NonDestructive Testing Methods to Ascertain the Quality of the Entire Weld

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It is due to the serious consequences that a number of methods of inspecting weld joints have been developed. It is however physically impossible to inspect each and every weld joint. Since the welding is done only by qualified welders who have been approved by the client, it forms an additional backup for improving weld efficiency. Depending on the application and the thickness of the material involved a set of weld seams are selected for inspection. These are tested using Non-destructive testing methods to ascertain the quality of the entire weld. (Interim Guidelines: Evaluation, Repair, Modification and Design of Steel Moment Frames, n.d)The liquid penetrant examination method is an effective method for detecting discontinuities which are open to the surface of nonporous metals. The common discontinuities that can be detected by this method are cracks, seams, laps, cold shuts, laminations and porosity. Prior to each liquid penetrant examination, the surface to be examined and all adjacent areas within 1 inch (25.4) shall be dry and free of dirt, grease, lint, scale, welding flux, weld spatter, paint, oil and free of surface defects that may hide these discontinuities and interfere with the examination process.A liquid penetrant is applied uniformly over the surface that is to be inspected using a brush or by spraying. This allows the penetrant to seep into the discontinuities. The time allowed for this penetration is 5-10 minutes. The excess penetrant is then removed using a cloth or absorbent paper moistened with solvent repeating the operation until the traces of penetrant has been wiped clean. Typical cleaners may which may be used are detergents, organic solvents, descaling solutions and paint removers. The area is then dried by blowing air and the developer applied. (Interim Guidelines: Evaluation, Repair, Modification and Design of Steel Moment Frames, n.d)