Kiskey NDT Consulting and Training

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Time of Flight Diffraction Specialized Weld Inspection #KNDT 003

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Summary: This is a course for technicians who will be inspecting ERW longseams in thin-wall pipe. The common assumption is that TOFD inspection is not useful on materials less than 6.35 or even 9.1mm in wall thickness. Specialized techniques take advantage of the physics of Time of Flight Diffraction to inspect for surface-breaking (or very near surface) defects, accurately measuring their length and depth. The course includes a detailed Written Inspection Technique compatible with an approved TOFD Procedure to use for ERW inspection.

Location: Various

Course Duration: 40 hours

Maximum number of students: 8

Candidate Prerequisites: Certification or documented experience in at least one of the following:
  • UT Level II or III
  • PAUT Level II or III
  • TOFD Level I
Course Fees: $10,000 + GST = $10,500 for up to 4 people.

$2,000 for each additional technician

Equipment to be provided by candidate: TOFD Inspection Equipment
  • TOFD capable flaw detector
  • Encoded scanner for TOFD probes
  • ERW Sample with natural or artificial defects (optional)
  • Software capable of analyzing TOFD data
  • Reporting system
PPE to be provided by candidate: As required for pipe & weld inspection

Certification: Yes

Procedure review and Technique: Yes

  • TOFD Principles Review
    1. What is Time of Flight Diffraction?
    2. History of TOFD Inspection
  • TOFD Limitations
    1. Lateral Wave Dead Zone
    2. Backwall Dead Zone
    3. Spatial Resolution
  • Procedure Review
    1. ASME V
    2. CSA Z662
    3. Acceptance and Rejection Criteria
  • Calibration and Setup for Thin-Wall Pipe Inspection
    1. Equipment Selection
    2. Probes and Wedges
    3. Scanner setup
    4. Encoder Calibration
    5. Flaw Detector Settings
    6. Screen Images
  • Scanning the ERW
    1. Determining the ERW’s location
    2. Guidance Markup
    3. Scan length
  • Assessing the Scan Data
    1. Checking for gate placement
    2. Checking for lost lines of data
    3. Checking Start and End of Scan
    4. Determining Sensitivity
  • Data Interpretation
    1. Signal Interpretation
    2. Measuring defect length
    3. Measuring Defect Through-wall Height
    4. Measuring Defect Depth
    5. Avoiding False Positives
    6. Laminations near the ERW
  • Challenges of Field ERW Inspection
    1. Surface Condition
    2. ERW Placement
    3. Ditch, Hoarding, Weather Challenges
    4. Data Storage and Transfer
  • Written and Practical Exam
    1. Technique Review
    2. Scan Analysis
Upon completion of the course, candidates will have proven ability to:
  • Scan ERW Thin-wall pipe of various wall thicknesses
  • Determine when the scan data is appropriate
  • Interpret scan data
  • Identify types of weld anomalies
  • Identify geometry vs. anomalies
  • Report findings to pipeline owners
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