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exploding petrol tank


Unkel Kunkel
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2 hours ago, PeteH said:

He died in 2006(ish). Complications from Diabetus allegedly.

One of the Guys on board ship had a shed load of his stuff, and Mike Harding. On an old reel to reel tape recoder, Used to play them regularly in the Bar when we where bored on long passages.

Pete

Edit:- https://en.wikipedia.org/wiki/Blaster_Bates

Blaster also was credited to the naming of "knicker brook" at Oulton Park.

Tony.

 

 

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Exploding tanks ... not fuel,but moving on to  compressor tanks..

A lot of us have compressors.

Hands up - I hardly ever look at mine and I neglect to drain it every  use.

Internal corrosion is the main cause of these explosions  and rather like petrol tanks the results can be spectacularly destructive  - if you’re lucky but can also result in serious injury and death.

Have a look on Utube .It seems  this is not rare .Some of the interiors of the of the exploded tanks   exposed by the  explosions  do look seriously rusty.

However, this raise a question( bearing in mind these are pressure vessels)  how do we ensure our tanks our safe?

Daily draining when used  is advised, - but what else ?

Hydraulic and endoscopy tests seem beyond the amateur’s resources. 

Does the compressor pump/ motor  etc pack up first for most people so they buy new?

or is there  simply a point reached when, “It’s x years old , better replace it”?

 
 

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Mine's been in use for almost twenty years now; I too neglect to drain it after every use but there is quite a quantity of water pours out the bottom even after two or three uses. Thankfully it's clear and not rusty brown. I always wondered if removing one of the pipes off the top and swishing a quantity of Jenolite round the inside would do any good?

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to aid moisture content when compressing we fitted a truck air brakes  air dryer into the charge pipe  ( well one that fell off the assy line  Hmm )

since got rid of the monster as all tools are now batterty and o dont doant more spraying

just got a 10 ltr unit for tyre inflation etc.

Pete

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1 minute ago, JohnD said:

I admit to rarely emptying the tank, but I do squirt WD40 into the intakes in the hope that this will protect the inside.

JOhn

I would worry that any kind of non-setting additive would come out via the gun, which may cause problems when spraying paint. That's why I had thought of liquid Jenolite, it would cure the rust and dry hard, so wouldn't affect any usage.

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8 hours ago, Colin Lindsay said:

I always wondered if removing one of the pipes off the top and swishing a quantity of Jenolite round the inside would do any good?

Not sure if I fancy picking my compressor up and swilling Jenilite round inside it, it weighs 350kg. 

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From what I can find out so far: 

There is a case for regularly draining the condensate, and from today I will aim to diligently drain it after each use.

- It can build up to eventually reduce the tank volume ( though it could be argued that any explosion would be proportionately   less, I suppose)

- The condensate aids corrosion so draining and leaving  the drain cock open  would seem a good measure.

-Phosphoric acid ie Jenolite seems acceptable but as the Scrapman points out there are practical issues ..

- I am a bit unsure about the idea of spraying any flammable  liquid  be it oil -(or WD 40 , John ) into the tank - a pressure vessel, and then pressurising  it to 150  psi .The temp probably doesn’t rise very high as the pressure  is increased but it is considerably pressurised  - just a bit uncomfortable with this - could this be an explosion risk in itself?

Perhaps rusty  drain fluid a sign that  a compressor needs replacing?

( I don’t know, that’s why I asked the questions)

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  • 3 weeks later...

“accident-prone” or “careless”?

I haven’t been  in an explosion since posting my cautionary tale.

 But I have been fairly close to one last week

but more of a mini “ conflagration”.

I use one of those MAPP gas blow lamps  -yellow cylinder etc.Use it quite a lot.

Turned it on. pressed the piezo  button to light...

At all of the same moment  it seemed, as the flame lit, (it seemed a bit smaller than usual)  I noticed a curious loud hiss, and the horrible MAPP  gas smell..

- Then “”woof” ( or “whoosh” ..I forget  if there was a noise),suddenly a bright yellow, smokey  cloud of gas and air ignited.I don’t know how big it was because I  seemed to be in its centre.The gas had escaped from a leak  before the burner from a fractured pipe.

The burner head decided to fall off at this point  ...This was immediately  followed by a long, mini flame thrower, bright   yellow flame  and lots of thick black smoke as gas escaped out from  from the pressurised  cylinder through the end of the fractured pipe.

I managed to turn off the valve as I ran with it to the door ready to chuck it outside .. but to my great relief it all went out.

Apart from the unpleasant and very  lingering smell of singed hair on forearms, eyebrow and forehead,  all was well.

Maybe it had been dropped; perhaps it had been stood on..I don’t know, but it had fractured through the threaded section of the pipe near the “O” ring.

The lesson ?  - check everything carefully before you use it...

 

3D6AAF6C-E2CA-4C5D-A927-F710FA938F63.jpeg

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I have an Air compressor. Orginally purchased to operated an "air nailer" when fitting acres of Plasterboard in a self build. From which I remove the end plugs every few years and examine the interior via an endoscope. It is about 15 years old, and shows small amounts of Corrosion. I have in my working life seen far more corrosion in vessels in daily comercial use, the "statutary" examination period is 2 years BTW under the "pressure vessel regulations". It was not at all unusual to have the pressure reduced when corrosion was seen to be beyond that which was allowed under it`s construction Reg`s. More to the point regular draining, (Mine has an extension of the drain valve, which allows easy draining, without grovelling under the tank). And testing of the relief (safety) valve, (ie; even just lifting it to ensure not stuck?) will normally be sufficient. In service we used ultrasonic thickness meter`s to check for thinning due to corrosion. Most Tanks are constructed to One of the Standards, When I was working (1990`s) it was BS1500 or 1515?. Usually stamped on the vessel. (Now CE Mark?) By which time corrosion allowances had been reduced. (BS 487-1948 required 1/6") New standards are now in place, some changes in 2021 to come. Regular draining reduces the amount of moisture that can get to air tools, even when filter/dryers are fitted. 

DO NOT. Coat the interior, or put any sort of moisture removing spray into a vessel, most contain light ends, and could in the right circumstances (Fuel/air Ratio) permit or encourage an explosion. In the comercial world sign of any such use would trigger an imediate prohibitation and a report to the HSE.

I have seen perfectly satisfactory vessels in use in excess of 80 years old, similarly, neglected ones scrapped under 5 years.

Pete

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PeteH,

Most interested in your last para.      Please explain why WD40 or similar is such bad news (I suggested it!) and what is meant by "light ends"?

I have a rather different professional interest.   A few years ago, not in my hospital, an oxygen cylinder, the lightweight GRP type, was turned on and laid on a patient's bed in preparation for them to be moved elsewhere on the bed.      A few seconds later, a 'bang' was heard and three feet of flame came out of the cylinder nozzle!      It burnt the patient, set light to the bed clothes and the curtains around the bed, ans started amajor fire in the Intensive care unit.     Several other people, staff and patients had smoke inhalation injuries, only mitigated by heroic action by the staff.     The ICU had to be closed for redecoration, but I never heard of any explanation.   See: https://associationofanaesthetists-publications.onlinelibrary.wiley.com/doi/full/10.1111/anae.12089   

 High-pressure oxygen is an extreme fire risk, yes, but what ignited it?           Aluminium fragments in the cylinder?    

  We become blase about the use of high concentrations of oxygen.        So blase, that it killed three US astronauts, Grissom, White and Chaffee in the Apollo 1 disaster.    Afterward the ICU incident, The Health and Safety Executive changed the protocol for the use of transport cylinders to say that they should never be used while laid on their side, always upright in the approved rack.      I should reassure everyone that this is a unique incident - there are millions of such cylinders in safe use in the NHS. 

John

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3 hours ago, PeteH said:

From which I remove the end plugs every few years and examine the interior via an endoscope.

What do you use to reseal them afterwards, Peter? Mine is hissing from one of the top pipes, I've tried PTFE but no good. I need some kind of stronger / thicker seal.

It's the bit in the photo to the bottom of the large brass connector, where it screws into the orange adaptor which then screws into the spigot on the tank. I don't want to seal it too permanently, unless doing that won't cause me any additional bother in years to come.

 

19E3D2E6-1332-490E-B0AA-333C1B77F98D_1_105_c.jpg

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As mentioned earlier, I used to work in the HSE laboratories where we dealt with compressed oxygen upto 4500psi/300bar.  If you open a cylinder valve too quickly you can cause a high pressure shock wave and the sudden compression of the gas can result in a temperature sufficient to cause an ignition, the same effect as in a diesel engine.  Therefore you must always keep oxygen systems oil and contamination free.  Substances burn extremely violently in an oxygen enriched atmosphere.  For example, if you try to ignite a piece of expanded polystyrene, it burns slowly with a great deal of black smoke.  However, if you dip a piece of the polystyrene in oxygen enriched liquid air, a small spark will result in a bright flash and no black smoke or residue.

Compressed air at 100 psi/7 bar will have an oxygen partial pressure 8 times that in the ambient atmosphere.  One reported incident involved applying a gas torch to an HGV wheel without de-pressurising the tyre.  The effect of the heat, high pressure and oil contamination on the inside of the rim resulted in a fatal explosion. In this case the source of heat was obvious but in other cases it could be caused by friction etc.  Introducing a fuel such as WD40 (XL?) which contains "light end" or volatile fractions of petroleum distillate is not a good idea.

We also investigated reports of ignitions in a certain design of oxygen cylinder valves.  We built a rig to automatically repeatably open and close the valve but even after introducing contamination, we failed to get an ignition.  In the case of the hospital incident, it was probably a combination of unfortunate effects which may not be able to be reproduced.

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2 hours ago, Colin Lindsay said:

What do you use to reseal them afterwards, Peter? Mine is hissing from one of the top pipes, I've tried PTFE but no good. I need some kind of stronger / thicker seal.

It's the bit in the photo to the bottom of the large brass connector, where it screws into the orange adaptor which then screws into the spigot on the tank. I don't want to seal it too permanently, unless doing that won't cause me any additional bother in years to come.

 

19E3D2E6-1332-490E-B0AA-333C1B77F98D_1_105_c.jpg

I cannot properly see what is under the base of the, what I suspect, is a Non return valve?. I would suggest it originally had a copper? or similar sealing washer, which has degraded?. I must admit to using PTFE on the end plugs, being tapered plugs it works well and they come out without issue.

Pete

 

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3 hours ago, JohnD said:

PeteH,

Most interested in your last para.      Please explain why WD40 or similar is such bad news (I suggested it!) and what is meant by "light ends"?

I have a rather different professional interest.   A few years ago, not in my hospital, an oxygen cylinder, the lightweight GRP type, was turned on and laid on a patient's bed in preparation for them to be moved elsewhere on the bed.      A few seconds later, a 'bang' was heard and three feet of flame came out of the cylinder nozzle!      It burnt the patient, set light to the bed clothes and the curtains around the bed, ans started amajor fire in the Intensive care unit.     Several other people, staff and patients had smoke inhalation injuries, only mitigated by heroic action by the staff.     The ICU had to be closed for redecoration, but I never heard of any explanation.   See: https://associationofanaesthetists-publications.onlinelibrary.wiley.com/doi/full/10.1111/anae.12089   

 High-pressure oxygen is an extreme fire risk, yes, but what ignited it?           Aluminium fragments in the cylinder?    

  We become blase about the use of high concentrations of oxygen.        So blase, that it killed three US astronauts, Grissom, White and Chaffee in the Apollo 1 disaster.    Afterward the ICU incident, The Health and Safety Executive changed the protocol for the use of transport cylinders to say that they should never be used while laid on their side, always upright in the approved rack.      I should reassure everyone that this is a unique incident - there are millions of such cylinders in safe use in the NHS. 

John

First off, let me say that I am no chemical engineer (Mech; Eng, Actually Marine discipline) So my discipline does not exactly cover the Chemical Science behind explosions, It is based on experience and reading up the aftermath of reported incidents. However, “Light Ends” are generally regarded as Fuels which are at the lower end of the “inflammable” range, (petrol for example). Many cleaning solvents and the “carriers” for the like of “Waxoyl” for example are flammable. Injected into a cylinder they could constitute a hazard in the correct proportion with air and in the presence of heat (eg; Hot carbon carried over from a hard worked Compressor?) Known as the combustion triangle. At the other end of the Range, I worked with Heavy Fuel Oil. Into which you could throw a lighted source and it would self extinguish. Until it was Heated (80`C) In order to be used in (very) Large Marine Diesels.

 

With certain exceptions NO cylinder should be used (ideally not even transported) any other than vertically. Unless designed for that orientation. Gas cylinders are often filled in such a way that the Gas is under pressure in fluid form, laid on the side the liquid can be ejected, expands exponentially (from memory LPG`s, for example expand by a factor of 250 (ish) from liquid to gaseous form) The use of grease for example, on Oxygen and Air cylinder connections is a no no! Regarded as fuel in contact with oxygen, it increases the hazard. It would take someone with more experience that I, to understand why “your” oxygen bottle to exploded in the manner it did, but if the 3 factors where in play Fuel. Oxygen. And an ignition source. Then it could happen.

As an aside. Powders, Flour is one, have been known to spontaeously combust in a violent manner, again you have Fuel, (Flour) Air, and often static electricity. 

 

Pete.

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on production all air brake pipe threaded fittings were sealed with Loctite 572

https://uk.rs-online.com/web/p/thread-lock/1271375/?cm_mmc=UK-PPC-DS3A-_-google-_-3_UK_EN_Thread+Lock_Loctite_Exact-_-Loctite+-+Thread+Lock+-+1271375+-+5-_-loctite+572&matchtype=e&kwd-3790733093&s_kwcid=AL!7457!3!481269986115!e!!g!!loctite%20572&gclid=EAIaIQobChMIheeyss7k7gIVBbd3Ch0OTw1WEAAYASAAEgKnGvD_BwE&gclsrc=aw.ds

Pete

 

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3 hours ago, Colin Lindsay said:

What do you use to reseal them afterwards, Peter? Mine is hissing from one of the top pipes, I've tried PTFE but no good. I need some kind of stronger / thicker seal.

Have used Locktite 55 on threaded joints.

Regards

Paul.

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no 572 is a paste you smear on the threads before fitting/screwing in  once air is excluded it sets really hard

can be a pig to strip down once its set  solved any leak problems .

we had a ultasonic device that could pick up an Ant farting at 50 paces , but often the olde soap mix and a brush  foiled it .... well say found it .

pete

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This is a problematic one because it's a non-tapered brass thread into a metal housing, but it has to align with a solid pipe, and when you align it to the pipe it's not fully tightened. I can tighten it up fully airtight, but then it's half an inch out from the pipe and has to be loosened again to meet. If I bend the pipe, it's quite a large bore and flared at both ends, and so if bent further might become too short to seal - I'd try that as a last resort.

If I use a flexible sealant it has to be able to withstand the air pressure inside the tank. PTFE is no good; tried and failed. What you can see round the base of the brass fitting in the photo further up is a rubber seal I fitted, but it made no difference. I might just end up using a good solid sealer and if it's permanent, then I suppose I have to ask: when am I intending to remove that valve ever again?

84B03B25-03C2-4715-9DC2-CCA15F7A4FD4_1_105_c.jpg.f18ee10677a174866dda172afce1d75b.jpg D41F5675-5FB4-45AD-960E-A0454DA50E0C_1_105_c.jpg.2251f65b536c7ecc3acefa1623cc22da.jpg

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