Q' about rigid pvc pipe for holding tank system

[Cotemar]

Originally Posted by er9

but what is your tank made from? what material? im planning on purchasing a ronco tank which has the connector stub that protrudes from the tank and the tanks are polyethelene which cant be glued. your connections look as though they are threaded/glued into your tank.

thank for the link and for your thread. it has helped answer a few questions.

My sewage tank was made from polyethylene and already had the threaded holes made into the tank.

The PVC fittings where just threaded into the sewage tank with Teflon tape.

I did that PVC install over 15 years ago and if you see it today, it looks and smells like a new boat, even today.

PVC piping is by far the way to go, as its done for the life of the boat.

Once and Done.

[er9]

Originally Posted by Cotemar

My sewage tank was made from polyethylene and already had the threaded holes made into the tank.

The PVC fittings where just threaded into the sewage tank with Teflon tape.

I did that PVC install over 15 years ago and if you see it today, it looks and smells like a new boat even today.

PVC piping is by far the way to go, as its done for the life of the boat.

Once and Done.

interesting...maybe i will order a custom ronco tank and have the holes threaded in instead of the protruding piece. seems it would be much stronger and would solve one of my problems.

[peghall]

Originally Posted by er9

interesting...maybe i will order a custom ronco tank and have the holes threaded in instead of the protruding piece. seems it would be much stronger and would solve one of my problems.

Not a good idea because a 3/8" wall wouldn't have enough threads for a secure connection. Ronco will make the spinwelded fittings flush with the outside of the wall if you specify that you want them to be when you order the tank. You can also specify the discharge fitting on the top with a pickup tube inside the tank if you want and have at least 5" clearance above the tank.

I hope that by "custom tank" you only meant custom FITTED tank. 'Cuz unless you want to pay 'em a huge amount to make a mold, the tank has to be one of the 400+ in their catalog. If you want a truly custom tank, you'd be far better off having a welded tank made. Ronco doesn't do that, but Triple M Plastics does, and they're top quality. Triple M Plastic Products Inc

[peghall]

Originally Posted by er9

but what is your tank made from? what material? im planning on purchasing a ronco tank which has the connector stub that protrudes from the tank and the tanks are polyethelene which cant be glued. your connections look as though they are threaded/glued into your tank.

I THINK he meant that you don't have to use a rubber coupler to connect the pipe to the tank...not that there's no hose or pipe fitting. And btw, hose or pipe does not go ONto that "stub"...it's a female tank fitting spinwelded into the tank, meant for a male threaded hose barb to be threaded INto it. And as I said in another post, Ronco will install them flush with the outside of the tank if you specify 'em that way.

Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

[masonc]

If you don't use a union, how are you going to service anything?
If I was going to use a rigid pipe on a boat, I'd use PPR. We use it for solar water heating. It's a little more flexible and fused not cemented, so the joints cannot leak. It's not well known in the US but very popular in Europe and Asia.
The post with the photos of a PVC install...I would not use that blue cement, it fails. The pool guys use it for wet repairs but it is the wrong stuff for new projects. Use medium clear cement only, first use pipe cleaner, primer then cement.

[Cotemar]

Originally Posted by peghall

I THINK he meant that you don't have to use a rubber coupler to connect the pipe to the tank...not that there's no hose or pipe fitting. And btw, hose or pipe does not go ONto that "stub"...it's a female tank fitting spinwelded into the tank, meant for a male threaded hose barb to be threaded INto it. And as I said in another post, Ronco will install them flush with the outside of the tank if you specify 'em that way.

Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

Peghall, I do not speak for you, so please do not SPEAK FOR ME, as I can speak for myself.

There is so much mis-information in these threads about PVC piping on a boat from people that have never installed PVC piping on a boat.

[Cotemar]

Originally Posted by masonc

If you don't use a union, how are you going to service anything?
If I was going to use a rigid pipe on a boat, I'd use PPR. We use it for solar water heating. It's a little more flexible and fused not cemented, so the joints cannot leak. It's not well known in the US but very popular in Europe and Asia.
The post with the photos of a PVC install...I would not use that blue cement, it fails. The pool guys use it for wet repairs but it is the wrong stuff for new projects. Use medium clear cement only, first use pipe cleaner, primer then cement.

PVC piping is SO CHEAP that IF you would ever need to service a PVC pipe you just simply cut out and replace a section for just a few $

PVC pipes will not leak once they are cemented.

That PVC install in the pictures is now over 15 years old and still like new.

[er9]

Originally Posted by peghall

I THINK he meant that you don't have to use a rubber coupler to connect the pipe to the tank...not that there's no hose or pipe fitting. And btw, hose or pipe does not go ONto that "stub"...it's a female tank fitting spinwelded into the tank, meant for a male threaded hose barb to be threaded INto it. And as I said in another post, Ronco will install them flush with the outside of the tank if you specify 'em that way.

Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

thanks...i did not realize thats how the fittings on their tanks were. i think that makes things easier for me then. will have to give them a call to get more specifics. i have never seen one of their tanks in person. by comparison...my aluminum tank just has a 1.5" o.d. male stub welded on that the hose clamps over. thats my only experience with tank fittings.

[Elie]

I have installed a stainless steel holding tank, and have used not PVC, but ABS tubing. I took the précaution to use short pieces of engine exhaust tubing to link the tank to the rigid ABS tubing. No problem what so ever, no smells at all. A definitive solution. I shall add that most of my ABS is enclosed in the a forward large front storage, separated from the living space of the boat.

[er9]

Originally Posted by masonc

If you don't use a union, how are you going to service anything?
If I was going to use a rigid pipe on a boat, I'd use PPR. We use it for solar water heating. It's a little more flexible and fused not cemented, so the joints cannot leak. It's not well known in the US but very popular in Europe and Asia.
The post with the photos of a PVC install...I would not use that blue cement, it fails. The pool guys use it for wet repairs but it is the wrong stuff for new projects. Use medium clear cement only, first use pipe cleaner, primer then cement.

thanks for the info but ive been mentally traumatized by sanitatiin odors and failed, permeated hoses and am goi g nuclear on this one with rigid pvc. i dont think i can deal with another failed sewage hose...im too close to the edge of sanity at this point...but thank you all the same.

[mcm]

Never use ABS pipe for anything on a boat, s/40 PVC pressure has a much highter smoke and flame spread rating as well as better structural integrity.

[boatpoker]

I replaced all sanitary hose with ABS on my previous boat 24 years ago After five round trips from Toronto to Bahamas with me and and two round trips from Toronto to Honduras with the new owner it is still leak and odor free. Two years ago my "new" boat got the same treatment and is still problem free.

[Tbonem17]

I don't understand why you'd buy a poly tank and then connect it up using something different. Why not use poly pipe and fittings as they will be the only material on your boat that will require zero maintenance and never degrade from contact with salt water.
Fitted correctly it will out last anything.
A real plus if you use compression fittings which are mostly made from a combination of polyethylene and polypropylene (forget the brass ones) it's a simple matter of just dismantling it to clean/descale and then put it back together again.
The weak point in the system will be any poly thread that's used including the thread in the tank.
When doing up a poly thread use plenty of thread tape. Do up to finger tight and then a nip more. Test it and if it leaks use more thread tape and do it up again. Don't tighten it further.
No matter what type of piping you use make sure that the fitting threaded into your tank imparts no stress on the thread. ie support the offtake. These tank manufactures make a Rolls Royce product with a volkswagon connection system.
It'd be way better customizing the tank by forgetting the threaded connection and just have them weld say six inches of poly pipe where you want your outlet so that a compression fitting can be used as the connector. They are virtually indestructible.
One step further would be to order your tank with a small coil of poly pipe welded as one piece as the outlet long enough for where you want the pipe to go. This way your piping would be joint less for its entire length and have nowhere to leak. There's very little difference to the manufacturer welding in a threaded fitting compared to welding in some pipe.
Any outlet from a poly tank should show some sign of having been reinforced using some extra weld. If you look through other posts on this forum you'll find the main problems experienced have been threaded fittings having their threads stripped from over tightening and in one case someone broke the fitting from the wall of their tank probably due to over tightening and lack of support.
Lose the thread and gusset the outlet will make these problems disappear.
Poly pipe will easily follow the contours of the hull and can be bent to 90 degrees or more in a very short length. Any fixings for the pipe shouldn't be so tight as to pin the pipe but rather just act as a guide to allow for expansion and contraction of the pipe. 2.5mm per metre per 10 degrees centigrade. Irrigation companies sell poly clips designed to do just that.
When buying poly pipe and fittings walk past the bargain bin as most things in there will have been made using recycled milk bottles and crates.
Buy only whatever conforms to your countries standards. USA = ASTM
Australia= AS and you'll never end up with junk and it will still be one of the cheapest things you'll ever buy for your boat.
As you've probably guessed I do this for a living.
For existing tanks that started life with some reasonable quality virtually anything is repairable for a lot less than you would think.
To reinforce an existing fitting or pipe in a tank or to insert a new fitting or pipe would take about 15 minutes for example.

[Elie]

Originally Posted by mcm

Never use ABS pipe for anything on a boat, s/40 PVC pressure has a much highter smoke and flame spread rating as well as better structural integrity.

As said before, mine est ABS, and never had an issue with this installation in 10 years. No odor. no breakage, nothing. There is no real pressure in the system , and as fire retardant, the few feet of ABS won't make any difference in cas of fire on boats equiped with propane gas, teak wood everywhere, foam matresses, diesel tank and engine, and all sort of electrical, batteries, equipment and wires. By the way, house sewage and drains are almost alway ABS fitted. So...

[masonc]

PVC had the scene smoke/ fire issues, which is why we are not allowed to use in plenum spaces, only metal conduit/pipe and plenum rated cables.