NEN EN 12953-3 : 2016

Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 Symbols and abbreviations
5 General
   5.1 Boilers
   5.2 Hot-water generators
   5.3 Design of principal welds
   5.4 Thermal design of furnaces tubes
   5.5 Dimensions of pressure parts
   5.6 Establishment of pressures
   5.7 Allowances
6 Calculation temperature and nominal design stress
   6.1 Calculation temperature
   6.2 Nominal design stress
7 Cylindrical shells under internal pressure
   7.1 Shell thickness
   7.2 Basic calculation
   7.3 Boiler support
   7.4 Reinforcing pads
8 Openings and branches in cylindrical shells
   8.1 General
   8.2 Efficiency factor, calculation by way of approximation
        and maximum diameter of an unreinforced opening
   8.3 Design of openings and branches in cylindrical shells
        (efficiency and reinforcement)
9 Ends
   9.1 Unstayed dished heads without openings
   9.2 Flat unstayed removable closures
   9.3 Flange connections
10 Supported flat plates, stays and stiffeners
   10.1 Breathing spaces for flat plates
   10.2 Stayed flat surfaces
11 Design of isolated openings in shell boiler flat end plates
   11.1 Unreinforced isolated openings
   11.2 Branch openings
   11.3 Manholes, headholes and handholes
12 Unpierced tubes and tube plates
   12.1 Thickness of straight tubes subject to external pressure
   12.2 Thickness of straight tubes subject to internal pressure
   12.3 Wall thickness and ovality of elbows and tube bends
   12.4 Stay tubes
   12.5 Smoke tubes
   12.6 Pitch of tubes
   12.7 Thickness of the tube plates within tube nests
13 Furnaces tubes, furnace tube components and reversal
chambers of cylindrical form subject
to external pressure
   13.1 Furnaces tubes
   13.2 Calculation length of composite furnaces tubes
   13.3 Tolerances of furnaces tubes
   13.4 Stiffeners
14 Access and inspection openings
   14.1 General requirements
   14.2 Types and minimum dimensions of access and inspection
        openings
   14.3 Minimum gasket bearing width and clearance for
   access and inspection doors
   14.4 Access and inspection openings in flat plates
   14.5 Inspection requirements
   14.6 Requirements for entry into boilers with a shell
   outside diameter greater than 1400 mm
   14.7 Accessibility and arrangement of entry and
   inspection openings
Annex A (normative) Calculation of tube plate temperatures
Annex B (informative) Calculation form for 'Walker' - type
         reverse curve sections or corrugations
Annex ZA (informative) Clauses of this European Standard
         addressing essential requirements or other provisions
         of the Pressure Equipment Directive
Bibliography

Defines requirements for the design and calculation of pressure parts of shell boilers as defined in EN 12953-1.