Re: [PSUBS-MAILIST] Brass vs. Bronze

[Andy Jensen <drewacard@charter.net>]

Bill it is not a crazy idea Deep Flight 502 was cast of Al i think it is like an  inch and a half thick only fits one person per pod. but it has been done.
Andy J.

---- Akins <lakins1@tampabay.rr.com> wrote: 
Hi Sean.

You make a lot of sense and good points. Oh well, it was just a conceptual idea anyway.
I guess if it was a good method to use, it would already be in use. Just another crazy idea of mine.
Bill Akins.


  ----- Original Message ----- 
  From: Sean T. Stevenson 
  To: personal_submersibles@psubs.org 
  Sent: Tuesday, April 11, 2006 5:36 PM
  Subject: Re: [PSUBS-MAILIST] Brass vs. Bronze


  While certainly possible, I think that there are a few practical 
  limitations to casting a submarine hull.  The obvious one is size - you 
  need to cast the entire thing in one continuous pour, necessitating a 
  foundry with that melt capacity.  The second is quality control - 
  porosity is much more difficult to avoid in casting than it is in weld 
  beads - once cast, every square inch of the hull would need to be 
  examined through non-destructive testing (x-ray, ultrasound, etc.), as 
  opposed to just weld seams, and then if you do find a problem, you may 
  have to scrap the whole thing and re-cast if it is not in an area that 
  is easily patchable.  The third is dimensional control - save for the 
  ideal case where you cast a perfect cylinder with no hull penetrations, 
  bosses, stiffeners, etc., variable cooling rates due to material 
  distribution within the cast will cause the finished casting to deviate 
  from the original pattern.  Ordinarily, foundries will account for this 
  by modifying the pattern to compensate (guesstimating), or by working 
  the finished castings in presses, etc. to bump them back into 
  compliance.  For commonly cast parts like pump housings, etc., this is 
  no big deal, but pressure vessels are somewhat more dependent on their 
  geometry for proper function.  This is not to say that it couldn't be 
  done, but my gut instinct is that it would be cost prohibitive, as well 
  as a lot of work.

  -Sean



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