Welding Tips and Tricks

Hello!

Ok, So a few months back I was doing a cooling job for a company, and the default cooling/heating/sanitary pipes here in Norway got 2mm wall thickness untill you pass 8" then it runs up to about 3mm / 4mm. All flanges comes with 3mm neck thickness. (These kind of installments rarely runs over 10 bars, but up to 2" or so is PN 40).

So, practice from school/certification is butt it up, and run one pass - dab filler and freehand is how these are done here.

Now, since I sometimes work with other welders from other companies or countries for that sake of matter I have noticed that no one does any walk the cup, weave or anything but freehand.

Since I`m a bit over average interested in my line of work I wonder, what practice do you do if you encounter any 2mm wall? What would the tecnique be? Weld width?

Also I have seen nobody cares about color, just burn it through, brush it - acid up outside - water flush and ready to go! And specialy the oldtimers here have a huge tendency to weld a outside weld with up to 6mm weld height and huge amounts of amps, wich I think is just a habbit from oxy acy welding which is still much used here (on steel of course).

For the reference there its not normal with any WPS on these kind of cooling/heating/sanitary work here much of this is not too critical.

Typically if it was a sanitary style joint they would be welded with no filler, just a very clean straight and flat cut, butted tight, back purge and welded autogenous (no filler) on .083" (2mm would be .078"). I will either walk the cup around 50amps, or do a nice straight pull 48-55amps, 3/32" tungs, #10-#12 cup, color will be a nice gold to blue, inside will be colorless. I pickle/passavate the outside and polish out with a scotchbrite belt.

I typically do not walk the cup under 4" in diameter, unless specified. If the inside needs to be smooth and free of "sugaring" you need to back purge stainless with Argon or Nitrogen to shield the weld. If the weld requires a fillet weld, it is still done with a back purge and I typically use a 3/32"-1/8" filler, height 1/8" or under respectively unless specified.

Your in luck I'm repairing a 4" pipe right now...316L stainless, sanitary for food processing.

Rick_H wrote:I will either walk the cup around 50amps

So there is no problem walking the cup on a pipe wich requires only one pass? I have just about tried it, can`t say the results are the best, but I get the feeling its easy to burst too much heat into it with the wtc method. For the record I only weld with pedal if its alu.

Thanks for a good answer by the way!

Fron wrote:

Rick_H wrote:I will either walk the cup around 50amps

So there is no problem walking the cup on a pipe wich requires only one pass? I have just about tried it, can`t say the results are the best, but I get the feeling its easy to burst too much heat into it with the wtc method. For the record I only weld with pedal if its alu.

Thanks for a good answer by the way!

No issues with walking the cup, but it is a little trickier with a smooth pipe as opposed to a sch 40 or 80 pipe where you have a gap to use a guide.

Would that be the equivalent to running a fusion weld on sch 10?

Rick_H wrote:No issues with walking the cup, but it is a little trickier with a smooth pipe as opposed to a sch 40 or 80 pipe where you have a gap to use a guide.

But you still have the struggle when it comes to walking the cap pass, right? Or do you feel it is easier to walk over the bead you have just layed when you are doing wtc on say "sch 80" cap instead of a clean-one-string 316 pipe if you get my question?

Poland308 wrote:Would that be the equivalent to running a fusion weld on sch 10?

4" sch 10 would have a .120" wall, I know with pipe we always did 2 passes (with bevel) with filler...Rick?

Fron wrote:

Rick_H wrote:No issues with walking the cup, but it is a little trickier with a smooth pipe as opposed to a sch 40 or 80 pipe where you have a gap to use a guide.

But you still have the struggle when it comes to walking the cap pass, right? Or do you feel it is easier to walk over the bead you have just layed when you are doing wtc on say "sch 80" cap instead of a clean-one-string 316 pipe if you get my question?

Definitely easier walking the cup on cover after a hot pass or root in my opinion. You can do Schedule 10 in one pass but the setting have to be right. I either double bevel or gap and weld...I haven't run an autogenous sch10 is awhile.

Good!
Just for curiosity;

What kind of piping is used in The States if you are manufacturing a cooling arrangement with say 6" on about 2 bars, wall thickness, steel or ss?

Thanks!

Fron wrote:Good!
Just for curiosity;

What kind of piping is used in The States if you are manufacturing a cooling arrangement with say 6" on about 2 bars, wall thickness, steel or ss?

Thanks!

It could go either way depending on budget, configuration and where it is located. since your only running 2 bars about @29psi the .083" should be more then adequate. Even seen PVC...

Do you guys back purge the stainless?

Okay!

Yes, my practice is purge on all stainless / 300 series.

That being said, there is no such trade in Norway as pipe welder, boilermaker, pipe fitter or any official trade with welding and pipes/tubes in it. Simply just plumbers who weld or mechanical companies who have specialized them self in some kind of welding niche.

When it comes to heating/cooling apps here, I have seen loads of "different".
From oxy/acy SS welding which turned out -- yep, the way oxy/acy turns out on SS.. To stick welded air lines who turns out to stick magnet or some company who never works on bigger pipes than 1" who gets someone to do the job for them and skips purging.. (never ever registed an NH3/air job with even some kind of welding supervision)..

NOW for my relief of frustration;
Due to the lack of plumbers who can weld here, the rising captains on their sinking ships (here being the plumber "union" in Norway) did some years back decide that groove and pressfittings were the way to go!

Okay, its ok for sprinkler (looks provisional in my opinion but hey, what ever works)
then they were to do turn it into the heating/cooling marked and this is were the fun starts when it has been running for some years.

Firs of all the groove pars are big and bulky and for the costs they are somewhat more expensive but it cuts down the assemble time (that is what THEY say)..
BUT you need one hell of a insulator to get these bad-boys to hold them self inside the insulation for more than a couple of years, not to mention the cost of the insulation job who goes on for a good more time than welding-parts, where you can get pre-made bends for all the parts wich is stock industrial standard.

Then you have the press-fittings wich is now standard procedure in any household-chopper-line arrangement and home heating installments. Soldering is more or less phased out.

They limit them self to 108mm and PN16 in chopper, galvanized and 316.
Fairly fast to assemble, easy insulation, will not do in an critical / sanitary situation -- but the cost..

A estimated price here for a 88,9mm x 2,0mm D=1,5 316 welding bend is roughly 30 bucks.. a 88,9mm x 1,5mm 316 press-fitting bend lands around $ 450...

This came out a little longer than planed :p