Slag Inclusion

Nonmetallic material (typically oxide-based) entrapped in a weld deposit or at the fusion boundary. Slag inclusions occur when the welder fails to properly remove slag from previous passes or uses improper welding parameters. They are readily detected by radiography and ultrasonic testing. Slag inclusions weaken welds and are generally unacceptable in critical applications. Proper welding technique and interpass slag removal are essential to prevent slag inclusions.

Detection and Assessment

Slag Inclusion 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 slag inclusion 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