1. Fernando Lidonnici Convenor of WG’C’/CEN TC54 Sant’Ambrogio Servizi Industriali SRL - Milano Comparison between American and European Pressure Vessel Rules
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8. JOINT EFFICIENCIES (of main welded joints) ASME : from 0,7 ( no NDT ) to 1 ( full NDT ). Joint efficiency 1 required for Lethal Service, large thicknesses, materials with particular welding difficulties. It is possible to use 0,7 also for large vessels. PED + EN 13445 : also from 0,7 ( no NDT ) to 1 ( full NDT ). EN 13445 limits the use of testing group 4 (joint efficiency 0,7) to carbon steels (temperatures +10 / +200 °C) and austenitic stainless steels (temperatures -50 / +300°C) only, with pressure smaller than 20 bar and pressure x volume smaller than 20000 (above 100°C) or 50000 bar x litre , provided the content is not dangerous (Group 2 Fluids only).
9. HYDROSTATIC TEST PRESSURE ASME VIII division 1 : the lower of (formula to be applied to all pressure parts of a specific vessel) PED (Recommended): the higher of (formula to be applied to all the pressure parts of a specific vessel), however not less than . Use of lower hydrostatic test pressures is permitted if alternative measures assuring the same safety level are taken. EN 13445.5 : the hydrostatic test pressure may be limited to the maximum value compatible with the actual thicknesses of the main pressure parts determined by design conditions. For Vessels of Testing Group 4 a higher test pressure is provided. Note : PS = Design Pressure, = ratio between nominal design stress at 20°C and nominal design stress at design temperature.
10. CERTIFICATION PROCEDURES ASME : Authorization given to the Manufacturer to affix an ASME Stamp (specific for the particular kind of pressure component concerned) after a survey carried out by ASME and the National Board of Pressure Vessel Inspectors . Design, fabrication and inspection activities carried out under the surveillance of an Authorized Inspection Agency . Particular precautions are to be taken for vessels in “ Lethal Service ”. PED : Specific certification procedures ( modules ) have been provided in order to cover 4 different hazard categories of vessels. Some modules are based on QC (Quality Control) procedures, other on QA (Quality Assurance) procedures (lower degree: self certification, higher degree: either full QC (step by step checking), or full QA (Qualification of the Manufacturer). For Vessels the hazard category depends on the content ( dangerous / / non dangerous ) and on its physical state ( liquid or gas / vapour ). Each module provides a different involvement of a Notified Body , specifically authorized by one of the European countries. Note: also assemblies made of several pressure component are subject to a certification procedure.
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