Fixing Plastic Freshwater Tank

[forsailbyowner]

Originally Posted by boatman61

Mark... the butane torch will be to fierce...

I repeat it worked fine, the heat given off is infinitely variable simply by the distance you hold it from the plastic. This isnt theory or guesswork I did the repair at the BOTTOM of the tank where the pressure is greatest and its held up to 4 years of fulltime liveaboard cruising and many thousands of miles. I found this method online while facing the same problem.

[Mark Johnson]

Polyethylene tanks are quite cheep, and the bonds to it somewhere between "so so" and "none". I'd replace it!

Mark

[CarlF]

I would only use the epoxy idea if the brand specifically claims to work on polyethene. I love Gflex and have found it works pretty well on flame treated HDPE but West specifically warns that G/Flex will not work on polyethylene. Almost all water tanks are polyethylene.

I don't know about you but in my experience the first idea I try never works - one of those boat laws. I always have a backup to the backup.

1. Try melted milk jug or glue stick first. If (when?) it fails you can scrape it off.

2. Get Mr. Sticky to ship to Grenada. I bet he can. I've never seen the stuff but his web site is pretty convincing.

3. Install an access plate in a flat part so you can get your hand in then sandwich a sheet of rubber and a sheet of plastic both inside and outside the tank at the crack. Install bolts all around. Be sure the bolts go through the rubber so it doesn't leak there.

Carl

[osirissail]

Listen to Peg Hall, polyethylene tanks are repaired by welding as she describes. Other fixes are in the category of "quick and dirty" and are ultimately only temporary fixes.
- - If the tank has become brittle then it is time to replace the tank.
- - If you cannot remove or access the area of the tank for welding, then the suggestion to add an "inspection" plate by cutting out the portion of the tank that is split and installing a mechanical sealing plate might buy some time. But if the tank has split of it own accord then that is a sign that the life of the tank has expired and it is likely that further cracks will develop. Replacing the tank is the ultimate fix.

[peghall]

Actually, the weight of the contents puts far more pressure on the sides and top of a tank than on the bottom of it. The contents just sit on the bottom of a tank...and, the bottom is supported as well. They push against the sides of a tank, which are rarely if ever supported on all sides...putting stress on the top as well as they try to expand the tank. Repairing a crack in a side or the top of a tank is rarely successful because the contents immediately starting trying to push it apart again the instant the tank is filled.

So there's a WHOLE lot more to heat welding a seam or a crack in the side or top of a tank than there is in mending one in the bottom of it... and it has nothing in common with simply filling gouges in the bottom of a ski (does that ever bring back memories of entire evenings of Ptex (what amounts to PE glue sticks), ski wax, ironing boards and old irons the night before club races!).

IMO, the least time consuming, least frustrating, least expensive and ONLY permanent fix for a cracked PE tank is a new tank.

[David_Old_Jersey]

If you are going for replacement maybe make an insurance claim - and blame it on a Rogue Wave.

[MarkJ]

OK so this is what I bought today.
See photo below.

Propane Torch kit $25
Glue sticks (doesnt say they are Polyethylene) $3.50
Polyethylene tube 1 meter $1

then at a Chandelry
Flex Set Epoxy Bonds Polyethylene (Says to use Flame treating on the Polyethylene) $22
Fibreglass mat $1

So I can have a few experiments and see what works.

I particulalry liked the Polyethylene tube. That should be easy to work with if the glue sticks don't work.

The Torch kit has other uses so that a reasonable buy. The Epoxy if it doesn't work on Polyethylene it might work on Hypolon.


Give me a few days and I'll report back

[Hud3]

Good luck, Mark.

I've always believed since my whitewater kayaking days that the only reliable way to mend polyethylene was by welding, but I just found a reference to a new product from TAP called Poly-Weld. If your attempts don't work out, you might want to give it a try, if you can find it.

TAP Poly-Weld Adhesive: TAP Plastics

Here's what they say about it...

TAP Poly-Weld Adhesive: Imagine being able to structurally bond Polyethylene!!! This has been virtually impossible in the past. Now, with a simple flame treatment and Poly-Weld, one can create strong joints on Low, Medium, or High Density Polyethylene. The famous marine King StarBoard®, also a polyethylene blend, can now be joined with Poly-Weld! Use for tank, door, pipe, irrigation, pond, marine, float, & automotive body repairs. Also bonds polypropylene, ABS, PVC, ceramics, rubber, fiberglass, metals, and glass. Exterior-rated. Non-sag formula.

[forsailbyowner]

Be very careful with that, the torch I used was a tiny pencil torch used more for projects like electronic soldering, there is a risk of heating too large an area and the plastic collapsing.$5 at harbor freight.

[allanpeda]

Originally Posted by Hud3

Good luck, Mark.

I've always believed since my whitewater kayaking days that the only reliable way to mend polyethylene was by welding, but I just found a reference to a new product from TAP called Poly-Weld. If your attempts don't work out, you might want to give it a try, if you can find it.

TAP Poly-Weld Adhesive: TAP Plastics

Here's what they say about it...

I posted a video from TAP above. It seems thorough.

[Nauticatarcher]

make sure you bevel edges of crack before welding

[MarkJ]

Originally Posted by Hud3

Good luck, Mark.

I've always believed since my whitewater kayaking days .

this tube of goop actually has a drawing of a kayak on the front so it must work

Maybe its you in the drawing!!


Mark

[MarkJ]

Updated news.

I have done the repair. But don't know till I fill the tank if the repair is effective (or for how long)

I used the technique in post #6 from Allanpeda in the video posted. It uses heat treating the polyethelene.

Also I blobbed on a few test dollops. They have stuck pretty well but they can be sctratched off. Maybe a few more days hardening, maybe it will be fine in the larger repair.

Mark

[zeehag]

mark--if it works, come on over and i will buy the beer and ye can help me with my kayak--has a hole in end......LOL......

[MarkJ]

Originally Posted by zeehag

my kayak--has a hole in end......LOL......

Of course it does. Thats where you sit.




yes, you're on for the beer