Ann: Quarterly Report and Appendix 5B , page-16

I have never welded stainless steel guessing stainless due to the acid (I Had a 6g in stick welding mild steel pipe )so really I don't know, nor have I seen the design.

the large diameter of the shafts means they would probably best be preheated before welding, there could be a number of problems air bubbles in the weld (inclusions) , incorrect welding rod,wrong temperature not enough penetration ie not qualified to weld that material just like I am not qualified to pass judgement
But why was it welded on why not bolt it on with perimeter bolts as be easier to take off
WHat they should do next time though is torque test the shaft and plate ie in a hydraulic press at say twice the torque needed prior to installation crude but effective.