Holding tanks - Construction/Repair - Plastic Welding

DaveVA78Chieftain · October 07, 2009, 08:31 PM

Sent: 3/22/2006

Here is one persons experience and view point regarding plastic tank construction.

http://www.gumpydog.com/bus/MC9_WIP/Plumbing/Holding_Tank_Fabrication/holding_tank_fabrication.htm

Plastic Winny tanks are Polypropylene so, the information is good both for building your own as well as repairing (permanent) them.

BTW - In a pinch, you can use hot melt glue to do a temporary tank repair to a plastic tank.

Dave

camperguynj · October 07, 2009, 08:33 PM

Sent: 3/30/2006

I have successfully used a fiberglass patch kit (Home Depot) to repair the sizable hole in the black water tank on my '68 D22

ClydesdaleKevin · October 07, 2009, 08:35 PM

Sent: 4/1/2006

My old brittle tank was full of cracks, and I couldn't find a tank that was compatible without re-plumbing my entire rig...so I went to a marina...

I say this because marina's with supplies have repair materials for boats, such as fiberglass. I simply bought a gallon of fiberglass resin and hardener, and a meter wide sheet of fiberglass a few meters long. I used my OLD tank, and covered it in multiple sheets, a few layers thick, with new fiberglass...my tank was too shot to repair, so I used it as a "stay in place" mold, and created a new fiberglass tank around it.

It worked...been a year more or less, and no leaks. I also made a new carrier for it, a sheet of plywood with metal straps that cradled it along its belly...see my pics in the Ark albums for specifics. A year of hard riding and putting the Ark away wet, and its still holding up.

Kev

kd4pbs-1 · October 07, 2009, 08:37 PM

Sent: 4/3/2006

QuoteI have successfully used a fiberglass patch kit (Home Depot) to repair the
sizable hole in the black water tank on my '68 D22

So did the guy I bought the RV from, but not much will stick to the polyethylene tank material for very long. He had tried to patch the black water tank and the fresh water holding tank where it had the studs that held it down. As a result, I had to rip the fresh water tank out of the RV, fix it right with the plastic weld, fix the rotten floor where the water was leaking, and put it all back in. The black water tank still leaks just a tad, but not enough to worry with. When it gets worse I'll try fixing it right with the plastic weld, or do like Kevin and make a whole new tank out of fiberglass and resin using the old one as a mold.

JDxeper · October 07, 2009, 08:38 PM

Both my grey and black water tanks are leaking. I think before I remove the tanks I will try this tape.
http://www.eternabond.com/install/tank.htm
I have used the eternabond roof tape and it works great. Has anyone used the A-seal tape?
http://www.eternabond.com/pop_tech.asp?id=tech/ASeal.pdf
I think the best price is from best materials
http://www.bestmaterials.com/SearchResult.aspx
I can get them welded but have to remove them. I am also asking for a quote from for new tanks from Mobility RV
Any other suggestion? D:oH!

tiinytina · October 07, 2009, 08:39 PM

We ended up using the 1min epoxy that you can get at any hardware store. I bought the stuff we used at the flea market as well as the can of spray foam stuff. We held the tank up with a jack and wire while the epoxy cured. We then used spray foam adhesive/insulation over that... All is still good on our tank. We don't travel with full tanks at all and all seems to still be holding fine. Will test again this coming weekend as we will be parked 4 days with 2-3 people using the shower etc and cooking for 5...

Tina

JDxeper · October 07, 2009, 08:39 PM

I just found the cracks in mine when they were over half full. Enough weight to pull them apart. Also don't travel with full tanks. I ordered the tape. We'll see what happens.
Later

LJ-TJ · July 20, 2014, 09:52 PM

Hey Guys I've been unable to repair my Black water tank were the pipe goes into the tank. We're getting ready to head for Ohio and was thinking of trying to pick up some of this product. It's not cheap but if you think it will work it's a lot cheaper than trying to tare out the hole system. Anyone got a Plus or Minus thoughts on it. i??

LJ-TJ · July 20, 2014, 10:01 PM

D:oH! http://solutions.3m.com/wps/portal/3M/en_US/Adhesives/Tapes/Products/~/3M-Scotch-Weld-Structural-Plastic-Adhesive-DP8005?N=6081374+3294307593&rt=rud

It's been one of those days.

DaveVA78Chieftain · July 20, 2014, 10:16 PM

All I can say is it at least says it applies to the types of plastic used for holding tanks:
Plastics (ABS, PVC, Acrylic), Metal, Plastics (Polyolefins and Thermoplastic Elastomers), Glass & Ceramics, Plastics (High Performance Nylon), Wood & Hardboard

3 minute work life
Make sure you are fully ready to apply it though with that short of work life.

Dave

LJ-TJ · July 20, 2014, 10:37 PM

Yep! That's about what I thought but I really wanted a sober second opinion. Thanks Dave. Doing the weight and balances and the number of folks who seem to be having a similar problem and we can't seem to come up with a good fix, I thought I'd take a shot at it and see what happens. Could solve our problems for others down the road.

ibdilbert01 · July 20, 2014, 10:44 PM

We tackled something similar last week. On ours the 3" pipe just slid into the black tank and at one time had some time of glue to seal it. With some careful sawing and prying we got the old pipe out of the tank leaving just the flange on the blackwater tank.. The flange was kinda weak so I built it up the outside using "Bondo Glass" and sanded it down till it was smooth. After that we just shoved a standard piece of PVC into the tank and used a rubber hose and some clamps to seal it off. Part of the rubber hose is over the newly built up flange, and the other is on the PVC itself making a tight seal.

tiinytina · July 21, 2014, 06:29 AM

The epoxy we used is still holding...(Knock on wood). I remember that we cleaned, and sanded out the area pretty well before applying the product then let it cure as directed before using the tank etc...

Froggy1936 · July 21, 2014, 11:34 AM

TJ This product sounds like it will work. Hm? It claims that no special preperation is needed , But if it were me i would clean and sandpaper as much area as possible . Also blow away all dust before application . And as Dave said before mixing product make sure you are ready , Rubber gloves would be a good idea in case touching sealer wile applying is necc. Have all tools spreaders etc ready . Good Luck Frank

DaveVA78Chieftain · August 20, 2017, 01:48 PM

I have never been able to get any form of adhesive stuff to stick for very long on the plastics the tanks are made of.
Fresh Water: polyethelyene (ice maker water tubing) for food grade plastics.
Black: ABS or polyethelyene

In the CW&VRV Search field field enter: Plastic Welding

Note: The Harbor Freight Plastic welding kit is to light weight resulting in the tip breaking off. I use a 80 watt soldering iron typically used for stained glass solder work

Tank must be bone dry in area of repair or the moisture will steam up leaving air bubbles in the repair resulting in leaks.