Inspection of Tee-Joint Welds on Bridge Members

General Description of the Application During the manufacture of bridge structures, a lot of automated welding is used to rapidly and efficiently build multiple parts. One of these welding processes is a system that uses opposing arcs to weld stiffeners to webs on the bridge parts. This welding process produces horizontal fillet welds simultaneously on both sides of a tee-joint.
One problem with this technique is that on thin stiffeners, the heat exchange on vertical parts causes the parts to crack in the upper part of the weld.

The best method to inspect this particular defect without doing false calls on unrejectable defects is to use an ultrasonic phased-array technique. The multiple-element probe can scan from 40 to 70 degrees simultaneously, allowing a user to inspect the complete volume of the weld in a single pass. When combined with the portable phased-array unit and the appropriate probe, the technique offers fast inspection and exact positioning of defects. Compared to conventional UT, this technique enables any inspector, with a few hours of training, to operate at least five times faster and present more reliable results.

Inspecting pipeline girth welds, both for onshore and for offshore use

Ultrasonic phased arrays present major improvements over conventional multiprobe ultrasonics for inspecting pipeline girth welds, both for onshore and for offshore use. Probe pans are lighter and smaller, permitting less cutback; scans are quicker due to the smaller probe pan; phased arrays are considerably more flexible for changes in pipe dimensions or weld profiles, and for different scan patterns. More important, some of the potential advantages of phased arrays are now becoming commercially available. These include:
• Seamless pipe inspections;
• Premium inspections on thick section risers;
• 1.5 D arrays for improved sizing in risers-tendons;
• Focusing for thin-walled, large diameter pipes;

Spot Weld Testing

Application: Evaluating the integrity of spot weld joints in metal.

Background: Spot welding is a common technique for joining two pieces of metal, usually thin sheets or plates, by means of a series of small circular tack joints. The process is widely used in the automotive industry for body assembly and some chassis joints, and by other types of sheet metal fabricators as well. Spot welds are made by pressing electrodes against both sides of the parts to be joined and passing a high current through them, which momentarily creates a pool of molten metal that solidifies into a round joint known as a nugget.

If the weld is improperly formed, it is possible that the two parts may not fuse completely, or that the area of the nugget may be smaller than what is required for a strong joint. These problems are seldom visible to optical inspection, and destructive pull tests are inefficient and limited to a few samples. However, with proper equipment and technique, ultrasonic spot weld inspection can quickly and nondestructively provide valuable information about weld quality.

Tube and Pipe Weld Inspection Using OmniScan™ PA

General Description of the Application

There are innumerable welded tubes and pipes in the oil and gas industry. From manufacture through the entire service life of these welded parts, they must be inspected and monitored because of pressure and toxic contents. Magnetic particle inspections are frequently used, but this technique is limited to surface or breaking defects. X-ray technique is also used, but is time consuming and requires a safety zone around the inspection area.

For these reasons, the use of ultrasonic inspections using the OmniScan™ Phased Array unit, manual scanner and 64-element probe provides major benefits: the most precise results, best images, fast inspections, and a nonhazardous inspection technique.