Thread: Pipe joins

Originally Posted by Legion

I got a bender and notcher. Made all sorts of joins. Pipe joins are awesome! Slag just pops off by itself, so clean. The only issue, and it's a big one, is the complexity of pipe to pipe joins. It's very hard to keep the rod angle correct. I'm working with 20NB so the rate of change is high. It would be easier with 40NB or larger but I've only got a smaller die and my structure only needs the smaller pipe anyway. Also, internal fillets on 45° joins is a waste of time. Pushing the 2.6mm rods in there, I suspect that even if I do get a successful looking weld there is probably slag underneath it - it's just too hard to get the rod tip close enough to the join to give proper penetration especially with the changing angles. My structure is fixed, so there is lots of positional work going on. Lots of overhead stuff and I've managed to get quite a few burns. Oh well. Lots of short welds seems to be the key, minimising the angle changes.

Firstly I hope it is black pipe.A lot of gal can make you crook without proper precautions.

It would seem you have some large scale work.Can't be a handrail though and 20 nb is bloody skinny and would be a real biatch to weld positional.

You should have a welding jacket.Nothing disrupts your welding concentration more than a molten glob of weld spatter making a beeline for your soft tissues.

You mentioned a notcher ,so are the joints all tee piece joints? Are the welds performed vertical up or vertical down ?What electrode type are you using on what welder and with what settings?.

Did the job specs require notching. Pipes can be flattened at the ends and fillet welded

Above all .wheres the piccies?

With some info maybe we can assist you to improve it.

Cheers
Grahame

Just happen to be on the computer right now, after another day off work and on the job.

Grahame, it's gal, but it's outside in the driveway and drafty.

The pipe structure is a frame on a trailer, for holding up a storage box and a mast and also all the lights etc that are required.

All the steel was Duragal and Supagal, except some heavy plate that is dipped and required heavy grinding. I'm just welding through the Dura/Supa, as you do. Lightest stuff is probably 2.5mm.

The 20NB stuff will be more than strong enough. I could jump up and down on it myself and it'd be no problem. It just needs to be expansive but stiff.

I counted in my head last night, 64 different pipe joins so far. A few flat (onto the trailer frame of RHS/SHS). Lots of tees, some 45 braces, some offset notches. Some tie-down rails on the bed of the trailer.

On top of that the trailer chassis was another many, many welds, but a lot more straightforward (75 x 50 x 3mm drawbar, 50 x 50 x 3mm chassis, 50 x 25 x 2.5mm cross members). The chassis is 3.5m x 1.2m. The whole thing is ~5m x 1.9m. There are outriggers from the chassis for a hoop frame.

The hoop frame has 6 hoops. There are rails that are offset notched along the hoops on either side, and then bent down and around back down to the wheel arches to fill particular constraints of the cargo. There are 45 braces on four of the hoops at the bottom and from the rails to the hoops in a couple of spots, to provide lateral support.

There's also a boat dolly that goes on the trailer, that is also bent 20NB. Only the floor triangle so far, but more bends and notches required to complete it once I get the boat to measure it against.

I have a jacket, but after a dob of weld landed on a tyre and caused a melty spot, the jacket is over the tyres. So it's cotton work overalls, and occasional smouldering smell. At one stage I could smell the smoulder but couldn't spot the burn. A piece of weld had landed in my pocket and was burning me there where I couldn't see it from the outside. Got a mark on the chest now.

The hose is laying in wait if it comes to that.

There are no job specs. I'm a hobbyist/backyarder, building my first trailer, out of necessity. It's evolved through very particular constraints via a CAD program and lots of sketches.

I like the idea of strength in the notches over flattened and filleted joins.

Machine is the Kemppi I was going on about in the other thread (Minarc Evo 140). Rods have been mostly Gemini 12 in the 2.6mm size, with a handful of 2.0mm for some finesse work. Amps anywhere from about 70A for some very open fits where penetration was assured, but more often 78A for 1G or 2G type work, 85A-88A for 2F, 3F and 4F. Occasional 92A for very tight crevices. 3F has been all vertical down, although I accidentally went up when following around a notch tee past the low point and managed to blow a hole in 2.6mm material.

This is the first job I'm using (your?) tip to use a file to clean off old slag. Previously I would just use a rough piece of scrap for striking and keep smashing it until the old slag fell off. But using a file, every restart it like a new rod. VRD isn't an issue.

Positions? Everything. Angles I've never even considered before. Right hand, left hand, travelling left to right (both hands), travelling right to left (both hands), looking down, looking up, bending over things looking back up upside down. Lying on the ground.

It's been a very big job for me. If I could have gotten the trailer made satisfactorily and reasonably by someone else I would have definitely considered it, particularly in hindsight. But it will be a very nice trailer when done. The end is in sight.

I'll put up pictures eventually, either here or in the trailer forum.

With those tight fillets, I've heard of guys that get tig filler rods and basically do the equivalent of laywire technique whilst stick welding over the top of the filler rod. Never tried it myself.

Not a bad idea. I occasionally use old rod stubs as filler rods if I burn a hole. With these impossible fillets, I've just either left them or made half-baked slaggy attempts. Not too concerned because it's always those internal brace joins and they're in compression and there's 3/4 of a weld around the rest of the join. But I might experiment with your idea on some scrap.

It's been finished for a while now. Well, I'm sure there will be some bits to touch up as they spring to mind, but here it is:




The dolly on top is just resting there because I put it on when the trailer was already where it is. Normally it fits behind the guards, slotting in from the back. The dolly is just the base frame and needs to be built but I need the boat at home to design it in situ.

Originally Posted by Legion

It's been finished for a while now. Well, I'm sure there will be some bits to touch up as they spring to mind, but here it is:

The dolly on top is just resting there because I put it on when the trailer was already where it is. Normally it fits behind the guards, slotting in from the back. The dolly is just the base frame and needs to be built but I need the boat at home to design it in situ.

Nice work Legion - it'll be good to see the boat in it.