HIPing is great for microporosity but does add cost. Repair welds are easier too. But it is limited to internal defects. Anything with a leak path to the surface will not be affected.
That's what they explained to me when I was talking to one of their engineers. My main concern has always been micro porosity in the chambers and deck. My hope is that having the castings HIPed will help me sleep at night. Oh and make for a better casting:)
We typically don't specify a hip for anything unless a cut up shows more internal porosity than we can live with. Again, cost driven. Sacrificing a casting for EDM slicing is really the only way to know what you have.
Oh you fancy pants facilities with your fancy pants destructive testing and analysis.
The foundry is still a production sand cast foundry and I'm doing one casting at a time right now and can't imagine doing anymore than four at a time so that limits my options. I'm really confident in my metal flow and risering at this point. The casting has mimicked my flow/thermal analysis exactly so I'm very confident that I'm not getting any huge internal inclusions.