Oil to water heat exchanger.
Got a chance to weld on these 3/4 s.s tube ends to this carbon head plate. It was so dirty oil keep coming out, after stoping oil and Welding I found every time I would weld on a thin spot the weld would pop,
Pretty frustrating, I used the CK machine with a pluse tig feature it helped a lot but, in the end it was the tube expander that did the trick.