EN 13831:2007

Foreword
Introduction
1 Scope
2 Normative references
3 Terms and conditions
4 Symbols and units
5 Materials
  5.1 General
  5.2 Materials proven by experience and current use
  5.3 Fasteners
  5.4 Non-pressurised parts
6 Design and calculation
  6.1 Design
       6.1.1 Requirements pertaining to the diaphragm
       6.1.2 Requirements pertaining to fresh water application
       6.1.3 Outside finish
       6.1.4 Inspection openings
       6.1.5 Connections
       6.1.6 Clenched joints
       6.1.7 Volume tolerance of vessels
       6.1.8 Fatigue
       6.1.9 Loadings
  6.2 Experimental design method
       6.2.1 General
       6.2.2 Preparations
       6.2.3 Vessels with PS x V <= 1000 bar x L
       6.2.4 Vessels with 1000 bar x L < PS x V < 6000 bar x L
       6.2.5 Vessel parts and components
  6.3 Calculation method
       6.3.1 General
       6.3.2 Symbols
       6.3.3 Cylindrical and spherical shells under internal pressure
       6.3.4 Dished ends under internal pressure
       6.3.5 Openings in cylindrical shells, spherical shells and
             dished ends
       6.3.6 Bolted circular flat ends under internal pressure
       6.3.7 Flanges and boltings
7 Manufacturing and welding
  7.1 Introduction
  7.2 General
  7.3 Manufacturing tolerances
       7.3.1 General
       7.3.2 Middle line and surface alignment
       7.3.3 Tolerances for vessels
  7.4 Weld details
       7.4.1 Recommended weld details
       7.4.2 Vessels made in more courses
       7.4.3 Joggle joints
  7.5 Welding
       7.5.1 General
       7.5.2 Welding procedure specification (WPS)
       7.5.3 Qualification of WPS
       7.5.4 Qualification of welders and welding operators
       7.5.5 Preparation of edges to be welded
       7.5.6 Execution of welded joints
       7.5.7 Attachments, supports and stiffeners
  7.6 NDE personnel
  7.7 Manufacture and testing of permanent joints
       7.7.1 Welded joints
       7.7.2 Clenched joints
  7.8 Forming of parts subject to pressure
       7.8.1 Ratio of deformation
       7.8.2 Forming conditions
       7.8.3 Heat treatment
       7.8.4 Visual examination and control of dimensions
       7.8.5 Test certificate
  7.9 Repairs
       7.9.1 Surface defects
       7.9.2 Repairs, elimination of defects
  7.10 Finishing operations
8 Diaphragm
  8.1 General
  8.2 Materials
  8.3 Hygienic demands
  8.4 Test concept
  8.5 Testing
       8.5.1 General
       8.5.2 Tests on diaphragms
       8.5.3 Cyclic stressing on vessels
       8.5.4 Diaphragm permeability test
       8.5.5 Repetition of tests
       8.5.6 Test report
  8.6 Tests by the diaphragm manufacturer
  8.7 Marking of diaphragms
9 Testing and inspection
  9.1 General
  9.2 Technical documentation
  9.3 Inspections during manufacturing
  9.4 Pressure test
  9.5 Marking
  9.6 Documentation
Annex A (informative) Standards for testing diaphragms
Annex B (informative) Proven diaphragm materials
Annex ZA (informative) Relationship between this European Standard
         and the Essential requirements of EU Directive 97/23/EC
Bibliography

This European Standard specifies requirements for the design, manufacture and testing of closed expansion vessels with built in diaphragm, which will hereinafter be called "vessels", and a)whose diaphragm serves to separate water on the one hand and air / nitrogen on the other hand in heating/cooling systems or fresh water systems;b)which are manufactured singly or in series;c)which may consist partly or entirely of (cold) deep-drawn parts;d)whose parts may be joined by welding, clenching or flanges;e)whose size is not limited;f)whose maximum allowable pressure is greater than 0,5 bar, yet not exceeding 30 bar;g)whose upper wall thickness is limited to 12 mm for austenitic steels and 15 mm for ferritic steels;h)whose minimum operating temperature is not below -10 °C, whose maximum operating temperature is not above 70 °C.NOTEThe maximum operating temperature of 70 °C is determined by the characteristics of the diaphragm materials. It may be higher, if suitability of diaphragm material is proven.Whatever the temperature in the heating system, for the vessel operation the decisive factor is the maximum operating temperature of the diaphragm. It is the system designer's responsibility to prescribe measures to protect the diaphragm from unsuitable temperatures (e.g. connection to the coldest part of the system in a heating system, to the warmest in a refrigeration circuit; thermostatic monitoring of connection to vessel or intermediate vessel).For cases where operating temperatures above 70 °C cannot be avoided the suitability of the diaphragm material is to be proven (see Clause 8).When reference is made in this European Standard to EN 13445-1, -2, -3, -4 and -5 respectively, all relevant provisions in the concerned clauses of these standards need to apply.