Defect

Any discontinuity or imperfection in material that reduces its service capability or performance. Defects include cracks, porosity, inclusions, lack of fusion, and delaminations. Not all discontinuities are rejectable defects; acceptance criteria in standards determine which indications constitute unacceptable defects. Characterization and sizing of defects through NDT is essential for fitness-for-service decisions and repair planning.

Detection and Assessment

Defect 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 defect 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