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Crane failures
8

Crane failures

Crane failures

(OP)
https://www.youtube.com/watch?v=nvQuFBMUko4
At the 3:22 area, what sort of material does that look like?
I wonder how many such failures have happened due to the use of the wrong size and type of materials used to construct the crane system?

RE: Crane failures

Cast iron jaw coupling in a hoist? at 3.24. This might be allowed under the design rules for a light duty crane, but specifying a light duty crane in a turbine hall where the load can easily be worth much more than the crane seems like an unwise cost choice (not even considering the safety aspect).

RE: Crane failures

I notice that the lower block came down with the load, but the upper didn't.


spsalso

RE: Crane failures

I was thinking it was a cable failure as well.

RE: Crane failures

3
I don't work in heavy industry so those of you who do can correct me as necessary:
1. Isn't the broken part a cable sheave? The system failed when the sheave fracture from its hub and the lift cables went from constant tension to sudden impact loading on the upper support structure.
2. Isn't this probably a fatigue failure and not an issue with improper specification or procurement of parts? The crane is built to the specification required for the turbine hall. This wasn't an ad hoc decision to do the lift. This would all be planned for and checked before the lift.
3. Isn't this a safety training video illustrating never go under a live load even if the equipment is rated for the lift, you trust your team, and you have done the same thing many times before - unexpected failure can occur?
This seems like a case of a critical part failing not because of ineptitude or malice but because it developed a hidden defect. More info would be needed beyond the short video to make a knowledgeable decision.

RE: Crane failures

Quote (xx)

1. Isn't the broken part a cable sheave?
The failed part looks (to me) like a jaw coupling, which is a part I would expect between the hoist motor and the hoist gearbox.

The lower grade of these couplings is made from cast iron, note the brittle fracture surface. These couplings can be obtained in steel, which is less likely to fracture.

It is unusual for a crane of this size to have a mechanical load break, so failure of this coupling results in complete loss of load control, but the load will accelerate slowly as it is still connected to the inertia of the gearbox. I would expect much faster acceleration if the hoist rope failed.

Quote (XX)

2. Isn't this probably a fatigue failure and not an issue with improper specification or procurement of parts? The crane is built to the specification required for the turbine hall. This wasn't an ad hoc decision to do the lift. This would all be planned for and checked before the lift.
The difference between a light duty crane, a heavy duty crane, and a port or steel mill duty crane is the design expected duty cycle. Turbine hall cranes tend to be designed as light duty, as the expected number of capacity lifts over the life of the crane is small. CMAA Class A, FEM 1Cm, ISO Class M2. Note the lifetime cycles and infrequent capacity loading in the table below.


Quote (XX)

3. Isn't this a safety training video
But it looks like a real event (although some of the video could have been staged after the fact).

RE: Crane failures

2
Only one of 4 teeth on the jaw coupling broke. This would not have caused the load to drop.

RE: Crane failures

There are more broken pieces than just the jaw coupling, it is not obvious what they belong to. Perhaps a bearing housing supporting the coupling??

RE: Crane failures

Yes, an extreme misalignment between the motor and gearbox would break the coupling in this manner. This coupling failure is a result of the load dropping, not a cause.

RE: Crane failures

The jaw couplings for the container cranes I have worked on were typically GGG Spheroidal cast iron. Its also common to have redundant brakes, typically 1 on the motor side and one the low speed side of the gearbox.

RE: Crane failures

Kor-Pac emergency hoist brake

when one of these beasts engages everyone hears it. Typical time to stop is less than 1/4 turn at high speed down, with proof test weight.
Reference http://kor-pak.com/product/crane-hoist-brakes/
Usually found only on cranes that handle high value material.

RE: Crane failures

FacEngrPE - typically what is used to actuate the e- brake system? A single-shot latching circuit reading acceleration from an encoder on the drum shaft? An inertial switch on the drum shaft?

RE: Crane failures

It's been 20 years since that job, so my memory is a bit fuzzy, this list might not be complete.
Emergency breaks set
  • Emergency stop signal.
  • Loss of power.
  • Hoist drive fault
We did not use an overspeed switch as the total available lift distance was too short to allow discrimination between normal fast motion and likely failure conditions. A container crane might make a different choice, as the lift is much longer.
The brakes themselves are spring to set on loss of power to the actuating coil (or air cylinder in the case of the pneumatic version).

RE: Crane failures

FacEngrPE - got it - thanks for the info on crane ratings and e- brakes.

RE: Crane failures

...are those disc brakes? I didn't know they used them on hoists. ponder

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: Crane failures

(OP)
In my opinion, I would think for such a mission critical device that cranes are, that top quality materials would be used. There should be nothing made of cast iron or similar material on any crane.
It is evident that in the above example some corner was cut in the design department.
How many crane failures happen that we never hear about?

https://www.youtube.com/watch?v=dqewYjK-ya8
Was any sort of engineering involved in the design of these cranes?



https://www.youtube.com/watch?v=n58YUZqhnqc
At the 0:37 area.

RE: Crane failures

We don't even know what caused this crane to fail... It's a bit premature to blame cast iron.

RE: Crane failures

(OP)
If a casting is broke then it is evidence that it could not handle the load. Then if cast iron is the choice increase the amount of material to handle what ever is thrown at it. That goes for engine blocks as well.
Yes the added weight makes it a bad choice to use.

RE: Crane failures

On container cranes disc brakes are the norm on the main hoist, I've seen drum brakes on the boom hoist (on the motor side of the gearbox, band brakes or disc brakes on the rope drum side) drum or disc on the gantry and trolly travel. Cast iron couplings are very popular, check out Bubenzer or Tschan most of their products come in cast iron.

RE: Crane failures

Thanks CC... didn't know that they used disc brakes for any cranes... I've never encountered them.

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: Crane failures

Enginesrus, the coupling did not cause the load to drop. Its construction is irrelevant.

RE: Crane failures

Sigh.

Here we go again.

Will this forum ever stop feeding the troll? I have my doubts.

RE: Crane failures

The coupling broke. There are broken parts not part of the coupling in frame. Without knowing more we can not guess what broke first.
  • I concur with the opinion that a cast iron coupling can be selected correctly for this application (at least per the OEM selection data). (Edit - it looks like a brittle fracture, not all cast irons are created equal)
  • I am of the opinion that the use of a cast iron jaw coupling in a hoist, is unwise due to the lack of ductility.

RE: Crane failures

For what it's worth GGG spheroidal cast iron is pretty ductile Link. But I would also add most hoist designs account for the possibility of coupling and gearbox failures.

RE: Crane failures

The incident happens in Harculo. There really isn't much information out there other than lots of speculation. Some observers noticed the crane is rated for 60 tonnes and comments say the rotor is 70-75 tons. I would be surprised a turbine hall would have a crane that wasn't rated to lift the turbine.

RE: Crane failures

This accident ?? October 17th of 2003 at the Harculo Power Plant Netherlands.
http://overheadmaterialhandlingregulation.blogspot...
https://www.reddit.com/r/ExpensiveAccidents/commen...


Over capacity lifts are never a good idea. Different location, simalar scenario ,

INVESTIGATION OF THE MARCH 31, 2013 TEMPORARY
OVERHEAD CRANE COLLAPSE AT ARKANSAS NUCLEAR
ONE POWER PLANT IN LONDON/RUSSELLVILLE, AR
____________________________________________________
U.S. Department of Labor
Occupational Safety and Health Administration
Directorate of Construction
August 2013 LINK

RE: Crane failures

This video, referenced in one of the links above:

https://www.youtube.com/watch?v=axjmK_vjYCM

shows a bit more information(and more clearly). At 3:01, there's a shot of a "void", up in the crane structure. On the left, there appears to be a motor, and the remnants of a brake. On the right, a gearbox. And nothing in between. The span distance between the two elements is interestingly long. Maybe two feet.

One could wonder if there was a brake on the gearbox output.


The crane capacity is clearly shown in another shot: 60000 kg.

I suspect the weight of the rotor was known, since it had to be transported; and the transporting entity would be very interested in that number.


spsalso

RE: Crane failures

It looks like the spreader bar capacity is 60kkgs. Perhaps the crane really was overloaded.

RE: Crane failures

Ah, yes. At 2:55, there is a photo of the spreader bar, and up towards the top; there appears to be that tag I saw earlier. And mistook for a tag from the crane, itself.

"werklast 60000 kg" = workload 60000 kg

"eigen gew 9000 kg" = own weight 9000 kg


So there's the weight of the rotor plus the weight of the spreader. And we don't know the crane capacity.

However, it doesn't appear the spreader bar failed. "Falled". But not failed.

The turbine blades, at least in one picture, appear to be single units. So only the damaged ones need replacing. Save a few bucks, there.



spsalso

RE: Crane failures

There is remarkably little info out there, but I guess it was 2003.

Brake failure is mentioned in passing in one report, but no details I can find on anything technical.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Crane failures

Quote:

I wonder how many such failures have happened due to the use of the wrong size and type of materials used to construct the crane system?

Do you have any clue at all why this one failed, or is this just more of your random "everyone builds everything wrong" crap?

RE: Crane failures

@LionelHutz: It's the second one

RE: Crane failures

At 3:01 on the left side is definitely the remains of a thruster actuated drum brake, clearly the the gearbox shaft failed. So was there a backup brake on the output side of the gearbox? The intresting thing about hoist brakes is that 99% of the time they are only a holding brake, the motor does the braking. It's only e-stops and other faults that would result in the brakes having to perform dynamic braking, which means if your brakes are not well maintained you can get yourself into a situation where the brakes hold just fine but fail in a dynamic situation (when you really need them to perform)

RE: Crane failures

Cool Controls and Spalso, does this screen grab show the area you are describing as the remains of the drum brake?

RE: Crane failures

Yes

RE: Crane failures

Cool Controls - so there is a good possibility failure of the braking system which would have been in use by the crane operator as the rotor was being eased into place changed an uneventful installation into a major loss. In one of the links in the comments it is mentioned the facility was being unmothballed so there is a possibility the braking system had not been receiving regular maintenance - thus being in line with the cause for failure you have described. The lovejoy-type coupling shown with damage was collateral.

RE: Crane failures

The crane was likely used to remove the old rotor, not terribly much earlier.

I don't see how that brake failing would cause the coupling shaft to disappear.



spsalso

RE: Crane failures

One thing strange, the video shows every moment of the lift except for the moment the crane fails. When the video cuts back in the load is already dropping.

RE: Crane failures

I think it DID show the "moment". Starting at 1:48 (of the new and improved video that I linked), the rotor is being lowered. A second later, there's loud noise, and the rotor falls.

That's the "moment". A few seconds before and after would have indeed been nice.

Interesting that the Dutch/Euros feel no need to inform the public about how this happened. Move along folks; nothing to see here.


spsalso

RE: Crane failures

Listen to the sound. When the video cuts in the sound is already very different than any other part of the lowering. That is why I believe the failure began before the video.

RE: Crane failures

I agree a brake failure would not typically cause a shaft to disappear.

RE: Crane failures

Yes, the sound from the biginning of the "drop" segment is different. And it stayed that way for about a second, until something failed, and the load dropped.

That sound could have been made by an element that was GONNA fail in about a second. Or it could have been ambient noise unrelated to the drop.

There WAS a loud snap noise when the fail physically happened. It's easy to pick out in the slo-mo versions.


spsalso

RE: Crane failures

FacEngrPE - isn't the failure of the crane at Russellville different from the Harculo incident?

https://www.osha.gov/sites/default/files/2019-12/2...

https://www.osha.gov/news/newsreleases/region6/092...

Russellville crane accident:
1. Temporary crane was brought in for this job and insufficient/incomplete lateral bracing was in place for the load conditions.
2. EOR signed off no need to load test system based on historical use but new installation was not an exact replica of previous use. And new beam sections were installed with no weld inspections.
3. Crane company EOR and team did not properly analyze the lift conditions and the utility and construction engineering teams did not question the crane capacity and installation calculations.
4. Utility and construction contractor engineers agreed to skip the required load tests.

The Russellville incident appears to me to be a case of procedural shortcuts and overconfidence added to create a failure.

Harculo incident:
1. On-site crane probably is sized with capacity for the rotor used in turbine hall. The crane capacity has not documented but it seems somewhat unlikely the turbine hall crane would not be sized to carry the loads expected for the equipment used.
2. Rotor weight is unknown so this may not have been an over- capacity lift - just titles in videos state the rotor weight - but reasonably, the rotor being installed would be a known value that would not change radically from any initial conditions of the installation facility. Unless the recommissioning of the facility changed out the turbine housing, the rotor being installed cannot be bigger than the rotor that was removed and the crane should have been designed for.

The Harculo incident seems to me (from the failure modes that been described using the limited available info) to be a mechanical failure that may have been hard to forsee.

The Russellville incident, unfortunately workers were allowed to be too close to the lift zone and one died and many were injured - the Harculo incident, two workers were lucky that they got out of the danger zone before tragedy struck.

RE: Crane failures

2
Russellville incident
The crane was designed for 100% of the lifted load, not 125% as required by the crane standard. The crane was not proof tested in the configuration it was to be loaded in, and some parts were not load tested at all. In this case the failure was structural stability (the crane fell over sideways).

In both cases the lift did not match the requirements of the standard so it is considered an "engineered lift" per the ASME crane standard. OSHA found fault with the engineers design.

I am unsure how Netherlands/EU standards would treat the situation. The legal landscape works differently in the EU, and the website is Dutch which I do not read.

Quote (https://osha.europa.eu/en/about-eu-osha/national-f...)

The Netherlands OSH
In the Netherlands, it is the employer and employees within a company who have primary responsibility for occupational health and safety policy.
I have a copy of FEM. It is quite detailed in applying load cycle analysis to design, with the intent that the result is fit to task, but not over designed. The risk is that if the crane designer misses the mark, or any of the components are under strength there is no "builders margin".

RE: Crane failures

Wow - building 'to fit task' seems to be risky!

RE: Crane failures

FEM is very detailed, my only issue with it is that it was orginally written in French and most of the English versions I have used had typos (sometimes in equations) and poor translations.

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