Welding Tips and Tricks

Hello

I'm going to take a test on pipe this friday. Haven't weld carbon steel for a while and that's why asking some advice from you guys
Joint will be tube to tube in a 6G position and pipe will be regular carbon steel (P250GH) in diameter of 42.4 mm and thickness 2.4mm. (1 3/4" x 3/32" ... in inches I guess)

Little bevel would help I guess, but what about gap? Filler size?

Thanks in advance

Hi Markus,
For this diameter and wall thickness I would use the following method:
30* bevel
2.3mm (tight) gap so a 2.4mm wire won't fall through.
2.4mm Tungsten. (I use lanthanated with 20* point). No.6 or larger lense cup.

First pass (root) use 2.4mm wire, 80amps. Lay the wire into the bevel and wiggle over it and get around the pipe fast. This fills the bevel without over penetration. Keep a tight arc and minimal torch angle. Allow to cool and wire wheel/brush.

Second pass (cap) use 1.6mm wire to avoid excessive reinforcement. 70amps.

Good luck and let us know how you get on.

By the way, if you are permitted to use ER70S-4 or -6 wire, for at least the first pass you will get a better result.

Coleman is right on very similar to how I do it, although I increase the amps about 5 on the hotpass or cap. I find the key is letting it cool nearly to touch between passes, brush the hell out of it also.

Thanks guys

I welded one stainless valve and had to focus on paper work too. So unfortunately didn't manage to try any tips at all
But tomorrow I have all day and even evening, so get ready for some pics

I think I will probably try to walk that cap. In the other hand it's sometimes harder to do as carbon bead seems to get more slippery like than in stainless.

Do you mean to wiggle back and forth or side to side Coldman?

I think it is possible do with S6 and S2 wire. After all there is quite minimum chemical composition difference.

Side to side wiggle. This fills the groove without over penetrating. S6 will flow better that's all and wet the sides easier. The idea with this method is to get around the pipe fast on the first pass. But its up to you. Good luck!

Thanks Coldman!


Btw I checked the difference of S6-S2. It's been up here many times before, but I always seem to forget it

Here:


ER70-S2
OK Tigrod 12.62
GTAW
Type Carbon-manganese

A tripple desoxidized copper-coated rod designed for GTAW of mild and fine grained structural and pressure vessel steels as well as shipbuilding steels. The rod is capable of producing high quality welds in semi-killed and rimmed steel as well as steel of various carbon levels. Because of added desoxidants, Al-Ti-Zr, the rod can also be used for welding steels with a rusty or dirty surface without any sacrifice of weld quality.
Welding current
DC(-)
[http://products.esab.com/Templates/T041.asp?id=2907]


ER70-S6
OK Tigrod 12.64
GTAW
Type Carbon-manganese

OK Tigrod 12.64 is a copper-coated Mn-Si-alloyed W4Si1/ER70S-6 solid rod for the GTAW of non-alloyed steels, as used in general construction, pressure vessel fabrication and shipbuilding. It has a slightly higher manganese and silicon content than OK Tigrod 12.61 to increase the weld metal strength. This also promotes low sensitivity to surface impurities and contributes to smooth, sound welds.
Welding current
DC(-)
[http://products.esab.com/Templates/T041.asp?id=124761]

Sorry guys, but no photos of carbon pipe Test is postponed with couple of weeks at least, because it will be done to higher strength material and that was not available at the moment.

However I will still take tests tomorrow on stainless 51x1.2 mm and 12x1 mm pipes on 6G position. Spent some hours today to practice those and let me tell you that 12 mm pipe can really suck You have to have just right amperes to create neat bead. Final adjustments on pulsing was made by increasing background current only with 3A

You've done a nice job there. Heat can easy get out of hand on small thin tubes and short coupons. Very well done!

Looks good Markus, your right the small diameter is tricky, that stainless gets heat soaked quick

The good news is, 12mm test coupons are very cheap.

Len

I'm betting the 12mm coupon was cut to that length AFTER welding, for inspecting the root.

I can't imagine a test coupon under 3cm total...

Very nice work, too

Steve S

Thanks guys!

So test day is behind and I'm quite confident about welds. These will be only x-rayed and after all basic austenitic should be pretty sure case anyway. Especially that 51 mm. I don't understand why some people struggle with these. Basically you only have to keep steady hand and that's that. Penetration comes almost by itself on that pipe thickness. On small pipes (12mm) I'm not that confident about passing, because you can't see inside the pipe that well. Outside looked just fine, but you never know...

Btw I had to weld tree of those little sucker ones, because standard told to have enough inspection length.



Small diameter pipe was done with micro pulse.
30 A / 0.01 s
12 A / 0.02 s