The inspection of thin-wall stainless steel (SS 304L) welds in cryogenic tank fabrication poses significant challenges due to their coarse dendritic grain structures. Traditional methods like Radiographic Examination (RE) and Ultrasonic Examination (UE) face limitations in detecting flaws. This case study explores the effectiveness of Phased Array Ultrasonic Testing (PAUT) for the volumetric inspection of 4mm and 7mm thick stainless steel welds.

Challenges

  • High Sound Attenuation: The coarse dendritic grain structure of austenitic stainless steel causes scattering and beam skewing, reducing ultrasonic penetration.
  • Thickness Variability: The weld thickness ranges from 4mm to 7mm, requiring precise calibration.
  • Small Reflector Size: The reference reflector dimensions are 5mm x 1mm x 0.5mm for lack of fusion (LOF), making detection challenging.

Solution

  1. Mockup Block Preparation: A welded SS 304L mockup block was fabricated with embedded notches and LOF defects to simulate real-world flaws.
  2. Probe Selection: A phased array probe with optimized frequency and focal laws was used to enhance beam penetration and focus.
  3. Beam Steering and Focusing: PAUT enabled precise steering of ultrasonic beams, allowing better flaw detection in thick stainless steel welds.
  4. Data Acquisition & Analysis: The advanced imaging and real-time defect visualization capabilities of PAUT facilitated accurate sizing and localization of defects.
  5. Validation: Results were compared with conventional techniques, confirming PAUT’s ability to detect notches and LOF in 4mm and 7mm welds.
  • Enhanced Detection Capability: Successfully identified all indications and notches, overcoming the limitations of RE and UE.
  • Improved Accuracy: Provided superior sizing and locational accuracy for defects in SS welds.
  • Non-Radiation Based Method: Eliminated the safety hazards associated with radiographic examination
Read More

Related Products

Send an Enquiry

    Enquire Now!

    Our Solutions

    About Us

    Quick Links

    Our Business

    Connect with us
    Copyright © 2023 Blue Star Engineering & Electronics Ltd. All rights reserved.