Visual-weld-inspectionto prove Weld Quality.SOLUTIONS with Effective, Practical AdviceVisual-weld-inspection represents the immediate critical observation of the external features visible on all welds. It is the first and most important assessment of quality to be performed as soon as the welding operations are accomplished. Other inspection procedures may be required to detect discontinuities not visible to the eye or present below the external surface. Whatever additional non destructive inspection methods are applied, they are performed only after visual inspection is successfully completed. The subject was addressed in our general page on Welding Inspection and in the even more general introduction to Weld Quality. A short article on Visual-weld-inspection was published (11) in Issue 8 of Practical Welding Letter for April 2004. Click on PWL#008 to see it. A page listing online resources on Visual Inspection and Requirements was published in Issue 49B of Practical Welding Letter, Mid Month Bulletin for September 2007. Click on PWL#049B. Visual-weld-inspection includes two different aspects of the operation. The first is the visual assessment of the external look of the weld. Its appearance has to correspond to engineering drawing requirements and to be evaluated in comparison with that of the best obtainable practice by anyone looking with critical eye at its characteristic features. This part has to be done first and foremost by the welder. The welder has to be proud of the production coming from under his/her hands. Any hints to indications of less than perfect results should be used to look for their causes and drive the search for required improvements of the welding technique. The second has to do with the formal documented assessment of the Visual Weld Inspector, the person in charge of verifying that procedures, materials and workmanship used to perform the job are indeed those specified and approved for the project. The Inspector has to be formally instructed and qualified, and his/her minimum visual acuity must be checked, certified and documented in writing, periodically, by an approved optometrist. Visual Inspection has to be performed according to a specific written procedure. To conduct adequate Visual-weld-inspection there is need of sufficient illumination and possibly of a low power magnifying glass. Surfaces inaccessible to unobstructed view may need additional aids like mirrors (dental or otherwise) and borescopes, slender instruments that include illumination and magnification, that can be introduced through narrow openings. When performing the Visual-weld-inspection job, the Certified Welding Inspector has to ascertain that each requirement of the approved WPS (Welding Procedure Specification) is correctly been taken care of. This is done by looking at the prepared list and verifying that each clause is met. Visual Welding Inspectors must know the requirements of Codes and standards, must be able to identify base metals and consumables, with reference to adequate documentation and markings, must measure dimensions and control tolerances, must check adequate fit-up and weld preparation, processes, positions, preheat application when required and correctness of welding parameters applied. The requirement to verify that Welding Consumable storage and control are indeed adequate means to check that conditions are suitable to prevent degradation and that mixing of products is carefully avoided. Visual-weld-inspection addresses completeness of welding performed, including eventual post weld heat treatments required, all dimensions and tolerances, visual indications of discontinuities and features of the weldments to determine if they are within the approved limits. In case of discrepancy a suitable Nonconformance Report has to be prepared by the Inspector and submitted to the person responsible for quality approval. Visual-weld-inspection is intended to find and mark for repair obvious visual defects such as cracks, surface porosity, dimensional discrepancies, excess concavity or convexity, unfilled areas, undercut, misalignment, craters, unacceptable arc striking spots and any other objectionable visual features. In case of doubt the indications have to be marked and then their importance assessed relative to drawings or applicable specifications. Visual-weld-inspection is conducted generally on production welds immediately after welding, but it may be required also for maintenance purposes at any time during the service life of welded items, to determine if corrosion or other damage intervened, and if there is a need for more accurate evaluation and eventual repair to assure continued usability.
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