How to build a PressuVessel?

--- In spacesettlers@y..., "victoriatangoman"
> When the time comes, how will be build it?
>
> For this question, I'm working with a cylindrical shaped habitat.
>
> 1.) Do we build an infrastructure of ribs, cover it with some
> material and then vaporize metal over the material? What material
> can be used for the covering that can withstand molten metal being
> spayed on it? Do you put a thin layer on the material and cover the
> entire surface and then go back and keep adding layers until you
get
> sufficient thickness for the pressure vessel? How do you get rid of
> the material substrate when you have enough metal built up on it?
>
> 2.) Build the ribs, and then weld plates over the ribs. This seems
> very time consuming and earth-centric but it avoids the problems of
> motlen metal being sprayed onto a material. Robots can do the
> welding.
>
> 3.) Inflate a ballon and then vaporize metal onto it and bypass
> ribs. Same problems as for number 1, but also introduces the issue
> of how to support the mass of the metal without an infrastructure
> underneath it. Could the thickness of the metal be enough support
> for containing the atmospheric pressure inside the habitat?
>
> 4.) Build the slag radiation shield out of rubble or cast blocks,
or
> concrete blocks and then vaporize metal on the inside of the
> structure. Would the direct contact between the vaporized metal and
> the radiation slag cause any problems? Thermal expansion co-
> efficeints for instance.
>
> 5.) Can concrete be used as a pressure vessel? How to address the
> issue of the concrete reacting with the CO2 to avoid the problems
of
> Biosphere 2. Can it be made gas impermiable?
>
> I'm trying to think my way through the nitty-gritty steps we'll
face
> one day and I'd like to read others thoughts on these questions.

Its only going to be holding <14.7 psi. That doesnt require much
strength. If it werent for junk and meteoroids you could live in
space in a inflated mylar balloon.

High pressure mooncrete will work just fine. Its what O'Neal
origiinaly planned and havent seen any reason to change it. Latex
sealent will make it gas impermiable- however I am more in favor of
blasting the exposed surfaces of the concrete with a high heat source
after casting and before final assembly to fuse the surface. Energy
is cheep out there and at least initially latex would have to come
from earth. As to a extra radiaton shield. perhaps for the factory on
the sun end to protect against solar flare events, but the original
Island 3 design called for windows almost 40 feet thick and concrete
sections almost 50 feet thick, excluding tunnels. There would be
landscaped dirt between 15 and 50 feet thick on top of that. Not much
radiation would get through that, while the windows are 40 feet of
quartz crystal glass, and any radiation penetrating that will have to
pass through 4 miles of atmosphere to reach a human from that side.
The factory on the sun end could need more shielding as much for heat
as for radiation, and the factory itself would add more shielding to
that endcap.

Using slag from ore refining to make cast hull pieces or bricks is
also a possiblity, but I dont know if its a better one. A important
consideration is to find out how much in the way of conductive metals
there are on the moon, copper or platnum, in order to make all the
wiring that this would need for electrical power. Glass fiber for
fiber optics can be made on the moon but it would be very bad if all
the copper to wire this station had to be lifted from Earth.

Most of the other methods you mentioned are too exotic and expensive
for a large station, though they would work fine for the creation of
spaceship components. And a all metal station brings up corrosion
problems, reparing the mirror frames is going to be a difficult
enough job do to atomic oxygen from the solar wind. Even if made from
titanium the window framing would still suffer some corrosion and
these colonies are ment to last hundreds, even thousands of years.