Weld TestingAll materials should be examined before welding begins and all welds should be inspected, at least visually. Visual inspection is simple and can identify many problems, thus avoiding further costly and, perhaps, futile work. Weldments should be tested further if appropriate and such testing would be either non-destructive examination or destructive testing. Non-destructive tests do not damage the weld and are normally used on production welds to ensure conformity with specification and absence of serious defects. Destructive testing renders the weld unusable and is intended to evaluate test welds, weld procedures and welder qualifications. Non-destructive examination includes such methods as dye penetrant, magnetic particle, X-radiography, Gamma-radiography, ultrasonic, eddy current, and acoustic emission. These look for defects such as cracks, porosity, and lack of fusion. Other tests include pressure tests, leak tests, and ferrite evaluations (in stainless steel). Destructive tests are tensile, bend, impact, hardness, and fracture tests, and may include stress corrosion, fatigue, and creep testing. These tests evaluate the strength, ductility, and toughness of the weldment and its ability to withstand certain applications or environments. Many of the non-destructive and destructive tests described require high levels of operator competence if correct interpretation of results is to be obtained. Personnel must be suitably qualified and trained for all these activities.
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