What is a generic CRN design?

A generic CRN design describes variable dimensions, materials, and feature locations of pressure equipment.  For example, a generic vessel CRN design can generally describe a variable shell length, all possible nozzle locations and sizes, together with proximities of nozzle groups etc.*  For vessels, generic designs cannot vary the head shape, shell diameter, maximum pressure, maximum temperature, or minimum temperature.  For generic fittings, many options are allowed, generally enabling you to register a whole series of fittings with one generic drawing specifying a range of dimensions, materials, and even design pressures.*   *Each situation is somewhat unique and requires careful consideration.  Other restrictions may apply subject to regulator acceptance.