Author Topic: Berlin AquaDom explosion - what went wrong?  (Read 12332 times)

0 Members and 1 Guest are viewing this topic.

Online tom66Topic starter

  • Super Contributor
  • ***
  • Posts: 7336
  • Country: gb
  • Electronics Hobbyist & FPGA/Embedded Systems EE
Berlin AquaDom explosion - what went wrong?
« on: December 16, 2022, 11:16:21 am »
https://www.bbc.co.uk/news/world-europe-639969827
https://www.dw.com/en/berlin-massive-aquarium-home-to-1500-fish-bursts/a-64119337

It's no more.  Quite a feat of engineering.  For it to fail catastrophically, it seems like there must have been unseen damage.  What isn't clear to me is what parts are acrylic and what are glass.  The news report talks of people injured by flying glass but the construction was mostly plexiglass according to the 'net, though I suppose in the confusion being cut up by exploding plastic is probably more or less the same. 

What might cause such a catastrophic failure?  I could see the tank leaking but for it to explode like that suggests some catastrophic stress failure. 

Also, the poor fish.   I hope there were no endangered species there.
« Last Edit: December 16, 2022, 11:18:53 am by tom66 »
 

Offline Twoflower

  • Frequent Contributor
  • **
  • Posts: 742
  • Country: de
Re: Berlin AquaDom explosion - what went wrong?
« Reply #1 on: December 16, 2022, 11:51:50 am »
There is, or better was, enough glass in the area around the aquarium that would have caused such injuries.

I just read that an earthquake station 15km away from the Hotel recorded the event as an earthquake with a magnitude of 1.2 (https://mastodon.social/@erdbebennews:wtf:
 

Offline rdl

  • Super Contributor
  • ***
  • Posts: 3667
  • Country: us
Re: Berlin AquaDom explosion - what went wrong?
« Reply #2 on: December 16, 2022, 12:34:52 pm »
I doubt it "exploded" that sounds like the media just getting a bit carried away. Catastrophic failure I could believe. All that moving water probably blew out the hotel windows causing the glass shards. It's a crazy thing to happen no matter what.
 
The following users thanked this post: NiHaoMike

Offline Twoflower

  • Frequent Contributor
  • **
  • Posts: 742
  • Country: de
Re: Berlin AquaDom explosion - what went wrong?
« Reply #3 on: December 16, 2022, 12:40:23 pm »
I totally agree, Ii don‘t think that it was an explosion. The effect looks like one. But with that amount of water that‘s no surprise.
 
The following users thanked this post: NiHaoMike

Online Ian.M

  • Super Contributor
  • ***
  • Posts: 13217
Re: Berlin AquaDom explosion - what went wrong?
« Reply #4 on: December 16, 2022, 01:10:21 pm »
It wasn't a bomb, it was a time bomb!

Acrylic plastics are notorious for stress cracking and poor chemical compatibility, and its generally inadvisable to use them under significant tension.  Simply drilling a hole near the edge of a sheet of acrylic with the wrong (or no) coolant can create micro-cracks that will grow under stress till critical failure.   Using  the wrong sealant, failing to deburr a hole so there's point loading on the hole to surface corner, or simply overtightening a fastener can also start it cracking.

As the outer wall at the base was carrying a hoop stress of approx 620 KN per meter height and (presumably for aesthetic reasons), it didn't have any tensioned reinforcing bands supporting it, all it would take is one tiny mistake assembling it, maintaining it or cleaning it, and future failure became inevitable.  It could have been as simple as using the wrong cleaning spray on its exterior!
« Last Edit: December 16, 2022, 01:18:48 pm by Ian.M »
 
The following users thanked this post: tom66, helius

Online tom66Topic starter

  • Super Contributor
  • ***
  • Posts: 7336
  • Country: gb
  • Electronics Hobbyist & FPGA/Embedded Systems EE
Re: Berlin AquaDom explosion - what went wrong?
« Reply #5 on: December 16, 2022, 01:25:19 pm »
Reading some of the information about how it was constructed.  Several large sheets glued together then brought into the lobby, with the remainder of the hotel constructed around it after completion.  Seems very unlikely it will be replaced without at least partial demolition of the hotel, unless there's some way to go in via the roof.  I don't know how much revenue the attraction brought in, it sounds like it was just an incentive to stay at the hotel, as the SeaLife aquarium was separate from it, so it might just be removed and the hotel remodelled.  Apparently there's a similar construction in Bahrain.
« Last Edit: December 16, 2022, 01:27:39 pm by tom66 »
 

Offline HighVoltage

  • Super Contributor
  • ***
  • Posts: 5560
  • Country: de
Re: Berlin AquaDom explosion - what went wrong?
« Reply #6 on: December 16, 2022, 02:55:49 pm »
It wasn't a bomb, it was a time bomb!

Acrylic plastics are notorious for stress cracking and poor chemical compatibility, and its generally inadvisable to use them under significant tension. 

I think it is only the press reporting on the material being Acrylic Plastic.
If that is true, it would be horrible.

I would assume it was made of Poly-Carbonate Plastic instead, which is much stronger than Acrylic.
But who knows....
There are 3 kinds of people in this world, those who can count and those who can not.
 

Offline ebastler

  • Super Contributor
  • ***
  • Posts: 7375
  • Country: de
Re: Berlin AquaDom explosion - what went wrong?
« Reply #7 on: December 16, 2022, 04:25:21 pm »
I tried to find some more technical detail on the 'net -- there must be some engineering firms who were involved in the initial construction and proudly explain how they mastered that challenge, which materials were used etc. Didn't find much yet, except for this little gem -- a firm specializing in leak sealing, whose services were needed right after the initial construction:

https://web.archive.org/web/20220807223255/https://www.webac-grouts.com/projects/aquadom-berlin/

That's an archived copy of the page, since this section of their live site has just been deleted, now throwing a few pages of Typo3 errors. I wonder why...  ::)
 
The following users thanked this post: edavid

Offline HighVoltage

  • Super Contributor
  • ***
  • Posts: 5560
  • Country: de
Re: Berlin AquaDom explosion - what went wrong?
« Reply #8 on: December 16, 2022, 05:07:31 pm »
Here is a small documentary (partially in English) of how this was built.
Allegedly, based on this video, this AquaDom was built in the USA and the material is acrylic.




There are 3 kinds of people in this world, those who can count and those who can not.
 
The following users thanked this post: tom66, ebastler, Jacon, RJSV, pcprogrammer

Online Ian.M

  • Super Contributor
  • ***
  • Posts: 13217
Re: Berlin AquaDom explosion - what went wrong?
« Reply #9 on: December 16, 2022, 05:09:45 pm »
@HighVoltage,
The manufacturer knows for certain - it was Acrylic: https://www.reynoldspolymer.com/category/aquariums-zoos/ (bottom right) which leads to:
https://www.reynoldspolymer.com/projects/aquadom/

Elsewhere you can find the common figures that the outer wall was 16cm thick at the top and 22cm at the bottom.

Allegedly it was fully drained for maintenance two years ago.  I wonder what was done then . . .  It would only take one idiot using Loctite on a bolt in contact with the Acrylic shell to trigger this.
« Last Edit: December 16, 2022, 05:18:58 pm by Ian.M »
 
The following users thanked this post: HighVoltage, ebastler

Offline coppercone2

  • Super Contributor
  • ***
  • Posts: 11340
  • Country: us
  • $
Re: Berlin AquaDom explosion - what went wrong?
« Reply #10 on: December 16, 2022, 05:15:53 pm »
I drilled a hole on the edge of a acrylic and tightened it with a screw, 1 month later it cracked. I used a acrylic drill bit too and drilled with coolant. Very sensitive material
 

Offline pcprogrammer

  • Super Contributor
  • ***
  • Posts: 4670
  • Country: nl
Re: Berlin AquaDom explosion - what went wrong?
« Reply #11 on: December 16, 2022, 05:20:32 pm »
And now you know why the other firm withdrew.   >:D

At some point in the video the American spokes person of the firm states that there are only two companies in the world capable of doing this and that they got the job, and a very impressive one, I must say. With the elevator in the middle. One can only wonder what caused this failure.

But like tom66 wrote, the poor fish indeed.

Offline tooki

  • Super Contributor
  • ***
  • Posts: 13157
  • Country: ch
Re: Berlin AquaDom explosion - what went wrong?
« Reply #12 on: December 16, 2022, 06:34:02 pm »
Poor fish!!  :'(

I also wouldn’t want to be their insurer: a million liters of water is already horrible for a building, but a million liters of saltwater could mean much, much bigger problems.
 

Online tom66Topic starter

  • Super Contributor
  • ***
  • Posts: 7336
  • Country: gb
  • Electronics Hobbyist & FPGA/Embedded Systems EE
Re: Berlin AquaDom explosion - what went wrong?
« Reply #13 on: December 16, 2022, 06:39:45 pm »
That's a good point. Also a lot of that water will have gone into sewers and underground.  It could easily corrode parts of the structure for the hotel and adjacent buildings if it is not cleaned up promptly.
 

Online SiliconWizard

  • Super Contributor
  • ***
  • Posts: 15800
  • Country: fr
Re: Berlin AquaDom explosion - what went wrong?
« Reply #14 on: December 16, 2022, 09:45:57 pm »
That's unfortunate.
 

Offline Zero999

  • Super Contributor
  • ***
  • Posts: 20363
  • Country: gb
  • 0999
Re: Berlin AquaDom explosion - what went wrong?
« Reply #15 on: December 16, 2022, 10:18:37 pm »
That's a good point. Also a lot of that water will have gone into sewers and underground.  It could easily corrode parts of the structure for the hotel and adjacent buildings if it is not cleaned up promptly.
I've heard too much sodium chloride can create other problems in the treatment plant, as the microbes used aren't the right type to deal with it.
 

Online The Soulman

  • Super Contributor
  • ***
  • Posts: 1046
  • Country: nl
  • The sky is the limit!
Re: Berlin AquaDom explosion - what went wrong?
« Reply #16 on: December 16, 2022, 11:54:59 pm »
 

Online EEVblog

  • Administrator
  • *****
  • Posts: 39026
  • Country: au
    • EEVblog
Re: Berlin AquaDom explosion - what went wrong?
« Reply #17 on: December 17, 2022, 12:03:08 am »
I wonder if AvE will do an analysis?
 

Online EEVblog

  • Administrator
  • *****
  • Posts: 39026
  • Country: au
    • EEVblog
Re: Berlin AquaDom explosion - what went wrong?
« Reply #18 on: December 17, 2022, 12:04:35 am »
I also wouldn’t want to be their insurer: a million liters of water is already horrible for a building, but a million liters of saltwater could mean much, much bigger problems.

Salt water, yeah, that's extra bad.
 

Online magic

  • Super Contributor
  • ***
  • Posts: 7454
  • Country: pl
Re: Berlin AquaDom explosion - what went wrong?
« Reply #19 on: December 17, 2022, 08:52:08 am »
Also, the poor fish.
The fish suffered for a while but they are in a better place now.

Poor are the men who thought that they knew what they are doing, for them hell is just beginning right now >:D
 

Offline EPAIII

  • Super Contributor
  • ***
  • Posts: 1165
  • Country: us
Re: Berlin AquaDom explosion - what went wrong?
« Reply #20 on: December 17, 2022, 08:56:40 am »
The coolant may have been the problem. I once sprayed a mechanical, multi-button switch assembly with a tuner cleaner because the contacts were dirty. It had clear plastic buttons on metal fingers and the spray apparently got up in those recesses. For the next several days almost every time someone pressed one of the buttons, it fell off in pieces. The tuner cleaner wicked into the stress cracks and lubricated them into progressing far faster than they were without it.

I had to buy and replace all the buttons. After that I removed the buttons before spraying the switch assembly.

So yes, some plastics can exhibit very rapid cracking when cleaners are used.



I drilled a hole on the edge of a acrylic and tightened it with a screw, 1 month later it cracked. I used a acrylic drill bit too and drilled with coolant. Very sensitive material
Paul A.  -   SE Texas
And if you look REAL close at an analog signal,
You will find that it has discrete steps.
 

Offline HighVoltage

  • Super Contributor
  • ***
  • Posts: 5560
  • Country: de
Re: Berlin AquaDom explosion - what went wrong?
« Reply #21 on: December 17, 2022, 09:10:29 am »
When studying at the Hamburg university, we had a little project, researching gases.
For this project I built a small pressure chamber
Acrylic tube, about 50mm in diameter and 50 mm long and 10mm wall thickness
The ends were closed with aluminum plates

At about 10 bar pressure, this acrylic chamber bursted into many pieces, even killing a light tube, 2 m above the chamber!
We were extremely lucky that nobody was near the chamber at the time.

Afterwards we used polycarbonate tubing in the same dimensions, tested it to much higher pressure and never had a problem again.

So, I learned early on, to never use acrylic plastic for critical applications.

That is why I am so much surprised to read that they used acrylic plastic for this AquaDom
But maybe its is a special acrylic.
The final investigation report will probably be very interesting.

 

There are 3 kinds of people in this world, those who can count and those who can not.
 

Offline pcprogrammer

  • Super Contributor
  • ***
  • Posts: 4670
  • Country: nl
Re: Berlin AquaDom explosion - what went wrong?
« Reply #22 on: December 17, 2022, 10:43:56 am »
What surprised me was that the tank was constructed from separate parts of the curved acrylic, and that they managed to stick them together without visible seams.

For the inner cylinder not to big a problem with a compressing force on it, but the outer cylinder must have had a lot of strain on these seams due to the outward pushing force. Can't but wonder how they did this bonding and make it so strong. It did hold for 19 years.

Offline Siwastaja

  • Super Contributor
  • ***
  • Posts: 9336
  • Country: fi
Re: Berlin AquaDom explosion - what went wrong?
« Reply #23 on: December 17, 2022, 11:19:13 am »
What surprised me was that the tank was constructed from separate parts of the curved acrylic, and that they managed to stick them together without visible seams.

With a suitable glue with refractive index close to that of acrylic, the seams just disappear completely from sight.

Acrylic enables visually stunning structures, clearly this is why they used it. I can confirm the chemical compatibility is total crap. Even just something like water with the usual contaminants in it can cause almost invisible micro cracking.

But polycarbonate does not look as nice. It has that smoky or purple tint in it, and a little bit of haziness, too.
 

Online tom66Topic starter

  • Super Contributor
  • ***
  • Posts: 7336
  • Country: gb
  • Electronics Hobbyist & FPGA/Embedded Systems EE
Re: Berlin AquaDom explosion - what went wrong?
« Reply #24 on: December 17, 2022, 11:19:51 am »
The bonding is claimed to be proprietary, but it's a reasonable guess that it's a case of polishing the mating surfaces and then using an adhesive of some kind, there are only so many ways to solve this problem. I wonder if it is possible that at the surface exposed to the water that adhesive could progressively allow water into the joint, which eventually forced two halves apart, especially if the low temperatures of the hotel lobby allowed for some kind of expansion-contraction against the 26C tank water.   

The problem with this explanation is this might lead to the tank bursting, but I'd expect to see some complete parts of the tank assembly either where the tank was, or at least on the floor adjacent.  That would be even more dangerous than the situation we've seen, because a ten-tonne piece of acyrlic crashing through the adjacent hotel block would probably tear a hole in some of the residences. We didn't see that - the pieces of acrylic are, at most, the size of a large sofa in the lobby.  Maybe that suggests that the bonding is not simply an adhesive but a plastic welding process, creating effectively a single continuous sheet of acrylic.  In which case, the only failure mechanism available is catastrophic.

I'm also surprised we don't see much of the central tube remaining, as I would have thought that would be safe from a failure of the outer walls.  Imagine if someone had been in that elevator shaft when the main tank burst.  That could have been deadly.
« Last Edit: December 17, 2022, 11:21:27 am by tom66 »
 
The following users thanked this post: MrMobodies


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf