Weld overlay for flanges

[jijoygopal]

Hi
I have a Low Temp (A350 LF2) RTJ flange which has requirement for weld overlay on flange face. My query is that
1) Can we deposit the weld overlay and then go for machining. in this case the gap between the two flanges will be increased by the weld overlay. Or is it general practice to machine and then put overlay so that the gap between the flanges after installation will be the same as that without overlay. Are there any standards for weld overlaying.
2) For overlaying the flange face, is it required to overlay a portion of the ID of the flange say about 25mm from the end of face. If so, then the ID of the flange will be in two steps. ie, the Flange ID would be bigger than the flnage ID where overlay is done. Is it acceptable.

3) The gasket used is Inconel 825. I beleieve the reason of overlaying is to avoid dissimilar contact between the Inconel and A350LF2.

 

[stanweld]

1. You will definitely machine after overlay and may machine prior to as well to achieve proper dimensions.
2.A portion of the ID will be overlayed by the overlay of the flange face. Additional overlay on the ID would not be required unless the Purchaser so demands.
3. It is doubtful that your reasoning for the overlay is correct. There is likely another corrosion concern of the Purchaser.