There is a saying "that welding is the fastest and cheapest way of joining two parts that don't need to be separated." This saying requires that the weld be properly performed, and this will usually happen if the welder properly follows a qualified welding procedure. The ASME Code provides excellent guidance and methods to do this. In some welding situations a procedure can pass the Code required testing, but can still not be satisfactory. In these cases knowledge of welding metallurgy and metallurgical methods of evaluation are essential to being able to determine the cause of the welding difficulty.