Liberty Ship trivia

[Jimdandy]

Here's a piece of trivia you don't here very often. I don't have any actual figure on how many of these ship were lost because of this problem but it was a lot.

In WWII the liberty ships were built with a new process for ship building that allowed them to be produced cheaper and faster. The process was arc welding. Of course arc welding had been around for quite a while before they started using it on the Liberty ships but the use of welding on such a large scale hadn't been used in ship building previously. The technics for making such a long weld such as the weld that matted the sections of the Liberty ships together hadn't been explored at all. They assumed the processes for smaller welds would work. Unfortunately this was a deadly assumption for the crews of these ships. Do to the flaw in the welding technic the ships would enter the cold water of the North Atlantic and the already prestressed weld would over stress and fracture. A fracture in metal travels at the speed of sound of the material. Thus when the weld broke the ship almost instantly split in two with an explosive bang. The ship would sink so fast survivors were rare. I wonder just how many ships were written off to subs before they discovered the problem. It is an example used to this day in the welding community on just how much stress can build up in a weld that is not properly executed.

[TheWobble]

Actually Jim I think the thing that made them so fast to build is because they were the first boats to be built assembly line style, they could just stamp them things out like they do cars not,  I see stuff on the History channel about them all the time, good stuff.


EDIT:  Cold water and it's affects on the imputities in steel back then was a major problem aswell,  you can take a piece of steel from back then that has say a 3 ton stress rating in 70 degree water and then put it in 20 degree water and it will fracture at half that or less, just becuase of a (at the time) relativly small amount of carbon and whatnot.

[This message has been edited by TheWobble (edited 02-12-2001).]

[Jimdandy]

 

Originally posted by TheWobble:
Actually Jim I think the thing that made them so fast to build is because they were the first boats to be built assembly line style, they could just stamp them things out like they do cars not,  I see stuff on the History channel about them all the time, good stuff...
[This message has been edited by TheWobble (edited 02-12-2001).]

Yes TheWobble I know. It was the welding that caused the problem in this case. I know they were mass produced like cars but riveted ships had been also. Riveting is far more time consuming than welding. The point of the story is the bad weld and it's consequences. That's what I was trying to emphasize more than the mass production. I was just trying to simplify the story. I know how metals react I'm a Mechanical Engineer. I just didn't want to right a complex story with metallurgy and fracture mechanics for a general audience. Your right the cold alone can cause major problems with materials that weren't designed properly for the conditions or had poor quality control. That is good information. They think that's what actually caused the Titanic to go down from what I heard last. Have you heard anything about it?

[This message has been edited by Jimdandy (edited 02-12-2001).]

[TheWobble]

Yes I did, i saw where they got a piece of steele from it and tested its stress at room temp, then cooled it to the temp of the waters it was in and tested it again, it rated at %30 of its room temp strenght.  They think thats why the iceburg was able to cause such catastrophic damage, because at that tem the ice was stronger than the Titanics steel.  And further to the point the steele faile exceedingly bad at shock testing (sudden mpact) it rated at %15 of its room temp strength, the excessive amounts of carbon in the steel caused it to have a tendancy to shatter at low temps insted of bending when sudden shock was applied.

[Jimdandy]

Thx Wobble. Isn't that neat that they were able to figure out after all these years what went wrong.

[TheWobble]

to be honest.....Im suprised White Star hasent been sued by some "victim's" relatives, or some crap like that.

[Jimdandy]

If they didn't sue for that reason there are several other things that were compromised in the ships original design that they have known about every since someone could get their hands on the original prints. The biggest one was the compromising of the water tight compartments in the original design. From what I understand they really did have an "unsinkable ship" in the since that they had made water tight compartments in the structure as they do in modern ships. In the quest for bigger ballrooms and state rooms they cut into the water tight compartments and negated what was a good design. They were conscious decisions made to compete with the other ocean liner companies. Decisions made based on profit at the expense of safety. Of course that's what shock everyone is that the ship went down so fast because it shouldn't have in it's original design.

[This message has been edited by Jimdandy (edited 02-13-2001).]

[TheWobble]

Ya, the bulk heads only went as high as the seventh story, so when the water reached that level it just spilled over, kilda like filling an ice cube tray.  It was all about the profit then, also before launch they never did any of the normally manditory lifeboat drills, they had enough lifejackets, but not enough life boats.

[Sorrow[S=A]]

Hey guy's!

One other unique thing is that Arc Welding was the reason why the Germans were so far ahead of the Allies in 1939. In Britain the Union for Riviters held back development of tanks by insisting they be built using Rivits because they were constructed in Locomotive shops.

 German shops were not constricted in any way- they had no Unions as they had been disbanded years before due to Communist infiltrations. They were testing mass produced tank construction using welded steel and factory line methods.

This is also why Subs were so well constructed and produced so fast- the pressure hulls were pre-fabricated as rings  then welded together.

[Jimdandy]

That's cool info thanks Sorrow.

[Karnak]

My paternal Grandma helped build them in the Sausolito yards, in the Bay Area.    And my paternal Grandpa served on them in the Pacific.    I never met him though, he died in a car/train wreck in October of 1963.  

------------------
We few, we happy few, we band of brothers;
For he to-day that sheds his blood with me
Shall be my brother

Sisu
-Karnak

[This message has been edited by Karnak (edited 02-15-2001).]