Welding galvanised steel trailer

[rcx132]

There's some damage on the cross member of my car transporter caused by previous owner's mis-use. Am I right to say I should grind back the zinc and then weld as normal? How far back from the weld should I go with the zinc removal? Will the steel then weld as normal ?

 

[wyn]

I'd grind the galv back about an inch......grinding galv is pretty nasty too........maybe use a respirator.

If it's tube or box section the galv inside will burn off aswell, as you weld it.

I recently had to alter some galv railings and bought a PAPR helmet to weld it.

 

[tom2207]

Id only usually go half inch , but dont breathe the white fumes , very horrid results.

 

[MoreWellie]

After welding some Zinga or similar would protect the metal ok providing it isn't in a place that will get scratched easily

 

[KemppiFrog]

I do quite a bit of this, just grind the area that I expect to weld on, mostly the chamfer. Plus a lot on not breathing the fumes..

 

[KemppiFrog]

Tend to find that when welding galv tube, the above reccomendation likely gets a bit of zinc in the weld. Result is that it tends to not rust so easily.. Not quantifyed this, just an observation. This is on gate frames, where the cheaper option is to used pre-galv tube, as galvanizing the finished product with plain tube is far more expensive. Low stress stuff, not critical, where one would look more carefully at the process.

Did an extension on the main drawbar of a boat trailer recently, so ground a bit more, to a margine outside of the weld area, just to be sure..

 

[Mma man]

The best advise on this is get someone else to weld it. Galve is horrible dangerous stuff and in my opinion should not be welded. You never seem to grind it all out so it always fumes. Iv always refused to weld it for the last 15 years or so. I'd rather find a new boss all day long

 

[rcx132]

Thanks all for the help, the repair went well, no visible fumes, used a fan to blow fumes away to be sure.

I believe welding zinc causes visibly bad welds with pores in them, these welds came out great so I'm confident I got all the zinc off.

I haven't invested in a respirator yet as I don't do a lot of welding, I just weld outside or with a draft going through the garage.

 

[Mick Annick]

I’ve a couple of cracks to repair on the trailer I acquired yesterday, will grind back as suggested and will do it outside, any other precautions to take please?

 

[KemppiFrog]

I’ve a couple of cracks to repair on the trailer I acquired yesterday, will grind back as suggested and will do it outside, any other precautions to take please?

View attachment 309962View attachment 309963

Fatigue failure, common on thin steel trailers with hard suspension.
I would put a big plate over the area, say 2/3mm thick and grind (flapdisc) the area on the galve where you are going to weld, say about 8mm wide.
If the thickness of adding a plate is a problem, cut out the galve to the size of the plate and let it in flush. Bit more tricky with the but weld on thin stuff..

Precautions: get the wind behind you and protect the weld from drafts with cardboard/sheet, so as to not blow the gas away. Assuming MIG. If stick, hope you are good at thin stuff..

 

[Mick Annick]

Fatigue failure, common on thin steel trailers with hard suspension.
I would put a big plate over the area, say 2/3mm thick and grind (flapdisc) the area on the galve where you are going to weld, say about 8mm wide.
If the thickness of adding a plate is a problem, cut out the galve to the size of the plate and let it in flush. Bit more tricky with the but weld on thin stuff..

Precautions: get the wind behind you and protect the weld from drafts with cardboard/sheet, so as to not blow the gas away. Assuming MIG. If stick, hope you are good at thin stuff..

I’m going to try stick (don’t have MIG) and plate it as suggested; as it was a freebie I have nothing to lose.

If all goes well I might adapt to carry something a little larger, perhaps a little French tractor?

 

[brightspark]

I’m going to try stick (don’t have MIG) and plate it as suggested; as it was a freebie I have nothing to lose.

put a piece of steel plate or copper underneath if your leccy welding it. it will dissipate the heat and wont burn through

 

[KemppiFrog]

I’m going to try stick (don’t have MIG) and plate it as suggested; as it was a freebie I have nothing to lose.

If all goes well I might adapt to carry something a little larger, perhaps a little French tractor?

I had a feeling there was a something behind this.....

 

[E T]

I did some welding on my cheap ,made in poland, one axle trailer this weekend.
These things are relatively cheap and heavily galvanised.
I made some changes to the top frame and the tarp and thought I ground of all the galv. The box sections are 2mm wall thickness, but it looks like half of that is zink. I made some good welds in the end with the Fronius Transpocket on pulse with 2mm 7018 rods but it took a lot of cleaning and there still was lots of white fumes from the galv.
No worries about the fumes because I was welding outside and using my Esab Sentinel fresh air helmet.
I've welded a fair amount of heavily galvanised steel and most of the time a good cleaning with a flap disc will get rid of most of the zink, but this cheap stuff is a different story. More zink than steel.