146 GMAW/FCAW Handbook Copyright Goodheart-Willcox Co., Inc. a welding procedure is to obtain a weld quality that meets the specifi and to deposit the weld mate- fication rial in a cost-effi manner. ficient Test Welds A procedure must be confi by test welds firmed before actual welding begins. A test weld and the required weld should have the same joint design, metal type, and material thickness. The test weld should be inspected for quality on completion. The weld must perform its intended function. Testing can be done by visual inspection, cutting welds apart and using a microscope to view the weld cross section, pulling apart for a tensile test, bending the welded joint in a press, applying a penetrant, or performing one of any number of tests. Qualified Welding Procedure Every weldment must meet a standard of quality for the particular weld used. Determining whether a standard of quality has been met can range from a casual look at a weld to see if the parts are joined, to a prescribed inspection for compliance with a specifica- fi tion. High-quality welds may require the use of test welds to establish correct parameters before produc- tion begins. Nondestructive testing is performed to verify quality, while destructive testing is performed to verify mechanical values. If the tests are accept- able, the welding procedure is considered a qualified fi procedure, and the product can be welded using that procedure. If changes are made to the welding values after qualifi testing must be repeated to requalify fication, the new procedure. Anytime you set up a machine, change the electrode, install a gas supply, or modify a parameter, run a test weld on a piece of scrap mate- rial. It is far better to throw away a piece of scrap metal than to ruin a production part. Visual Inspection Visual inspection is the fi rst and most commonly fi used type of inspection method. This involves viewing the weld on the front or top surfaces (and penetra- tion side, if visible). In addition, measuring tools, scales, squares, mirrors, a fl ashlight, and other weld fl measurement instruments may be used to determine the condition of the weld. See Figure 17-1. The following common defects can be identified fi by nondestructive visual examination: • Excessive or inadequate crown height. • Incorrect crown profile.fi • Underfi or low weld. fill • Undercut. • Overlap. • Surface cracks. • Crater cracks. • Surface porosity. • Weld size. • Weld length. • Joint mismatch. • Warpage. • Variation from dimensional tolerances. • Inadequate or excessive root side penetration. • Incorrect root side profile.fi The legs of a fillet weld are required to be a fi specifi c size. Unless otherwise specified, fi the leg size fi should be of equal length, unless otherwise indicated on a print. See Figure 17-2 and Figure 17-3. Fillet welds may also require inspection of the throat dimension, Figure 17-4. Goodheart-Willcox Publisher Figure 17-1. A variety of tools for measuring, observing, and documenting welds are used during the visual inspection operation. Goodheart-Willcox Publisher Figure 17-2. A fillet weld gauge is used to check the leg size.