Power transformer oil leak mitigation -- technology assessment. Final report
Technical Report
·
OSTI ID:10140167
- Ontario Hydro Technologies, Toronto, Ontario (Canada)
An assessment of in-situ power transformers leak repair technologies was performed, addressing the severe multi-stress environment of an operating transformer, combining vibration, extremes of temperature (from {minus}40 C to well over 100 C), UV exposure, and thermal aging, in addition to poor application conditions on oily surfaces. Oil leaks can originate from gas relay piping, packing on valves, CT pockets, tap changers, radiators and main tank covers; focus on the present activity was on flanges for radiators and pumps for units 25 MVA and up. The range of applicability of welding technologies was established. The recommended process for field weld repairing is Flux Cored Arc (FCAW), either in the semi-automatic mode (hand held) or in a mechanized mode (travel carriage). SMAW (Shielded Metal Arc Welding) should be considered as a second choice after FCAW (only for materials 1/4 inches and thicker). Welding repairs completed with an oil backing have no risk of paint carbonization; with an air backing, 1/2 inch material and thicker can be welded without concern while a multi-pass technique should be used for welding 1/4 inch thick material. The best welding procedures were compiled into a free standing document, ``Guidelines for Repair Welding Transformer Components Using the Shielded Metal Arc Welding and Flux Cored Arc Welding Processes,`` included in the present report. It is recommended that further development be undertaken in the more challenging vertical welding position using both SMAW and FCAW. In addition, it is recommended that repair welding techniques be developed for repair of corrosion leaks on radiators.
- Research Organization:
- Electric Power Research Inst., Palo Alto, CA (United States); Ontario Hydro Technologies, Toronto, Ontario (Canada)
- Sponsoring Organization:
- Electric Power Research Inst., Palo Alto, CA (United States)
- OSTI ID:
- 10140167
- Report Number(s):
- EPRI-TR--111593; ON: UN99002850
- Country of Publication:
- United States
- Language:
- English
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