Thread: Welding pipe at angle onto RHS

Hi Forum members!

I am currently building a fence (chicken wire/plain wire farm style) that uses 50mm square rhs (2.5mm) as fence posts, and intend to use 25mm NB pipe (medium gauge) as the stays. I had intended on cutting the pipe at the appropriate angle and welding it onto the flat face of the square post and concreting in the other end at the appropriate distance.

When I mentioned my plan to a mate, he raised his eyebrows and reckons I'll have a hard time making the weld neat without blowing holes due to the angle. He reckons I should weld a flat piece onto the post and bolt the stay to this. He also reckons this will help if the fence moves.

The fence is a large house yard so I'm trying to be neat, but can see his point. I haven't done a practice run yet, as I thought I would get some opinions first.

I have a crappy fan cooled stick welder (like a GMC) and will inevitably be working off a pretty long extension lead (although I have 15 amp leads to use). I was planning on using 1.7mm rods, but haven't got any yet. Welding skills are "rudimentary".

Should I abondon the weld idea and go with bolted joints? Some welding is still obviously required, so I can't avoid it altogether.

You're not working with very thin wall stuff so do a practise run,
that will tell you the best way

If you take it easy and practise as said above should be ok the hard bit will be on the inside where the v is formed.

Cut the pipe square.
Hammer end flat.
Weld across post. 1 weld on the flat.

You could do as DavidG suggested with an extra step of cutting the flattened bit on an angle and welding it to the post with the flattened bit vertical (instead of horizontal).

This will enable you to easily weld both sides of the flattened bit and is probably "slightly" stronger than when horizontal.

I agree with Vernon. Go for the vertical weld. Much smaller chance of problems down the track.
Kevjed

I've done this type of weld countless times. It can be done, just take your time, do it in a few small beads not one run. It is hard to contort your wrist to maintain proper electrode angle around a small diameter pipe. Grind the sharp point away on the pipe first and with the V in the angle just flare the arc out a bit to make sure the weld metal is blown in and it also increases the heat so that you are less likely to get slag inclusions.

why not drill the posts get the pipe in long lengths and push through ,then weld together where they join
and just tack them underneath. bob

Originally Posted by acton

Hi Forum members!

I am currently building a fence (chicken wire/plain wire farm style) that uses 50mm square rhs (2.5mm) as fence posts, and intend to use 25mm NB pipe (medium gauge) as the stays. I had intended on cutting the pipe at the appropriate angle and welding it onto the flat face of the square post and concreting in the other end at the appropriate distance.

When I mentioned my plan to a mate, he raised his eyebrows and reckons I'll have a hard time making the weld neat without blowing holes due to the angle. He reckons I should weld a flat piece onto the post and bolt the stay to this. He also reckons this will help if the fence moves.

The fence is a large house yard so I'm trying to be neat, but can see his point. I haven't done a practice run yet, as I thought I would get some opinions first.

I have a crappy fan cooled stick welder (like a GMC) and will inevitably be working off a pretty long extension lead (although I have 15 amp leads to use). I was planning on using 1.7mm rods, but haven't got any yet. Welding skills are "rudimentary".

Should I abondon the weld idea and go with bolted joints? Some welding is still obviously required, so I can't avoid it altogether.

Bend the pipe say three or four inches at the end so the pipe is square to the post and then angles down to the ground .
If your using galvinised pipe grind the gal back a bit on the end where you are going to weld it ,after its cooled give it a spray with some zinc rich paint.

Kev.

Thanks guys, sounds like welding is the preferred method. I like the bashing flat approach, although if I have it vertical I still need to cut at an angle. Thanks for the tips .. I'll have a crack at it in a less obvious place first!

Originally Posted by acton

50mm square rhs (2.5mm) as fence posts, and intend to use 25mm NB pipe (medium gauge) as the stays.

I was planning on using 1.7mm rods, but haven't got any yet.

Hi Acton,
Is the 25NB pipe galvanised.? If thats the case that will add that extra degree of difficulty. If galvanised remove same with a a/grinder before attempting the weld.

Because you are welding 2.5 w th heat control is paramount to avoid a burn through. Try this:
Welding from bottom to top -strike an arc hold it short- then break it by flicking up but while the rod end is still red hot -re ignite the arc.

Do this over and over again. Welds do not need to completed surround pipe- may be 12mm length- each side.


With the long lead weld in short cycles 2mins -then take a 5 minute break- otherwise anticipate problems with breakers dropping out etc.

Can long lead be eliminated and whole assembly welded near powerpoint?

hope this helps
Grahame

No, just plain painted pipe and posts. To be painted at a later date. I'll up the joints with cold galvanising paint.

Thanks for the tips. I have seen the stop start trick used with great success, and gave it a bit of a try making two short lengths into a longer length with good results (although probably not necessary).

I had a burst of energy and have already concreted the strainers in ... I have a steep block, and it got too hard trying to pre-fabricate.

My friends main concern was two fold:
1. The angle makes a thin bit on top that melts away, operator panicks, and holes get blown
2. He's dubious I'll cut the angles neat enough so I'm not rying to fill gaps. I intend to weld first and concrete 2nd to avoid this problem.

Thanks everyone

Originally Posted by DavidG

Cut the pipe square.
Hammer end flat.
Weld across post. 1 weld on the flat.

I'd be doing what David has suggested. If your not an experienced welder, attempting to weld the vertical runs, especially on the job, will prove a problem. Surely a single run across the top of the flattened section would be adequate. Another option if they're just to brace the fence is to cut it on the angle and do quite a few spot welds because trying to weld material that thin around an oval shape will be pretty awkward.

Bob K

Acton,
Some more random thoughts

• Where its thin, weld first.
  
• A little of water will cool down the metal.Be cautious enough not to allow you and it to become part pf the electric circuit. A rag in a bucket and soak and cool works ok.
  
• Keep the majority of the arc on the thicker of the two components. 2/3rds coverage on the thick side works ok.
  
• To further allow cooling chip off and brush between welds.
  
• Some electrodes will weld over their own slag with few holes, others won't.
  
• With a long lead you will need greater than normal amps to overcome voltage drop. In turn this will increase the cool down time cycles of your welder.

Higher amps ,short arc should get you there.
regards

Grahame

Great tips Collin, thanks for that ... any rod recommendations? In my experience they can make a huge difference. I picked up a pack of rods recently with a trade brand I don't recall, and whilst they are a little tricky to start, are brilliant to work with. Cigweld rods seem to end up as slag inclusion city for me. I pinched some old 1.7mm rods off my old man, but they look like they have been sitting there for twenty years, so I don't have high hopes for them. I'll sneak them into the oven tonight when the missus isn't looking!