4 ms·

> At $8/lb and 6000 tons (12 million pounds) you're talking about $100mm just in materials and that's before you do anything. The Seawolf Class submarines cost

by jkyle 11y ago

> At $8/lb and 6000 tons (12 million pounds) you're talking about $100mm just in materials and that's before you do anything. The Seawolf Class submarines cost about $3.3 billion. There's 3 of those in service, they were seen as too expensive post cold war and were replaced with the Virginia Class subs that cost around $2.2 billion and are scheduled for service through 2070. $100 million would come out to about 4.5% of the total cost for materials. . . pretty negligible. edit With the welding, when I worked construction on large titanium pipes they'd fill the inside of the pipe with argon. But no tents or fresh air. The welder had also had a argon tube blowing on the weld point iirc. For larger titanium welds, they did it section by section. But still no fresh air needed. But this was a long time ago and Titanium welds were a rare job...so my memory could be failing me on details. I'm certain no fresh air was needed. I wasn't the welder, I was a fitter....so this was usually break time for me.

msandford 11y ago
Right, but what if you're welding a 40ft long plate to another 40ft long plate? You need to cover a large portion of both the front and back in argon. At some point it becomes easier to instead of constantly rigging up and tearing down back-shields to just put up a huge tent, bring all the various sub-assemblies in there and weld everything up. You don't have to keep the whole sub in the tent from start to finish, just while you're assembling all the various small parts into the large overall hull. If it's a 3 year build, I'd guess you'd only need it that way for a few months. Also 12 million pounds of steel would cost you less than $12 million. And that's before you have to machine, cut, fit, weld, anything. All of those things get much, much more expensive when you're talking Ti. I suspect that an order of magnitude across all aspects is reasonable, for material cost, machining cost, welding cost, etc. So if you had $10mm of steel and $100mm of fabrication for the Seawolf hull, you'd have $100mm of Ti and $1b of fabrication for the all titanium sub.

by jkyle 11y ago

msandford 11y ago

Right, but what if you're welding a 40ft long plate to another 40ft long plate? You need to cover a large portion of both the front and back in argon. At some point it becomes easier to instead of constantly rigging up and tearing down back-shields to just put up a huge tent, bring all the various sub-assemblies in there and weld everything up. You don't have to keep the whole sub in the tent from start to finish, just while you're assembling all the various small parts into the large overall hull. If it's a 3 year build, I'd guess you'd only need it that way for a few months. Also 12 million pounds of steel would cost you less than $12 million. And that's before you have to machine, cut, fit, weld, anything. All of those things get much, much more expensive when you're talking Ti. I suspect that an order of magnitude across all aspects is reasonable, for material cost, machining cost, welding cost, etc. So if you had $10mm of steel and $100mm of fabrication for the Seawolf hull, you'd have $100mm of Ti and $1b of fabrication for the all titanium sub.