The main pressure-bearing parts are the parts, which constitute the envelope under pressure, and the parts which are essential for the integrity of the equipment.
Examples of main pressure-bearing parts are shells, ends, main body flanges, tube sheet of exchangers, tube bundles.
The materials for these main pressure-bearing parts of equipment of categories II to IV shall have a certificate of specific product control (see PED Guideline G-05).
See also PED Guideline G-08 for bolting parts (fasteners).