AUWI

The TD-SCAN automated inspection system is a development of Technology Design. It applies pulse-echo ultrasonic technology to perform and digitally record Automated weld inspections.

THE TECHNOLOGY

Automated scanning system examining vessel girth weld.

Automated Ultrasonic inspection uses conventional and special transducers to generate sound in the test materials. These transducers are mounted to robotic crawlers, which articulate to cover both sides of the weld on the test surface. The data collected is then displayed in color in multiple AScan, B-Scan, C-Scan, and D-Scan images. A-scan representation is the view in which the signal amplitude is shown as a vertical excursion from the horizontal sweep time trace. The B-scan and D-scan presentations are two-dimensional views of cross-sectional planes through the test object on different axis. This imaging is helpful in distinguishing mid-wall inclusions such as laminations and blistering, from back-wall discontinuities like erosion and corrosion. The C-scan image is a two-dimensional plan view of the object. Indication of depth is color coded to provide the image with qualities which resemble a topographical map viewed from the inspecting surface.

PULSE-ECHO WELD INSPECTION

Pulse-Echo weld inspection uses single or multiple search units, set at specific angles, to inject sound into the test weld to search for discontinuities and defects. These angled and zero degree search units can be mounted onto a robotic crawler which enables the inspector to cover large areas of weld in a reliable and repeatable manner, and in a shorter amount of time than doing the work manually. Depending on the thickness of the test material and the angle of the search unit sound path, the crawler rasters the transducers in a perpendicular motion to the weld in order to get full volumetric coverage of the material with the search units. This is performed simultaneously from both sides of the weld.

This technique detects, locates, sizes, and identifies the nature of the flaw. Any defects found with AUT weld inspection are manually checked by the certified technician to be sure of reliability. Most vessel and piping welds may be examined with pulse-echo ultrasonics whether they be existing, repaired, or new production. It is the most widely practiced and commonly used technique in weld inspection today. Up to 300 linear feet of weld can be inspected per day with AUT weld scanning.

Half Inch Weld

The data comparison above shows data from both a raster scan and a zoned line scan, as well as TOFD data from a half inch weld sample. The data clearly shows all three indications located on the Sonaspection report were found with these methods.

Zoned Weld Inspection

Zoned weld inspection is another product of AUT weld inspection. The search unit or units, are set at a specific surface distance from the weld, depending again on the thickness and angle used, and focus the sound on a particular area of the weld. The crawler is then used to traverse the weld in a linear parallel to search for defects. Since no raster is needed, this is one of the faster AUT weld inspections and provides detection and flaw length information. It is possible to inspect up to 500 linear feet of weld per day with AUT Zone Weld scanning.

Manual encoded scan system for Zoned Weld Inspection

ADDITIONAL ADVANTAGES OF AUTOMATED WELD SCAN TECHNIQUES

In addition to substantial cost-savings through the elimination of the need to grid large areas or employ several manual technicians, there are further advantages:

• Can be used with ferrous and non-ferrous materials.
• Can be modified for higher temperature inspections.
• Provides a digital documented record of inspection.
• Easily repeatable for future outages or monitoring projects.