Beware the washing up

[Speedy Builder5Participant @speedybuilder5]

Lucky escape this morning as the handle literally dropped off the saucepan while taking it out of the dish washer. Lucky it wasn’t full of hot food when it “let go”.

It’s a stainless steel pan and handle riveted on with “composite” rivets.  I have never seen rivets like these before.  They are aluminium rivets with mushroom heads that have a very thin stainless steel cap encapsulating just the head.

I guess the pan is 10 years old and is (was) in daily use – now relegated to the workshop.

So, do your partners a favour and give all your pan handles a good work over and make sure its safe to go into the kitchen !

[Brian WoodParticipant @brianwood45127]

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

[Tony Pratt 1Participant @tonypratt1]

Dishwasher tablets are alkaline so will soon dissolve the aluminium rivets. Most of our pans have now been upgraded to stainless screws and dome nuts.

Tony

[NealebParticipant @nealeb]

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.

[Gary WoodingParticipant @garywooding25363]

The dishwasher detergent dissolves aluminium. I had exactly the same problem but, because the actual pot was really good stainless steel I simply drilled the ally rivets out and made up some brass replacements. Worked a treat.

[BazyleParticipant @bazyle]

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.

[Mark RandParticipant @markrand96270]

The saucepans look to be the perfect excuse justification for the purchase of a TIG welding set…

[Martin KyteParticipant @martinkyte99762]

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

[NealebParticipant @nealeb]

My coffee machine has an aluminium boiler. With our soft Devon water, the corrosion falling off the inside of the boiler used to keep blocking an internal pressure release valve. I ended up making a little filter out of brass mesh to go over the outlet pipe, and every few years I dismantle the boiler and clean it out. One day it’s going to give way…

On the other hand, we used to live in a very hard water area and then the thing used to block up with limescale! Sometimes you can’t win…

[Speedy Builder5Participant @speedybuilder5]

Well, I was going to consign the saucepan to the workshop, but the management put in a repair request.  Fortunately, I had a couple of 1/4″ mush head aluminium rivets in stock (hoarded away since I did my apprenticeship with Vickers in 1963) , so I estimate that these should give the pan a few more years life! I will carry out a corrosion inspection on a more frequent basis !

Bob

[Nealeb]

On Nealeb Said:

My coffee machine has an aluminium boiler. With our soft Devon water, the corrosion falling off the inside of the boiler used to keep blocking an internal pressure release valve. I ended up making a little filter out of brass mesh to go over the outlet pipe, and every few years I dismantle the boiler and clean it out. One day it’s going to give way…

On the other hand, we used to live in a very hard water area and then the thing used to block up with limescale! Sometimes you can’t win…

That’s interesting. I was really talking about the mildly alkaline results of the water softener. Sounds like supplied water in soft water areas is alkaline too.
regards Martin

[Martin KyteParticipant @martinkyte99762]

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

[Robert Atkinson 2Participant @robertatkinson2]

Onthe SS saucepand and aluminium rivets. It’s not just the dishwasher detergent dissolving the rivets it’s electrolytic corrosion between the aluminum and stainless steel. This will happen with any conductive electrolyte. But being highly alkaline does make it worse because it helps breakdown the aluminium oxide layer.

[Nigel Graham 2Participant @nigelgraham2]

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.

[Howard LewisParticipant @howardlewis46836]

We don’t have a dishwasher, and the local mwater is hard.

Have repaired ine or two saucepans / fring pans, with ordinary pop rivets, (Head inside pan) without problems.

Maybe the problem is a combination of electrolytic corrosion (Which will happen whenever different metals are used in an elctrlytic environment) and the chemicals used in the dishwasher?

Howard

[Gary WoodingParticipant @garywooding25363]

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.

[Grindstone CowboyParticipant @grindstonecowboy]

+1 on the dishwasher tablets being (at least part) of the problem. I once popped an alloy oil-cooler adaptor in the dishwasher (whilst still single!) and found it corroded it in parts.

Rob

[Nigel Graham 2Participant @nigelgraham2]

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

[David George 1Participant @davidgeorge1]

When I was involved in National caving association as the equipment officer it had started to be the pratice, in some caves to fit semi permenant anchors which were expanding rock anchors which you bolted a piece of 1/4″ x 1 1/2″ x1 1/2″ aluminium angle to the cave wall or roof with an 8mm high tensile bolt or cap screw. The piece of angle had a hole for the bolt and a another hole in the other side of the piece about 3/4″ dia for a shackle to clip into. It was found that the hole in some anchors  was wearing or eating through the aluminium at a rate which was not expected. With some help from Manchester University it was found that the electolitc action in the damp or wet atmosphere between the steel and aluminium was causing the wear which was considerable. The Caving association put in place to replace or remove these if possible of these and replace with a system of stainless steel anchors resin fixed into the rock.

David

[Nigel Graham 2Participant @nigelgraham2]

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.

 

[Simon Williams 3Participant @simonwilliams3]

Having migrated from the effect of caustic soda on aluminium to discussing the effects of electrolytic corrosion between dissimilar metals, can I take this thread one step further way from its origins.

There are jointing compounds designed to reduce or remove the electrolytic corrosion effects between metals, one such is a barium chromate based paint called Duralac, sold as a joint medium for interfacing aluminium  and copper overhead conductors.  It has the same properties between ally and galvanised steel.

In a previous galaxy far far away I used a grease called Unial made by BICC for the same purpose.  We also used it as a non-galling lubricant on 316/A4 grade stainless threaded fasteners.  This seems to have been the same Barium Chromate base but formatted as a squidgy paste rather than a glutinous paint.

 

[Speedy Builder5Participant @speedybuilder5]

Duralac – that’s a name from the past.  When building aircraft in the ’60s, we sometimes had to use a feather of Al alloy to pack out the skin of the fuselage, wing etc to make more aerodynamic.  These feathers were alachromed and then ‘painted’ with the yellow Duralac to prevent corrosion.

Most toolboxes had a well squished tube of it in the bottom tray !

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