Inspectioneering

Integripedia Topic
Advanced Ultrasonic Backscatter Technique (AUBT)

Explore this topic

Advanced Ultrasonic Backscatter Technique (AUBT) involves a collection of ultrasonic techniques used for detecting High Temperature Hydrogen Attack (HTHA) in process equipment. AUBT is well-documented in API RP 941, Steels for Hydrogen Service at Elevated Temperatures and Pressures in Petroleum Refineries and Petrochemical Plants.

Key steps in the AUBT procedure include:

  • A pattern-based backscattering technique is used as the initial screening method on the external surface that has been flapper-wheel (200 grit) prepared.
  • Depending on the backscatter pattern observed, one of several follow-up techniques, including frequency-dependent backscatter, velocity ratio, spectral analysis, and spatial averaging, can be used to determine the cause of backscattering signals.
  • Note the velocity ratio, because of the lack of both speed and sensitivity, is used only when backscatter shows uniform microstructure (i.e., this indicates either no damage or near through-wall damage), to determine if damage really exists.
  • Spectrum analysis uses Fast Fourier Transform (FFT) to convert the signal readout from amplitude versus time to amplitude versus frequency. This technique compares spectra of back-wall echoes measured from suspect locations with a "clean" reference spectrum taken from a "no damage" area. This follow-up technique is used because of its speed and sensitivity to HTHA.
  • A spatial averaging technique may be used where velocity ratio and spectral analysis have difficulty determining whether nearly through-wall HTHA exists (e.g. for clad nozzles, etc.)
  • For weld and heat affected zone (HAZ) inspections, angle-beam techniques based on backscatter and spectral analysis principles are used. These angle beam techniques do not require flush grinding of weld crowns for inspection.

Related Topics

Topic Tools

Share this Topic

Contribute to Definition

We welcome updates to this Integripedia definition from the Inspectioneering community. Click the link below to submit any recommended changes for Inspectioneering's team of editors to review.

Contribute to Definition
Articles about Advanced Ultrasonic Backscatter Technique (AUBT)
    Downloads & Resources related to Advanced Ultrasonic Backscatter Technique (AUBT)
      News related to Advanced Ultrasonic Backscatter Technique (AUBT)

        Inspectioneering Journal

        Explore over 20 years of articles written by our team of subject matter experts.

        Company Directory

        Find relevant products, services, and technologies.

        Talent Solutions

        Discover job opportunities that match your skillset.

        Case Studies

        Learn from the experience of others in the industry.

        Integripedia

        Inspectioneering's index of mechanical integrity topics – built by you.

        Industry News

        Stay up-to-date with the latest inspection and asset integrity management news.

        Blog

        Read short articles and insights authored by industry experts.

        Expert Interviews

        Inspectioneering's archive of interviews with industry subject matter experts.

        Event Calendar

        Find upcoming conferences, training sessions, online events, and more.

        Downloads

        Downloadable eBooks, Asset Intelligence Reports, checklists, white papers, and more.

        Videos

        Watch educational and informative videos directly related to your profession.

        Acronyms

        Commonly used asset integrity management and inspection acronyms.