Key takeaways
- A good weld is even, fully fused at the edges and free of cracks and holes.
- Beauty is not strength, but ugly welds are often a warning.
- Cracks, porosity and undercut are red flags.
- Critical welds need testing, not just looking.
What a good weld looks like
A sound bead is fairly uniform in width and height, with ripples that are even and a smooth blend into the base metal on both sides. It does not sit on top like a ridge of glue, and it does not leave a groove along its edge.
Good welds are also clean: no scattered holes, no slag stuck in them and no cracks, including tiny ones at the ends.
Common warning signs
Cracks are the most serious sign. Porosity, small holes or a spongy look, comes from contamination or poor shielding. Undercut, a groove melted into the base metal beside the weld, weakens it. A weld that looks like cold, rounded blobs may not have fused with the metal.
None of these can be judged perfectly by eye, but they are good reasons to ask for a closer look.
When looking is not enough
Structural, pressure and safety-related welds may need testing by an inspector, such as dye penetrant, magnetic particle or X-ray, depending on the specification. If your project has a code or an engineer's requirement, ask for the testing in writing.
Our practical assessments are visual and hands-on, and we recommend a certified inspector when a job demands it.
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Quick answers
Can I check a weld with a magnet or a hammer?
Not reliably. A magnet only tells you about the base metal, and tapping a weld can miss hidden defects. Visual inspection by someone trained, and testing for critical joints, are better.
Does a pretty weld mean a strong weld?
Often, but not always. A neat-looking weld can lack penetration, and a rough one can be sound. Penetration and fusion matter more than looks.
Ready to talk it through? Get a free estimate or call 615-209-7643.