Automated UT Corrosion Mapping
Automated Ultrasonic Testing (AUT) covers a range of ultrasonic inspection techniques using powered, mechanical scanners to locate inherent defects within a given material. AUT is the term used to describe corrosion mapping inspections, pulse-echo weld inspection, Phased Array and Time of Flight Diffraction.
- To obtain repeatable corrosion maps, with this we:
- Measure flaws in the base material and show their position, extent and depth
- Detect pitting, general corrosion and laminar defects including inclusions, plate laminations and blistering
- Obtain routine and repeatable corrosion maps from room temperature to 350 ⁰C (662 ⁰F) and higher
- To assess pressure vessels and piping for blistering, Hydrogen Induced Cracking (HIC also referred to as stepwise cracking) and Stress Oriented Hydrogen Induced Cracking (SOHIC) damage; for these inspections we can use ‘Tri-element’ probes
- To differentiate between laminations, blistering and stepwise cracking
- To inspect as-fabricated welds
- High degree of repeatability
- Position and size data for every flaw can be compared for repeat scans of the same area to track flaw growth or corrosion rates both generally and for individual pits
In-service inspections, specially high temperature examinations, require extensive preparation and cooperation between pressure containing operating personnel and AUT personnel.
AUT SCANNING BASICS
IRISNDT offers a range of automated and semi-automated ultrasonic scanning systems. The primary system comprises an Olympus MS5800 instrument coupled to a general purpose (GPS) or remotely controlled (GPA) scanner. The scanners operate with a full range of ultrasonic probes including straight beam, angle beam, tri-element and TOFD. Ultrasonic signals are acquired and evaluated, providing multiple views of the ultrasonic data including the raw ‘A-scan’, C-scan top view and sectional views of the area being inspected.
The scanners have magnetic wheels that hold them on the vessel. Mild steel tracks clamped to the scan area are used for non-ferromagnetic materials or high temperature scans.
IRISNDT uses HydoFORM Phased Array scanning for internal and external corrosion-erosion mapping on piping. This allows the probe to scan rough and uneven surfaces while maintaining consistent coupling of the ultrasonic beam through the water column.
Ferrous and non-ferrous alloys and non-metallic materials can be inspected depending on their acoustic transmission capabilities.