The end is nigh.

[bellebouche]

Eight years of brewing with this kettle and I'm on the cusp of a vessel-fail. One of the original Catering Supplies/French ebay Chinese stockpots is starting to give up the ghost.

I drew 50l of water a few days ago - I normally let it stand before I start to heat to drive off the chlorine and let it de-gas. I'd noticed yesterday evening that the small wooden pot-stand I use (to protect the underside of the pot) had a little dampness on it and on checking... probably 20l gone. So... empty it, a detail inspection of the underside shows a number of pinhole-spots that are 'maybe' suspects and one obviously has a tiny fissure and is enough to leak.



So, due care and attention? Well I always thought that they were a little on the thin side and needed a bit of TLC so it has been well looked after (mostly) but clearly the use and minor abuse it's had over the years has brought it to this. No doubt the constant heating and cooling (I use a 10 kW butane burner) has work-hardened some of the stainless and made it a bit more crystalline and liable to pitting and fracture.

I will isolate the leaky-spot, flux it and backfill with silver-solder but it'll only be a temporary reprieve until I have to retire this pot.

I've been putting off a system upgrade for some time... what I have has served me well now for the last eight years... but nothing lasts for ever.

[Hogarth]

What??? I was told if I went stainless I'd never have to replace anything. Ever.

Do you reckon it failed because it's cheapo-Chinese stainless? I mean, I've never had a regular saucepan develop a leak, even after decades of use. (Instead, the handles fall off.) If so, I wonder if investing in a posher stockpot like one of the 'Vogue' ones would prevent this sort of thing.

EDIT: Sorry for your loss, though. I know this must be a difficult time for you.

[bellebouche]

hrm, I've got actual kitchenware with thick sandwich bases - tank-built... and never going to fail,

This pot is paper-thin and with one thing and another.. it's about to meet its maker!

I shalln't lament its passing - it has served me well!

[Kev888]

When I first started using the stock pots I'd clean them out on the yard, sitting them on the abrasive concrete. It caused them to start rusting in small spots here and there, I'm sure the end result would have been the same had I not noticed in time. I remember something similar in someone's corny too, caused by overenthusiastic use of bleach (I think), but of course that was from the inside.

FWIW breweries can even wear out extremely thick tanks, though it takes a long time. I had a professional/industrial 100L tank, which was 'very' hard to move about due to the weight, so the stock pots being thin perhaps isn't all bad. I see Mr Lard/Homebrewbuilder has some thicker ones, but I've no experience of them myself.

[Secla]

The ss brewtech pots are noticeably thicker than the standard bergland pots

[bellebouche]

Science is underway at Chez Bellebouche!

Broke out a microscope for a proper look - 500x closer!

First off, the undersurface of the pot here. This is the stainless given a mirror polish with some stropping compound and a felt wheel. It wasn't this shiny when it arrived.


here's some 'normal' pot - un buffed and with a tiny hairline scratch and some corrosion (or dirt!) in the trench.


Here's where it gets cool. Buffed out the dirt and corrosion from one small bit of pitting... and the DOF of the focal plane on the microscope reveals the crystalline structure of the stainless below.




and it got better




And down to business. The image I shot above was the worst I could find on the bottom of this vessel. Total false alarm. The actual failure point was miles away - it's not corroded through at all.. it's a tiny tiny hole (the calibration mark alongside is 0.03mm) my guess is that is a mechanical impact (small stone or suchlike) that i've dropped the pot on when I've been heaving it around with 50kg worth of load on board or perhaps something on one of the support arms on my burner.




So, easy fix with some silver solder and a propane torch and I'm back in business, passed the leak test. I'm also taking a flapwheel and a grinder to my burner now too to make sure the surface contact points play nice in future.

All of this mischief is a distraction from an actual brewday. Brewdog Candy Keiser underway

[Kev888]

Good stuff! I may start looking after mine more carefully now; with things like fish tanks they are usually sat on a mat of some kind to avoid the sort of point-loading you think is responsible. Not quite so easy with a burner (though you can get heat-proof caulking/rope I suppose) but for other situations it seems doable.

[bellebouche]

Post match analysis.

Only after I'd fixed the leak and got forensic on the whys and wherefores did I reach the following conclusion.

The corrosion and pitting.. not necessarily to blame. Looking at the inside of the pot where I'd made the repair to the leak (on the outside) I could see a marked radial line where the pot has been resting on the burner arms. Mechanical stress was the downfall for sure.


Here's how I fixed it.. have to say I'm pleased with my efforts to repair and while I was at it I took steps to patch up the worst of the visible pitting I could see. I'm no metalworker at all (McCoy would say.. "I'm a doctor, not an engineer!") so it took some research but working stainless was tricky. I cleaned, acid etched, cleaned again, keyed, cleaned, fluxed, soldered, ground and buffed.

It worked.



It made me take a good look at the burner arms. Also a touch over eight years old now and a little gnarly....



and whilst I had a stainless flapwheel on my grinder... I took the rough edges off. Mmmmyeah, eight years too late!



So, happy ending. It passed the leak test, passed a full boil today. It might spring another leak next brewday... it might last another eight years but from now on I'll pay close attention to having a clean bottom.

[Kev888]

heh-heh, I suppose clean is usually good where bottoms are concerned.

The burner is quite a difference; its amazing how these things can build up over time, yet so gradually they go unnoticed. Glad its working now!

[Hogarth]

Awesome! Top science there, Bellebouche, and I'm glad the kettle's still usable for now. This is going to make me treat all my pots with a bit more respect. No more dragging a full fermenter across a cement floor, and that sort of thing.