Catastrophic Failure of Pressure Vessels

[Colin WhittakerParticipant @colinwhittaker20544]

This is a very old safety video about what happens when pressure lines and pressure vessels fail. Given that we are unlikely ever to see a boiler explode this is the next best thing with the added benefit of no death, injury or PTSD.

When working on a 3000 psi gas well I would treat them with the greatest of respect but I remember colleagues who seemed to lack the imagination of what would could happen at 100 times a typical car tyre pressure.

[Colin WhittakerParticipant @colinwhittaker20544]

[Paul LousickParticipant @paullousick59116]

Pressure has to be respected, especially when it is hot and why boiler safety and inspections are so important.

One of my previous jobs was designing equipment for underground coal mines, using hydraulics at 5000 psi. One of the dangers was being hit if a hose burst. A flying hose can break bones and at that pressure the fluid it will pass thru your skin into your body and can cause a lot of serious health problems.

Another danger is if there is a very fine leak. The spray can be so fine that it cannot be seen (especially in an underground mine) and can sever your arm.

[not done it yetParticipant @notdoneityet]

But there are a lot (including model engineers) who don’t think that their air receivers, at 150psi, are a threat!

[Howard LewisParticipant @howardlewis46836]

In an American book on the B&O Railroad, there is a photo of the after effects of a boiler explosion on a post WW2 large articulated loco.

the boiler was torn from the frames and turned upside down, as well as damaging the track severely.

If anyone doubts the potential damage from a boiler explosion, remember not only the pressure energy, but the heat energy contained in the steam.

Steam at "only" 70 psi will be at about 170'C. When it condenses, every gramme will release 70 calories, plus 536 calories of the latent heat of vapourisation, at 100'C

So if you are in the line of fire, you will receive nearly 700 calories for every gramme of steam.

No wonder high pressure steam strips skin from the unfortunate victim.

A colleague lost the end from three fingers when a compressed air tank exploded.

Treat all pressure vessels with care and respect.

Howard

[Brian HParticipant @brianh50089]

My only experience of boiler failure was when a company that I worked for decided to build a range of domestic boilers to a German design, under licence.

One of the requirements was that we would have to carry out a destructive test using hydraulic pressure.

The boiler withstood over 5 times its design limit and then split in a non welded area. The lack of anything dramatic happening was somewhat of a disappointment but convinced me that a hydraulic test was the safest way to test a boiler.

Brian

[noel shelleyParticipant @noelshelley55608]

Howard and paul are both right ! Next time you use a small hydraulic jack think on that it may well be working at 10,000psi – for those who doubt that do the maths ! ANYONE using or making a steam boiler should be made to read Alan Mc ewans book – Historic Boiler Explosions – The photos and descriptions are truly awsome, Redcar steel mills is a good one – UTTER DEVASTATION ! Noel.

[Ady1Participant @ady1]

Looked after a dodgy donkey boiler output heater on a ship. The banging and booming of an expanding and contracting steel vessel leaves little room for the imagination, it's a bit like god banging on a drum

[Perko7Participant @perko7]

Further to Paul Lousick's post, I was involved at one time on the construction of valve stations on a high pressure (5000 psi) gas line across outback Australia. A pinhole leak from a flange gasket would cut your arm off if you walked too close. Safety procedures in that field are understandably rigorous.

[Paul LousickParticipant @paullousick59116]

All pressure vessels / compressor tanks, etc containing gas are potentially dangerous and could explode which is why hydrostatic pressure tests are done with water. Water does not compress like a gas and the pressure is quickly reduced if the tank ruptures.

[Clive FosterParticipant @clivefoster55965]

In general hydraulics are considered safer because there is no stored energy to drive an explosion. The fluid leak rapidly takes the pressure away once it becomes large enough. Pinhole leaks like the gas line Perko7 alludes to are pretty much just as dangerous.

I wonder what the relative safety of a simple air over oil system is compared to pure pneumatics or pure hydraulics.

My motorcycle lift has an X frame under the platform with a big vertical air over oil ram to do the lifting. The actual ram is hydraulic but its operated via an airline plugged into the top via the usual input and bleed valve controls.

Clive

[Speedy Builder5Participant @speedybuilder5]

When I worked for the CEGB, we received a safety bulletin once a quarter. One issue showed a boiler under test where the complete 20foot diameter domed end of the boiler had detached itself under moderate hydraulic pressure. A 20 foot domed end probably weighed a ton or so. Failure was due to brittle weld fracture. Reason:- The boiler was being tested in winter and the water was very cold. It was later found out that the weld material had temperature limitations and was not suitable for use in low temperature environments. (Didn't the Americans have similar problems on welded WW2 ships ?)

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