Crane thread got bumped? Ah, i thought, new info in the crane hook failure, excellent, click… Matisse painting?
Serves me right for checking the gCaptain forum on a Sunday afternoon…
Good find! Dominoes just falling.
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Does anyone think that the ship has too much pre-ballast? Appears that they had ballasted for more than the hook broke at which I know was only about half of the total lift they were going to make. Would be interested to know what the ballasting plan was for the lift and if they were going to use anti-heel pumps during the lift to keep up with list? Many stability manuals and crane operations manuals warn of issues for loss of hook load. I know hook failure was ultimate cause, but just curious about the peanut galleries thoughts on ballasting.
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the ship looked like there was no old fashioned ‘what if’ risk assessment.
According to this article in Riviera Newsletter most of the machinery and equipment on the Orion 1 was delivered by Wartsila:
It is therefore logical to assume that this include the anti-heel system:
https://www.wartsila.com/encyclopedia/term/intering-anti-heeling-systems
It is also logical to assume that this system was in use and in auto mode during this test lift.
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Why would it be logical to assume it was in auto mode? Many lifts are made everyday without using the auto function of the anti-heel system.
What’s “too much”? One might presume the test plan / preps included a certain amount of ballast pre-lift and perhaps alternating load on the hook with counter ballasting stepwise. Sudden failure presented a whole new mechanics problem.
Some cranes have boom stops that can come into play but doubt they are designed to decelerate the boom springing back in these circumstances. In the end the A-frame remained standing and acted as the ultimate boom stop. The forces involved though just folded the boom over it. Likewise anti-heeling system specs probably far from being able to compensate that rapid a change.
I was wondering if the crane had active (or passive) load compensation as part of the design? Since it was the hook assembly that failed that probably could not have been used as a safety feature in this case. However in an overload condition cranes typically prevent boom down. Idly thinking can boom down reduce the boom hoist tension to any degree before it imparts the force required to spring it back? Then again the ship rolling and shifting the free body diagram picture might still be more than could be stopped by any control.
I know Liebherr generally had built in data logging so would be interesting to see some trends of various points to see the time scale of say hook load, boom angle, anything on the boom hoist if being recorded.
It was a Liebherr technician that told me how to avoid a situation like this. The ship had 20 ton capacity Liebherr cranes that could be run in dual mode for a 40 ton lift or in “quad mode” had a 80 ton capacity.
We had a lift of over 20 tons coming up so to the tech showed me how to “twin them up”. Out of curiosity I asked him about running them in quad mode. The Liebherr cranes we had were really nice cranes, but old and in rough shape. He thought for a second and said; “If they want to do that you should plan to be on vacation at the time.”
That would have been a good trick to use for this weight test.
It certainly looks like the case … cracking the whip.
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My opinion Liebherr some of the best there is. Including their service department. Makes this all the more hard to understand. I assume we will eventually see what was the nature of the hook assembly outsourcing and QC requirements for the various components of that.
Tried staring at the video at moment of failure to see if it is possible to detect smaller piece of the stem coming out the bottom of the main hook forging but my eyes fail me there. Also I can see what seems to be a “normal” boom stop constructed off the leading edge of the A-frame and as the boom travels up to that point it seems to become obstructed/blurry in the video but sort of looks like it just folds up. Just too much to handle.
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Where`is the problem? The hook slipped off the block assembly when the load was 5500 tons (if you believe it). The test weight (a 5500 tons barge) just dropped into the water! The crane ship w/o test load therefore rolled suddenly in the other direction and hit the quay, when the crane arm was knocked off. The hook/block assembly should of course have been tested in a work shop with a static load of 11000 tons earlier.
“Liebherr said the failure occurred at a load of around 2,600 tonnes”
Take your meds and go back to bed.
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Super-heavy lifts (over 5000 m.t.) by floating crane are becoming more common, but most are done with sheerleg cranes and over stern by SSCV.
I have been involved with many over the years, since the early 1980 with the Hermod and Balder. At that time the ballast system was operated manually to control the trim.
With modern automated trim/heel systems available it is usually done in Auto mode.
Lifts over side of monohull crane vessels exceeding 5000 m.t. are extremely rare still. (That was what was planned here, although they never reached that weight)
With a modern anti-heel system installed I would be surprised if they were trying to do it manually.
PS> To watch the Capt. on Hermod or Balder at the ballast panel, opening and closing large flap valves remotely, was like watching a virtuose piano player performing a complicated classical piece of music.
No pumps involved. The upper tanks were charge before lifting, while the lower tanks (below surface) were empty.
The large flap valves could empty the upper tanks and fill the lower tanks in 45 sec. when fully open. (500 T/s)
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No anti-heel system can work at the speed needed to compensate for such a sudden change in loading condition.
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The A-Frame was the boom stop . . . . it did stop the boom . . . . but the momentum of the boom buckled it over the A-Frame.
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Due to the sudden heel, the boom was already past vertical (and accelerating) before it hit the A-frame.
Discussions re anti-heeling systems and boom stops are thus pointless. This was an instantaneous event that set off huge forces due to inertia (mass), velocity and acceleration. Such dynamic events are clearly not part of the design.
However, during a trial of this nature, the events were not completely unforeseen or unpredictable. When the trial was planned, somebody should have realised that slings or hook could fail . . . . if that was considered, the consequences were predictable. (40 years ago I witnessed a small crane pulling a concrete foundation block out of the ground - when the block broke free, the crane jib took off and flew over backwards. I this must be a common failure mode with cranes)
I did NOT say that the anti-heel system would be able to react fast enough to stop the vessel from listing when the hook broke.
As you say it is not part of what it is designed for.
It is designed to compensate for weight that comes on (or disappear) at a reasonable time frame.
If the system cannot cope, slow down the lifting/lowering to allow it to catch up.
Interesting case.
According to Liebherr, the overload test for the HLC 295000 was planned for a load scenario of 5 500 tons. The test should have been carried out through the hoisting of a barge out of the water
Currently known facts indicate that the incident occurred at a load of only 2 600 tons causing a chain reaction which led to the accident. I thought the hook slipped off its block assembly.
However, videos show that the barge was hardly out of water when the hook failed. The ship was apparently moored along a quay.
The giant crane, measuring more than 145 meters, could lift nine fully loaded Airbus A380 aircraft in one go. Imagine that!
Say that the 5 500 tons test load was hanging 15 m from the center line. It means that you have to carry 11 000 tons ballast water 7.5 m from the center line in the opposite direction, when the crane is fully loaded/barge out of water. Ship’s deadweight must be >16 500 tons to do it. I have no further details of the ship.
Evidently, if the 5 500 tons test load suddenly drops off, the 11 000 tons ballast 7.5 m from the center line on the other side, will heel the ship in that direction. There is no system that can suddenly de-ballast 11 000 tons.
The test should better have been done at sea and not along a jetty. It seems the ship and the crane were damaged when the ship rolled and smashed against the quay. Stupid test procedures, to say the least.
From Liebherr, a leading designer of cranes, it must be. Usually it would mean destruction of a sacrificial or sub-component that prevents complete destruction of the entire crane. That video posted yesterday is quite helpful in seeing the chain of events. It is quite right that the sudden roll could never be quickly compensated for with ballast movements/anti-roll. However, watching that video over and over you can see a couple of things:
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The boom angle relative to the load path is not such that the sudden loss of load would cause the boom itself to snap back to the A-frame. The physics doesn’t support that. The event happens pretty quickly in that video, but there is no significant movement of the boom before the vessel rolls.
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You can see the shock to the hoist cable. The boom, as a lattice, is a very rigid structure at that angle, with the sudden loss of load mostly transmitted to the pedestal and hull.
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The loss of load causes the vessel roll, which appears to me to cause the boom to swing back.
The boom swinging back to the A-frame upon the roll of the vessel is something I refuse to believe could not have been an anticipated event. Any sort of design and operational risk assessment would identify this. That would mean the designers never considered the possibility of a rigging failure, or that the main boom could ever be in a position greater than 90-deg from horizontal? My question is why would there not be a physical mechanical system in place to prevent the boom from passing over the straight up vertical point?
Liebherr was quick to state publicly that because the initial failure was of the hook, therefore:
“A design or production error of the Liebherr crane can therefore be excluded”
If a simple rigging failure at 50% rated load causes the complete destruction and loss of your crane, I’d say there is a pretty large design or production error of the crane.
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Yes
I was talking about the anti-heel system not being designed to compensate for such events.
There was; Probably well before the “Vertical point” when the vessel was not listed. I.e. to stop the crane boom from being topped passed a certain angle to horizontal. (Probably by other means than physical stops, not mechanical)
Nothing could stop the boom from buckling when it hit the A-frame at such high speed (impact force at lower end of boom would have been immense)
BTW: The boom is NOT designed to accept large bending forces.
Big seatbelt-type inertial lock on a guy rigged below the boom?