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A harmonised standards is a standard considered by the European  Commission as satisfying some of the directives essential safety  requirements.

Harmonised standards are covered by three types of European  Standard:-

  • Harmonised Product Standards
    These are application codes  that cover the design and manufacture of Pressure Vessels, Boilers and  Pipework
  • Harmonised Support Standards
    Welding, NDT and other  standards that supplement the application codes.
  • Harmonised Material Standards
    A material specified in a  harmonised standard will satisfy the requirements of the directive in terms of  ductility, toughness and strength but does not guarantee that the material will  be suitable for a specific application.

Each harmonised standard will contain an annex stating  which essential safety requirements it satisfies.  The advantage of using these  standards is that no additional justification is required that essential safety  requirements have been met and providing the standards have been correctly  applied the design of the equipment can not be challenged.

Another advantage of using Harmonised Standards is that they  provide an interpretation of the directive.  For example if a pressure vessel is  to operate below zero the impact tests on the material and welding procedures  have to be carried out the lowest operating temperature the vessel will  experience according to ESR 7.5.  This is not current practice as far as either  PD5500 or ASME VIII is concerned as both these standards permit, under certain  circumstances, warmer impact test temperatures.  The European Unfired Pressure  Vessel Standard prEN13445, currently in draft form, appears to follow an almost  identical approach to that contained in PD5500 when determining impact test  temperature.  Therefore when this standard is published it will be possible to  argue a case for using warmer impact test temperatures.

Harmonised Standards are not essential, any appropriate  standard can used but the satisfaction of essential safety requirements must  proved.  Both PD5500 and ASME VIII have produced annexes stating how and which  essential safety requirements they claim to satisfy, these annexes have not been  approved by the European commission and therefore neither standard can claim to  be harmonised. 

Note PD5500 has nothing to do with the PED, it is simply the  latest revision of BS5500, it no longer has the status of a British Standard  because it will conflict with BSEN13445 when its published.  It is now a  Published Document rather than a standard,  This will make no difference to it  as it will continue to be supported as long as its popularity remains

The harmonised standard for the qualification of welding personnel is EN ISO 9606, for operating procedures it is EN ISO 15614. (Note EN ISO 15614  only satisfies the requirements of E.S.R 3.1.2 it does not satisfy the requirements for welding consumables stated in E.S.R 4)

{Only EN versions of ISO 9606 are harmonised and EN ISO 9606 Parts 1, 2 and EN  ISO15614 are not available until early 2004}

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Last Modified 13 April 2002