Mechanical vibrations at shafts and bearings are dealt with in the pertinent ISO Standards 7919 and 10816, thus there is no uncertainty if one follows the standards.
For hydraulic pulsations (for instance pressure swings) there are no internationally accepted limit values. Nevertheless guarantees show up in most projects. Of particular concern are single-regulated reaction turbines, i.e. the Francis, pump- and propeller (fixed-blade Kaplan) turbines. The impact of measured pressure amplitudes in terms of mechanical stress is normally not known but in practice machines with a ‘normal’ level of pulsation can be considered safe. Thus it makes sense to specify a guarantee that may be fulfilled by a decently designed machine. Unfortunately the newer literature has no figures, nor are there any applicable standards for admissible intensities. Quantitative data may be found in the textbook by Dörfler/Sick/Coutu.