Black tank repair / ABS puncture remedy

[Tiny-House]

I have read the ABS black tank "crack" repair posts and was very impressed with the techniques and materials used to repair the cracks ... but I wanted to let folks know about a product that solved a "puncture" or "hole" type breach in my black tank. Bleaching and cleaning the tank area around the hole is imperative and drying the area thoroughly before you begin the repair is necessary. I found a "patch" that is a no-nonsense solution to any hole that can be covered with a 3" by 6" patch. The product is called FLEXI-PATCH (FP-36). It is made by a company called DiversiTech. It is a self adhesive repair patch that is extremely durable, fiberglass reinforced and is cured with a UV light for a long lasting, permanent repair. After it has cured out for a couple of days, I even over coated it with the black, flex seal spray (like seen on TV) and you can hardly tell that it was patched. Has lasted over 2 years now. I have seen this product on Amazon for around $22.00. You will need a small "black light" to wave over the patch for a few minutes to "cure" it. I also added a couple of coats of the flex seal spray for extra strength. It beats replacing the tank!

 

[JohnGB]

Hi Tiny-House,

I looked up the Flexi-Patch,

The manufacture,
https://www.diversitech.com/en-US/i...ealing-compounds--adhesive/flexi-patch--FP-36

Their U tube

Where did you buy it at? It seems to be on the industrial outlet stores. It does who up on Ebay https://www.ebay.com/itm/175284130881

Thanks for passing along.

John

 

[Tiny-House]

DiversiTech Flexi-Patch (FP-36) for black tank hole repair:

Thanks for the links and info John. I first saw this product at a swimming pool Expo in Orlando, Florida and spoke to the manufacturer's rep about it. He was intrigued about my idea for using the product to repair a hole in my camper "black tank" so he actually gave me the FP-36 foil pack AND he even gave me the small, handheld black light that is used to "cure" the patch once it is in place. Once I had prepped the tank for the "fix", I used the patch (per the instructions) and was completely satisfied with the result. Once the Flex-patch hardened, I did over-spray the entire repair area with the black, Flex Seal spray in a can (that you see on TV) for extra strength and to "hide" the patch which also worked perfectly for that purpose. Perhaps it was ebay (not Amazon) where I saw the Flex-patch for sale? Thanks again for the info!

 

[JohnGB]

You are welcome Tiny-House,

We need good repair methods and the Flexi-Patch looks to be a good option. Club members posting their successes and failures helps all of us. Thanks for doing this post.

How flexible was the Flexi-patch? I have run into all kinds of ABS plastic repair jobs. Some over simple flats surfaces, others over lots of bends and sharp turns. The ABS solvent weld method does work on the odd ball shape turns and bumps as it flows everywhere you put it. But it takes 3 days to complete the coats/repairs.

If the Flexi-patch at least works on even smooth shapes, that still is a big deal, the cost is not that bad once past the UV light.

Here is some of the odd shape repairs. This one is a cracked grey tank pipe into the tank. The prep, cleaned, ground out, and dry

I did one coat of the solvent weld cement, then inserted fiberglass screen to reinforce it and more cement. Did this 3 times.

Here is the cured 2nd coat. The 3rd looked similar just thicker

Would the Flexi-patch bond to itself? Doing the pipe fix above with Flexi-patch. Cut a donut of flexi-patch, slide over pipe with a tight fit to the pipe OD. Cure in place to the pipe and tank.

The once donut cured, then wrap the pipe OD about 3" long and butt it tight on top of the first patch, cure the 2 patches together and fused to the pipe.

Any idea if that combo would work?


Thanks

John

 

[Tiny-House]

Tank crack around drain pipe:

The repair method for the cracked tank (below the drain pipe) that you have described and illustrated looks great. My only concern would be ... what stresses caused the crack to happen the way it did (in the first place)? To my eye, it looks like there is some "downward" force on the drain pipe (from looking at the relaxed position of the pipe that is cut away / with the rubber coupling). If so, I would maybe install a hanging strap to the camper flooring above the pipe after re-joining the pipe rubber coupler in an effort to try and keep that downward force from "working" that pipe intersection area from trying to push the tank in at the bottom again in the future. I would probably use a plastic pipe strap and stainless wood screws / washers while keeping the plastic strap over the rubber coupling to help with road vibration when traveling. As to whether the Flex-Patch (3x6") would work here as a "donut" around the pipe? I would first need to know the PVC pipe size. It could be 2" PVC... or maybe just 1.5" from the pics. The Flex -Patch is just 3" wide so there may not be enough "patch" left to reinforce the side areas of the rectangle shaped patch? I like the idea of mixing ABS plastic pellets (or shavings) with MEK (Methyl Ethyl Keytone) in a slurry and filling the crack to a thickness which is sufficient to strengthen that area around (and especially below) the drain pipe... in effect, thickening the tank at that juncture. HAYWARD POOL PRODUCTS used to sell an ABS pellet / MEK repair kit for repairing cracks in pressurized pool filters which work perfectly for this type of repair. It's kind of like "welding". The good news is that there is no "pressure" on this type of waste tank other than the weight of the water.

 

[JohnGB]

Hi Tiny-House,

Your assumptions are correct, there was a mounting flaw on this pipe from the factory. It has happened on other floor plans on the grey water dump pipe. The routing of the pipe is rigid from the tank outlet to the dump valve. These ABS tanks are large in size and flex downward when filled. That downward flex adds stress on the rigid pipe and over time will crack it at the weakest point. In this case the tank connection.

Towing with enough water in the waste tanks with this rigid pipe setup makes it all much worse. The tank bottom breaths flexing up and down with each bump in the road, moving the discharge pipe with it. The water weight inside combined with the standard RV suspension without shocks, creates a lot of bouncing/flexing of the pipe on every little bump. After enough years of this, the pipe cracks.

This was camper I was helping fix for a friend who tows a lot. I repaired the tank port and added flex joints with strapping that would flex the whole pipe and move with the flex to help prevent the pipe from failing again.

The old rigid setup

The repaired and now flexible setup on the 1 1/2" drain pipe. It will flex on both ends of the pipe heading to the dump valve area. Removed 1/4" of pipe at each Fernco coupling joint so it can flex.

The support strap will swing in the direction of flex, but support vertical loading

I'll have to contact the company to see if they offer larger patches.

And yes I know of MEK, I used to work at an injection molding plant at one time welding wire ABS wire spools together after they came out of the injection mold. And MEK is one of the main ingredients in the ABS cement I use, along with some acetone. And thanks for the tip on the HAYWARD POOL PRODUCTS, I'll have to look them up for their kits.

Thanks again.

John

 

[Tiny-House]

Rigid drain / dump piping coonections to flexible ABS tanks under camper:

Wow John, that was quite an undertaking you did for a friend... we could ALL use a "friend" like you! I was a swimming pool contractor for 36 years before I retired and have had to deal with many rigid pipe situations that needed more "flexability" due to stresses and vibrations of all kinds. Another solution for PVC pipe connections that may be slightly "off" on alignment or have pressures or vibrations that don't do well under "rigid" plumbing conditions is: Flex PVC pipe. I used to purchase it by the rolls from standard 1" to 2" PVC sizes but you can buy any size you need (by the foot) at LOWES, HOME DEPOT, etc. This type of PVC pipe is rated schedule 40 (just like the rigid) but just might give you the allowance you might need for these awkward tank drain connections. If you do use this flex pipe, I recommend the "blue glue" / "Rain-or-shine" in the blue and white can from OATEY. Glue connections need to be held firm for about 45 seconds before letting go of them so they don't "back out" of it's fitting/s. Of course you will still need to support the piping runs with strapping as they will want to sag a little along the way... especially when the air temperatures are higher. You can spray paint this flex pipe black if you think someone is going to look under your camper.

 

[Chris Boyd-SUN]

I have a '89 T-170. On fender skirt was damaged in the middle section between the wheels by a flat tire before I bought it. ICON does not have a skirt that fits the dimensions, and it is just missing a section about 2"x 5". I'm thinking I could use this to fill in the missing section from behind as a backer, then recreate the contours with Bondo. Hmmmm.

 

[JohnGB]

I have a '89 T-170. On fender skirt was damaged in the middle section between the wheels by a flat tire before I bought it. ICON does not have a skirt that fits the dimensions, and it is just missing a section about 2"x 5". I'm thinking I could use this to fill in the missing section from behind as a backer, then recreate the contours with Bondo. Hmmmm.

Hi Chris,

Other options to consider: If you are missing a section, they sell ABS plastic sheets in various sizes and thicknesses. You can warm the plastic to form curves, solvent weld in the new material, and repaint the whole thing to match.

I have done several ABS repairs, from cracked pipes to door bezels, fender skirts, and grey tanks, and they came out very well. The process takes time between curing coats, but the cost of materials is low. If you have not seen this post, it was after my tire blew out, which took out the door bezel that ICON does not offer. They would make them if you sent the old parts, etc., but the cost of the first one is high if you can repair it yourself. This may give you some ideas to build on.

ABS Plastic repair, Fenders & Door Trim (Bezel)

The Bondo buildup may work, too. The only downside is that if you have to remove the fender skirt for other repairs, you may have to redo the Bondo work.

Good luck with your repair, and let us know how it comes out. We all learn from each other.

John