Welding Tips and Tricks

I've done a bit of gas oxy-acetylene welding years ago. I was doing DIY repairs to my car rusty-sheet-metal body-work, bought the O/A kit and taught myself how to use it, after a fashion. The welds were OK for my purpose at the time but in no way "invisible", in no way forming a smooth join between sheets.

Now, what I really like to be able to do is to be able to make very high quality, professional looking and strong "invisible" butt welds in stainless steel sheet, oh say around 0.8mm to 1.0mm (0.031" to 0.039") thick. For my new application, not car body work this time, thicker welds, lap joints, etc, just won't do. This time, I need to not exceed the sheet thickness in the weld because I need to have it go smoothly through a bead roller and a thicker weld would cause problems through the rollers.

So not knowing how to do this "invisible" welding, I googled "invisible welding" and found this video on YouTube of what I think is TIG - Tungsten-Inert-Gas pulsed welding -

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This video also features on a welding tips and tricks webpage here. Most informative. Thank you.

I was impressed by the smooth, apparently seamless weld to the extent that you are not quite sure where the weld line is, certainly better looking than I could ever do with my oxy-acetylene gas torch. Then again, I was not trying to do "invisible" welding at the time. Perhaps it is possible with O/A kit?

I can't tell how strong that guy's invisible weld is but it certainly looks good.

Now I want to buy equipment that can do that and see if I can learn to use it properly.

So my first question is - is a pulsed TIG welding machine the best generic type of welding kit to buy for my application - "invisible" welds in sheet stainless steel? If not, what is better kind of kit to buy?

From the welding tips and tricks page

pulse tig is used to weld. You can count the pulses and its exactly 3pps or 3 pulses per second. Personally, I hate to weld with low frequency pulsing like this. It drives me nuts. I much prefer to set the pulse frequency to around 30 pps. That way my eyes do not have time to adjust between pulses. You still get the benefit of reduced heat input and agitation of the weld puddle without the eye strain and headache.

Though the author differs with the welder in the video as to the ideal pulse frequency nevertheless he too seems to be recommending "pulse TIG" as opposed to non-pulsed TIG, right?

My second question is what maker would you recommend to buy (bearing in mind I am buying in Scotland / Britain / UK and I want to buy locally from what is easily available here)?

For example, I am looking at SIP right now because my local tool shop sells those and I asked them about this product they offer.

SIP 05268 Weldmate P188HF TIG / ARC Inverter Welder With Pulse

Would that be suitable for my purposes?

My local shop also offers the Sealey line of TIG welding kit, which seem to be lighter but don't seem to mention the "pulse" facility, so I am wondering if those ones are not so suitable. Do I really need pulse?

I gather that I would need a AC-TIG if I ever wanted to weld aluminium but the issue with the SIP products there is the SIP welder with AC/DC TIG and pulsed is a lot more expensive. Whereas the DC only with pulse might cost me around £450 , the AC/DC TIG with pulse would be more like a whopping £1,300. It also weighs in at a hefty 26Kg to lug about.

So I am tempted to sacrifice the aluminium welding and save £850 and my back muscles by opting for the DC only TIG with pulse but if there was another make that offered what I need for my invisible welding plus an aluminium weld capability at a more affordable price, I'd like to know about that now.

So am I on the right lines for what to buy and what would you recommend? Thanks!

I am across the pond from you, and am unable to comment on the specific brands available to you, but I'll offer the following general comments.

Pulsed TIG is an excellent solution for the task at hand. A very tightly and squarely fitted joint will not require filler metal, and the pulse feature minimizes shrinkage. For the best result, you'll need a way to purge the backside of the weld, and ideally access to both sides (100% penetration from one side requires more heat input--bigger heat affected zone-- than 50-60% from one side at a time).

The details of the work, to easily backpurge, and to avoid distortion, can wait until you're ready to begin.

Your OA experience will make the TIG transition a short learning curve. The processes behave similarly.

As for HFAC to weld aluminum, this is a feature than can be added later, but it requires more than twice the power to weld aluminum of the same thickness, i.e. you might TIG weld 1/4" steel at 100A, but you'll want 220A to do the same with aluminum, so keep that in mind if you buy DC only with the thought of adding an HFAC unit later.

Steve S

Otto Nobedder wrote:I am across the pond from you, and am unable to comment on the specific brands available to you, but I'll offer the following general comments.

Understood Steve and thanks.

Otto Nobedder wrote:Pulsed TIG is an excellent solution for the task at hand. A very tightly and squarely fitted joint will not require filler metal, and the pulse feature minimizes shrinkage.

OK, buy new pulsed TIG, consign old O/A kit to history. Got it.

Otto Nobedder wrote:For the best result, you'll need a way to purge the backside of the weld, and ideally access to both sides (100% penetration from one side requires more heat input--bigger heat affected zone-- than 50-60% from one side at a time).

The peculiarities of this welding job mean that access to both sides will not be practical I suspect. An approximately 10 metres / yards x 1.5 metres / yards stainless steel sheet has to be slid and curved into place and then welded in situ to make a cylinder oriented 1.5m high.

Therefore access must be from the outside of the cylinder and the weld line must be vertical.

I notice that in the example video I quoted, the welder used a copper backing plate on the back side to "self purge" the backside of the weld. Perhaps he is using thinner sheet metal than I would but I presume that I could use a similar technique?

Otto Nobedder wrote:The details of the work, to easily backpurge, and to avoid distortion, can wait until you're ready to begin.

Sure.

Otto Nobedder wrote:Your OA experience will make the TIG transition a short learning curve. The processes behave similarly.

Well I'm a lot older now. My learning curves tend to be that bit flatter and longer these days.

Otto Nobedder wrote:As for HFAC to weld aluminum, this is a feature than can be added later, but it requires more than twice the power to weld aluminum of the same thickness, i.e. you might TIG weld 1/4" steel at 100A, but you'll want 220A to do the same with aluminum, so keep that in mind if you buy DC only with the thought of adding an HFAC unit later.

Steve S

Some welding machines specifications quote a duty cycle percent implying that

• "180 amps @ 60% duty cycle"

is very much better than

• "160 amps at 35% duty cycle".

I'm not quite sure how to compare the specifications taking account of duty cycle percentage; perhaps you can advise Steve?

Is 180 amps @ 60% duty cycle somehow equivalent to 108 amps effectively
and
is 160 amps @ 35% duty cycle equivalent to only 56 amps effectively?

Does one multiply nominal amps by duty cycle to get a performance indicator or what?

I've never figured out how to appropriately apply "duty cycle" to a hobby/small scale situation.

I look from a productivity side...

If what I'm welding will take seven minutes, then three minutes to set up the next weld (hypthetical example), and requires 120A to weld, then my machine must have a 70% duty cycle minimum at 120A.

Duty cycle only becomes a major factor when you're running up against it. If you expect to regularly weld at 150A, and rarely at 225A, look for a machine that has at least 75% at 150, and be carefull on the rare 225A work.

I hope that made sense.

Steve S

Otto Nobedder wrote:I've never figured out how to appropriately apply "duty cycle" to a hobby/small scale situation.

I look from a productivity side...

If what I'm welding will take seven minutes, then three minutes to set up the next weld (hypthetical example), and requires 120A to weld, then my machine must have a 70% duty cycle minimum at 120A.

Duty cycle only becomes a major factor when you're running up against it. If you expect to regularly weld at 150A, and rarely at 225A, look for a machine that has at least 75% at 150, and be carefull on the rare 225A work.

I hope that made sense.

Steve S

Yes it did. Thanks Steve.

So when considering welding 0.8mm to 1.0mm sheet stainless steel together then would it be right to assume that's a lower amp requirement than the typical 160 amp supplied by an entry level TIG welder?

Would it be correct to assume the welder could run all day at that low amps required and therefore the duty cycle at that current be as near to 100% as makes no difference because I will be finished the 1.5 metre / yard weld job or have reached my own personal duty cycle and stopped for a tea-break / given up for the day long before the welder has exceeded its capacity to weld?

Take the example video above. The man, the welder, he takes 5 minutes to do the complete job including clamping, welding, grinding, cleaning and planishing and inspecting his work as he goes along. I guess he doesn't get anywhere near to reaching the ability of the welding machine to weld given his own personal demands on the machine.

Would the welding machine's duty cycle require me to do the 1.5 metre / yard weld in small sections, allowing the welding machine to cool down or could I do the complete 1.5 metre / yard weld in one go without worrying if the welding machine would pack in because it had exceeded its duty cycle and needed to cool off for a time?

It's not like mass production when I am doing one 1.5 metre / yard weld then immediately another 1.5 m weld then another.

There will only be the one 1.5 metre / yard weld to do then it's back to the store cupboard with the welder for days / weeks / months until I need it again.

Peter, my response was aimed at the idea of the capacity to do aluminum at some future date, so I didn't hit at the task at hand. When I weld 16 ga stainless (usually in short stitches, though the answer still applies), I'm not above 30A, expect maybe briefly to establish the initial puddle. I don't have pulse features currently, but if I did, the effective/average current would still be as low, so I'd expect a 160A machine to be able to do it in one go. I'd doubt even the torch will get too hot to handle.

Add to that, this is not a weld that can be done in one go. To minimize distortion, you'll be skipping around a bit for lots of short natural pauses, as well as the reasons you mentioned. I'll stop often to let what I'm working on cool, get a cup of coffee, or the other obvius break that results from too much coffee...

Steve S

As a fellow Scotsman (born Brechin/Forfarshire) and new to welding I can offer no experiential assistance like all these other welders/scientists. I just bought the Inverter Fusion 200PHP (made in Devon, UK) which incorporates pulse and HP start plus some other interesting stuff. Also check out its duty cycles.

Like you, I was about to purchase a SIP Weldmate but was put off by some folk with some service issues when their kit went wrong. This is hearsay but I steered away nevertheless.

Good luck with whatever you buy. All the best.

Otto Nobedder wrote:Peter, my response was aimed at the idea of the capacity to do aluminum at some future date, so I didn't hit at the task at hand.

Talking of which I've produced this image to show the welding task required.



So the task (in imperial units) is to weld a supplied stainless steel sheet most likely supplied as a coil, thickness 0.8mm to 1.0mm (0.031" to 0.039") of length of about 10 metres (yards) length and up to 1.5 metres (yards) high.

The sheet has first to be slid into the custom bead rolling gear before then it is welded in situ so that means the weld has to be done vertically.

I think you call this kind of weld a butt seam weld but I'm pretty sure I can't afford one of those professional seam welding machines. Don't know how much they are but since I'd have to ask that's a sure sign that I can't afford one.

Ideally I'd want the welding gear to be reasonably portable so that I can load it up in a van and move it to where the job is being done. Whilst there might be room in my back garden to do this job, I don't think the neighbours would be too happy about it, so I'd have to hire a small light industrial premises to get the job done, or maybe a large double garage would be big enough. Well let's not worry about that now. The main point is that I can't load up any really heavy equipment in a hired van myself. So all the kit for the job has to be portable.

Otto Nobedder wrote: When I weld 16 ga stainless (usually in short stitches, though the answer still applies),

On stitch welding, if the required end result is a continuous seam weld, after welding the stitches, does one revisit the weld and weld in between the stitches?

How small can one make the stitches and the distance between them assuming thickness 0.8mm to 1.0mm (0.031" to 0.039") .

I got praise aged 7 for my very neat stitching at primary school so my inclination might be to stitch small, or at least as small as my eyesight would allow these days (is there anything to be gained by wearing magnifying glasses while doing stitch welding?) but there must be a limit how small the stitches can be and how close together you can stitch without the stitches running into each other and you end up with a continuous seam weld, right?

So how small can the stitches be? If the thickness of the sheet was "X" how small could the length of the stitches be - 2X, 3X, 5X, 7X, 10X, 15X, 20X, what? Likewise what's the smallest distance between stitches in X?

Otto Nobedder wrote: I'm not above 30A, expect maybe briefly to establish the initial puddle. I don't have pulse features currently, but if I did, the effective/average current would still be as low, so I'd expect a 160A machine to be able to do it in one go. I'd doubt even the torch will get too hot to handle.

OK.

Otto Nobedder wrote:Add to that, this is not a weld that can be done in one go. To minimize distortion, you'll be skipping around a bit for lots of short natural pauses, as well as the reasons you mentioned. I'll stop often to let what I'm working on cool, get a cup of coffee, or the other obvius break that results from too much coffee...

Steve S

Define "skipping around" please.

On minimizing distortion, I'd like to ask for more information about the use of a copper backing plate.

First to quote what the WeldingTipsandTricks.com: Welding Sheet metal Video - How to make an invisible weld

The welder begins by doing something interesting that a lot of welders are not aware of...

He uses a small piece of copper sheet for backing.

Vise grip type sheet metal clamps are used to hold everything together and pulse tig is used to weld. You can count the pulses and its exactly 3pps or 3 pulses per second. Personally, I hate to weld with low frequency pulsing like this. It drives me nuts. I much prefer to set the pulse frequency to around 30 pps. That way my eyes do not have time to adjust between pulses. You still get the benefit of reduced heat input and agitation of the weld puddle without the eye strain and headache.

Anyway back to the part about the copper.

Sheet metal Copper backing does 2 things:

1. It draws heat out of the metal you are welding (if it is in close contact like with a chill block)

2. and it also traps argon in the weld puddle area. The back side of the weld on sheet metal gets hot and molten and needs shielding gas too.

Argon is actually absorbed into the molten metal, but gets squeezed out the back side upon solidification.

That small amount of argon on the back side of a sheet metal weld prevents excessive oxidation and allows the puddle to be a little bit cleaner and actually lets the puddle be more fluid because of less oxides floating around.

Many have mentioned to me the issue of distortion in welding thin stainless steel sheet and I so wanted to ask about using a copper backing plate, not only to keep oxygen out of the back side of the weld but to use to help take heat out of the sheet near the weld.

The guy in the video doing the invisible welding used a copper backing sheet / strip - maybe 6cm (2") wide and maybe 1mm 0.039" thick.

For a long straight weld I presume I will need a long straight copper backing strip, right?

If this welder had a thicker piece of copper like about ¼” thick, the weld would look even better. The good thing about using thin copper for backing for sheet metal joints is that you can form it to fit contours and can even tape in to the back side of a joint.

One caution….A little piece of copper like this one will get hot enough to burn you really quick. All the heat it absorbs from the weld is just waiting to make you holler if you pick it up too quick. So use copper backup for welding sheet metal.....but be careful.

No need to fit contours in my case and I'll be clamping the sheets together for the weld so no tape required.

Thicker is better presumably because thicker copper would take more heat out, help keep the sheet cool and reducing distortion, right?

I've seen 50mm x 10mm copper bar for sale but not from welding supply shops, on Ebay actually.



So that's 10mm thick or 0.4" which is thicker than the tipped 1/4" which I presume should be plenty thick enough, right?

Would that size of copper backing be suitable or would I be better with something wider / thinner / thicker?

I am curious as to why I don't see copper backing plates advertised as for sale by welding supply companies.

Why not? Why are a lot of welders not aware of copper sheet for backing?

Is copper backing sheet until recently an invisible-welder's professional trade secret, that the mass of welders don't know about, are not seeking copper to buy to use, that not even welding supply companies know about as yet, so that's why you don't see copper backing sheet sold as a welding accessory?

Where do expert sheet metal welders buy your copper backing plates and what size do they use? Does anyone supply copper bar specifically for the purpose of welding backing plate and what, if any, is the standard thickness of copper used?

Also what do you do to stop the copper backing plate melting and getting welded on the to the work piece?

Is it just a question of making sure the copper is dirty / oxidised or does the copper never get hot enough because it conducts heat away so fast even if in direct contact with the weld puddle or what?

I notice that in the video, the guy's copper backing plate has a little ridge in it. Is that relevant?

Do you need a small gap to keep the copper plate off the welding puddle but then how do you make sure the copper contacts the sheet either side of the puddle for good cooling but not the puddle itself?

melrel wrote:As a fellow Scotsman (born Brechin/Forfarshire)

I've passed that way a fair bit as I live in Aberdeen and have family in Fife.

What's it like trying to rent workshop premises in that part of the country? You don't live there now?

Aberdeen is the most expensive place in Scotland to rent property. We are talking around £25 per week to rent a single garage or even a gated parking place in the city.

I've a lot to do before I simply must rent a workshop for my welding task - meantime I can buy my welding stuff and practice my technique in my back-garden shed - but I have considered that it might be cheaper to rent outside the city and perhaps down your birthplace way might be cheaper, though it is a more rural part of the country and so fewer buildings available to rent.

Perhaps some farmer might have an empty barn at certain times of the year? So long as it has an electricity supply and water supply and the price was right, it might be worth my while renting further afield.

As you possibly know, in some parts of the Scotland businesses can even rent properties rates-free, so keen is the government to stimulate the economy in those areas. Not that I am "a business" - not yet anyway. I'm certain that I would not qualify for any grants or support for my personal projects.

melrel wrote: and new to welding I can offer no experiential assistance like all these other welders/scientists.

Well you read like you have expertise in something. I'm a computer scientist originally with wider science and engineering interests these days. I've been a bit of a Braveheart political writer/campaigner in my time too when the urge for FREEDOM strikes!

So what are your specialities if not welding, melrel?

melrel wrote: I just bought the Inverter Fusion 200PHP (made in Devon, UK) which incorporates pulse and HP start plus some other interesting stuff. Also check out its duty cycles.

I presume you mean the Fusion 200PHF TIG Welding Machine?

If you are new to welding I'd caution you to always wear eye and preferably head protection against the blindling light of the arc. I've never used electric arc welding and was very careful to protect my eyes from the bright welding flame while doing oxy-acetylene welding but I know of someone who was very foolish and neglected this the first (and probably last) time he did arc welding and got a very bad injury to his sight.

There are other dangers for sure but protecting your vision has to be on your mind 100% of the time you are near welding equipment which is being used, even by someone else.

melrel wrote:Like you, I was about to purchase a SIP Weldmate but was put off by some folk with some service issues when their kit went wrong. This is hearsay but I steered away nevertheless.

Well I am looking at SIP welders because Gibb Tools in Aberdeen that I've bought tools from before are selling them but I'd like to hear from some happy SIP customers before buying SIP.

melrel wrote:Good luck with whatever you buy. All the best.

Thanks melrel.

Wow!

That's a lot of questions all at once!

If you try to weld that in one go, the metal will expand ahead of you and the gap will grow. You'll want to do it in short sections, far apart from each other.

Suppose you want a 1.5mm gap. Cut a piece of 1.5mm wire about 5cm. Bend it to 90*, and grind a "flat" about 1/3 through one leg. Use this to tack the material together, as a spacer. Using the broad side as your gauge, make your first tack, about a cm above it. Let it cool, turn it 90* and pull it out. Insert it again, skinny side, about 2.5-3cm below, and turn 90* to push the metal apart, and again tack above. Let it cool... repeat every 2.5-3cm, until the whole thing is tacked up.

Then weld between tacks, one near the top, one near the middle, one near the bottom, staggering where you're welding giving each time to cool.

If you can use copper (or aluminum) strips as heat sinks, this is an advantage, for all the reasons you mentioned. A groove in the strip of copper or aluminum allows the root to go where it naturally would, as opposed to being "blocked" by metal in the way.

Steve S

Otto Nobedder wrote:Wow!

That's a lot of questions all at once!

Well thanks for attempting any answers at all. I am getting ahead of myself as usual since I haven't even chosen a welding machine to buy yet.

Otto Nobedder wrote:If you try to weld that in one go, the metal will expand ahead of you and the gap will grow. You'll want to do it in short sections, far apart from each other.

So that's what you meant by "skipping around"? Understood.

Otto Nobedder wrote:Suppose you want a 1.5mm gap.

Gap where? Between the two sheets to be welded?

If you suppose you want a gap there that means you must fill the gap with the material from a steel welding rod?

That means you are supposing it's better having a gap and filling it than to attempt to simply fuse the two sheets together using a zero gap, clamping the sheets so that they press against each other at the butt and simply applying heat via the TIG torch to fuse the two sheets together?

That's not a technique I've ever tried with my oxy-acetylene car repair since the edges to be welded were not straight edges and getting a really close fit between the body work and repair panels was out of the question.

But for this task, hopefully the sheet will come supplied cut perfectly square with nice straight edges and so maybe a close-fitting clamp and fuse weld might be possible, and simpler and quicker, with no need for a filler welding rod and a much easier clean up of the weld, doing it that way. Feasible?

Otto Nobedder wrote:Cut a piece of 1.5mm wire about 5cm. Bend it to 90*, and grind a "flat" about 1/3 through one leg. Use this to tack the material together, as a spacer. Using the broad side as your gauge, make your first tack, about a cm above it. Let it cool, turn it 90* and pull it out. Insert it again, skinny side, about 2.5-3cm below, and turn 90* to push the metal apart, and again tack above. Let it cool... repeat every 2.5-3cm, until the whole thing is tacked up.

Then weld between tacks, one near the top, one near the middle, one near the bottom, staggering where you're welding giving each time to cool.

Hmm. This seems quite time consuming. It's a 150 cm weld and tacking every 2.5-3cm means 60 - 50 tacks and your suggestion of fiddling about with a wire and letting it cool between each tack means it will take a long time. Yours doesn't seem to be a method which is suited to automating the task, allowing a welding novice, like me, to complete the task in no time, with little chance for error.

Unless the job is pretty much fool-proof on the day, I fear that I would make a mess of the weld necessitating a major re-think. I'd rather do my thinking in advance than on site.

Ideally I'd want to keep my torch in hand to tack the whole 150cm following prepared 2.5-3cm indicator marks on the sheet or clamps. Maybe complete the tacking in half an hour, which is maybe 30 seconds at most between tacks.

Then set up for the welding between the tacks and then complete that part of the weld in an hour. That sort of time scale would be acceptable.

Otto Nobedder wrote:If you can use copper (or aluminum) strips as heat sinks, this is an advantage, for all the reasons you mentioned.

I'd like to put some thought into what the best arrangement to cool the work might be. Since it is a straight vertical line it may not be too difficult to integrate a water-cooled pipe into the clamps?

Might it be possible to design a tacking strip heat sink that cools only the parts not to be tacked, allowing the tacked parts only to be easily heated to welding temperature?

I've got the time - weeks, months maybe - to think of a smart solution for this particular welding task which may involve designing and building a lot of custom tooling but which would save a lot of time on site while doing the weld.

Otto Nobedder wrote: A groove in the strip of copper or aluminum allows the root to go where it naturally would, as opposed to being "blocked" by metal in the way.

Steve S

Hmm. I'm not too keen on allowing molten metal to go where it naturally would. I really want to end up with a neat weld, not a "natural" weld with the molten metal flowing as it likes.

So grooves in the backing strip or bar where I want the tacks, yes, but perhaps fill the grooves with a high temperature insulator, to keep the molten metal in place?

On closer examination of the video, the bend / ridge in his backing sheet was more or less at right angles to the line of the weld. My guess now is that it is more likely it was an old sheet which had been bent for some other task and then later flattened for the backing sheet function.

Now back to stitch welding. Here'a nice photograph of a butt stitch weld.



from here.

So they had a gap and filled it from a welding rod.

OK, but assuming a 1mm thick steel sheet, how small is it possible to make the stitches, tacks or spot welds and how close together can they be, using a TIG (Tungsten Inert Gas) torch, with pulse?

For example can you have stitches which are 2mm long, separated with a pitch of 4mm, with a 2mm unwelded part between each stitch. Or is that not possible?

I'll try to stay straight on the meat of the matter this time...

Yes, ideally with a good square cut you can simply fuse weld this bead with no filler. This is the common practice in the food and beverage industry. Do a search on "sanitary welding", and I'm sure you'll find tons of specific information, and maybe even better suggestions on your specific application.

As for the tacking, yes, laying out a series of reference marks, say 3cm apart, is the way to go, but you'll still not want to start at one end and work straight to the other. This is for efficiency as much for finish. Pick a starting point, perhaps the middle, place a tack, then tack 12cm above, then below the original tack. This way you aren't waiting for tacks to cool, and can keep going. Then, return to the starting point, and, in the same sequence, tack the mark 6cm between each of the previous tacks, and so on until it's all tacked up. Then you can start at one end, weld the space between two tacks, skip the next, and keep going until you're half done. Then go back to the start and fill in the blanks, and you're done.

As for cooling, you did say this is stainless steel? Since you'll want a back-purge anyway, at this low heat the purge gas itself can be your coolant. A pipe (thin copper or aluminum, soft) sliced in half and hammered a bit on the bench to broaden/flatten it some can be taped to the backside of the weld (the sanitary guys can suggest a high temp-low cleanup tape... I've seen it, but not used it so don't know the brand), and argon (or nitrogen, if you have access... it's cheaper, so you can flow it faster for cooling) pushed through it to both cool and backpurge the weld.

A comment on nitrogen as backpurge... 300 series stainless steels can suffer "nitrogen embrittlement", meaning for a fused weld, the inner face of the weld may be effectively "case-hardened". This only matters if the duty is pressure, or sees sudden temerature cycles.

If you're doing a tight-fit fusion weld, you wont have to worry about what the backside is doing, as long as it's shielded from oxygen.

I don't think I've asked; What is the finished product to be?

Steve S

Otto Nobedder wrote:
I don't think I've asked; What is the finished product to be?

Steve S

Scotland? It must be a distillation vessel of some sorts.

rake wrote:

Otto Nobedder wrote:
I don't think I've asked; What is the finished product to be?

Steve S

Scotland? It must be a distillation vessel of some sorts.

Unlikely. In Scotland, they know to use copper for that process...