Understanding Weld Discontinuities and Its Causes

06 December 2018

It’s all very well having a welding inspector’s report in hand. The papers are typed, and they’ve been delivered to multiple engineering departments. It’s the contents that are alarming, though. There are weld discontinuities noted in the report, plus a series of appended photographs. They frame the trouble spots. To beat the problem, to execute a cost-effective solution, those project head honchos need to know all about weld discontinuity science.

What Is Weld Discontinuity?

The structure of a weld is interrupted. More than irregularly applied, the weld is physically disconnected. And this type of fusion breakage doesn’t just apply to cracks or propagating fracture networks. No, material porosity is another major issue, as are depth penetration problems. Worse still, it may not be immediately obvious, this lack of depth penetration. Likewise, porosity problems can be hard to detect, while cracks and fractures lie hidden below a weld’s surface. In fact, to a casual observer, metal fusing work can look perfect, but, as every welding inspector knows, looks can be deceiving.

Weld Discontinuities: The Causative Factors

More than deceiving, a weld discontinuity, concealed or not, undermines the structural integrity of two or more fusion-anchored elements. For structural beams, larger than life and made of hardened steel, cracks develop. They propagate and undermine weld coherence. So, what causes weld discontinuities? The inspector has done the job, hence the report and those photographs, but there’s no way to address the weld irregularities until a cause is determined. Well, dirty or oily base materials cause porosity problems, so the area must be prepped before the equipment sparks to life. Moisture and gas shielding errors are next on the list. Welders work dry, they don’t just expect the heat to burn away excess moisture. As for shielding gas glitches and other equipment malfunctions, entire articles have been written about such weld-undermining influences.

Conceiving Systematic Weld-Correcting Solutions

Instead of referring back to past posts, let’s think about weld discontinuities for a minute. Pages of troubleshooting tips could easily fill the next few lines, but there’s another way to conquer the issue. Understand weld discontinuities. Understand hot and cold cracks, the temperatures that cause those fractures to develop. On understanding the underlying cause, a truly effective process-diagnosing campaign dissects the flaw. The longitudinal or transverse fracture patterns are analyzed. Probability studies trace the weld interruptions, and a cause is discovered. Generally, the environment or the equipment or the equipment’s operator are found responsible. Every so often though, weld discontinuities occur because of substandard filler rods or structural preloading difficulties.

More than a source of frustration, weld discontinuities endanger entire structures. A tiny, almost invisible flaw on a project might seem unimportant, but that’s an unacceptable way of approaching a critically important job. After all, welding inspectors understand the weakest link principle. No weak links can be allowed to exist, not if an engineering inspector is doing his job right.

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