aluminum pitting

May 05, 2006 3 Replies
L

The following website:

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shows a picture and makes this comment (back in 2002 -- the design may have changed since):



"Again in my experience the Gaggia boilers tend to corrode internally. They are attached to a brass group, and the combination of dissimilar metals and hot electrically conductive water simply eats the aluminium. This can also happen with aluminium thermoblocks, which is why some of the more upmarket ones are now lined with stainless steel."



Is there any way to remediate a corroded boiler (assuming no replacement is available) such as an immersion bath or other form of plating that is food-safe as a vessel for boiling potable water as also able to withstand the high temperatures of the heating element?



Thanks Liam



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J

In short, not likely, even if you tried to coat it and fill in the pits with a plastic. As soon as you have pitting, it probably can't be assuredly cleaned to be made food-safe. Also, all coatings have holes. (That's the normal assumption for coatings. Someone will argue with that, though.) If a hole and a pit coincide, you have a reservoir for microorganisms.

If cost is no object and the vessel is big enough, you may find some imaginative ideas on how to refurbish it, but I've never encountered a case where cost is no object. Cost always objects!

Buy replacment(s) or re-design to work with whatever parts you CAN get.

My $0.02. (non-inflation adjusted)

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M

Liam:

The problem is likely galvanic corrosion. Go take a look at the Alubook. The solution would not be to coat the aluminum (anode), but rather the cathode, since it is the cathode (other more noble metal) whose area would be controlling the corrosion rate. See:

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and also see the advice on: How to avoid or minimize galvanic corrosion at:
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may have the electrolytic problem deposition mentioned if you have copper tubing upstream of the aluminum boiler. This is a special form of galvanic corrosion. Also see the comments on design at:
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It's hard to fix a lousy design.

Pittsburgh Pete

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B

i like that disclaimer.

FWIW, if you zincate the interior, and then tin plate it, then polish it out, you very well could save it.

expense?

hoo boy....

>
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