Carl + Jeff,
first off, happy new year to both of you.
It shouldn't be too late for this.
I have posted a similar question already yesterday, but addressed to THOR, then I have deleted it again due to not wanting to run into the risk to be finally "downrated" to 10^-9 some day.
However, here I am again, since it wouldn't have been me if I had let this be the final word at this.
Thus once again my question, and this time a bit more "differentiated" and asked to both of you as you are two of the most experienced forum fellow members in this field.
How are e.g. cap- or even the layers beneath the cap-layer (in a multiple pass joint on cracking susceptible steel stainless steel grades e.g. pure austenitics) being removed to get access to a flaw lying e.g. in the centre of the transversal cross section of the joint, e.g. slag inclusions. Is it being performed by grinding? And if so, what are the precautions to avoid a contamination of the layer to be repair welded with e.g. ... sulphur, originated from the binder of the grinding wheel. This again forming very low melting Nickelsulphide-Eutectics or even Nickelcarbosulphide-Eutectics? Are there special grinding wheels used or is the weld metal being removed by machining which must be accomplished again without hydrocarbon containing cooling agents?
However, if, which is just an assumption, a grinding wheel was used containing binders which are containing sulphur again, then, again just my assumption, it would be explainable why the material was free of cracks before it was repair welded and full of cracks subsequently to the repair. And if, so my assumption, once sulphur is within the material and being diluted again by each repair weld, then, so my assumption, it might be a hard untertaking to get crack free repairs at the end of the day, since each repair welded layer would dilute at least traces of it into the layer underneath the welded one.
I am sure that THOR is an outstanding expert as well and his company or employer has the appropriate means for repairing, thus please see this my question just as a very general questioned one - just for my personal interest, so to speak.
Stephan