The Pressure Equipment Directive (PED) and Regulations on Technical Requirements for Designing, Manufacturing and Conformity Assessment of Pressure Equipment bring a number of changes to the design of pressure equipment in relation to the Technical Regulations for Stable Pressure Vessels, 1983. Among the most important changes are the essential safety requirements for pressure equipment. The changes in the formula, for all materials, for calculating the allowable stresses, as well as the change in the value of the test pressure, the new Regulations use the 1.0% proof strength as the relevant value for calculating the permissible membrane stress and thickness of pressure equipment walls. In this paper, the differences in the allowable stresses, the required wall thicknesses, and the approximate savings in the material in the case of a milk reservoir, calculated according to the requirements of the Directive and the new Regulations on one hand, and the old Regulations on the other, are presented.
Keywords: pressure equipment, maximum allowable stresses, austenitic steels, technical design requirements, tensile strength, yield strength