So what’s all the fuss about welding stainless steel with TIG?/GTAW

Like everything else, it’s all a matter of careful preparation and some practice! Welding can be shown in ten minutes – the rest of your life is added experience through practice = learning!

As an important notice, I would like to draw your attention to the fact that all photographs are actually huge (if only ‘phone quality’), so if you want to see them full size, just click them to enlarge. I would also hasten to add that what follows are only my way of doing things. Like in almost all other things, there are more ways than one to reach the same goal…

Never mind about the theory – that you can read up ‘anywhere’ on the internet, here are some practical tips to help you on the way. The only thing that I would want to emphasize is to get a decent helmet, keep everything spotlessly clean and grease free – and to keep those needles pointy! The gas used here is ArgonW2, with the addition of 2% Hydrogen, which makes the arc hotter and reduces burn and discolouration by bonding with the oxygen around the weld, therefore excluding oxidation. Pure Argon will give a duller/matter finish and a more colourful weld, but can be used for Aluminium, too.

The examples I have chosen to show are primarily to do with welding sheet between 0.6mm and 5mm, and applying different surface finishes. Some of the jobs, like welding our own kitchen basins or the hygienic welding of potable water standpipes, require the oxygen being excluded (purged) from the other (in-)side of the weld, to reduce or eliminate corrosion of the welded area; we do these welds manually  , though typically in an industrial pharmaceutical or food industry environment – where there is space – pipe-welding is often  accomplished with orbital welders or other advanced fabrication technologies.

For us, though, a typical task might be to weld a 0.8mm stainless sink or drainer into a 5mm hot-rolled, laser-cut sheet of stainless for a kitchen top – as cleanly as possible, without any distortion or other anomalies. The welding done here is ‘fuse welding’, i.e. melting the two pieces of metal together without the addition of extra material (rod or wire), in this particular case using around 50-60Amps.

So let’s take a relatively simple example of such a task and walk through the setup, preparation and actual welding, followed by a cleanup and the final product!

So this is what we start with, a 5mm sheet, cut to size and with a sizeable hole in it, in which the sink eventually fits (the smaller holes are for the taps etc.):

The hole is, of course, cut to the right size to closely fit the cut down (you will see why later) sink unit, with corners correctly radiussed etc.

Next, we have the sink (which, if you are lucky, is more than 0.6mm thick!) which always has a 90˚ rim all the way round (which would normally sit flat on the worktop). This rim will have to be cut off with a guillotine and the (out)sides of the sink ground flat/level with an angle-grinder to fit directly into the hole in the thicker (5mm) top. Here a sink with a step and the visible flat rim at 90˚ all the way around the top.


Rim now gone after the guillotine ‘chop’ and…

(a different sink) with the edges ground flat

Next up is to check that the whole plot fits together, so sellotape at the ready, I sit in front, balancing the sink on my knees and offer it up to the hole from underneath, and once placed properly in the cutout (ideally on the first ‘fitting’!), tape it into the top in a few places, so that it doesn’t fall out and damage itself, while I get the other stuff ready!

At the ready to fit in from underneath…

Sellotape now holding it in place.

Another pair of basins tack-welded and to go…

You can see in the photo directly above, that the bottom of the sink is lined with styrofoam and some cardboard. This is to protect it from anything that might fall in and dent or scratch the surface finish – more about that a little later. It also raises the bottom, so that I don’t need quite so many bits of ply (following photos show what I mean) to support the copper bar that I use as a welding guide and heat sink:


The big fat copper piece has been cut with different radii to fit as well as possible into the corners of different sink units from various manufacturers (Caressi, Blanco etc. – the close-up is a bit small for the radius of the basin, but if you look closely, it can be seen that the other end is actually correct, but I didn’t bother to turn the copper bar around for the actual weld) It should be obvious what I mean from the photos.

A large copper bar is also placed on top of and along the edge of the intended weld, about 1/8th of an inch back from the edge and another bar can also be placed UNDER the top (see photo above), up against the side of the basin. These are held in place with g-clamps to keep them from moving around.

Here is the spreader-clamp that I use to keep the copper bar on the inside pressed up against the edge along the weld. This is for a very good reason, as when the thinner metal of the sink heats up ahead of the welding arc, the metal expands and it can cause gaps between the top and the basin, which leaves the welded edge either wavy along the side of the wash-basin afterwards or can lead to unwanted ‘holes’ being left behind as one is welding, or both – neither desirable!

Sometimes the data is wrong and the corners can be cut incorrectly and the fit is not good. If the radius cut is too large, the basin will be too tight and the radius can be ‘adjusted’ carefully with a dynafile, as marked here, you can see why that is acceptable, if a nuisance.

If the radius is cut to small, then you end up with a huge gap, which will need filling or dinging into the gap with a stainless rod or bar and judicial use of a hammer.

What I didn’t mention at the start was that the inside of the basins shown have been finished with an orbital sander before being cut and shut into the top, which is left untouched until after the basin is welded in – and THEN finished.

The sander is ‘challenging’ to get into the corners for an even, matte finish, which you can see below (10mm or 3/8″ radius in the corners and a six inch disc on the sander!), but there are ways around that, as the close-up shows of the finishes corners. First sanded with a 60 grit disc they are then finished off with 600-grit mesh sponge disc to flatten off the scratches, otherwise they get dirty (and unhygienic) rather quickly.



Once welded in all round, the edges have to be blended in and all signs of a weld ‘disappeared’. This can be done with a ‘dynafile’, an angle-grinder or the orbital (and even with a good old flat bastard or half-round file!), all a matter of choice and, of course dependent on the quality and smoothness of the weld. It didn’t take long to realise that the orbital is perfectly adequate if the weld is clean and straight, so I don’t waste time and risk using anything else any more… One slip with an angle-grinder and the whole job can be for the bin.

Here a few welds, showing what we are looking for – straight and clean, no dents, holes and ripples if possible!


Corners are always the trickiest bit to freehand cleanly and there is often a bit of a bump or carbon over-blow.


Below, three shots of the same corner:

1) before welding,

2) Right half blended after welding with the orbital into the corner, left side as welded

3) Finished corner blended all round

A finished basin blended into a 5mm top (sorry about the lens distortion!)

The tops then get a scrub with ‘Fizz’ (scouring cream), are rinsed thoroughly and once dry are then given the sanding treatment with the orbital, this time with 40 grit. All around the edges of the top are then also sanded, the corners all made ‘finger-friendly’, de-burring with a sanding block and the job is done, ready for final treatment with ‘Pelox’ (a de-oxidising agent) and then covering with plastic foil and corrugated cardboard ready for casing up and shipping.


Here just a few photos of other jobs that come and go in a day’s work…

A brushed stainless top and basin. The challenge here is keeping the finish on both basin and top after welding. EXTREME care is required to avoid any scratches or blemishes. Anything like that could ruin the job completely or if not, take much too much time to amend economically:

A handy tip for welding along a guide that might be rough – wind teflon-tape around the head and it will glide as smooth as silk along the surface without any ‘judders’ in the weld.

Tack-welds on the right, the beginning of the weld-seam on the left (going leftwards):


Doubled up plates tacked together ready to weld along the length to thicken the edge to 10mm:

… and now seam welded along the length

A basin made ‘at home’: Laser cut 1mm sheet, n0w having been bent to shape.


… and welded in

The dreaded brushed stainless top and basin, which requires eyes like a hawk and infinitessimal precision and caution:

An interesting solution:

Water standpipes for a camping-site, purged of oxygen from the inside while welding to keep the welds free of oxide and to avoid corrosion starting in the future, done according to hygiene rules for drinkable water distribution. They also have to be pressure tested, of course. Square for a marina and the round ones for a caravan camping-site