High cycle fatigue of welded structures: Design guidelines validated by case studies

• Vibrating screens fail at stresses below the fatigue limit in design standards.
• Evidence from failures has shown that a fatigue limit at 1 × 107 or less is incorrect.
• A design guide is proposed for welded vibrating equipment in the giga-cycle regime.
• In non-corrosive conditions a fatigue limit stress range at 4 × 108 is proposed.
• A lower fatigue limit is proposed for welds in corrosive environments.

Experience with fatigue failures, of both welded and non-welded details, has demonstrated that the design guidelines in many fatigue codes are inadequate for fabricated equipment that requires a life exceeding 107 cycles. Stress ranges from strain gauge testing and finite element analysis of vibrating screens, combined with the actual life results, have been used to establish design criteria applicable to machinery operating in the giga-cycle range. Case studies from recent investigations are used to illustrate the validity of the design criteria.