A CWI is conducting a post-weld visual inspection of a fillet weld that connects a stiffener to a beam. The WPS specifies a 1/4 inch (6 mm) fillet weld size. Using a fillet weld gauge, the CWI measures the actual weld size as 3/16 inch (4.8 mm). The governing code, AWS D1.1, allows for a maximum undersize of 1/16 inch (1.6 mm) for fillet welds, provided the reduction does not exceed 10% of the specified size. What is the status of this weld?
- AAcceptable, as the reduction is less than 10% of the specified size.
- BAcceptable, as the undersize is within the 1/16 inch allowance.
- CUnacceptable, as the weld size is below the specified 1/4 inch.
- DUnacceptable, because it violates both the absolute undersize limit and the percentage reduction limit.
Show answer & explanationAnswer & explanation
Correct answer: D. Unacceptable, because it violates both the absolute undersize limit and the percentage reduction limit.
Specified weld size = 1/4 inch (6 mm). Measured weld size = 3/16 inch (4.8 mm). Undersize = 1/4 - 3/16 = 1/16 inch (1.6 mm). The code allows a maximum undersize of 1/16 inch (1.6 mm), so this is at the limit. However, the code also states 'provided the reduction does not exceed 10% of the specified size.' 10% of 1/4 inch (6 mm) is 0.025 inch (0.6 mm). Since the actual undersize (1/16 inch or 1.6 mm) is greater than 10% of the specified size (0.025 inch or 0.6 mm), the weld is unacceptable.
Why the other options are wrong
- A. The reduction (1/16 inch) is significantly more than 10% of the specified size (1/4 inch * 0.10 = 0.025 inch).
- B. While the absolute undersize is at the limit, it fails the percentage reduction criterion.
- C. This is true, but the reasoning needs to encompass both code criteria.
Fillet Weld Undersize Limits (AWS D1.1)
AWS D1.1 specifies limits for undersized fillet welds, typically allowing a maximum undersize of 1/16 inch, but this reduction must also not exceed 10% of the specified weld size.
- Both absolute and percentage limits must be met.
- Undersizing can reduce weld strength.
- CWI must use a fillet weld gauge for accurate measurement.
Memory trick: Absolute AND Percent - Both Must Pass.