Welding HDPE Plastics


Does anyone in this forum have experience welding HDPE? I need advice on a decent, cost effective plastics welding rig, initially to work with plastic barrels. I do not want the cheapest ‘soldering iron’ type rig, but need a budget conscious unit that is acceptable for both learning with, and for advanced work.

(Larry G) #2

I have a co-worker who prototypes in plastics using 3D printers, extrudes, and other peripherals, which are mostly either home built or heavily modified.

I will ask him tomorrow.


Thank you. I’m trying to create a new type of digester. I expect the demonstration scale to be around 80 gallons, by welding up barrel sections.

(.) #4

I kind of thought about this kind of rope making, and than
someone already did it.
Now just to make the original threads kind of melt together, by
running it through something hot.


The HDPE “welders” generally all work the same, with the difference usually being in the quality of the controls and the size of the heat surface.

If you can apply heat just under the melting temp (about 266°F) - so as to penetrate deeper without melting the exterior - and then step up the temp a few degrees … you should be able to weld fairly deep.

An alternative process would be to gradually build up the HDPE surface, and then drill a hole and full it with LDPE … and then cover both sides with more layers of HDPE. Not as strong, but generally acceptable if shear stress isn’t the issue. (And in a barrel, it usually is not.)

Are you wanting to weld square totes and/or round barrels … or something else?


Barrels, at the moment. Start with an open top with lid and ring, add a segment below the bottom, among other things.


Consider building a metal roller on the inside … to press against and make a solid connection between the two layers of plastic.

(Larry G) #8

My colleague is going to get me the brand name of the one he uses. It’s a “3D printer pen” so it’s not just a soldering iron. It has a filament feed through the pen that is button controlled and variable heat settings.


Does he use it to weld plastics, too?

(Larry G) #10

Yes, exactly. You can freehand some 3D projects, fill in where a printer left gaps, or weld pieces together. The heating tip does what a soldering iron does, but rather than holding pen in one hand and filament in the other, it dispenses the melted filament on demand as you solder the pieces, leaving a hand free to manipulate your project.


Going to order this for starters, and find a local source for bottled Nitrogen (welding supply)


So… What does welding of HDPE plastics have to do with Seasreading… ?

My goal is to build a unique Biogas Digester system that takes normal food wastes, separated sewage (poop and urine, separately) and paper, to produce Methane fuel, and sanitary liquid fertilizer and tie it to an aboveground gravel grow bed, to show the feasibility of doing so.

Once I have it functioning satisfactorily, I plan to work at making it into a flush and forget type system, where the only real obligation is to plant and harvest food crops, flowers, whatever plants one chooses. Don’t want your food coming from your fertilizer? Grow decorative plants… No problem.

The goal is to take wastes, make fuel, eliminate biohazards, and make use of something that has to be dealt with, in an environmentally conscious, eco-friendly manner, rather than collect a mess, pay to have it removed, then pay to have it processed and disposed of.

IF it can reduce food and fuel costs, while eliminating added handling and expenses, then it becomes a bargaining chip, as well.

We CAN make a while new paradigm, creating an eco-friendlier way of living, do so at sea, and change the world for the better, rather than just creating a bigger mess and killing more of the planet.


A worthy goal.

Since HDPE (and LDPE) is so easy to melt and mold, it’s a good material for waste system experimentation.

Looking forward to hearing your results, @JL_Frusha.

(Larry G) opened #15


Been too busy, myself… Bought materials, have the welder, just finished a Puxin Digester training, with instructor certification.

It IS leading to a new set of design parameters, for a pair of ~33 gallon digesters, for the stuff I have…


How effective is the HDPE welder?

I was thinking of buying one for some small projects, but I was hoping for a review from you first, @JL_Frusha.


Have been a bit too busy. Still have plumbing to the water tower to finish, been gone a lot, too. Working out a new-to-me design for hdpe barrel digesters, with new properties to explore. It is, however, a nice, professional design. I didn’t get a soldering iron type, but one that uses Nitrogen gas, to keep from Oxidizing the plastic, which makes it brittle.


Maybe I’ll play with the wood-burning toy to tack weld things. :yum:


Was in the ER, last night, Influenza A… Yeehaw and Me…(cough, cough)…rry Chri…(cough, cough)…stmas!

Gimme another couple days. I am almost ready to cut plastic, before welding…