Design, 2022
- undefined
- 1 Scope
- 2 Normative references
- 3 Terms and definitions, units and symbols [Go to Page]
- 3.1 Terms and definitions [Go to Page]
- 3.1.1 Symbols
- 3.1.2 Abbreviations
- 4 General requirements [Go to Page]
- 4.1 Functional requirements
- 4.2 Service life
- 4.3 Preliminary investigations
- 4.4 Determination of project class [Go to Page]
- 4.4.1 Risk assessment
- 4.4.2 Project classes
- 4.5 Design documentation [Go to Page]
- 4.5.1 General
- 4.5.2 Operational data
- 4.5.3 Data related to the pipe system
- 4.6 Route selection and positioning of the pipes [Go to Page]
- 4.6.1 Minimum distances between parallel pipes
- 4.6.2 Parallel excavations and works of third parties
- 4.6.3 Minimum distance between district heating pipes and underground structures
- 4.7 Venting and draining
- 4.8 Valves
- 4.9 Procurement of materials [Go to Page]
- 4.9.1 Manufacturer of pipeline components
- 4.10 Quality control [Go to Page]
- 4.10.1 General
- 4.10.2 Design phase
- 4.10.3 Installation phase [Go to Page]
- 4.10.3.1 General
- 4.10.3.2 Companies performing assembly of casing joints and PE welding on casings
- 5 Requirements for components and materials [Go to Page]
- 5.1 Basic requirements
- 5.2 Steel service pipe components [Go to Page]
- 5.2.1 General
- 5.2.2 Specification
- 5.2.3 Characteristic values for steel [Go to Page]
- 5.2.3.1 Steels with specified elevated temperature properties
- 5.2.3.2 Steels without specified elevated temperature properties
- 5.2.3.3 Elasticity modulus (E) and linear thermal expansion coefficient (α) at elevated temperatures
- 5.2.4 Specific requirements for bends and T-pieces [Go to Page]
- 5.2.4.1 General
- 5.2.4.2 Bends
- 5.2.4.3 T-pieces
- 5.2.5 Specific requirements for small angular deviations
- 5.2.6 Specific requirements for reducers
- 5.3 Polyurethane foam thermal insulation
- 5.4 Casing
- 5.5 Materials for casing and thermal insulation of field joints
- 5.6 Expansion cushions [Go to Page]
- 5.6.1 General
- 5.6.2 Materials
- 5.6.3 Stiffness properties
- 5.6.4 Selecting required thickness of expansion cushions
- 5.6.5 Marking
- 5.7 Valves and accessories [Go to Page]
- 5.7.1 General requirements
- 5.7.2 Marking and documentation
- 6 Design and calculation [Go to Page]
- 6.1 General procedure
- 6.2 Pipeline components, areas, conditions and interfaces to be included in the analyses [Go to Page]
- 6.2.1 Components
- 6.2.2 Areas requiring specific analyses
- 6.2.3 Special conditions
- 6.2.4 Interfaces
- 6.3 Simplified analysis procedure
- 6.4 Actions [Go to Page]
- 6.4.1 General
- 6.4.2 Classification of actions and load combinations
- 6.4.3 Temperature variations
- 6.4.4 Top load from soil
- 6.4.5 Traffic loads [Go to Page]
- 6.4.5.1 General
- 6.4.5.2 Effect of road constructions in reducing traffic loads
- 6.5 Global analysis and pipe-soil interaction [Go to Page]
- 6.5.1 General
- 6.5.2 Modelling pipe-soil interaction [Go to Page]
- 6.5.2.1 General
- 6.5.2.2 Flexibility of pipe components
- 6.5.3 Pipe to soil friction (axial) [Go to Page]
- 6.5.3.1 General
- 6.5.3.2 Friction coefficient
- 6.5.3.3 Axial friction at horizontal directional drillings (HDD) in the operational phase
- 6.5.3.4 Axial friction at horizontal directional drillings (HDD) in the installation phase
- 6.5.4 Horizontal soil reaction (lateral) [Go to Page]
- 6.5.4.1 General
- 6.5.4.2 Influence of large depths or stiff street cover
- 6.5.5 Combined lateral stiffness of steel service pipe, PUR, expansion cushions and soil
- 6.5.6 Soil properties
- 6.5.7 Thermal expansion of buried pipe sections:
- 6.5.8 Pipe systems with single use compensators (SUC’s)
- 6.5.9 Specific requirements for vertical and horizontal stability [Go to Page]
- 6.5.9.1 General
- 6.5.9.2 Vertical stability
- 6.5.9.3 Horizontal stablity
- 6.5.10 Parallel excavations [Go to Page]
- 6.5.10.1 General
- 6.5.10.2 Reduced friction
- 6.5.11 Requirements for soft soils and settlement areas [Go to Page]
- 6.5.11.1 General
- 6.5.11.2 Differential settlements
- 6.5.12 Specific design requirements for above-ground pipelines with factory made pipe and fitting assemblies
- 6.5.13 Insertion into protection pipe
- 6.6 Determination of stresses and strains [Go to Page]
- 6.6.1 General
- 6.6.2 Cross section analyses, steel
- 6.6.3 Assessment on the basis of a resultant (equivalent) stress
- 6.6.4 Stresses and ovalization from top load [Go to Page]
- 6.6.4.1 Circumferential stresses due to vertical load
- 6.6.4.2 Directly transmitted vertical load
- 6.6.4.3 Horizontal soil pressure, resulting from global analyses
- 6.6.4.4 Horizontal support pressure from trench backfill compaction
- 6.6.5 Deflection
- 6.6.6 Bends
- 6.6.7 T-pieces
- 6.6.8 Single Use Compensators (SUC’s)
- 6.6.9 PUR and casing
- 6.7 Fatigue analyses [Go to Page]
- 6.7.1 General
- 6.7.2 Action cycles
- 6.8 Further actions
- 7 Limit states [Go to Page]
- 7.1 General
- 7.2 Limit states for service pipes of steel [Go to Page]
- 7.2.1 General
- 7.2.2 Limit state A: Failure caused by plastic deformation [Go to Page]
- 7.2.2.1 General
- 7.2.2.2 Limit state A1: Ultimate limit state for force controlled actions (load bearing capacity)
- 7.2.2.3 Limit state A2: Ultimate limit state reached by stepwise plastic deformation caused by cyclical actions
- 7.2.3 Limit state B: Failure caused by fatigue [Go to Page]
- 7.2.3.1 General
- 7.2.3.2 Limit state B1:SN curves for low cycle fatigue (repeated yielding)
- 7.2.3.3 Fatigue strength data, detailed design
- 7.2.4 Limit state C: Failure caused by instability of the system or part of it [Go to Page]
- 7.2.4.1 General
- 7.2.4.2 Limit state C1: Local buckling (folding)
- 7.2.4.3 Limit state C2: Global instability (flexural buckling and loss of equilibrium of the pipeline system)
- 7.2.5 Limit state D: Serviceability limit state [Go to Page]
- 7.2.5.1 General
- 7.2.5.2 Ovalisation
- 7.2.6 Survey of limit states for steel
- 7.3 Limit states for PUR and PE [Go to Page]
- 7.3.1 Compressive stress
- 7.3.2 Limit state for !axial" shear stress
- 7.3.3 Limit state for PE
- 7.4 Limit states for valves
- Annex A (normative)Design of piping components under internal pressure [Go to Page]
- A.1 General
- A.2 Straight pipe and bends [Go to Page]
- A.2.1 Straight pipes
- A.2.2 Bends
- A.3 T-pieces and branch connections [Go to Page]
- A.3.1 General aspects and limitations
- A.3.2 Reinforcement [Go to Page]
- A.3.2.1 General
- A.3.2.2 Dissimilar material of shell and reinforcement
- A.3.2.3 Thickness ratio
- A.3.2.4 Calculation method for reinforcement area
- A.3.2.5 Reinforcement by increased wall thickness
- A.3.2.6 Reinforcement by compensating plates
- A.4 Reducers and extensions
- A.5 Dished ends [Go to Page]
- A.5.1 General
- A.5.2 Ellipsoidal Dished Head Minimum required wall thickness for internal pressure
- A.5.3 Straight cylindrical shells
- Annex B (informative)Soil properties and geotechnical parameters for pipe/soil interaction analyses [Go to Page]
- B.1 General requirements
- B.2 Geotechnical parameters for global analysis (pipe-soil interaction)
- B.3 Geotechnical Study [Go to Page]
- B.3.1 Field study
- B.3.2 Typical values, referred to mean value
- B.3.3 Investigation of interface friction
- B.4 Characteristic values for soil properties [Go to Page]
- B.4.1 Typical values, referred to mean value
- B.4.2 Spatial variation of soil properties
- B.5 Model uncertainty when determining geotechnical parameters
- Annex C (informative)Flexibility and stress concentration of pipe components [Go to Page]
- C.1 General
- C.2 Flexibility factors for pipe components [Go to Page]
- C.2.1 Bends
- C.2.2 T-pieces
- C.2.3 Other components
- C.3 Stress concentration in pipe elements [Go to Page]
- C.3.1 Butt welds
- C.3.2 Bends [Go to Page]
- C.3.2.1 Stress concentration factors for bends: Simplified method
- C.3.2.2 Stress concentration factors for bends: exact calculation
- C.3.3 T-pieces [Go to Page]
- C.3.3.1 General
- C.3.4 Small angular deviations
- C.3.5 Reducers
- Annex D (informative)Calculation of heat losses [Go to Page]
- D.1 General
- D.2 Heat losses of thermal insulated pipes [Go to Page]
- D.2.1 Pair of single pipes — calculation of specific heat loss
- D.2.2 symmetrical and (a) antisymmetrical heat loss factors according to zero-order multipole formulae:
- D.2.3 Using Zero-order approximation for (s) symmetrical and (a) antisymmetrical problem the heat resistance can be calculated:
- D.2.4 specific heat loss of pipes
- D.2.5 Twin Pipes — calculation of specific heat loss
- D.2.6 temperatures of pipes
- D.2.7 (s) symmetrical and (a) antisymmetrical heat loss factors according to first-order multipole formula:
- D.2.8 specific heat loss of pipes
- Annex E (informative)Specific requirements for twin pipe systems [Go to Page]
- E.1 General
- E.2 Component and materials [Go to Page]
- E.2.1 Twin Pipe assembly
- E.2.2 Fixing bars
- E.3 Max. allowable stresses for specific twin pipe system elements: [Go to Page]
- E.3.1 Project classes
- E.3.2 Soil friction, twin pipe friction length and pipe expansion
- E.3.3 Axial stress in the flow and return steel service pipes
- E.3.4 Dimensions of the fixing bars [Go to Page]
- E.3.4.1 General
- E.3.4.2 loads on the fixing bars type A
- E.3.4.3 loads on the fixing bar type B
- E.3.5 Stress proof of the fixing bar
- E.3.6 Proof of the welds
- E.3.7 Vertical and horizontal stability of the twin pipe assembly in the soil
- E.3.8 Stress concentration factors for bends, T-pieces
- E.3.9 Fatigue
- E.4 Installation requirements [Go to Page]
- E.4.1 Installation methods:
- E.4.2 Straight pipe section terminations:
- E.4.3 Use of insulated twin pipe valves:
- E.4.4 Use of transition assembly (twin pipe — single pipe):
- E.4.5 requirements for welding and testing of steel service pipe joints:
- Annex F (normative)Compressive testing of expansion cushions
- Annex G (informative)Principles for determination of bending moments and axial forces for testing of district heating valves [Go to Page]
- G.1 Introduction
- G.2 General considerations for determination of test values for bending moments
- G.3 Determination of bending moments from soil settlements
- G.4 Calculation results and evaluation
- G.5 Resistance to axial forces
- Annex H (informative)Scope of EN 13941 in relation to Pressure Equipment Directive (PED), 2014/68/EU, May 15th, 2014 [Go to Page]
- H.1 General
- H.2 Guidelines
- Annex I (informative)Quality control program and documentation
- Annex J (informative)Casing: Formulas for Miner Rule
- Annex K (informative)Strength calculation of horizontal directional drillings [Go to Page]
- K.1 Introduction
- K.2 Determination of pulling forces [Go to Page]
- K.2.1 Pulling force, resulting from the roller system
- K.2.2 Pulling force, resulting from a straight section of borehole
- K.2.3 Pulling force, resulting from curved sections of the borehole [Go to Page]
- K.2.3.1 General friction force
- K.2.3.2 Friction resulting from elastic soil reaction in curved borehole sections
- K.2.3.3 Friction due to the axial pulling force in curved borehole sections
- K.2.3.4 Total force in a curved section
- K.2.4 Total pulling force
- K.3 Determination of the longitudinal bending moment
- K.4 Determination of the circumferential bending moment from top load
- K.5 Determination of stress
- K.6 Assessment of possible collapse of the pipeline due to external drilling fluid pressure or external ground water pressure (risk of buckling)
- K.7 Assessment of maximum soil pressure on PUR and casing
- K.8 Determination of maximum allowable pressure in the bore hole
- K.9 Vertical soil load after completion of horizontal directional drilling (HDD) [Go to Page]
- K.9.1 Introduction
- K.9.2 Arching
- K.9.3 Calculation method for vertical soil load (homogeneous soil mass)
- K.9.4 Calculation method for horizontal support pressure (with reduced vertical load) [Go to Page]
