How the heck do you weld around a circumference?

Hello,

I am working on an exercise contraption that has a number of pieces of horizontal pipe, welded on the main structure, which provide a convenient place to hang the weight plates when they are not in use.

I am at the part where I have to weld the pipe sections on to the main structure. The pipe sections are five inches long, and are 1.25" schedule 80 pipe, and they will be fillet welded around the circumference where they join the main structure (the main structure is made from 2.5" square tubing).

So I'm all ready to weld these on, I have the main structure laying on supports on the shop floor, and I have the first one clamped up, ready to be welded around

Here's my question: how the heck to I maintain the correct rod angles as I go around the circumference?

I played with a couple pieces of scrap yesterday, and while I can get my weld started just fine, when I go to move *myself* around the work, I find it nearly impossible to maintain the proper angle/distance/speed of my electrode.

So how do you do it in a situation like this? Is the trick to give up on the idea of doing one continuous bead, and instead do the weld in two or three sections, so that you don't have to move your entire body while trying to weld at the same time?

What's your technique?

Jon

Weld positioners exist for a reason, move the part, not yourself.

Are the pipe pcs vertical? That will be much easier than if horizontal.

Also, idn't sched 40 normal? Sched 80 very heavy? I"da thought sched 40, in 1.25, would be more than strong enough.

Proly difficult without a rotary sumpn or other. I would certainly break it up.

Just last week, I had an exhaust leak in my car. The source of the leak was a flange connecting two pieces of pipe between the catalytic converter and the muffler. Since I don't currently own the proper equipment to do this m yself, I took it to a local muffler shop.

The guy cut out the offending flange with a sawzall and spliced in a new pi ece (about 5 inches long) of pipe. He supported the existing pipes with som e pretty neat adjustable jackstands and then tacked the new pipe in place. Then he migged the circumference of each joint in four or five sections. Th e part of the joint at the top of the pipe had barely enough clearance to f it the torch, and I was a little worried about the quality of the weld ther e. The guy gave me a mirror, and I took a look. I have to say, I'm impresse d. I could not see where one section of weld ended and the next began.

Though my upcoming welder purchase will almost certainly be a TIG, I now ha ve a new respect for MIG.

Don't know if it's the way the pros do it, but I tack opposite sides

6-8 times, then weld between tacks. I pretty much had to do that with a muffler that split circumferentially or it would have distorted too badly to make up. Going to have to have a healthy bevel to get penetration on that schedule 80.

Stan

Stanley Schaefer fired this volley in news:844e07ea- snipped-for-privacy@b20g2000yqo.googlegroups.com:

If you're not an exaggerated case of athletic eye-hand coordination, and you can't put the work on a turntable, you're pretty much limited to "segment" welding. If done well, it can look good, though not as good as a continuous bead.

LLoyd

I can weld around a pipe in two halves.

Ignoramus8993 fired this volley in news:obCdnUCc6M_asu3MnZ2dnUVZ snipped-for-privacy@giganews.com:

That's still 'segments', Ig. You must be more coordinated than the average Joe, but you still can't WALK around the circle and keep your angles, can you?

Lloyd

Tack the pieces in at least 3 places. Remove your clamps. Weld from above, moving the rod around the joint. If you can't manage a full circle, do it in 2 halves.

For prettier welds use a 7014 rod. Much easier to run and plenty strong for weight lifting equipment.

Lloyd, I will try practicing without the arc, it helps a lot, maybe I can learn to do it in one circle.

i

The technique is that of pipe welding and you need to move your hand (holding the rod) faster than the weld is progressing so that the rod angle to the work remains constant as you weld around the pipe.

Welding a pipe, at the top of the pipe the rod angle is say 15 degrees to the pipe surface but when you are half way down the side of the pipe while the rod angle reference to the work has not changed the angle of your hand holding the stinger is closer to 105 degrees and when you get to the bottom the rod is pointing backwards.

Thanks Ernie, and everyone else who replied. I ran a couple of test pieces yesterday, and was able to do them in two passes. It was a lot easier to run the bead without having to move my body at the same time, so despite having to join two welds, the resulting weld looked a heck of a lot better (and should be a lot stronger as well).

Thanks again,

Jon

I would have considered this, and while it would have worked on the test pieces, the actual part I am doing the work on is too big (7' x 3') to rotate in my shop.

Jon

Thanks Stanly, I actually didn't bevel it, but just ran a fillet along the outside; hopefully that will be sturdy enough for the application.

Jon

Hey Lloyd, the tricky part (at least for me) is joining the two segments. I've learned how to reverse the travel angle to fill in the crater at the end of a run, which at least helps to finish one segment.

Jon

That means you dont have any interjoint bonding. Just glued around the edges.

If its a low dynamic joint..not problem. If it is a dynamic joint...expect to reweld it again..and again...

Most of the time..you can get away with it. Usually. Kinda sorta, mostly.

Gunner...remember his spare tire that disappeared? No bevelling and not enough heat....

Isn't basic fillet welding just welding on the perpendicular faces? That's the way it looks in the Navy manual, anyway.

Oh yes I remember that story! It was before I started welding, but I have always kept it in my mind as a reason to make sure that my bead has melted into the surfaces of both materials I am joining.

Jon

A properly sized unbevelled fillet is just as good as a groove weld. The choice to bevel is usually comes down to economics. A fillet requires no prep but more weld deposit; most groove welds require some sort of prep but less weld. As the material gets heavier the cost of extra weld deposit tends to outweigh the cost of prepping joints.

For examples of prequalified code quality fillet welds see the AISC Steel Construction Manual or Lincoln's Procedure Handbook.