After boiling down all the complex elements of this job, this is what it comes down to in the end: how does a welding inspector distinguish good welds from bad welds. It maybe seems like an oversimplification of what’s rarely a simple discipline, but that’s not the case, not at all. At the end of the day, especially in what’s essentially an exacting engineering application, the job really should be measured in blacks and whites.

A Black And White Engineering Discipline

Shying away from the shades of grey, a welding inspector’s job is to transform “maybes” and “could be’s” into certainties. Okay, enough with the colourful metaphors, how does a welding inspector distinguish a properly implemented weld joint from one that’s not up-to-par? Step number one in the inspection handbook suggests a visual examination. Going back one extra step, before the visual inspection, what kind of welding technique is this? What’s the equipment, and what are the expected results?

MIG Welding Analysis

This is Metal Inert Gas welding, which is viewed by many as the most easily mastered metal joining method available. Consumable fillers and electrodes are at work, and there’s an electric arc generating the heat. A good weld has no discontinuities or metal discolouration. A bad weld is documented as a series of seam discontinuities and/or cracks. There’s discolouration around the weld and the seam is too thin. To correct these issues, clean the weld area, adjust the weld voltage, and bring in a welder who can maintain the travel rate of the electrode arc.

A TIG Welding Troubleshooter

Operator expertise is mandatory when working with Tungsten Inert Gas welding gear. Because of that fact, it’s easier for things to go wrong. There’s less leeway between a “Good” weld and one that’s gone “Bad.” Moving in closer and lower, the bottom side of the weld has insufficient penetration. There’s also an erratic or poorly formed bead. Worse yet, due to some trapped shielding gas, the heat application zone is full of small holes. This is metal porosity, yet another sign of a bad weld.

Oxy-welding seams suffer from the same problems, with insufficient underside penetration topping the list off jointing gaffes. Then there are the obvious porosity and cracking issues, plus a whole series of possible seam discontinuities. Still, just because a weld doesn’t look like it’s in pristine condition, that doesn’t always earn it a failing grade. It’s the same thing with seemingly good welds. Visually, the joint might look good, but those good looks could be hiding a buried discontinuity. As a quality control mechanism, welding inspectors use non-destructive test instruments to check seemingly good welds. As a test of an outwardly bad weld, those same test instruments come to the rescue.