Pressure loads (burst and collapse)
The burst and collapse loads are calculated by taking the difference (Pi-Pe) between the internal and external pressure profiles for each load case.
If the resulting load line is mainly positive, it is called a burst load line (BLL); if it is mainly negative it is called a collapse load line (CLL). The net pressures (positive or negative) are then compared with the API burst or collapse ratings of the casing.
Collapse or burst loading can occur during drilling and production.
When considering an internal . . .