Equipment with a pressure of 0.5 bar or more is subject to the Pressure Equipment Directive (2014/68/EU). The way in which the directive is applied depends on the design specifications of the equipment; the working pressure, pipe diameter or vessel capacity, together with the medium in the equipment, determine which category the product falls under. The Directive distinguishes various hazard categories, for which different assessment procedures must be carried out.
In addition, various items of equipment are excluded from the Directive. For instance, category I equipment is excluded from the Pressure Equipment Directive when the Machinery Directive or the Atex Directive apply.