rectangular pressure vessel
ED
I read the postings here regularly and have a few
welding/fabrication questions.
I'm installing a wood fired boiler in my home and
need a hot water storage tank. Something around
500 gal and sized for entry through a standard doorway.
That precludes a propane or other such type tank.
It has occured to me that maybe the local welding shop
could fabricate such a tank but I am aware that there
are issues with a rectangular pressue tank even though
is operates at a low pressure of 10-12 psi's.
Would it be adviseabel to try such a thing? 12 ga 5'x6'x2.5'
in size mild steel. Bent corners, flat ends, closely spaced
internal baffles/exterior bracing?
Hydro test to 1.5 operating pressure.
Any thoughts appreciated. ED
Ecnerwal
ED <albieguy...@yahoo.com> wrote:
> Any thoughts appreciated. ED
Practically speaking, you'll do better to build an insulated box that
will hold multiple prefabricated round pressure vessels that add up to
your desired volume - or do what most of the commercial installs do -
have an un-pressurized insulated hot water tank with a pressurized heat
exchange coil or coils.
Rectangular is a lousy shape, and results in a lot of extra work - and
finding a weldor qualified to work on pressure vessels is often a bit of
a search, and costly when completed. I have such a pressure vessel,
which I unfortunately only intercepted when the outer shell (it's a wood
fired water boiler) was partly cut off by the folks getting rid of it
(since they had set it up with no heat storage, it never quite worked
right, so they were getting rid of it, and wanted to lighten the lift
out - I would have happily hired riggers to get it whole, but too late).
It has an array of straps tying the flat sides together every few inches
(and is a mere 15 lb vessel, as you intend). Would be a lot of welding -
I'm just thinking to reuse the firebox in some non-pressurized or
non-water (sand, perhaps) setting.
--
Cats, coffee, chocolate...vices to live by
ED
Thanks, I was afraid that, i knew there had to be valid reason for
not seeing anything like that commonly used.
Automotive radiators are a rectangular
pressure vessel, and I know that on off shore rigs where space
is at a premium they are used..
I have a 500 gal propane tank but would have to build something to
hold it and then run lines ect. Where does the pressure tank have
to be installed in relation to the storage tank? Tkns ED
MaxweII
"ED" <albieguy...@yahoo.com> wrote in message
news:jcnh64t0qlc1lcuqo...@4ax.com...
What is the operating pressure, maybe 100 psi?
If you go rectangular, you could do something like 3/8 or 1/2 tie rods on
about 12" centers to greatly reduce the required plate thickness. But a 500
gallon "box" that operates at normal water pressures is going to require the
involvement of a good engineer to be safe.
Another possibility might be using something like a bundle of up to 6" pipe.
Unless ASME has changed, since the last time I looked (about 30 years ago),
vessels less than 6" in diameter, or I think less than 5 psi are exempt.
Ignoramus5615
>
> "ED" <albieguy...@yahoo.com> wrote in message
> news:jcnh64t0qlc1lcuqo...@4ax.com...
>>
>>
>> I read the postings here regularly and have a few
>> welding/fabrication questions.
>>
>> I'm installing a wood fired boiler in my home and
>> need a hot water storage tank. Something around
>> 500 gal and sized for entry through a standard doorway.
>> That precludes a propane or other such type tank.
>>
>> It has occured to me that maybe the local welding shop
>> could fabricate such a tank but I am aware that there
>> are issues with a rectangular pressue tank even though
>> is operates at a low pressure of 10-12 psi's.
>>
>> Would it be adviseabel to try such a thing? 12 ga 5'x6'x2.5'
>> in size mild steel. Bent corners, flat ends, closely spaced
>> internal baffles/exterior bracing?
>>
>> Hydro test to 1.5 operating pressure.
>>
>> Any thoughts appreciated. ED
>
> What is the operating pressure, maybe 100 psi?
He said 10-12 PSI.
> If you go rectangular, you could do something like 3/8 or 1/2 tie rods on
> about 12" centers to greatly reduce the required plate thickness. But a 500
> gallon "box" that operates at normal water pressures is going to require the
> involvement of a good engineer to be safe.
>
> Another possibility might be using something like a bundle of up to 6" pipe.
> Unless ASME has changed, since the last time I looked (about 30 years ago),
> vessels less than 6" in diameter, or I think less than 5 psi are exempt.
>
>
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Maxwell
"Ignoramus5615" <ignora...@NOSPAM.5615.invalid> wrote in message >
> He said 10-12 PSI.
>
He sure did, sorry I missed it.
wmbjk...@citlink.net
wrote:
>
>
> I read the postings here regularly and have a few
>welding/fabrication questions.
>
> I'm installing a wood fired boiler in my home and
>need a hot water storage tank. Something around
>500 gal and sized for entry through a standard doorway.
>That precludes a propane or other such type tank.
>
> It has occured to me that maybe the local welding shop
>could fabricate such a tank but I am aware that there
>are issues with a rectangular pressue tank even though
>is operates at a low pressure of 10-12 psi's.
>
> Would it be adviseabel to try such a thing? 12 ga 5'x6'x2.5'
>in size mild steel.
I have a similar application, for a solar water-heating setup. Used
(home made) copper heat-exchanger coils inside a rectangular tank
fabricated from mild steel to hold about 80 gallons of hot
water-glycol mix at 160F, zero pressure. Figured the corrosion
inhibitors in the anti-freeze would prevent problems. After a year or
so the flaking was incredible. Rebuilt it with stainless, no more
problems.
Wayne
Jim Wilkins
> I read the postings here regularly and have a few
> welding/fabrication questions.
>
> I'm installing a wood fired boiler in my home and
> need a hot water storage tank. Something around
> 500 gal and sized for entry through a standard doorway.
> That precludes a propane or other such type tank.
How about two home oil tanks or ten 55-gallon drums?
I would NOT close the tanks if there is the slightest chance of water
boiling anywhere in the system.
Bruce in Bangkok
wrote:
>
>
I suggest that the question is whether this tank is a pressure vessel
or not?
I know that you mention 10 - 12 PSI but where does that number come
from? It is hardly sufficient to use for a household pressure water
system. Are you perhaps thinking of the pressure exerted by the head
of water inside the tank?
If the latter then it is not a "pressure vessel", as the term is
normally used, and there shouldn't be any problem in building a
rectangular tank.
In fact I'm sitting in a shipyard looking at several fuel tanks,
temporally removed from a trawler, of the size you mention, welded up
from mild steel plate, that have probably been in use for 5 - 6 years
with no problems.
Bruce-in-Bangkok
(correct Address is bpaige125atgmaildotcom)
ED
<decypher_...@signature.line> wrote:
>On Mon, 30 Jun 2008 07:31:10 -0600, ED <albieguy...@yahoo.com>
>wrote:
>
>>
>>
>> I read the postings here regularly and have a few
>>welding/fabrication questions.
>>
>> I'm installing a wood fired boiler in my home and
>>need a hot water storage tank. Something around
>>500 gal and sized for entry through a standard doorway.
>>That precludes a propane or other such type tank.
>>
>> It has occured to me that maybe the local welding shop
>>could fabricate such a tank but I am aware that there
>>are issues with a rectangular pressue tank even though
>>is operates at a low pressure of 10-12 psi's.
>>
>> Would it be adviseabel to try such a thing? 12 ga 5'x6'x2.5'
>>in size mild steel. Bent corners, flat ends, closely spaced
>>internal baffles/exterior bracing?
>>
>>Hydro test to 1.5 operating pressure.
>>
>>Any thoughts appreciated. ED
>
>I suggest that the question is whether this tank is a pressure vessel
>or not?
It is for a hydronic hot water heating system, average operating
pressure of 10-12 psi but could go as high as 30 psi in
some circumstances.
>
>I know that you mention 10 - 12 PSI but where does that number come
>from? It is hardly sufficient to use for a household pressure water
>system. Are you perhaps thinking of the pressure exerted by the head
>of water inside the tank?
There are circulation pumps in the system along with heat loads
and the general head of two stories.
>
>If the latter then it is not a "pressure vessel", as the term is
>normally used, and there shouldn't be any problem in building a
>rectangular tank.
>
>In fact I'm sitting in a shipyard looking at several fuel tanks,
>temporally removed from a trawler, of the size you mention, welded up
>from mild steel plate, that have probably been in use for 5 - 6 years
>with no problems.
Thats what I was thinking of when I posted this question
How do you think they would handle the forces of 15 psi?
> ED
Bruce in Bangkok
wrote:
>On Tue, 01 Jul 2008 14:53:25 +0700, Bruce in Bangkok
><decypher_...@signature.line> wrote:
>
>>On Mon, 30 Jun 2008 07:31:10 -0600, ED <albieguy...@yahoo.com>
>>wrote:
>>
>>>
>>>
>>> I read the postings here regularly and have a few
>>>welding/fabrication questions.
>>>
>>> I'm installing a wood fired boiler in my home and
>>>need a hot water storage tank. Something around
>>>500 gal and sized for entry through a standard doorway.
>>>That precludes a propane or other such type tank.
>>>
>>> It has occured to me that maybe the local welding shop
>>>could fabricate such a tank but I am aware that there
>>>are issues with a rectangular pressue tank even though
>>>is operates at a low pressure of 10-12 psi's.
>>>
>>> Would it be adviseabel to try such a thing? 12 ga 5'x6'x2.5'
>>>in size mild steel. Bent corners, flat ends, closely spaced
>>>internal baffles/exterior bracing?
>>>
>>>Hydro test to 1.5 operating pressure.
>>>
>>>Any thoughts appreciated. ED
>>
>>I suggest that the question is whether this tank is a pressure vessel
>>or not?
>
> It is for a hydronic hot water heating system, average operating
>pressure of 10-12 psi but could go as high as 30 psi in
>some circumstances.
Sorry, never heard of a "hydronic" heating system. Is that a thermal
syphon system?
I've seen hot water heating systems in New England, called Base Board
Heating because the radiators were located close to the floor, and
they did not use a pressurized reservoir.
>>
>>I know that you mention 10 - 12 PSI but where does that number come
>>from? It is hardly sufficient to use for a household pressure water
>>system. Are you perhaps thinking of the pressure exerted by the head
>>of water inside the tank?
>
>There are circulation pumps in the system along with heat loads
>and the general head of two stories.
I hesitate to comment as I am not sure how you have the system
designed but what is the advantage in pressurizing the reservoir? It
would seem simpler to heat the vented reservoir and pump the heated
water through the system.
>
>>
>>If the latter then it is not a "pressure vessel", as the term is
>>normally used, and there shouldn't be any problem in building a
>>rectangular tank.
>>
>>In fact I'm sitting in a shipyard looking at several fuel tanks,
>>temporally removed from a trawler, of the size you mention, welded up
>>from mild steel plate, that have probably been in use for 5 - 6 years
>>with no problems.
>
>Thats what I was thinking of when I posted this question
> How do you think they would handle the forces of 15 psi?
>> ED
When you mention 15 PSI and then say that pressure might go to 30 PSI
you are talking about a 100% increase in pressure.
Certainly you can design a rectangular vessel to hold 30 PSI but it
will probably either be made out of thicker gauge then necessary or
internally braced to prevent the flat sides from dish panning.
Jim Wilkins
> ...
> Thats what I was thinking of when I posted this question
> How do you think they would handle the forces of 15 psi?
> > ED
Considering the insurance issues if it fails, this deserves a properly
engineered design or a commercial tank of known properties. My
homebrew hot water tank is in an insulated box outdoors, and not
connected to the water mains.
Ecnerwal
When burning oil or gas (as is common) they only have a small reservoir,
so small you might not notice it - like a 2-1/2 to 15 gallon captive air
tank. There's also a "boiler" water feed valve, not that the water is
ever supposed to boil, or even get to 212F/100C - but 15 PSI is a
typical system pressure, with a relief valve that should go at 25 but
given the vagaries of time and age and manufacturing tolerances allowing
for at least 30 is good practice. If the house it tall, more pressure
may be required in the basement.
ED
wrote:
>
>
>
>Any thoughts appreciated. ED
Thanks to all who posted, the question has become academic
at this point. Making pressure vessel has more down side than
up side. I'm instead going to use a non pressurized tank aka a
concrete hot tub with a copper pipe heat exchanger array. ED
ED
<decypher_...@signature.line> wrote:
The older hot water systems work like that, the ones with cast iron
radiators in particular.. they have an expansion tank at the highest
point. My system has one of their
boilers-->http://www.weil-mclain.com/
And due to the high cost of fuel I'm adding one of
these-->http://www.alternativefuelboilers.com/
The whole thing is somewhat complicated, there's
a group of pretty sharp folks over here
--->http://www.hearth.com/econtent/index.php/forums/viewforum/21/
doing a lot of inovating..hence my look at a different
sort of tank.. which I may do, just not in the house
but out in the shop..
Tnks
ED
<---->snippage
Pete C.
"Hydronic" just means that the system uses hot water (not steam or air)
to carry the heat to the rooms. Baseboard radiators, in floor radiant
tubing and ceiling mounted hot water fed forced air heaters are all
"hydronic" heating system. The hot water is typically sourced from a
misnamed "boiler" that doesn't actually boil. These systems have a
closed loop with an air chamber or diaphragm expansion tank to
accommodate the changes in water volume as it heats and cools, and
typically operate at about 15 PSI.
The most cost effective setup for the OP is most likely to use one or
more of the off the shelf heavily insulated "indirect fired DHW tanks",
which are just a big storage tank good for 80+ PSI and containing a heat
exchanger coil inside which in normal operation is plumbed as a zone on
the hydronic heating system.