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Author Topic: info on PVC pipe based WTCs  (Read 2485 times)

redboat219

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info on PVC pipe based WTCs
« on: February 11, 2013, 10:21:54 AM »

Does anybody have any info they can share on how to build a WTC from a PVC drain pipe? I want to build my own but since it's impossible to procure clear polycarbonate tubing here my best option would be PVC. ( although I've seen a few of those tall clear plastic tubes with faucets at the bottom which they fill with several liters of beer at the pub. But I think they're made of acrylic)

I want to make one with a gas/snorkel based ballast tank with a vent valve on top.
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Davy1

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Re: info on PVC pipe based WTCs
« Reply #1 on: February 11, 2013, 11:43:28 AM »

Hi,
What would you like to know?
It has been my favoured approach for many years and about half a dozen WTCs.
(I have never quite seen the need for clear tubing. If you need to spot leaks all the time you are building it badly!)
I use polycarbonate end caps which are a push fit in the tube with standard Nitrile O rings in grooves.
The only downside is that you need a lathe or access to one to machine the end caps.
Also  if you are using the standard PVC soil pipe (which is excellent stuff , really tough with a good wall thickness BTW) then your scale options are limited. I tend to find that I am building to 110mm OD PVC pipe scale these days!
David
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redboat219

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Re: info on PVC pipe based WTCs
« Reply #2 on: February 11, 2013, 01:41:56 PM »

Hi,
What would you like to know?
Would it be possible to build a wtc in a similar configuration to those made by D&E but using PVC  instead of polycarbonate? 
Has anyone made a PVC ballast tank complete with a vent valve?
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thegrimreaper

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Re: info on PVC pipe based WTCs
« Reply #3 on: February 11, 2013, 03:01:48 PM »

Dont know why you cant procure clear tube where you are a lot of guys off here use E-bay but PVC is probably cheaper and easier to get hold of, Garden centeres and also B & Q spring to mind
 
David I lilke building out of clear tube this has nothing to do with spoting leaks all the time, or building badly its good when you take the hull top off  and instead of talking jibberish (which it probably sounds like to someone not in the know) to a bystander you can actually point and describe through the tube how it all works and what do's what, possibly converting a boat runner or car / aircraft user to the Black art of submarines.
 
     Mark.
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profesorul

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Re: info on PVC pipe based WTCs
« Reply #4 on: February 12, 2013, 10:14:34 AM »

There are several reasons for that can not use PVC pipes for ballast tanks:
- there are differences inside diameter,
- are oval,
- and suffer changes in diameter depending on water temperature.

Some of You wheel gonna say: are not big differences but piston diameter is extremely well made and a ring can not cover those variations in diameter, and if the pipe is oval piston hangs somewhere and pass water beside him .... an undesirable fact for a submarine with so much electronics in it.

That's way is generally used Plexiglas tube,or for those who have financial resources that can be processed Aluminum Tube to rate extremely precise, so necessary a piston!.
 I bring to your attention these things because I personally tried and did not work.
 
Each one is free to do according whit!.
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Davy1

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Re: info on PVC pipe based WTCs
« Reply #5 on: February 12, 2013, 11:22:39 AM »

I agree profesorul.
Piston Ballast tanks using PVC  would not be very good for all the reasons you give.
But PVC pipe is good for WTCs (Water Tight Cylinders.)
David
 
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Subculture

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Re: info on PVC pipe based WTCs
« Reply #6 on: February 12, 2013, 01:23:12 PM »

PVC is no worse than other thermoplastics when it comes to thermal expansion, and is consideably better than some. I understand the concerns with internal finish, which varies greatly, but is chiefly to do with the way the pipe is manufactured and specified, and you get these issues with all types of plastic pipe, not just PVC.

My concerns with using aluminium in any wet area of a submarine is that it corrodes very badly. You could anodise the surface I suppose, that would offer some protection and also gives the opportunity to die the metal in an attractive or garish-depending on your sense of taste- finish. Seamless austenitic grade stainless steel tubing would probably be the best metal, but where do you find that in small quantities at reasonable cost? I expect they use it in fullsize subs, or perhaps the aviation industry.

I've found some types of plastic tubing that have an accurate and consistent internal tolerance ideal for piston tanks. The type used in silicone/mastic caulking tubes is very good, the PVC tubing used for condensing boiler flues is also excellent and also the tubing used to make stirrup pumps. Caulking tubes can be found easily enough for nothing, as builders discard them once the contents are used, but you are limited to a 46mm bore, which is fine for smaller models, but will restrict you if you need a big tank. The flue pipe is also very accurate, with a slightly larger 55mm internal bore, unfortunately quite expensive. I got my section out of a skip, but looked it up online- about 30 a metre! The stirrup pumps provide a much larger cylinder, but that's also a rather expensive way of purchasing tubing!

Unlike plastic plumbing pipe, these pipes have a high level specification for the internal diameter. Plumbing pipe is chiefly designed to seal around the external circumference, so that is where the high level of finish is. Has anyone had a crack at sealing around the outside of the pipe with simple commercial fittings? Wouldn't look as slick, and you will end up with a slightly larger diameter than internal sealing caps, but I can't think of a reason why it wouldn't work, and it could be useful for those without lathes.


essex2visuvesi

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Re: info on PVC pipe based WTCs
« Reply #7 on: February 12, 2013, 01:56:49 PM »

A daft question


But does the WTC have to be a round section?
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Subculture

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Re: info on PVC pipe based WTCs
« Reply #8 on: February 12, 2013, 03:40:26 PM »

No, but I'm personally not a big fan of box type enclosures in submarines.

profesorul

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Re: info on PVC pipe based WTCs
« Reply #9 on: February 12, 2013, 03:48:16 PM »

@essex2visuvesi, NO is not necessary.Depending on space you have inside the sub (the round section is preferred because You gain space,if the model has Round section most of his body),and the Skills/materials available.
 
@ Davy1, YES you are right about using the PVC pipe (no mater what type) for the WTC as long you can made the caps with O-ring,
 
@Subculture: "...My concerns with using aluminium in any wet area of a submarine is that it corrodes very badly...." I think for the inside surface is not a problem as long is necessary put some oil or grease to make the slide of a piston facile...and for the outside can be used any paint as long You clean the surface properly.
 
Those ar guest my opinions.
 
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Subculture

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Re: info on PVC pipe based WTCs
« Reply #10 on: February 12, 2013, 05:24:14 PM »

There's a company called Beiersdorf who make aluminium packing. Chiefly aerosol cans for things like anti-perspirant, shaving gel etc.

These are very thin gauge, typically 0.5mm or slightly under and are coated on the inside with a clear lacquer or resin of some sort that appears to be very tough and should protect the inside from the corrosive effects of water. The accuracy is very high, and I think these would work well with one reservation- the thin gauge makes them easy to dent when handling.

However like the mastic cartridges, I've only found these cans in relatively small diameters. Okay for a smaller boat, or as a trim tank on a large boat.
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