Phased Array Ultrasonic Testing in lieu of Radiography
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Phased array ultrasonic testing (PAUT) offers several advantages over conventional ultrasonic testing for pipeline inspection. It uses multi-element transducer arrays to provide increased beam steering and focusing capabilities. This allows for accurate multi-dimensional sizing of defects and generation of ultrasonic images of welds in various 2D orientations. PAUT inspection is more efficient and cost-effective compared to conventional UT, while providing higher quality ultrasonic data and images that can facilitate engineering critical assessments and fracture mechanics acceptance criteria. Its use is gaining acceptance in pipeline codes and standards due to benefits like increased production, improved safety by eliminating ionizing radiation, and potential for lower repair rates.
Phased Array Ultrasonic Testing in lieu of Radiography
- 1. Phased Array Ultrasonic Testing Inspection Solutions for Today and Tomorrow
- 2. PAUT Training and Certification Requirements •ASNT added PAUT in 4th quarter of 2011 •Prerequisite to PAUT is UT level II Certification •Minimum 80 hours classroom training •Training course outline is specified in CP-105 •Minimum 160 hours on the job (hands on) training •Specific examination consisting of a minimum 30 questions on PAUT
- 3. Levels of Responsibility • ASNT does not address PAUT level I’s. It’s assumed that a PAUT inspector will be an experienced UT level II. • General Industry Level II PAUT under ASNT • Additional Performance Demonstration Qualification (PDQ) certs under • EPRI • API • Per Contract Documents • No certified Level III PAUT per ASNT, only in house or contractor designation as Subject Matter Experts (SME).
- 4. Codes and Standards Accepting PAUT • ASME • First through Code cases 181 and 2235 • Now as direct acceptance through article 4 and mandatory appendices • ASTM E2700 – Standard Practice for Contact Ultrasonic Testing of Welds using Phased Array • ASTM 2491 – Standard Guide for Evaluating Performance Characteristics of Phased Array Test Systems • API 1104 – Welding of Pipelines and Related Facilities • AWS D1.1 – Structural Welding Code – Steel • AWS D1.5 – Bridge Welding Code
- 5. History of PAUT • 1801 – Constructive/Destructive interaction demonstrated • In phase combination = reinforcement • Out of phase combination = cancellation • 1960’s – Researchers begin to develop systems using pulsed multi-point transducers to direct mechanical waves • 1970’s – Medical imaging diagnostics appear • Beam steer offers cross sectional image views
- 6. What is PAUT • Phased Array Ultrasonic Testing is an advanced ultrasonic technique used for flaw detection, sizing, and imaging • Uses multi-element (array) probes for increased beam steering and focusing compared to conventional UT • Like having many small conventional UT probes in one pulsed at predetermined intervals
- 7. How Phased Array Works Each individual wave generated within the scan goes through the pulse/receive cycle as shown below
- 8. How Phased Array Works • Each received analog A-Scan is digitized and rendered into 2D display formats • Signals from the entire sequence are compiled into various image formats for evaluation
- 9. PAUT Views • A data view is a 2D graphic rendering of the ultrasonic data • Data views • A-Scan • B-Scan • C-Scan • S-Scan • ToFD • Ray Tracing • Strip Charts
- 10. A-Scan View • Source by which all other views are created • Amplitude vs time • An A-Scan exists for every sound beam • One for each segment of a linear scan • One for each angle of an S-Scan • Rulers allow presentation of information in time, sound path, or true depth • Amplitude is linked to color pallet
- 11. B-Scan View • A side view looking from the back side of the probe • Represents data collected through the entire scan length for one A-Scan • View changes dynamically as angle or VPA is scrolled
- 12. C-Scan View • C-Scan is a plan view/top view • View is generated based on gate positioning and mode (may be configured for gate A and B independently) • Data can be presented in amplitude or position (thickness) formats
- 13. S-Scan View • Presents all A-Scans within the group in an angular sector or sweep range • A-Scans are converted to color coded lines representing amplitude • May be corrected for delay and true depth relative to the ultrasonic axis as shown here
- 14. Time of Flight Diffraction (ToFD) • The ToFD display offers a B-Scan representation of the diffracted signals detected in “pitch catch” conventional UT probes • As with all other image views ToFD is built off individual A-Scans
- 15. Ray Tracing View • Provides 2D representation of the weld, showing rebounds of the beam path and A gate position for the first, last and active focal law • Should only be used as a reporting tool
- 16. Master Thoughts • It’s still UT • Anything UT can do PAUT can do better • Technology enabled • UT is not new, neither is PAUT • Computer assistance of proven technology • Advancements in transducer material/design • Medical use and capability perfected • Adapted for use in industrial sector • Key elements • Multi-dimension sizing offers more accurate assessment of integrity • Weld images provided in multiple 2D orientations, giving 3D of views • Raises production while reducing costs
- 17. PAUT for Pipelines API 1104 21st Edition
- 18. API 1104 21st Edition Appendix A Option 1 Engineers Critical Assessment (ECA) • PAUT has been accepted since 19th Edition of API 1104 • Approved by PHMSA • Approved by The Ohio Gas Association • Multi dimension sizing allows for use of ECA • ECA/Fracture Mechanics acceptance criteria used and can reduce reject and repair rates.
- 19. Why PAUT? Why Now? • No dangerous ionizing radiation • Reduced safety factor • Increased production • Possible reduction in reject rate • No expensive regulatory fees • Accurate permanent records • Equipment generated reports with detailed indication tables • Physical and cloud storage of data with no degradation • Multiple weld images included with data • Results auditable onsite or remotely every day • Setup and equipment data/configuration automatically included in report
- 20. Why PAUT? Why Now?Pipeline NDT PAUT RT Mainline crew $120/hr $175/hr Data/Film $5/per weld $35/weld Equipment fees $600/day $800- $1200/day Tie-in/HDD NDT crew $95/hr $175/hr Project lead N/A (combined with other service position) $1200/day Licensing N/A $1000- $10,000 per project Auditing $5/weld $1000/day • Tremendous cost savings • Lower hourly fees • Less manpower • No regulatory costs • Lower data vs film cost • Remote auditing offering lower costs • No production interruption • Lower liability consideration due to safety • Safety • No ionizing radiation • Less manpower • Only seasoned personnel are certified • ECA criteria more accurately reflect likelihood of failure
- 21. •Benefits Recap • Increased production • Increased usefulness of data • Increase in job safety • Decreased costs of inspection/NDT • Decreased repair/rejection rate An investment in innovation is an investment in a safe profitable future!