Fatigue Crack

A crack initiated and propagated by repeated cyclic loading below the static yield strength of material. Fatigue cracks typically initiate at stress concentrations (welds, notches) and propagate gradually until sudden failure occurs. NDT methods like eddy current and liquid penetrant are excellent for detecting surface fatigue cracks. Early detection is critical in fatigue-critical applications like aircraft and rotating machinery.

Detection and Assessment

Fatigue Crack must be detected early and accurately characterized to determine safety implications. Multiple NDT methods may be required for comprehensive evaluation.

Acceptance Criteria

Industry standards such as ASME Section V, AWS D1.1, and API standards provide specific acceptance limits. Whether a detected fatigue crack is acceptable depends on material, component function, and applicable code.

Best Practices

• Always follow applicable NDT standards and procedures
• Use properly calibrated and maintained equipment
• Ensure personnel are properly trained and certified
• Document inspection procedures and results completely
• Keep current with industry standards and best practices