This paper presents a code review (API 17G, ASME VIII Div 2 and ASME VIII Div 3) for addressing the fatigue capacity of steel cylindrical bodies and conduits subjected to cyclic pressure only. The fatigue capacity for pipes with a yield strength of 75ksi and 90ksi and with rated working pressures (RWP) ranging from 5ksi to 30ksi have been considered using both the S-N approach and the fracture mechanic approach. The S-N based fatigue lives from API 17G are found to be much longer than the corresponding S-N based fatigue lives from ASME VIII Div 2 and Div 3 and by the fracture mechanic (FM) approach as required in ASME VIII Div 3 for vessels where a leak-before-break condition can not be demonstrated. The S-N predicted fatigue lives are found to decrease with increasing RWP while the FM based fatigue lives are found to be rather independent of the RWP. The S-N based fatigue lives from ASME VIII Div 2 and Div 3 for free corrosion conditions are found to be shorter than the corresponding FM based fatigue lives for RWPs ≥ 25ksi and ≥ 20ksi, respectively. Based on this work, it is recommended to establish the fatigue capacity of steel cylindrical bodies and conduits subjected to cyclic pressure using either ASME VIII Div 2 or Div 3. The FM approach is considered to give a lower bound fatigue life as the number of cycles to initiate a crack is disregarded. Guidance on when it is considered applicable to use the API 17G criterion is given in the conclusion section of this paper.

This content is only available via PDF.
You do not currently have access to this content.