process begins that technology plays a heavy role in quality assurance. Live Weld Viewing Most commonly, visual examination of welding occurs before and after the actual welding takes place, but live viewing remains very limited due to the bright and harmful UV light produced by the arc. It is possible to view a live weld with welding glass shields or helmets, but this still may remain difficult. Specialized wide-dynamicrange cameras provide valuable information during the welding process to give CWIs added advantages to control welding quality, and therefore save valuable time and material. New digital camera technology along with software is able to take different exposure values of the bright arc and compile them into one homogenous, viewable image — Fig. 3. Certified Welding Inspectors are able to use these images to analyze live welds in order to keep its quality up to industry standards. For example, in automated tube fabrication, an inspector/operator is able to notice when alignment is off or the arc shape is malformed, and is able to adjust or shut down the automated process to save valuable time and material. With cameras that have recording capabilities, CWIs can analyze the footage of the root pass and filler passes to verify electrode alignment with the weld joint. There are opportunities to view arc shape and the molten metal pool size. This visual evidence reinforces what caused an unsatisfactory weld joint during the postweld inspection. These images also are very important educational tools that a CWE can use in the classroom. Live Weld Viewing in the Classroom Viewing a live weld arc by welders in training proves to be very valuable in a classroom. Visual examination techniques are easily taught with AWS Standards (AWS B1.11, Guide for the Visual Examination of Welds) for preand postweld inspection. Teaching what to look for during the welding process proves more difficult. Using weld viewing camera images on large monitor display gives students vital examples as to why welding defects may occur — Fig. 4. With live weld viewing cameras, the CWE can show multiple students at once on a display monitor what improper arc shapes and colors look like, bad alignment of the electrode/torch in relation to the welding joint, and the pool formation and size. Postweld Inspection To effectively complete a thorough welding inspection, it is sometimes imperative to use appropriate NDE equipment, and at times, use destructive examination techniques to achieve total weld quality assurance. Defects such as incorrect weld geometry, porosity, and cracks are easily identified by the eye, but not all weld defects are discoverable from a surface visual NOVEMBER 2015 / WELDING JOURNAL 49 Fig. 4 — Live weld viewing in the classroom proves to be a useful learning tool. Using the Visible Welding WeldWatch V 2015-Z camera, the three images are from the same GMA weld pass. A — A well-formed conical arc shape and pool; B — a point where an exhaust fan comes too close to the weld and pulls the shielding gas away from the arc; C —the arc shape becomes blob-like and inconsistent, therefore causing porosity in the finished weld. Fig. 5 — A cross section of slag inclusion from flux cored arc welding using Flux-Core Dual-Shield 710X-U feed wire. This defect is not visible unless radiographic or ultrasonic nondestructive methods are used or destructive methods are used in postweld inspection. A B C
Welding Journal | November 2015
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