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myles
that is best guess numbers without knowing the
material and thickness, the shape of the head and so on.
i put the end caps for mine out
to bid. for one inch end cap 36 inch dia with a min thickness of 3/4 cost
980.00ea the shell rolled and rings tacked 3500.00. that is cheap
insurance. that is for a hull with a 1000ft operational limit. save
money in other areas.
rick m
rick m
----- Original Message -----
Sent: Monday, October 31, 2005 6:55
AM
Subject: Re: [PSUBS-MAILIST] Propane
tanks
Rick,
So, according to your calculations,
we are talking a safe operational depth of 20M ?
Myles.
----- Original Message -----
Sent: Sunday, October 30, 2005 11:37
PM
Subject: Re: [PSUBS-MAILIST] Propane
tanks
shipmates
i posted to qiuckly
the numbers i gave you are for maximum allowable working pressure not
failure.
rick m
----- Original Message -----
Sent: Sunday, October 30, 2005 8:12
PM
Subject: Re: [PSUBS-MAILIST] Propane
tanks
guys
i know that propane tank seam to be an
easy way to start. But the cost of the hull tube conponents are a small
frastion of the total cost. and you still have to weld the rest of it
together. buy decent end cap and shells. For the cost testing the tank
material you can buy the hull.
rick m
----- Original Message -----
Sent: Sunday, October 30, 2005 7:26
PM
Subject: Re: [PSUBS-MAILIST]
Propane tanks
From a manufacturer: Tanks are rated at 250 psig from -20° F. to
125° F. All tanks may be evacuated to a full (14.7 psi) vacuum.
I'd be curious as to what depth guys are
getting on a new 500 gal propane tank (without ribs). 10M ?, 25
M ??
Myles.
----- Original Message -----
Sent: Sunday, October 30, 2005
5:41 PM
Subject: Re: [PSUBS-MAILIST]
Propane tanks
Hi Myles,
I've cut a couple, 250 gallon or so, I
think were over 1/8th.
Newer and smaller tanks have thinner walls. Could be the steel
is stronger, could be they are not as overbuilt as the old school
stuff?
Anybody else have experience here?
-PK
Peter,
Is that some sort of
custom tank ? It seems to me they aren't that thick.
Don't quote me, I've never cut into one but I thought they were
closer to 1/8 " I'm referring to your run of the mill
residential tanks.
Myles.
----- Original Message -----
Sent: Saturday, October 29,
2005 10:37 PM
Subject: Re:
[PSUBS-MAILIST] Propane tanks
My propane tank sub has been to 300 feet. One thousand
gallons, 4 by 10 feet, 1/2 in thick cylinder with 5/8 inch end
caps. No reinforcing rings.
Peter K.
Hi Myles.
I would definately consider one
for an ambient, but no way for a 1 atm. There was some
discussion here a long time ago about
how the tank's holding internal
propane pressure did not necessarily cross over to keeping
pressure out the same way. I can't recall
what was said though, but I
remember it was discussed. Some guys have built them (1 atm)
and I have seen some for sale made from propane
tanks. But I'd want a thicker
hull for a 1 atm if it was me. I wouldn't trust a propane tank
hull, even with reinforcement rings.
I mean, if you are going to build
a 1 atm with all the trouble it takes....you might as
well make it where it can go
relatively deep and build it with a thick pressure
hull
and get down 600 feet or
more. Most of the good non picked over wrecks are
deeper than scuba depths because the divers have already
picked most of them over.
Most wrecks (okay not all) at
scuba depths have already been found too and there isn't much
to discover new unless you go beyond scuba
depths.
But for an ambient? Like I said I
think it would be great for that for all the reasons you
listed. I think it would be very durable for an ambient and
if
you are still contemplating
building an ambient, that would be an inexpensive way to
go.
Bill.
----- Original Message -----
Sent: Saturday, October
29, 2005 8:39 AM
Subject: Re:
[PSUBS-MAILIST] Propane tanks
Bill.
Yes, agreed.
When I was looking into the feasibility of a propane tank
pressure hull, I was certainly only thinking of a new
one. There is no way in hell I would put my torch to a
used one. The reason I was considering one as a
possibility is because:
1) I'm not looking to go
very deep.
2) They are, by their
very nature, pressure vessels complete with hemi-spherical
end caps.
3) Cost. Being mass
produced, you would expect them to be relatively cheaper
than a scratch build.
4)
Availability.
5) Convenience of having
a pressure hull with end caps already.
Having said all that, if I'm
taking the time to cut, grind, and weld, I was just as soon
scratch build a hull that is a little more
durable.
I don't know, it was something
I was pondering but I'm leaning towards a scratch
build.
Myles.
----- Original Message -----
Sent: Saturday,
October 29, 2005 2:29 AM
Subject: Re:
[PSUBS-MAILIST] Propane tanks
Hi Myles.
There have been some subs
made from propane tanks but most of the knowledgeable
subbers shun them.
Because...
1. They can explode from
residual propane when you grind cut or torch them.
2. They are of an unknown
metalic strength.
3. They are usually too thin
for deep dives.
4. The interior of an empty
one may be corroded if the valve was left open and hence
you have something useless when you cut it
open.
There are some other reasons
I have heard of too, but that's all that comes to mind
right now.
If you do use a propane tank
I have always heard to make sure you buy a brand new one
that is shipped to you without any gas ever
having
been put into it. Then it is
safe to grind cut or torch.
I wouldn't use one for a
pressure hull myself, but I think they might be good for
an ambient.
Bill.
----- Original Message
-----
Sent: Friday,
October 28, 2005 8:20 PM
Subject: Re:
[PSUBS-MAILIST] remove me second kind request
Patrick,
Speaking of
propane tanks for pressure hulls, is there any merrit to
that, convenience or expense wise, or is a guy just as
smart to scratch build the hull ?
Have you done
any research on the propane tank thing ?
Myles.
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