A warning for mango chutney boiler users!

[JackA]

I decided to brew today. I treated my water, set the temp controller and came back when it was up to temp. I was greeted by a little pool of water under my mango chutney boiler/HLT.

Turns out there was a leak in the bottom. Here are a few pics:

Closeup:


This looks wide from the top, but was thankfully hairline underneath. Water drips out when the plastic is warm - hence why I didn't notice it when I treated the water and it was still cold.

To give perspective (crack is on the left):


And here's some detective work. Left is a new chutney barrel, right is the barrel with the leak:


Notice how the bottom which touches the ground is bent up. It has melted at high temp and stayed like that.

From the side:


You can see it's been pushed up by about a cm. Must be putting quite a lot of stress on the plastic!


So, be careful using these boilers. Turns out chris was right

[boingy]

The same risks apply to any plastic boilers, especially now that the extra thick walled ones are not available.

[sparky Paul]

I'm glad it wasn't more serious. Excellent post, and worth a sticky IMHO.

The same risks apply to any plastic boilers

I'm not sure about that, HDPE is very different to polypropylene... the melting point of PP is over 170°C, HDPE fully melts at 130°C.

The maximum recommended working temperature for HDPE under low load conditions is 100-104°C, if you are regularly boiling this material it is bound to deteriorate. PP has a higher maximum working temperature, and should not deform at boiling temperatures.

...or go shiny.

[JackA]

'The brew must go on' I thought!

So, I drilled some holes in a new chutney barrel, plugged everything in, switched on at the wall and 'POP!'. Fiddled around for a while and decided an element had blown, so replaced it with a spare Tesco element I had lying around. Plugged everything in and switched on at the wall. 'POP!'

Turns out the old 'heat resistant' kettle lead had melted though and shorted live and neutral. Here is the result, after cutting away the sheathing:





This also blew one of my controller SSRs. Fantastic.

So it's now 3pm and water is almost ready to mash. Just waiting for the next disaster!

[sparky Paul]

Wow, not having a good day, are you?

[Kev888]

Crikey, initially i couldn't see much change, but suddenly you realise how much the base has sagged upwards - assuming thats not just manufacturing variation anyway - nice one.

I've described before how a plastic boiler split on me, and sent a tidal wave of boiling sticky wort in the direction of my legs. In light of the new respect I gained rather suddenly for all that hot liquid, I've personally decided not to go there again with plastic. But I know many people are very happy with mango tubs and the like so i'm not expecting to win many people over, really.

Its something thats beginning to concern me a bit actually - although stuff often doesn't seem very different, I do believe that materials are getting cheaper or thinner and so on and components like elements are being built down to ever cheaper specs. That 'may' be okay for the specific things they're designed for, but the margins for us turning them to other uses could perhaps be narrowing more than is outwardly apparant - and some of them were probably quite close even to begin with!

Cheers
kev

[mark]

.....although stuff often doesn't seem very different, I do believe that materials are getting cheaper or thinner and so on .........

Totally with you there Kev, I bought a new Youngs 5 gallon FV the other week and was totally shocked at how thin the lid is
In fact, the whole vessel is no where near as good as the one I previously bought.
Fortunately this is only for cold liquids.

[WishboneBrewery]

Hopefully my mango HLT which only ever reaches about 81c will last a bit longer with 44kg of liquor in it.
A possible way to avoid this in future Mango Boiler builds would be to cast a base to sit it on, a bit of Plaster in a shallow tray maybe so that it fills the base contours????

[JackA]

Crikey, initially i couldn't see much change, but suddenly you realise how much the base has sagged upwards - assuming thats not just manufacturing variation anyway

Yup, the new boiler is boiling away as I type... it has already sagged into the position of the old boiler. It's actually a little scary. I think I'll be buying a stock pot soon

[JackA]

Finally finished at 10.30pm... what a sh!tty day

[Kev888]

It's actually a little scary. I think I'll be buying a stock pot soon

That was pretty much my own feeling after my 'little incident', too. I now only use metal tanks and heavier duty elements for heating, and it feels much more reassuring so the extra cost was worth it for me - it doesn't actually seem much when you think how much use a boiler gets, and it should last longer too.

Its a pity that there aren't more reliable sources of cheap metal tanks like there are plastic ones really; the best I have done so far is trying to find a hot water cylinder without much competition on ebay - it was excellent value and came pre-insulated for less than the sleeping mats would have cost me - but ideally we'd be wanting stainless rather than copper, with many of the cleaning potions in comon use, so thats never going to be cheap I guess.

Glad you got there in the end, anyway - what a day!

Cheers
kev

[bigdave]

Very glad I opted for metal now! Still intending using a mango barrel as an HLT but with temps not exceeding 75-80º I cant see there being an issue.

[pantsmachine]

This is a good thread. My HLT sheared off a wall and hit/drenched me when i was building my brewery and testing it(with cold water). My whole body clenches when i think of the result if it had been boiling water. Good chance the shock would have killed me. Obviously my using substandard fixings initially has nothing to do with wall thickness and slump in HDPE boilers. The end result would be the same though.

I don't think anybody should be boiling(prolonged or short) with HDPE.

In saying that, i think the same about heating elements and their cables for prolonged boiling. Pay your money and take your chance as the saying goes.... Or don't and invest in decent gear that will work safely and efficiently for you.

[bigdave]

Can I just bring this back into perspective by saying this so far is a one off. The number of people using mango barrel boilers on the forum alone is quite high so 1 incident is to be expected. It's very likely that at some point the barrel has taken a knock that's caused this fracture which has then been emphasized by the heat.

The 'slumping bottom' is something you would probably expect from any plastic vessel shaped like that which holds upto 50kg boiling liquid. The barrel it's self hasn't collapsed, and from a quick google is very unlikely to do so during the brewing process as HDPE is quite safe to use upto temperatures of of 120ºC with a melting point of 130ºC, which reinforces my theory of the barrel receiving a knock prevously.

Boiling in plastic with elements will always carry a greater risk than SS and gas but unfortunately £1000+ isn't a sensible budget to set as a starter kit for a hobby.

[sparky Paul]

The barrel it's self hasn't collapsed, and from a quick google is very unlikely to do so during the brewing process as HDPE is quite safe to use upto temperatures of of 120ºC with a melting point of 130ºC.

I don't think your link says that it is safe to use at 120°C. Whilst it does say that 120°C is the maximum temperature for HDPE, it will not be stable under load, and it also states further up the page that this temperature is only permissible for short periods.

BS EN1519-1 only gives a safe working maximum of 95°C for HDPE pipework, and many manufacturers of HDPE tanks recommend a maximum continuous temperature of 82°C, and only 100°C for intermittant use.

This manufacturer says...

HDPE has a working temperature of 212 degrees F - 220 degrees F under low load conditions

212-220°F equates to 100-104°C. I guess wort will boil at over 100°C, so I reckon I would stick to PP, stainless or aluminium.