The single items of pressure equipment shall be classified according to their inherent characteristics (PS, V, DN, …). However, their integration in the safety chain is conducted using a category IV conformity assessment module or a module for the category of the equipment for which the chain is specifically designed.
When items of pressure equipment are integrated in a safety chain, they are considered as parts of the safety chain and therefore fall under the analysis of the hazards and risks of the safety chain, which include the pressure containment aspect of this item. When the analysis of the safety chain shows that the failure of an individual item of pressure equipment within the chain would have no detrimental effect on the safety function to be ensured (i.e. fail-safe), the requirements of a category lower than category IV for the said “item of pressure equipment” can satisfy the requirement resulting from the analysis of the hazards and risks of the safety chain.
Note:
This does not preclude the use of standard CE-marked items of pressure equipment as parts of a safety chain.