Tank help please!!!!!

[John316]

Jeremy, I just saw your post.

I am not sure about machining a recess. I assume that you are referring to cutting a hole the exact size of the pipe. If so, we would like to have a seal of some sort on there.

.....my brain is hurting by now . We are trying to figure something out....

God bless,

John

[bobofthenorth]

You can't get inside the tank to install the bulkhead - right?  But you could reach through the "big" hole to install a bulkhead for the vent fitting.  If it is an awkward reach I have installed bulkheads by threading a wire between the two holes and then sliding the fitting along the wire to the hard to reach location where you can grab it from the outside and pull it through the hole.  As for the main hole the idea of bolting the fitting in place by reaching through the hole sounds like a winner to me.

[edroelle]

I did not see where you identified the material of the tank.  If it is polypropylene or polyethylene , you can weld the fitting with a plastic welder because those materials cannot be glued.  You would need to weld like materials.

This company has many plastic fittings, like clamping a gasket between tank and fitting.
http://www.usplastic.com/catalog/default.asp

Use a rubber connector (from Lowes or Home Depot) and clamps to connect tank fitting to toilet fitting.  This give some give and allows easier repairs if needed.

Ed Roelle
Flint, MI

[Singing Land Cruiser]

Hi John, I will try my hand at this. All I can tell you is what we did. Here is a link to our blog, I will start there.

http://singinglandcruiser.blogspot.com/search/label/toilet

Then I placed the black in the bay but did not affix it to the floor. Then we went to Home Depot and built the ABS drainage piping right on the store floor. We used S/S Tanks so a 3" no hub connector was used to connect the 3" ABS pipe to the tank.
For the toliet, we used a standard flange 4" to 3" (as seen in the blog) and a "FELT" gasket. Hope this helps, M&C  

*****Looks like you are further along from yesterday*******

Have you thought of taking the tank to a RV service center and have them install that fitting?

[Chuck Newman]

John and Clifford,

From the photos, the tank looks like ABS, and your pipe appears to be ABS.  I know most use the grommet technique, but why not use ABS glue on the inlet (toilet and vents) pipes?  Just curious, in case I run into a similar problem.

Chuck

[Jerry Liebler]

John,
  The best answer is:  1. Find out from the tank maker what material the tank is made of.  2.  Purchase couplings in, made of the same material, 3" FPT and 1 1/2" FPT.  3. Purchase plastic welding rod of the same material.  4. Cut the couplings in half to make 2 threaded inserts from each.  5.  Weld the couplings in place in each hole holes at at the location you chose.  6. Test by installing plugs in each hole and filling tank with water. 7. Repair any leaks and repeat step 6.  
  If you don't know how to 'hot air weld' plastics or you lack the equipment, find someone who has the equipment and knows the technique.  Welding in the 4 fittings is about a 1 hour job.  (I'd gladly do it if you brought the 'kit' to me here in Kentucky.)  Once you have the threaded inserts in place use a threaded adapter on the outlet valve and short pieces of pipe, threaded on one end to plastic clamped couplings to connect to the bus plumbing.
  An alternative that is ,IMHO far inferior is to use a router around each hole to reduce the thickness of the tank to the 1/8" required by the grommets you have.
Regards
Jerry 4107-1120

[Airbag]

John try these guys they make the stuff you need and for waste tanks.

http://www.polyfab.biz/HDPE_couplings_flanges.htm?gclid=CLWKk8zyxpwCFSYoawodPGTAJg

http://www.icontechltd.com/productcart/pc/Holding-Tank-Fittings-and-Accessories-c37.htm

[JohnEd]

My comment is to incorporate the/any rubber material in the connection as per all RV designs.

John

[John316]

Thanks for the replies!!!

First off. The tanks are polyethylene. One of our gray tanks is roto molded, the others are welded together. Our black tank, that was made with a fitting in the wrong place, was shipped back today. They will fix it, and we will have it Wednesday.

Great idea BoboftheN. Thanks for the tip. If we go with bulkhead fittings, you can bet that we will use your idea.

Ed, thanks for the link. Great resource, and good idea.

M&C, Thanks for the info. That helps. We would take it to somebody, but nobody has the fittings, and has never worked with a .5" tank. Theirs are always thinner. So since they don't know how, and I don't, that puts us in the same boat (except our wallet is staying the same thickness ).

Chuck, the tank is Polyethylene.

Jerry, that is a kind offer. We live in Kansas, so it would be a bit of a drive. I have tried to find somebody around here that can weld polyethylene, but they can only weld polypropylene. I agree, though, I like the welding idea.

Rick, thanks for the links. I like some of those flanges.

JohnEd, what do you mean by your comment?

That said, here is what we have come up with. We will take those connectors (that are to small), and we are going to cut the lower half off. Then we will use it as normal, except securely clamp the pipe, so it can't come out, and will stay in the tank. We are thinking about then screwing a flange over the top of the grommet to keep that in place.

Thanks again for the replies!

God bless,

John

[JohnEd]

John,

The preferred layout is with the toilet directly over the opening in the black tank.  By design.  There is a stub tube sticking up from the tank and the toilet flange outlet is a stub 3" tube, as well.  Connecting those two "pipes" is one of those flex rubber connectors with the hose clamps on both ends.  The rubber coupling lets you disconnect the black tank to remove it and it also gives you flex coupling that won't crack the pipes when in use.  A big plus is that the upper and lower pipes only need to be close to be connected cause the rubber is, well, rubber.  Even the ones that have tanks that are not directly under the toilet and have 45 degree slopes to the pipe also have a section of rubber coupling.  I have seen tanks that only had a few inches of clearance connected with a short rubber coupling.

My apologies if I weren't clear.  Happens all the time to me so don't feel guilty.  I hope that is better.  Call me at 541 915 083two and we can talk.  Most of the posts here have gone into more detail than I can and the ideas are faultless.  I was only adding that r couplings are also, or should be, part of the design.  If anybody has info that contradicts, I am all ears.

God luck,

John

[Jerry Liebler]

John,
  Anyone who can weld polypropylene can weld polyethylene, they just need the right coupling and rod. They just haven't tried it, the technique is exactly the same and the temperatures are very near the same also.  BTW there are two kinds of polyethylene, high density and low density and you need the correct match in both rod and fitting to successfully weld.
Regards
Jerry

[paul102a3]

My tank fitting is a standard off the shelf bronze plumbing flange with four mounting holes. The walls of my tank are also 0.5 inches thick. The four mounting holes are 1/4 X 20 tapped right into the plastic.

Mine started to leak after 21 years so I backed out the screws, installed a new gasket with some sealant, reset the screws and no more leak.

The tapped holes went right through the tank so when I reset the screws, I made sure to dip each screw into sealant before threading them in.

Paul

[Skykingrob]

John
Where in Kansas? I ask that because I know a man who lives between Joplin and Neosho MO, just over the border from southeast Kansas who welds all the time. He just built our grandaughter a sand box using 1/2" flat stock.

Rob
91 Prevost LeMirage XL
Missouri

[John316]

Thanks a lot you all!

JohnEd. Thanks for the explain. Makes a lot of sense, and we will do that. You made yourself clear now, thanks. We will also do that for all of our other connections. Good ideas. Our head sits right over the black tank. A straight drop.

Jerry, We talked with a guy that welds all the time commercially, and he said that he had never been able to get it right welding the polyethylene. That is where I got my info from.....

Paul. Sounds interesting. What do you mean by a off the shelf bronze flange? Could you post a pic? That would really help out. I assume that you are talking about how you connect the toilet, and gray water connections.

Rob, we are north of Kansas City.

Thanks again.

God bless,

John

[paul102a3]

John,

I can't take a picture as the flange on my tank is hidden behind the hot water heater. Here is a link to a PVC version and it is similar to what I have on my tank. This sample is schedule 80 so it is expensive but a schedule 40 would be a lot less expensive.

I don't know how to get the following address to be an active link but if you paste it into the address line of your browser, it should work. http://www.usplastic.com/catalog/variant.asp?catalog%5Fname=USPlastic&category%5Fname=13670&product%5Fid=1221&variant%5Fid=27340&cookie%5Ftest=1

As I said in my prior post, line it up, drill the four mounting holes, run a 1/4 X 20 tap through the holes, make a gasket, coat both sides of the gasket with whatever sealant goop you like and run the screws.

Once the flange is mounted, any PVC pipe fitting will thread into the flange.

Hope this helps.

Paul