Has anyone ever welded on heat exchangers?

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I welded a cracked laser weld in a heat exchanger tube in a carrier gas package central unit about 4 years ago with a  weld pak 100 mig welder. I never thought it would last a few months, but it lasted this long. It was the tube closest to the access panel so i was able to do it with the exchanger still in the unit, i was just lucky I know, but has anyone ever done this before. I really didn't want to do it but the people i did it for didn't have the money to replace the heat exchanger, much less a new unit & it was about this time of year so they had no heat, so i gave it a shot & it worked. I just wondered if anyone here has ever tried this .
Reply:LIABILITY LIABILITY......when the crack that you welded opens up and the house is filled with co and everyone is dead..thats a bad thing...if the manufacture recomends welding repair , they probably wont..replace the exchanger..not something to play around with..it might be weldable and it might work well but at what price are you willing to chance it..
Reply:Originally Posted by lstiltsI welded a cracked laser weld in a heat exchanger tube in a carrier gas package central unit about 4 years ago with a  weld pak 100 mig welder. I never thought it would last a few months, but it lasted this long. It was the tube closest to the access panel so i was able to do it with the exchanger still in the unit, i was just lucky I know, but has anyone ever done this before. I really didn't want to do it but the people i did it for didn't have the money to replace the heat exchanger, much less a new unit & it was about this time of year so they had no heat, so i gave it a shot & it worked. I just wondered if anyone here has ever tried this .
Reply:Thanks for the replies, liability was not an issue as I had the customer sign a statement indicating that the attempted repair was unsatisfactory, & that the unit was unsafe to operate in the state it was in at the time. The unit was left with the power removed. The customer operated the unit at their own risk & against professional advice. At that time I had already been in business for 15 years so I was & am very aware of the issues of liability. The unit has since been changed out, so it's a done deal. Anyway back to the heat exchanger, this unit had a stainless steel material for the tubes & the wire I used was copper coated steel I don't remember the heat, or wire speed settings that were used, but I was amazed at how easy it welded. After I changed the unit out I scraped the old unit I noticed it had the weld was still holding on that tube, however two other tubes had cracked welds like the first one, which always seems to be the case for defective heat exchangers.Last edited by lstilts; 01-27-2011 at 08:49 AM.
Reply:There are shops that do it all the time.  Mine is one.  If the HX is ASME stamped, there's paperwork and the proper procedures need to be followed, but it is quite common.