I had exactly that problem with otherwise excellent quality saucepans from Lakeland who honoured the guarantee and replaced the failure with another one just the same!

I have since replaced all these attachment rivets with stainless steel button head screws and blind nuts to keep the rest of them from a similar form of failure.

The silly thing is that these were sold as “dish washer safe”

Brian

I’m not sure that aluminium and dishwashers are that compatible. About 50 years ago I bought a cheap table knife from Woolworth – I was a student and needed something at short notice when I found that I had to fend for myself on Sunday evenings! –  and it has remained in almost daily use since. I traditionally use it for toast and marmalade in the morning. Anyway, I recently noticed that I was catching my thumb on something and realised that the aluminium handle was smaller than it used to be, losing its pattern, and exposing the corner of the stainless steel blade where it used to be inside the aluminium. I put it down to slow corrosion in the dishwasher. The aluminium has disappeared uniformly across the whole handle, not just where dissimilar metals are in contact. I can imagine an aluminium rivet in an enclosed space where it might stay in contact with liquids containing who-knows-what for longer periods could suffer as well, and more quickly.

Funny topic to come up today. As I poured my tea into a mug this morning it started leaking. Big crack down the side but I had only used it after supper last night and not dropped it or anything untoward.

For the same reason do not be tempted to connect a water softener to the feed for your heating system. Modern gas boilers have aluminium heat exchangers rather than cast iron and the softened water will eat it.

regards Martin

The plot thickens 🥴

Just had a bit of a Google on water softening and aluminium heat exchangers and there are many posts refuting this. To be fair my original post I was quoting my plumber so who knows.

Martin

Hard water is very slightly alkaline but probably not enough to harm aluminium alone. So I too, wonder if the more important effect is that the minerals make it more conductive, so enhancing its ability to corrode dissimilar metals in contact.

My grill pan is an aluminium pressing. It is prone to getting a good coating of grease and is far easier to clean in the dishwasher BUT, even though its not in contact with any other metal (all the racks are plastic coated) it suffers from corrosion. So I think its the dishwasher tablets that do it.

Detergents have to be fairly strongly alkaline to dissolve fat and grease, and aluminium-alloys are not very resistant to alkali generally.

The corrosion of those aluminium hangers would very likely have been accelerated if water from spray or a film trickling down the wall, perhaps only in wet conditions, met it. Water exiting as vapour in the air is effectively distilled but cave water holds dissolved calcium-carbonate or is slightly acid from atmospheric CO2 and/or organic compounds in the soil above the cave.

After all, it is this natural acid that dissolves the limestone to make the cave.

These hangers replaced M8-threaded expanding steel inserts in holes drilled in the wall. The rope was attached to these via aluminium hangers taken along with the ropes, and removed on exit. All very well but the steel of these building fixings obligingly corroded even without dissimilar-metal help, and constant use wore the threads.

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My work involved dangling test-pieces in a tank of tap-water – hard in Dorset – kept clean with swimming-pool filters and additives: calcium hypochlorite disinfectant,  copper sulphate algicide and acid or alkali pH-corrector. The water was perfectly safe for us, but I was forever trying to tell people that the lovely black anodising of their prototypes of equipment intended for sea-water immersion, cannot protect the aluminium from the stainless-steel screws* even in slightly electrolytic, fresh tap-water! (Anodising is slightly porous.)

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What of aluminium railway track?

The whole thread does make me think of miniature railways assembled from aluminium-alloy rail using mild-steel or stainless-steel fishplates and fastenings.

A raised track might not suffer too badly, and is readily-accessible for repairs, but even the best-maintained ground-level track will inevitably collect some leaf-litter and even soil around it, especially in wet windy Winters; helping keep the joints moist with more electrolyte-rich water.

A steel fishplate can be insulated from the rail by an interposed plastic or rubber shim, but there are still the screws to consider.

Incidentally, even stainless-steel can corrode in certain contact conditions, depending partly on the alloy; but in contact with aluminium it is still the latter metal that is eaten.

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*Stainless-steel screws and nuts…

As we know these can gall, a topic sometimes aired on this site.

My work also involved assembling some test-pieces, and one had a ring of M5 st-stl screws and ‘Nyloc’ nuts on flanges inside a narrow recess. One galled… The only answer was to keep tightening it until the screw sheared.