Flaw

A discontinuity or defect in material that may affect its service capability. The term "flaw" is sometimes used interchangeably with "defect" and "discontinuity," though flaws specifically refer to undesirable discontinuities that exceed acceptance criteria. In NDT, the goal is to detect all flaws of sufficient size and type to warrant repair or rejection. Flaw characterization and sizing are critical for fitness-for-service assessment.

Detection and Assessment

Flaw 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 flaw 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