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The advantages of the new calculation methods provided in the harmonized Pressure Vessel Standard EN 13445 Part 3. Comparison with the national standards used up to now. Fernando Lidonnici Convenor of WG’C’/CEN TC54 Sant’Ambrogio Servizi Industriali SRL - Milano.
The advantages of the new calculation methods provided in the harmonized Pressure Vessel Standard EN 13445 Part 3. Comparison with the national standards used up to now.
Convenor of WG’C’/CEN TC54
Sant’Ambrogio Servizi Industriali SRL - Milano
EN 13445.3 permits higher stresses for:
For Fine Grained Steels the present issue of EN 13445.3 still provides a safety factor of 2,4 on the room temperature tensile strength: the problem will be solved shortly with an amendment already approved.
For Cr-Mo steels of large thickness subject to heat treatment the values of the ASME code are higher than the values in the corresponding EN standards: these values however are not guaranteed and therefore they are not reliable.
There is an advantage in using EN 13445.3 for domed ends, particularly at higher pressures. At low pressure the formulae of the ASME Code may be less conservative.
Either under vacuum or at higher external pressures EN 13445.3 permits lower thicknesses than ASME for a given unsupported shell length.
EN 13445.3 permits lower thicknesses particularly at higher pressures. It also permits greater angles without transition knuckle.
The alternative method of Annex G is a definite progress in respect of the old Taylor Forge and DIN methods. Although further gasket parameters are needed, the savings in thickness and weight may be substantial.
The alternative method of Annex J is a definite progress in respect of the old Gardner’s theory. The savings in thickness and weight may be substantial, particularly for fixed tubesheet heat exchangers.
The “Direct Route” of Annex B permits to ignore secondary stresses in all cases where there is no need to consider them (constant loading conditions).This is a substantial advantage in the design of structures where the classic DBA (based on elastic analysis) caused an unnecessary increase in thickness.
SECONDARY STRESSES AT THE CONNECTION BETWEEN A CYLINDRICAL SHELL AND A CIRCULAR FLAT END (Note: In DBA based on elastic analysis and stress categorization the Flat end thickness must be increased in order to limit secondary stresses on the shell)
EN 13445.3 is the most advanced Pressure Vessel standard in the world.
It permits substantial economies in Pressure Vessel Construction.
Using a single European Pressure Vessel standard means a greater competitiveness for the European industry: the most important Users and Notified Bodies must be convinced that it is now time to replace the old Pressure Vessel standards with EN 13445.
All the resources of the interested industry must be put on the further development of EN 13445: the further development of the old national Pressure Vessel codes is a waste of resources that goes against the interests of Europe.