A CWI is performing an in-process inspection of a groove weld being made by the Shielded Metal Arc Welding (SMAW) process. The WPS specifies an electrode classification of E7018. The CWI observes the welder using an electrode marked E6010. What is the primary reason the CWI must stop welding immediately?
- AE6010 electrodes are typically used for root passes only, and this is a fill pass.
- BE6010 electrodes have a lower deposition efficiency, which will slow down the project schedule.
- CE6010 has a different tensile strength and chemical composition, which are essential variables that can drastically alter weld properties.
- DThe E6010 electrode produces more spatter, making post-weld cleaning more difficult.
Show answer & explanationAnswer & explanation
Correct answer: C. E6010 has a different tensile strength and chemical composition, which are essential variables that can drastically alter weld properties.
The electrode classification (e.g., E7018 vs. E6010) denotes significant differences in tensile strength, chemical composition, and other mechanical properties. This is an essential variable, and a change without re-qualification of the WPS can lead to welds that do not meet the design requirements for strength and toughness, potentially causing failure.
Why the other options are wrong
- A. While E6010 is often used for root passes, the primary concern is the difference in weld metal properties, not just its typical application.
- B. Deposition efficiency is a production concern, not the primary quality/safety reason for stopping work due to essential variable deviation.
- D. Spatter is an aesthetic and cleanup issue, not a primary concern for weld integrity compared to essential variable deviation.
Electrode Classification Deviation
Using a filler metal of a different classification than specified in the WPS is a deviation of an essential variable, fundamentally altering the weld's mechanical properties and making the weld non-compliant, requiring immediate cessation of welding.
- Electrode classification defines strength, chemistry, and usability.
- An essential variable, change requires WPS re-qualification.
- Can lead to welds with inadequate mechanical properties.
Memory trick: Wrong rod, wrong weld, properties foretold.