Weld Spatter
Weld spatter is small droplets of weld metal expelled during welding that adhere to the base metal adjacent to the weld, generally a cosmetic defect but capable of acting as a crack-initiation site under cyclic loading.
Definition
Spatter is caused by long arc length, incorrect polarity, or excessive amperage. It must be removed before inspection and before painting/coating, since it can produce false MT/PT indications.
How this damage forms
Molten droplets expelled during welding that adhere to the surrounding surface. Cosmetic at first glance, but consequential for inspection and coating.
How it is detected
Visual examination identifies it; the issue is what it hides and disturbs — spatter masks the weld toe where fatigue cracks start, holds moisture against the surface, and breaks coating continuity.
What causes it, and what prevents it
Acceptance criteria commonly require removal before inspection and coating, and surface methods (MT/PT) are unreliable over spatter because it traps particles and penetrant indiscriminately.
Codes that govern assessment
AWS D1.1 visual acceptance addresses it; coating specifications (SSPC/NACE) require its removal as surface preparation.
The common reporting error
Performing MT or PT over spattered surfaces to save prep time. The background indications generated make the examination unreadable, and the toe — the location that matters — stays hidden.
Where Weld Spatter fits in an inspection programme
A term is only useful when it connects to a decision. Weld Spatter appears in written procedures, in technique sheets, and in the records an owner or accreditation body reviews afterwards — which means the way it is defined in your documentation has to match the way it is applied on site. Where the two drift apart, audits find it. Atlantis writes and reviews procedures against the governing codes, trains inspection personnel to apply them, and builds the record-keeping that makes the evidence retrievable years later. Procedure development and code consulting · NDT training and certification · Ask us about your programme.
Related terms
- Undercut — Undercut is a groove melted into the base metal adjacent to the weld toe that is not filled with weld metal, reducing wall thickness and acting as a stress concentrator.
- Overlap — Overlap is the protrusion of weld metal beyond the weld toe without fusion to the base metal, producing a notch-like discontinuity that reduces fatigue performance.
More defect terms
Crack · Lack of Fusion · Lack of Penetration · Slag Inclusion · Porosity · Burn-Through · Lamination · Lamellar Tearing · Hydrogen-Induced Cracking · Stress Corrosion Cracking
Where this comes up in practice
Terms like this one appear in three places that matter commercially: the written practice that governs how your personnel are qualified, the procedures and technique sheets that define how an examination is actually performed, and the evidence an auditor or client asks for when they want to know why an inspection was accepted. Getting the terminology right is the easy part; being able to produce the qualification record, the calibration traceability and the procedure revision that applied on the day of the inspection is the part that decides audits.
Atlantis NDT provides NDT training and certification against ASNT SNT-TC-1A and ISO 9712, ASNT Level III consulting for written practices and procedure approval, inspection management software that holds qualification, calibration and procedure-revision evidence in recoverable form, and an asset integrity platform that binds inspection results to the asset they describe. Browse the full NDT glossary or ask a Level III directly.