BIG lift!

[Cody danos]

Awesome Thanks

 

[Welder Dave]

Never thought I'd spark a debate about a heavy lift. I have helped carry stuff up steps and the bottom side definitely seems heavier. The vessel in question was close to 2,000,000lbs. with extra stuff added before the lift. It's over 300 feet long so I think the lifting lugs could be down 100 feet and it would still lift it vertical. They aren't down that far but are down a way's from the top which I would think might put more weight on the ring crane. One of the articles said the crane was at 97% so couldn't boom out which I thought was the ring crane but it didn't specify. When going from horizontal to vertical could the tail crane lower slightly while the ring is lifting to lessen the weight on it slightly? Mammoet are pretty much the experts on big lifts but doubt they'll join the conversation. Could the placement of the lifting lugs be engineered for the cranes being used to lift the vessel? This was a project with years of planning.

 

[Welder Dave]

This is from the article I posted earlier. It looks to support the theory that the tail crane is at 97% which would be 727.5 tonnes. The ring crane would have to be at 1552 tonnes to be at 97% and the vessel "only" weighs about 1000 tonnes. I'm not a lift engineer and I don't want to take sides but real world experience can outweigh what a book says and Crane Op has posted enough pics. there's no doubt to his experience. The last pic. from the book where it shows the part tilted and weight goes up on the higher side seems odd. I would think the load would still be about equal.

“We had to make sure it was precisely located so there wouldn’t be any interference for tailing the vessel,” Tremblay said. “Because the vessel was so heavy, the crane during the lift was at 97 per cent, so there was limited room for the operator to actually boom out further from the crane. We had to ensure the placement of the vessel, when it came on-site, was as-per the engineered lift study because we were playing with inches.”

 

[Big Iron]

some crane some trucking

4600 loading out 2 SX45 Macks 1 with married 150tn lowboys the other with single 250 tn lowboy with sea lift mods

100+ tn derrick tandem lift

Z pad loading the 4600 full CW and 150 ft of boom Mack 1803 and double 250 tn lowboys

Mack bed truck and sow each w/ 100tn of CW moving the entire pipe shed and related components

 

[Cody danos]

Wow great pictures. I love those big Mack’s. That in Canada?

 

[Big Iron]

North Slope Alaska yea it was fun

 

[Cody danos]

here’s a 1/50 model I have in the hallamore version

 

[Hank R]

Now we must see the crane behind the Mack. Thanks

 

[Cody danos]

Sorry hank....ain’t no crane there. Something even better!

 

[Cody danos]

 

[crane operator]

Well I'm a a$$.

And I don't know what I'm talking about.

And owe Big Iron a BIG apology. So here it is- "I"m sorry, and evidently don't know what I'm talking about".


I set up two cranes in the yard, and picked up my big spreader bar, with tensionmeters on each end- and put both screens in one cab. Stood the bar up and down so I could actually watch what was happening on each scale as I made a tandem lift. And I worked it all around in a couple different configurations, and it was a great learning experience.

With the bar and both cranes free swinging, weight stays pretty even until about 30 degrees, then it starts climbing on the upper crane and constantly climbs on the upper crane until it pulls it off of the tail crane.

The only time it raises the weight on the tail crane, is if the rigging jumps a little as it is rolling in a shackle, and "shock" loads the lower crane. I think you could push a little onto the lower crane also if someone was on a swing brake or off center a little, but I didn't really try that out with the bar.

But it doesn't load up the tail crane more if they are both freely suspended.

Interestingly enough, it is different if you remove the tail crane, and stand the bar just like you would stand a tank or tower with only one crane. Then you can actually loose pressure on the head crane as it "balances" itself - when it is breaking over center so to speak. Then the weight drops off of the head crane considerably as it stands at the end. Which I have trouble wrapping my head around how its actually different if the bottom is suspended from another crane vs. standing on the ground, but its different.

With the lmi idiot lights in the cranes, the raise in weight on the tail cranes that we see, must be rigging moving, causing shock loads to the tail crane. . Most of the things we stand up and lay down- don't have lugs on each end for raising and lowering. We are just steel chokering steel legs, or nylon roundups choked on the flat bottomed tanks we stand. So when the load approaches vertical, its not unusual to see chokers slide or rigging reseat itself.

That's the only explanation I have for the rise we see in the tail crane standing and laying down tanks. Its the momentary shock load as it goes vertical, and its rigging moving that blips the christmas tree lights. NOT the weight transfer of breaking over center.

If the raise or lower is smooth- the weight transfer stays even.

So all in all- Big Iron and the books are right, and I learned something. Too bad I just can't take someones word for it. And again, I'm sorry for being a jerk about it.

 

[mitch504]

I admire you for making this post.

I guess you could say my hat's off to you!

 

[Welder Dave]

Kudo's to Crane Operator for doing a test lift and posting his results. I think sometimes on a job things can go different than what they're supposed to as well. Now I am confused if it was the tail crane or ring crane that was at 97% for part of the lift of the big vessel. It seems hard to believe the 1600 ton ring crane would be at 97% capacity (1552 tons) on a 1000 ton lift. I wonder if the speed of the tail crane driving in while the ring crane is lifting isn't timed perfectly to the speed the vessel is lifted could put more weight on the tail crane? If the cable was pulled ahead of the speed of the tail crane seems like it could put more weight on the tail crane? Also could it depend on how the vessel was constructed, ie/ the bottom section is a lot heavier than the top section? This is all interesting stuff.

 

[Big Iron]

Thank you C/O however you are correct in saying that that book is not always correct. Unfortunately for those of us pulling levers we are not always in the perfect world that the book assumes and you are right to question it with the experience you have gained through your career. No apologies needed I am glad that my experience could be helpful to you and others. By the way that post you made tells me a lot about your character, I made an assumption earlier about that about your character was completely wrong and for that I apologist.
To welder dave I think they were referring to the tail crane. In the photos i saw it looks like he had a lot more boon than just basic (but and tip) which is how the crane is rated for max load (750 tn) with the boom he had in he was considerable less than than rating (not having a load chart for that machine I don't know what the deductions would be) hope this helps

 

[Welder Dave]

Thanks for that. I thought the tail crane too. They had to have it far enough away from the house when it went to vertical. Like Mammoet said they were working in inches. Still impressive how precise the lift was. It would be interesting to know how much the vessel cost and how much to move and set it upright. Had to be 10's of millions. What would they have done if the job was suspended because of Covid 19?

 

[Impact]

I wasn’t sure who was right, so I remained silent

 

[terex herder]

Crane Operator, in your examples the person doing the lifting for the upper end is exerting much more sideways force than vertical force. You would never allow your crane to exert horizontal forces (cable not vertical). If you would try the log experiment with the ground tailing the log on an icy surface you would get a different result. The ice would prevent any substantial horizontal forces, just allowing vertical forces.

The only difference between theory and reality, is, in theory, there is none.