How do you measure a concave fillet weld?

Measuring a concave fillet weld involves determining the throat dimension, which is critical for evaluating the weld's strength and ensuring it meets design specifications. The most precise method for measuring this characteristic is by using the throat side of a fillet gauge. The fillet gauge is specifically designed for assessing fillet welds and provides a direct measurement of the throat, which is the shortest distance between the weld root and the top of the weld face. This measurement is essential as it directly impacts the weld's load-bearing capacity and integrity.

Using a fillet gauge allows for consistent and accurate measurements, as it easily accommodates the unique geometry of concave welds. Other tools like tape measures or calipers may not provide the specificity required for assessing the throat of a fillet weld accurately. While a protractor could be useful in measuring angles or assessing the alignment of the weld, it is not employed for measuring throat dimensions. Thus, the throat side of a fillet gauge is undoubtedly the best choice for measuring a concave fillet weld and ensuring compliance with welding standards.