Welding Polyethylene

[Bryan Kemler]

I have an odd-shaped tank in a Newport 33 that Ronco doesn't sell, so I want to try to fix it before I pay for a fabrication. All I need to do is to get a piece of plastic tubing out of the bottom of the tank. What I am thinking of doing is cutting a hole in the top, and then using a tool to get the hose out, cleaning the inside in the meantime, and then fusing the cutout piece back into the top with a polyethylene welder. Anyone ever tried such a thing?

[Solitude]

What about using a water bladder ?

[s/v Beth]

Why don't you just put one of those 6 inch plastic ports in it, then you can clean your tank anytime you want!

[Bryan Kemler]

Well it is a waste tank. I've only heard bad things about flexible tanks, and since I've already got this one that forms to the side of the hull, I want to at least try to salvage it. I love the idea of installing a 6 inch plastic port, cuz I am a clean freak, is that something I could do on a waste tank though?

[gonesail]

ronco makes an installable inspection port .. you will need a 4.5" hole saw for a 4" port.

[David M]

I agree with adding a permanent inspection port. You may need it in the future.

[marshmat]

Polyethylene seems to be one of the few materials that'll stand up to sewage long-term with no ill effects. I have yet to see a bladder-tank material I would trust with such a job

An inspection port sounds like the way to go.... just make sure it's a well gasketed one that you can seal tightly. Sooner or later, something always gets clogged up: for example, if the deck pumpout is damaged somehow, it would be nice to be able to pump out the tank through the inspection hatch before effecting a repair.

[Bryan Kemler]

An inspection port it is. I called Scott at Ronco plastics and he agreed that it was the best solution as well. Thanks much! I would not have thought of that.

Cheers, Bryan

[s/v Beth]

Your welcome- all my tanks in the Valiant have inspection ports, so I guess it was not my idea, I just noticed how the PO put the boat together. The septic one gets used unfortunately.

[Ocean Girl]

Glad I read this. I hope it is ok to butt in here. I am in the middle of installing a ronor holding tank. What should of been a one day project has turned into...well much more. The intake is installed on the wrong side so I need to move the intake to the stb side (my fault). Anyways, the other boner I pulled was that I didn't have them install an inspection port, my rational was - the less ports the less odor. So now I need to install that too. ARRRG...
My question: is there any difference between the Todd port relocation installation kit and the one ronor sells? Has anyone ever used the Todd and the roncor? I can get the Todd one mile away at my west marine, roncor would need to be shipped. What kind of sealer between the plastic and the port? and are you using thread tape for the big inspection too.
Would love to hear from someone that has done this.
Erika

[Ocean Girl]

Also, I am near my witts end with the bend radius of the odorsafe hose (where is the smiley face that is twitching?). Do you all know any tricks? At one point I need to make a near 90deg! unless I drill another hole in the bulkhead... which I am tempted to do. My poor boat, she deserves better that what I seem to be able to do! Have I said ARRRG already? Still waiting for the Holding tank fairy to install my tank while I am sleeping, so far that fairy is a no show.
Thanks for letting me vent (ya get it? vent. Its an old plumbers joke)

Er (twitch twitch) ika

[forsailbyowner]

I fixed my polyethylene water tank a few years back. The process was pretty simple and the repair has lasted. I took a $2 polyethylene cutting board and made a plug to fit in the hole where I cut out a damaged welded in fitting. For welding I used a butane pencil torch $6 harbor freight and some high heat hot melt glue sticks. Weld just like acetylene or arc welding. Form a puddle and feed the glue stick in to get a neat bead. Care must be taken to not heat an area too big so it collapses. The glue sticks are ethylene and are just the ticket.

[sparrow409]

I worked for a while fabricating custom PE tanks. Your plan is doable but it would be MUCH better to use a larger piece of plastic to cover the cutout completely. If you can't get a piece of plastic, install an inspection port. Trying to weld the same piece back in would present many problems even to a very experienced welder and ultimately would not be a reliable repair. Also, the tank has to be weldable- crosslinked PE isn't. Most standard water/waste (and often diesel) tanks are PE and can be easily be modified, repaired or reinforced. In fact,taking a stock rotomolded tank and modifying it- adding baffles, mounting tabs and reinforcement pads- can result in a VERY good tank at a reasonable cost.

Bert
SV Sparrow

[Therapy]

Originally Posted by sparrow409

I worked for a while fabricating custom PE tanks. Your plan is doable but it would be MUCH better to use a larger piece of plastic to cover the cutout completely. If you can't get a piece of plastic, install an inspection port. Trying to weld the same piece back in would present many problems even to a very experienced welder and ultimately would not be a reliable repair. Also, the tank has to be weldable- crosslinked PE isn't. Most standard water/waste (and often diesel) tanks are PE and can be easily be modified, repaired or reinforced. In fact,taking a stock rotomolded tank and modifying it- adding baffles, mounting tabs and reinforcement pads- can result in a VERY good tank at a reasonable cost.

Bert
SV Sparrow

Is there a way one can tell or must one know from the manufacturer?

[sparrow409]

If the tank is able to hold gasoline it could be CXPE. Usually a tank has a label on it somewhere stating the builder and capacity this label should also have the material. For a non gas tank you want to see HDPE - high density polyethelene.

Bert