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Up Topic Welding Industry / General Welding Discussion / Having issues with 316H stainless passing X-Ray
- - By local7welder01 Date 06-04-2016 18:45
My welders are having some issues with sch. 80 316H stainless. They keep getting dingged for lack of pen. and lack of fusion on their roots. I'm wondering if they're running too hot after the root as the root looks good before hot pass most of them are running between 150 and 200 amps. Could this be causing severe suck back? Also they are using 316L wire as 316H wire is not a shelf item and time restraints on job did not allow time to order it. Any suggestions would be greatly appreciated.
Parent - - By 803056 (*****) Date 06-04-2016 21:48
The amperage is way too low for sub arc. You might have to change to a different flux.

Now, if you want a real answer, provide some real information.

Al
Parent - - By local7welder01 Date 06-06-2016 09:47
The pipe is being open butt TIG welded not Sub-Arc. Not exactly sure what other info i may have missed just looking for some suggestions as to what might be the problem these are very skilled and experienced pipe welders and it is frustrating them. I thought perhaps i would get some helpful feedback not arrogance and sarcasm but i guess i was mistaken thanks for nothing AL.
Parent - By Lawrence (*****) Date 06-06-2016 11:46 Edited 06-06-2016 11:49
If the only issue is "suck-back" and the root passes are being inspected and are ok, your assessment that the second pass might be too hot (too much current or two slow travel) makes a lot of sense.

From a welders standpoint for GTAW, 316, 308 and 321 fillers behave pretty much the same, Meaning operators usually don't need to change technique.  If they have good success with one, they usually are ok with the others.

Things like consistent root openings (don't what it is), root faces (don't know what it is) and operator experience can play a role too... You say the welders are experienced, but I would wager from the information given that the issue is technique.

200 amps is pretty high if you look at the old "rule of thumb"  one amp per thou. of thickness.  The root pass probably at most deposited a bead about .125 eh?

Are the second passes (hot pass) being applied freehand or are the welders walking the cup?

If the operators are using higher current to accommodate a very large filler wire diameter (you didn't mention diameter) or if they are using high current to move faster, but not actually moving faster, it might cause the suck-back you mentioned.

Are the pipes being rolled or welded "in position"  Are the defects at a common place (like 6'oclock at the bottom? or 12 o'clock at the top?)  What is the bevel angle?

Are standard purging practices in place? or is the inside of the pipe possibly pressurized by backing gas?   Are you using Argon or Nitrogen to purge?

What is the pipe diameter?

Probably Al wanted some of the information I'm asking about  :)
Parent - By 803056 (*****) Date 06-06-2016 21:18 Edited 06-06-2016 21:21
Garbage in, garbage out my friend.

Based on the information provided, they could be using any one of a number of welding processes, any groove detail, i.e., square groove, bevel groove, V-groove, etc., any groove angle, any root face, any root opening.

Garbage in, garbage out.

Silly me, I can't read some one's mind. I should have rubbed my crystal balls a little harder.

Al
Parent - - By js55 (*****) Date 06-06-2016 12:12
Couple issues.
First, you may wish to look at the sulfur content of the base metal. Real clean SS's are notorious for IP issues. Sulfur aids in wetting.
Or, did you use feather edge preparation?
If so perhaps you can increase the bevel angle a bit.
Second, did you get approval from the engineer to use L grade wire? The SMTS's are not the same and H grades are often used in high temp applications where L grades are not.
Parent - By js55 (*****) Date 06-06-2016 12:13
It could also be that your welders are not used to the viscosity of the SS wires and are trying to compensate with higher amps. This won't work.
Parent - By pipewelder_1999 (****) Date 06-08-2016 13:05
You don't state a wall thickness so the amperage setting are meaningless, nor do you refer to a joint preparation/fitup.

150-200 amps for a 2nd pass in a "Typical" pipe joint is excessive though in almost all cases. If they are running this hot and the WPS says so, I would question the WPS and the individuals that prepared it. If they are given a range yet choose the higher end, I would question the experience and qualifications of the welders. If there is NO WPS then I would question the entire project. That does not mean those are not use-able ranges in some cases but could be something to consider based upon the wall thickness, groove angle, root pass thickness.

You mention LOF and LOP yet indicate the roots "look good" so I'm not sure about the LOP part. If they are trying to fill a joint too quickly (Thick/Slow 2nd pass) then the possibility of internal concavity increases in some conditions (bottom and vertical sides of a horizontal run) as does the possibility of LOF from carrying a puddle that is too thick (Keep the arc near the front of the puddle ).

Parent - - By kcd616 (***) Date 06-08-2016 15:42
ah
TIG of SS pipe
I love it:smile:
pays great $ and clean and simple to weld:cool:
150-200 amps big range there:eek:
going into Kent mode:eek::evil::twisted:
your union
union+EOR= epic fail:razz::twisted::evil:
your GTAW SS pipe, a hot pass????????????
your not burning out wagon tracks
after the root all are fill passes
next you will be telling they are walking the cup fine:eek::roll:
free hand it....run about 155 amps DCEN 1/8" cer tungsten, 1/8" 316LC SS filler
that is for the fill passes
btw keep your purge running for all passes
you did NOT say the pipe diameter or I would give you CFM for the argon, both shielding and purge
but your union and have an EOR
this sets up for an epic fail
sincerely,
Kent
Parent - By kcd616 (***) Date 06-13-2016 06:18 Edited 06-13-2016 06:21
after some thought
best would be 75% AR 25% HE
might be wrong be just IMHO
sincerely,
Kent
P.S.: yes Lawrence I love helium :razz::wink::twisted::evil:
Up Topic Welding Industry / General Welding Discussion / Having issues with 316H stainless passing X-Ray

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