If there is incomplete fusion in the root, the weld fails. The weld must exhibit fusion to the root, but not necessarily beyond the root.
Al
The question is not, 'how do you measure' but instead should be, 'WHY WOULD YOU measure' a weld leg when it is obvious the fusion is not to the root?
If there is good reason to measure the leg, it would appear obvious you would only measure the area that displays fusion. But, per most any code and application I am aware of there would be no need. It failed the moment you were able to determine fusion did not go all the way to the root.
He Is In Control, Have a Great Day, Brent
Good Day,
Lets back up and answer a couple of your other questions as well as the most recent one.
So, all fillet welds are actually measured by throat dimension. That is how the Engineer has calculated the required strength of the weld. And, it is usually this measurement that is on the engineered drawings for proposals and bids. Then, the detail calls out the welds per leg size based on the D1.1 or other applicable code equation for such since this is the best, fastest, easiest way for welders and inspectors to check weld size. We ASSUME it is the correct size based upon all the previous generations of successful welding with a given process to a specified WPS with welders proven qualified to get fillet welds with fusion to the root.
SSSOOO, does the answer change if the weld is concave instead of convex? NO. Only the part of the fillet weld gauge used to inspect the weld changes in order to make sure the correct leg and thus throat dimension is achieved. The concave gauge is using both a determined throat and leg to make sure it is of proper size; not really sure I described that well but it works.
Now, if you really want to include a dimension on the report to illustrate how poorly the weld was fused, go ahead. Nothing says you can't. But, your statement that it is N/A or just 'Rejected for Incomplete Fusion to the Root' is adequate.
The code isn't going to tell you how to fill out the report and there are some items that are difficult to word on a standard report. Too much detail can mess things up. Use a Supplemental page and put something like 'See Note 1' on the report. Then place that note on the other page.
He Is In Control, Have a Great Day, Brent