Magnet on the exchanger will confirm cast steel or not.
The riser appears to be stainless steel.
Jim...
PS: The amount of Carbon in the riser should not be an issue. Looks very clean considering hours on genset.
The amount of deposit on the riser does look normal and should not be a problem. But the amount of deposit on the HX does not look as normal to me. Here's one of the original images prior to cleaning with the arrow that
@All U Get put in to indicate where the leak was.
This image to me is rather confusing. You can see the 8 holes from the mixing elbow imprinted onto this flange, but none of those holes line up with holes on the flange itself. In this image, it appears that the gasket is still on the flange. It's a square gasket, smaller than the HX flange with four holes closer together than the holes on the HX. Here's the image with the surface cleaned off:
Looking closely into the holes, they don't even look like bolts were in there. How were these two parts held together? It's just not all making sense to me. It looks like mismatched flanges and however they bolted them together may simply have not given the correct sealing pressure.
I think at this point, all I can do is wish
@All U Get good luck in getting home. Do let us know what you find out in the end. From my arm chair position, I can't reliably give an answer to this problem. I'd have to see the whole setup.
dj