Transformer Leak Repair

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I have a call to repair a leak in the weld around one of the pipes/ nozzles on a large industrial transformer. I have an asme R stamp as well as AWS certs and have made countless welds like this before. Prob is the procedure calls for oil to stay in the transformer at a min of 4 inches above the leak point. This we have not dealt with before. Plan is to pean the leak shut, clean it and weld it . I have been pondering using a tIg torch to close the leak completely prior to re welding the area with 7014(7014 is what the procedure calls for) I am hoping someone has some experience with this that might have some 2 cents to help us out. Thanks in advance!!Nick
Reply:The reason for keeping the oil in is so the oil dissipates the heat internally and doesn't allow the oil to burn. TIG doesn't like oil. IMHO you'll be better off keeping with the stick. Start your arc away from the leak so you'll have a good hot puddle going before you get there. You may need to weld a layer, then grind most of it off and weld another layer until you get it sealed up. Cleaning and peening is a good start. If they'll allow, you might consider a good hot seal pass with 6010 and then capping with the 7014.
Reply:Interesting, as a non-pro I happen to like 7014 rods, but this is the first time I've heard anyone say they were specifically required on a job.Do you know the reasoning for using them?Dave J.Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:I have done a lot this type repair over the years for our local electric company. The wps called for 7014 but the inspector allowed 6010. Is it the power company requesting this or someone else? If the transformer belongs to the power company don't fool with it until they have a inspector onsite.
Reply:Just curious, do you know the primary and secondary voltages of this trasnformer?
Reply:Is the transformer one with a nitrogen blanket on top of the oil or a conservator tank?  Can the owner (whomever) pull vacuum on the transformer while you are doing the repair.  Ideally to the point where there is zero (differential) pressure at the repair point.   I was involved with the change out of leaky seals on a tap switch on a "large industrial transformer."  This was a warranty repair.  The mfr's field guy pulled vacuum while changing the seal.
Reply:A couple thoughts.  Do you know why it started to leak in the first place?  This might affect how the repair should be made.   Did the leak occur because of rust and corrosion, or did the leak happen because of some external force on the pipe/nozzle?  Or did the leak start because the pressure inside the transformer became very high?  I would approach the repair preparation differently in each of these three cases.In any case, I don't think I'd opt to try and seal the weld with a TIG torch first.  I'd just proceed with the 7014 rod called for in the procedure you have.  Doing anything else puts you in the deeper in the 'hot seat' if something goes wrong.Rust or corrosion would have me rethinking the peening, as you could punch a hole in the shell or further weaken the surrounding material.  Maybe the nozzle needs a saddle around it to make the repair if the shell of the transformer is rusted?   If the pipe/nozzle was cracked because someone or something bent it, then your plan as suggested makes sense.  I'd check for other cracks using some dye penetrant before welding to ensure you're repairing all the damage.  If the leak is due to some kind of overpressure event, I'd make certain the transformer was safe and that the root cause of the crack was fixed before repairing.  If that all checks out, your proposed repair procedure makes sense.  A safety question:  Do you know if the oil in the transformer is free of all PCBs?  If not, do you have the PPE and safety precautions in place to deal with PCB contaminated oil that's already leaked or could leak if the repair goes bad while peening or welding?  PCBs are nasty and very bad for your health.  Like asbestos, it's not a big deal if you deal with it properly, but you want to have your safety plans well thought out and in place; just in case. Originally Posted by TMW llcI have a call to repair a leak in the weld around one of the pipes/ nozzles on a large industrial transformer. I have an asme R stamp as well as AWS certs and have made countless welds like this before. Prob is the procedure calls for oil to stay in the transformer at a min of 4 inches above the leak point. This we have not dealt with before. Plan is to pean the leak shut, clean it and weld it . I have been pondering using a tIg torch to close the leak completely prior to re welding the area with 7014(7014 is what the procedure calls for) I am hoping someone has some experience with this that might have some 2 cents to help us out. Thanks in advance!!Nick
Reply:Is a patch piece or pieces an acceptable option to avoid the leak area with your weld and strengthen the affected nozzle area at the same time?MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:Thanks for all the input. There is no nitrogen blanket its all oil and has no pressure. The procedure allows for 6013 and 7014. The more i read I do agree that the tIg option is prob not a good idea due to the heat and possibly growing the leak. It is a new transformer that has a pin hole type leak at what looks to be the start and stop point of the factory weld.Thanks guys!!!Nick
Reply:In my younger days the shop I worked at made repairs like this on a fairly regular basis. We used a vacuum pump to draw a slight negative pressure to stop the active leak prior to welding. The amount of vacuum was always specified by the manufacture. the job paid well and was fairly simple most times. Extra safety gear for the PCB filled units and extra pay. Most of the repairs were on PCB filled units, if they could repair with out draining the oil they didn't have to replace the transformer with a non PCB model. If i remember correctly it was always 6010/7018 for the repairs.
Reply:Originally Posted by TMW llcThe procedure allows for 6013 and 7014.Nick
Reply:Originally Posted by MinnesotaDaveThe procedure allows for 6013 too?  Awesome, I think I just heard some people's heads explode!  Haha! Dave J.
Reply:Interesting procedure.  Looks like they left you a lot of room for decision making.Dave J.Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:Originally Posted by pin2hotIs the transformer one with a nitrogen blanket on top of the oil or a conservator tank?  Can the owner (whomever) pull vacuum on the transformer while you are doing the repair.  Ideally to the point where there is zero (differential) pressure at the repair point.   I was involved with the change out of leaky seals on a tap switch on a "large industrial transformer."  This was a warranty repair.  The mfr's field guy pulled vacuum while changing the seal.