Thanks for the replay,
I did goof up, the tube is A519, CDS 1018 material, not 513
The weld is a fillet weld.
The wire meets the AWS 71T-12 spec, ultimate strength 70-90ksi, with 79ksi being typical.
There is enough weld for the service loads, so I used a wire that would not be too hard even if welded slightly improperly.
In running test, I have found the weld can become very hard - sometimes harder than the spec says it should become, so in this case I erred on the safe side.
I know allot of folks weld solid, round collars on tube, but the welder I am using had concerns about this, so I am addressing his concerns by getting more inputs.