HDZ Fasteners Corrosion
HDZ Fasteners Corrosion
(OP)
Hi, I need some advice/suggestions on the root cause of this. The HDZ bolts are used on the LV side of a transformer and it shows signs of corrosion. The location is in doors, dry, no signs of moisture ingress. The transformer has been in operation for 3 years+.





RE: HDZ Fasteners Corrosion
A closer picture would help.
What kind of facility is this inside of?
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P.E. Metallurgy, Plymouth Tube
RE: HDZ Fasteners Corrosion
http://files.engineering.com/getfile.aspx?folder=e...
RE: HDZ Fasteners Corrosion
The Zn is supposed to be the sacrificial coating. It corrodes to protect the steel.
I am guessing that you see Zn oxide.
This has been wet, maybe condensation?
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P.E. Metallurgy, Plymouth Tube
RE: HDZ Fasteners Corrosion
RE: HDZ Fasteners Corrosion
It is unlikely to have moisture ingress, it is a energised distribution transformer that has been in operation for about 3 years. It is location in-doors.
I am sorry but that's the best picture I can get, as the client is reluctant for us to open up the LV cable box.
Yes, I agree that Zn is sacrificial coating, but what is strange about this situation is that the connection is running "hot" most of the time (approx. 140F). The copper bars are tin coated.
I an just throwing this question out here, by any chance could it be due to some form of organic gas? At the present time I have not visited the site.
Thank you
RE: HDZ Fasteners Corrosion
What is the base material and surface coating on the mating part?
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P.E. Metallurgy, Plymouth Tube
RE: HDZ Fasteners Corrosion
The fasteners are all hot dipped galvanized steel and the copper bar is tin coated.
Thanks