Welding stainless

[Bigmuz7]

All I've ever welded was mild/hard steel with a stick, from 10 mm down to about exhaust type thickness, whereafter I switch to gas, ... never having welded stainless, a fareing on the RIB needs a couple of straps re attached, can I just gas weld it like I'm used to doing with some gash stainless lying about, or will I need to gets me some funny rods and do it with the stick ? The straps are only about 3 mm thick going back onto some tube

ps will I get heat discolouration etc ?

[Anchorhandler]

How thick is the tube?
The last thing you want is to blow holes in it with the arc welder!

[Pikey Dave]

You can stick (arc) weld stainless with ordinary rods but the weld will rust. Best to get some proper rods. It would help to know the composition of the stainless you are welding, 316, 304 etc, as you can buy rods specific for type. You can get general purpose stainless rods that will do the job ok. You will get heat marks, you will need to pickle the welds with pickling paste to clean them up & this will get rid of the heat marks. Beware of the pickling paste, it's evil stuff if you get it on your skin. I find stainless easier to weld than ferrous.
TIG's best if you can do it

[Bigmuz7]

Originally Posted by Anchorhandler

How thick is the tube?
The last thing you want is to blow holes in it with the arc welder!

I'd imagine about 1.5 , its only 15 mm OD or so

Originally Posted by Pikey Dave

It would help to know the composition of the stainless you are welding, 316, 304

By eck .. its shiny .. thats my limit I'm afraid


Because of the anticipated tube thickness,.. I'd prefer to use gas, but Ive never attemped with either, and just wondered if it was possible with gas, is there any difference in melting point for example over mild steel ?

[Pikey Dave]

Originally Posted by Bigmuz7

I'd imagine about 1.5 , its only 15 mm OD or so



By eck .. its shiny .. thats my limit I'm afraid


Because of the anticipated tube thickness,.. I'd prefer to use gas, but Ive never attemped with either, and just wondered if it was possible with gas, is there any difference in melting point for example over mild steel ?

I'm more than willing to stand corrected, but I don't think you can gas weld stainless in the traditional way. I know for a fact you can't cut it with gas like you can with mild steel. It doesn't melt & pool, it just sags & blobs. If I could, I would take it to someone who could TIG it, a much better job.

[martini]

I'm not going to advocate gas welding stainless, it'll make a mess with discolouration etc that will be a bugger to clean up but more importantly there'll be a lot of heat going into what is probably fairly thin gauge tube, distortion could be a issue.

But if you must use a carborizing flame (excess acetylene) and a flux like Solar Flux, get the torch as close in to the joint as poss.

If you can't get hold of any filler rod without buying a kilo for couple hundred quid I've got some thin gauge 316 rods, could chop a couple in half and post 'em

Get an inverter down on your Xmas list, they're pretty cheap these days

[Mollers]

Originally Posted by martini

Get an inverter down on your Xmas list, they're pretty cheap these days

I have a couple going cheapish.

[Downhilldai]

Originally Posted by Mollers

I have a couple going cheapish.

Do you now? How much?

[martini]

Originally Posted by Mollers

I have a couple going cheapISH.

[Mollers]

Originally Posted by Downhilldai

Do you now? How much?

I have two Thermal Arc Thermadyne ?model. The lads at work are saving-up to buy them. Should have more next week. I'll let ya know.

[Bigmuz7]

Better than submitting to Satan *spits used electrode* and getting a Mig set up you rekon ?

[Downhilldai]

Originally Posted by Mollers

The lads at work are saving-up to buy them.

Hmmm, don't like the sound of that. I was hoping for something more along the lines of:
"Here's a fiver. Pop into town, get me a pasty and pick up a Thermadyne from Mollers on the way back with the change"

[jwalker]

Originally Posted by Bigmuz7

Better than submitting to Satan *spits used electrode* and getting a Mig set up you rekon ?

I've gas welded stainless a few years ago. It worked ok but the weld was pretty course and scruffy. I tried it with and without flux but neither was good. It's odd stuff on gas because it doesn't conduct heat well so you don't get a nice molten onion puddle to fill.. at least, I didn't. Tig is good, even a cheap scratch start tig is pretty ok and if you can gas weld you will be able to tig weld. When the arc strikes, there is the equivalent of a flame so it's a two handed job similar to gas welding. Of course, you need to invest in a cylinder of shielding gas, a regulator and a torch too along with the inverter. It needs to be a torch designed for use with an inverter because you need a manual gas valve on the torch. There may be more modern stuff available nowadays.. dunno.

[Anchorhandler]

Hi
I hate to be the bringer of bad news but because of the difference in thickness 3/1.5mm, you are going to have to be a very skilled welder to glue it all together with an arc welder.... To get decent penetration on the 3mm plate you will have to have the amperage up to a point where you risk blowing the 1.5mm tube.... Could get very messy indeed.
To do it properly you would need to have it tig welded using a good make of 316 filler rod and Argon.
Shouldn't be too expensive to get it done though seeing as it's only a small amount. It's worth it as (IMHO) there is nothing worse than nice shinny stainless with rusty weld beads tacked onto it.
Tig welding ensures a contaminate free weld which, after polishing, should prevent the weld from rusting (even if you use a good 316 electrode on the arc welder I reckon it will start to rust)
If you do have a go yourself then remember that preparation is key to a good finish... Make sure you clean the surface as best as possible prior to welding and weld it inside where there is no wind.... Oh ang get yourself a stainless steel wire brush otherwise a mildsteel brush will probably deposit shite in the weld resulting in it rusting later on...
Hope this helps
Simon

[biffer]

the polishing is important, not only does it make it shiney but it also makes a barrier to stop it rusting, if you left it unpolished it would rust, i did know the technical name for it, about 30years ago!
tig is the only way really, it is 1.5mm wall on most tube and it's only 316 on boats

[Bigmuz7]

Originally Posted by Anchorhandler

because of the difference in thickness 3/1.5mm, you are going to have to be a very skilled welder to glue it all together with an arc welder.... To get decent penetration on the 3mm plate you will have to have the amperage up to a point where you risk blowing the 1.5mm tube...

Well I rekon thats why its failed in the first place. Its just light tube and just welded on the outside face, and probably had one too many hairy ars*d diver knock against it,... I think I'm up to the job ok, but fek it .. its too small a job to invest in some nooo kit .. mabes I'll just whip it orf and take it down to me local machine shop then .. Ok .. thanks for all your advice chaps

[PeterR]

I have got a stainless steel welder that i want to sell .I have mentioned it before and some one did put their name down for it but cannot remember who it was the price is £300 it has only been used for three hours comes complete with gauges.If the person who wanted it before can have first refusal.I will advertise it in bits and peices

[billboat10]

hi all i have been a welder from when i left school a long time ago the best way is tig but tig set are dear the other one is mig with stainless wire and pure argon gas that way it dont rust i have just used this method on my aframe hold good and is neat so if you know any one with a mig you can just buy a small rool of wire about a tenner and give it a go

[willk]

Biggers...

Ask him if he has the Manual

[martini]

Originally Posted by willk

Biggers...

Ask him if he has the Manual