Butt welding large HDPE barrels

Hello everyone
My name is Kees and i am trying to figure out what the best way is to connect two HDPE barrels together to make a larger tube.
suggestions anyone?


Have you considred “Plastik Welding” i dont know much myself and if it would stand up to temperature change…
Or just some rivets, metall wish washers? or plastik rivets? and some basic silicon gel should defently work?!

What is it for??

No need to go with expensive setup.
In the spirit of ubuntu…try this. Sheet of plywood or mdf. Trace ODs for two barrel heating elements and then screw down rings of notched large cylinder shaped ceramic beads around middle circumference area to be bonded. Run vape nichrome wire along inside and then weave back to outside of cylinders as one pull -terminating with at least one spring mechanism to keep wire taught during heating.

Throw a rheostat on each circuit and use laser temp gauge to dial in temps.
Make sure wire is as far away from wood base as possible (could use spacers of aluminum foil tape between posts making sure not to create circuit through foil). Use a scope sight minimum wire grid to elevate barrels over heating elements. You’ll prob heat too fast directly above wires compared to my first specs posted above and you will likely have 4 divots per half  barrel from grate but those should blend with proper heating. Again. practice with scraps before rolling out production. You should have plenty of time (10 sec) to remove and stack parts  together and gravity will aid in the rest.

Allow extra time to cool unless you blow air up inside with fan.

Hope this inspires a DIY solution

Do not use a 3D pen for heavy load like this. I guarantee unless you use a hot air or hot wire preheating before you lay a bead with your pen – this will only create a fracture quite easily.

Best luck I have had is clamping components in a jig then using platen heating at near 280 celcius for about 60 seconds. About a 5 -10 cm gap from platen depending on profile. Then a gentle 2 or 4 mm bond with an immediate air purge for cooling.  Practice with scraps to perfect first. If it smokes or burns… cut it clean again and restart…or this will break too.

When done properly, I have done stress tests that proved I achieved bond results stronger than the virgin substrate itself.

Good luck.

Thanks.  That makes sense.  It was similar to soldering copper without cleaning and fluxing.  I’ll give it another try soon.

Hi, you need to scrape the surface down a bit as the plastic will have oxidised, basically you need a new surface for welding from my experience.

You and I are on the same path.  I’ve seen the ways that people make docks and boats from 55 gal HDPE drums and strap them on.  I made a pontoon boat with 12″ pipe back in the mid-’90s and it worked quite well until the stainless steel worm screw clamps came off the pipe because the screws in them were made of steel and rusted.  By then I had a nice open bow boat with a 115 hp outboard and wasn’t using the pontoon with a 9hp any longer so I scrapped the pontoon.  I have built 3 boats in my life and I plan to build an 8′ wide trailer-able houseboat when I retire in a year or so.  I think the HDPE barrels would be the way to go.  At work one day I saw 4-55gal barrels full of liquid chlorine fall 5 feet.  Not one drop leaked out.  They are tough.  I just tried a week ago to try to weld 2 ends together and failed.  My “welding rod” was a 1/4″ wide strip of the barrel.  It would probably work better if the welding rod was a material that had a lower melting temperature.  I’ve welded an HDPE tote and snow shovel with success using milk cartons.  I might have better success if I rough up the surfaces with coarse sandpaper.  I used Methyl Ethyl Ketone on all surfaces before welding but the bond was poor.  The amount of heat varied from just right to too hot.  I used an electric heat gun and also tried a propane torch from a distance.  Harbor freight sells a cheap plastic welder that seemed to work well on the videos and some people seem to like.  You must remember to shut off the heating coil before you shut off the fan or the coil will burn up. I’m also going to get some HDPE – High-Density Polyethylene Welding Rods from Boat Outfitters.  After welding the two ends together I might also melt an 8″ wide strip over the joint, cutting the strips from barrels.

I am working on a similar problem only I want to make them into a larger sheet. Another idea I have for you is maybe make one of the open ends hot and flange it out so it overlaps the other barrel end a few centimeters, might make it easier to weld the two together if you use a different way to butt fusion. Issues are that the barrels are blow moulded so when you heat the HDPE up it wants to return to the thick wall tube it was before moulding with compresed air.

Have you thought of using the soldering iron and some stainless steel mesh, a strip maybe 5cm wide. Use the soldering iron to sink the mesh just into the surface. How long a tube are you wanting to make and why from barrels?

Hello Guys sorry for the late reply !
i have seen the barrels tied to a deck with metal stringers but I don’t like the look and it looks more like a raft then a pontoon boat…
an extrusion machine would probably do the trick but that’s an investment I can’t afford right know… if there is a workspace near amsterdam I would consider it. Butt welding with a hot plate looks promising but a professional set up is expensive as well. I’m figuring out a cheaper way of hot plate to weld on …. I will keep you posted.

Please write me if you have any other Questions.
I would love to see the tub when you are done.

Greetings Jonathan

So i did some more research, the air welders are like “feared” mostly very expensive.
So I would take some wire and tie the two barrels together and then use some “HDPE” maybe even from Milk Jugs ect. to connect both of the barrels together. Ideal would be to use Heat gun if you have one (the Hotter the better) to attach thin HDPE over the whole weld and maybe even use an old soldering iron to finish it up, melt in the wire ect.

Warning Plastic gases can be Deadly, so only in a “well ventilated” area…

While using a 3d pen definitely will work to connect the pieces it definitely won’t be too strong.
With plastic welding I have seen two ways untill now either with hot air, very small nozzle or just using a very cheap sodering iron.
Check out this video for a more in-depth explanation: Delboy's Garage, Simple skills # Plastic welding - YouTube

While using a sodering iron is definitely cheaper and very handy for small, tasks for a whole barrel it would definitely be worth looking into the hot air welding, though more expensive it would be way more time efficient, for big tasks…

But for a one-time thing I would probably go for the soldering iron.

How exactly do you need the barrels connected together, cut in half??

Greetings Jonathan

I did use a 3D pen to fuse 3D printed parts into a bigger product. (yes… human scale). First we glued the surfaces together and with the pen we did melt a v-shape on the connecting edges which we filled with the 3D filament.


I don’t think it produces big enough  for your application but maybe you can build a bigger version of a 3D pen from the extrusion machine