And what country can preserve its liberties if their rulers are not warned from time to time that their people preserve the spirit of resistance? Let them take arms. The remedy is to set them right as to facts, pardon and pacify them. What signify a few lives lost in a century or two? The tree of liberty must be refreshed from time to time with the blood of patriots and tyrants.
It's the reason that WWII Liberty ships had a big band on both sides of the midsection welded on, after the first were out for about 6 months, and found the flex was breaking ships in half.
I shipped on plenty of Libertys in the 1950s, and the problem was that they were welded, not riveted. They didn't allow for the necessary flex. I don't remember ever seeing the "big band" of which you speak. (Have you ever even been aboard a Liberty? I doubt it.)
Yes. Later Liberties were modified during construction with better ribbing and thicker hull plating, and better attention to rounded edges. The early Liberties did suffer, due to, like you said, being welded and not having any flex. Thus, the easy fix? Weld a big strip, adding rivets when necessary. Also rounding edges of portholes and hatches (shades of the DeHavilland Comet, where structural failure from squared windows and doors were causes of stress cracks (and also one of the suspected failures in the Titanic)) and reducing the stiffness and brittleness of the steel.
Having one crack upon launching was kind of embarrassing.
Fix any one of the issues - squared edges, more ductile steel, more reinforcing along the hull - and the issue would be pretty much solved. Fix two? Problem goes away. Fix all the issues? Yer good for a 100 years, mate.
The 'big band' is just a 10' tall strap of hull steel, welded from the bottom of the main deck down, so it really is hard to see. Seriously. It's there, just hiding in plain sight.
Watched a guy bringing a very big (80' x 3') bridge beam into spec with an oxy-acetelyne rose bud torch and an air/water cooling hose. With the beam laying on it's side, he heated an area on the web red hot, and then cooled it with the air/water. Each time he blew the water on that hot metal, the beam would flex six inches or more on the ends.
It's the reason that WWII Liberty ships had a big band on both sides of the midsection welded on, after the first were out for about 6 months, and found the flex was breaking ships in half.
ReplyDeleteI shipped on plenty of Libertys in the 1950s, and the problem was that they were welded, not riveted. They didn't allow for the necessary flex. I don't remember ever seeing the "big band" of which you speak. (Have you ever even been aboard a Liberty? I doubt it.)
DeleteYes. Later Liberties were modified during construction with better ribbing and thicker hull plating, and better attention to rounded edges. The early Liberties did suffer, due to, like you said, being welded and not having any flex. Thus, the easy fix? Weld a big strip, adding rivets when necessary. Also rounding edges of portholes and hatches (shades of the DeHavilland Comet, where structural failure from squared windows and doors were causes of stress cracks (and also one of the suspected failures in the Titanic)) and reducing the stiffness and brittleness of the steel.
DeleteHaving one crack upon launching was kind of embarrassing.
Fix any one of the issues - squared edges, more ductile steel, more reinforcing along the hull - and the issue would be pretty much solved. Fix two? Problem goes away. Fix all the issues? Yer good for a 100 years, mate.
The 'big band' is just a 10' tall strap of hull steel, welded from the bottom of the main deck down, so it really is hard to see. Seriously. It's there, just hiding in plain sight.
Here's an article about some of the issues.
https://metallurgyandmaterials.wordpress.com/2015/12/25/liberty-ship-failures/
rest assured, those containers are NOT water tight.
ReplyDeleteThank you Mr Beans.
ReplyDelete"The only people that think steel is rigid are those who have never worked with it."
ReplyDeleteYou can see the ribs on old ships because the hull plates have been beaten in by years of wave action.
IF you would like to feel & see flex? Get to the top floor of SEARS TOWER on a really windy day.(or as high as you can go)
ReplyDeleteWatched a guy bringing a very big (80' x 3') bridge beam into spec with an oxy-acetelyne rose bud torch and an air/water cooling hose.
ReplyDeleteWith the beam laying on it's side, he heated an area on the web red hot, and then cooled it with the air/water.
Each time he blew the water on that hot metal, the beam would flex six inches or more on the ends.