Imploding vacuum tanker

box

Member
Livestock Farmer
Location
NZ
Looking for wisdom, failing that ‘quick bodges and creations’.
Elderly but functional slurry tanker is beginning to implode.
If everything but the tank wasn’t working fine I’d probably scrap the thing but as it only gets occasional use for 3-4 loads at a time the sensible options are limited.
No point in buying a new one really and not enough work to call in a contractor.
I’m unlikely to be able to source a sensibly priced replacement tank ( unless anyone knows otherwise) which leaves one other option..
Can anyone think of an expanding foam/reinforcing layer of product that I could line the inside with to delay the decay?
Theoretically it’s just the rear dome that’s paper thin but I expect the main barrel won’t be far behind!
Loosing some volume is bearable.
Thanks

A local man was killed a few years ago when he was hit in the chest with shrapnel from a pressurised tank which exploded while he was transferring fluid, but lets not dwell on the past.

The obvious solution, while it's still functional and in one piece, is to clean it up, list it on ebay "as is" and let someone else worry about it. Or trade it in on one that's not rotten.

I don't see any kind of internal coating lasting too long. Roll some 2" pipe or SHS to the shape of the dome and stitch weld it onto the outside to create an exoskeleton. 3 or 4 pieces which criss cross through the centre will divide the dome into 6 or 8 pieces and stop the whole thing from flexing, imploding or exploding. Extend it forward and add more bits to the barrell if you want. If it's too rotten to weld to, consider a 2 part epoxy.

You're only delaying the inevitable, but you haven't really got many options if you're not prepared to cut the tank up and start reskinning it - but it looks like you've only got until 2025 before an upgrade is imminent anyway so no point spending too much money.
 

Bury the Trash

Member
Mixed Farmer
Looking for wisdom, failing that ‘quick bodges and creations’.
Elderly but functional slurry tanker is beginning to implode.
If everything but the tank wasn’t working fine I’d probably scrap the thing but as it only gets occasional use for 3-4 loads at a time the sensible options are limited.
No point in buying a new one really and not enough work to call in a contractor.
I’m unlikely to be able to source a sensibly priced replacement tank ( unless anyone knows otherwise) which leaves one other option..
Can anyone think of an expanding foam/reinforcing layer of product that I could line the inside with to delay the decay?
Theoretically it’s just the rear dome that’s paper thin but I expect the main barrel won’t be far behind!
Loosing some volume is bearable.
Thanks
what sort of condition is the pump in aamoi ?
 

335d

Member
If the measly max-on-a-good-day of -15psi suction is causing it to implode, it is very likely to explode in blow mode. Scrap it before someone is hurt.
the vacuum will be much less than -15 psi, and should be less than -4psi. The positive pressure would also be around 7psi. But the shape of the tank means it is more likely to implode than explode. the sight glass is normally first to go
1 bar is roughly 14.5 psi
Screenshot from the hispec manual
 

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Old tanker 35 years old had air in tyres, no lights, no brakes and a pump with seals gone yet again. Ok for a water bowser sort of thing. Sold to a mate for scrap money plus a pint.
New to me tanker has pretty wheels, tidy pump, over 1500 gallons and with valves, hoses and an hour in the workshop good to go. First load and it’s pinhole leaks drawing air. That can only mean one thing as discussed at length here.
Seems a waste to scrap a second tanker in as many months! Just bought a dud one but still up on scrap money I reckon!
 

Cowabunga

Member
Location
Ceredigion,Wales
the vacuum will be much less than -15 psi, and should be less than -4psi. The positive pressure would also be around 7psi. But the shape of the tank means it is more likely to implode than explode. the sight glass is normally first to go
1 bar is roughly 14.5 psi
Screenshot from the hispec manual
Sight glasses blow out though, mainly because the plastic gets brittle with age.
Tankers almost always implode rather than explode. The better built ones will have strong hoops welded to the inside of the tube to prevent implosion. Poor ones will not and might use thinner plate for the tube. Star brand tankers were built and sold cheap at one time and were notorious for imploding after a good few year’s use.

If one has started to go, and the further from the ends the bigger the danger, it presents a very high risk of imploding completely. It has, after all, done the hard part which is to start bending the tube inwards. The finale may well be sudden and dramatic.
 

Netherfield

Member
Location
West Yorkshire

Munkul

Member
Pressure system safety regulations apply I believe. No specific knowledge, but I'd expect that periodic inspection by a competent person would be a requirement, and embargo of anything that doesn't look right would be mandatory. I think in terms of the regs, it's a case of of you have to ask, you already know the answer.
I think I can weigh in here, pressure vessels are part of my day job :)
The Pressure Equipment Directive PED (now PESR post brexit) applies when building these tankers, but the Pressure Systems Safety Regulations (PSSR) do not apply, Schedule 1, regulation 3(2) point (19) specifically excludes slurry tankers.
So, no formal periodic inspection by competent person. Just the informal inspection by the user, making sure it's not about to fail altogether.
You just have to maintain it to a good enough standard to prevent harm to anyone in the event of a foreseeable failure.

In this case, the OP is savvy enough to have carried out his informal inspection (ie he used his eyes!) and spotted a problem indicating it IS going to fail in the somewhat near future.
I would respectfully suggest he stops using it and gets another tanker. If it fails at a bad time and causes damage to people/property through leaking/spraying slurry everywhere, or whatever, he's directly liable for that.

If it's not leaving his property and can only leak onto his own fields, then probably no harm done... but why delay the inevitable? Why would you wait into it's totally unusable and you have a load of slurry to spread, before looking around for a replacement? It's just common sense IMO.
 
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bitwrx

Member
I think I can weigh in here, pressure vessels are part of my day job :)
The Pressure Equipment Directive PED (now PESR post brexit) applies when building these tankers, but the Pressure Systems Safety Regulations (PSSR) do not apply, Schedule 1, regulation 3(2) point (19) specifically excludes slurry tankers.
So, no formal periodic inspection by competent person. Just the informal inspection by the user, making sure it's not about to fail altogether.
You just have to maintain it to a good enough standard to prevent harm to anyone in the event of a foreseeable failure.
:geek:
Love it when someone can quote chapter and verse. Thanks for clarifying; at least I was looking in the right place, even if I got the wrong answer...

I read up-thread that slurry tankers operate at a positive pressure of 1bar; does that put them outside the scope of PSSR anyway?

Does PSSR apply to pressures below 0 gauge (i.e. vacuum), or is it just things that can explode?

(Also, as a matter of interest, what's your day job?)
 

aidan

Member
Location
Ireland
I think I can weigh in here, pressure vessels are part of my day job :)
The Pressure Equipment Directive PED (now PESR post brexit) applies when building these tankers, but the Pressure Systems Safety Regulations (PSSR) do not apply, Schedule 1, regulation 3(2) point (19) specifically excludes slurry tankers.
So, no formal periodic inspection by competent person. Just the informal inspection by the user, making sure it's not about to fail altogether.
You just have to maintain it to a good enough standard to prevent harm to anyone in the event of a foreseeable failure.

In this case, the OP is savvy enough to have carried out his informal inspection (ie he used his eyes!) and spotted a problem indicating it IS going to fail in the somewhat near future.
I would respectfully suggest he stops using it and gets another tanker. If it fails at a bad time and causes damage to people/property through leaking/spraying slurry everywhere, or whatever, he's directly liable for that.

If it's not leaving his property and can only leak onto his own fields, then probably no harm done... but why delay the inevitable? Why would you wait into it's totally unusable and you have a load of slurry to spread, before looking around for a replacement? It's just common sense IMO.

good we have someone that knows something about pressure

i have a question, how come tankers typically implode rather than explode
 

Runs Like a Deere

Member
Mixed Farmer
I don't feel Implode is really the right word for this.

The reason they tend to crush rather than explode is because they when they crush the structure buckles across the spanning material where as to explode it would be a tensile failure. material can buckle due to a force being applied well below what would cause it to yield from a tensile force.
 
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Munkul

Member
good we have someone that knows something about pressure

i have a question, how come tankers typically implode rather than explode
:geek:
Love it when someone can quote chapter and verse. Thanks for clarifying; at least I was looking in the right place, even if I got the wrong answer...

I read up-thread that slurry tankers operate at a positive pressure of 1bar; does that put them outside the scope of PSSR anyway?

Does PSSR apply to pressures below 0 gauge (i.e. vacuum), or is it just things that can explode?

(Also, as a matter of interest, what's your day job?)

Haha, I know enough to be dangerous anyway! I have done 4 years of Asset integrity for a industrial manufacturing company, developing the job role from nothing.
Vessels and pipework containing steam, compressed air, and nasty chemicals - keeping things legal, inspected, and safe. 3 major regulations keep me in the job - PSSR, COMAH and DSEAR.

PSSR applies to any vessel containing steam at any pressure, and pretty much any substance held under pressure. Compressed air receivers fall under PSSR if they are bigger than 250 bar.litres (pressure x volume) so if you have a big old compressor on farm, keep quiet ;)
Some things are generally exempt (e.g. military stuff, refrigeration systems under 25kw); some things are specifically exempt like slurry tankers.

It's more or less a common-sense regulation - about stored pressure energy, and preventing failures. Especially steam. That's why they're not too bothered about slurry tankers imploding themselves. Very unlikely to hurt someone.

It's the shape of the vessel that determines whether it fails on vacuum or pressure. A cylinder is always stronger from the inside than the outside.
A vaccum tanker operates roughly between -1bar and +1bar pressure, if atmospheric pressure is 0.
-1bar vacuum = +1bar atmospheric pressure higher on outside.
Eventually a vac tanker corrodes to the point where it can still hold 1bar internal pressure, but not 1bar external pressure.
So it will nearly always fail under vacuum first, and this will buckle it inwards.
If that makes sense?
 

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Man fined £300 for bonfire-related waste offences

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Written by William Kellett from Agriland

court-640x360.jpg
A man has pleaded guilty at Newtownards Magistrates’ Court to waste offences relating to a bonfire next to the electrical sub-station on the Circular Road in Newtownards, Co. Down.

Gareth Gill (51) of Abbot’s Walk, Newtownards pleaded guilty to two charges under the Waste and Contaminated Land (Northern Ireland) Order 1997, for which he was fined £150 each and ordered to pay a £15 offender’s levy

On June 25, 2018, PSNI officers went to Gill’s yard, where they found a large amount of waste consisting of scrap wood, pallets, carpet and underlay.

Discussion with Northern Ireland Environment Agency (NIEA) officers confirmed the site...
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