CAESAR II can calculate an occasional stress or a fatigue stress for harmonic loads.

I would suggest a fatigue approach for harmonic loads. To calculate a general von Mises (or equivalent) stress for fatigue evaluation, specify a number of cycles in the harmonic input. You will then see a stress type of (FAT) rather than (OCC). If you entered a fatigue curve in your (static model) piping input, CAESAR II will compare the calculated stress to stress amplitude associated with the cycles provided. You may, instead, use a fixed limit to this stress based on API 618 or ASME OM-3