This part of ISO 9328 specifies the requirements for flat products for pressure equipment, made of thermomechanically rolled weldable fine grain steels as specified in Tables A.1 and B.1. The steels are not suitable for hot forming. Until now, no sufficient data for the standardization of the elevated temperature properties of these steels are available. If their use at such temperatures is intended, the conditions for this are specially agreed upon between the interested parties. The requirements and definitions of ISO 9328-1 also apply to this part of ISO 9328. NOTE 1 Fine grain steels are understood to be steels with a ferritic grain size of 6 or finer when tested in accordance with ISO 643. NOTE 2 This part of ISO 9328 offers the possibility of specifying products in accordance with European design codes and ASME-type design codes.