I'm not sure about the qualification ramifications; but don't forget that solar flux is only good for one pass. If you don't put in a perfect hot pass, you will likely still wind up with oxidation on the pipe ID.
Charles
We have used it on piping used for potable water. We always clean it mechanical really well before the client runs his CIP. Never did anything with our procedure
Just assuming you are working with GTAW process, QW-408.9 (backing gas) is an essential variable so if the WPS was qualified with backing and then used without backing it would require requalification. QW-404.50 is a non-essential variable dealing with flux so you could use it or not use it as long as it were addressed in your WPS but you'd still have to deal with the essential variable of backing gas.
Also, in looking at the MSDS for Solar Flux, it is considered a carcinogen due to the silicon content, it seems the owners would want their systems flushed pretty well for potable applications!
chall makes an excellent point too about it only being good for one pass... normally we require a minimum of 1/2 joint thickness before purging can be removed (depending of course on "standard" thicknesses!).
Good luck!
Jon, QW-408.9 addresses the use of P-41 thru P-49 P-10I,J,K,and P-51 thru P-53, & P-61 thru P-62. I am unsure as to how this applies to
P-8 (although I think it SHOULD). QW-408.5 is listed as a non-essential.What am I missing here?
Deb, you caught me! Yep, I goofed, looked at the charts without reading the variable ~ a very common trap! Thanks for pointing that out to me. Well, on the rebound, I would say as a minimum your welders would have to requalify under QW408.8. I'll find out why omission of backing isn't an essential variable because it could certainly affect the mechanical properties of the weld, in my humble opinion...
Jon,
I think what we would need to do is look at QW-251-2 which defines an essential variable. In my opinion I think because of the glass like residue that is left when using Solar Flux and that residue would impede passivity and therefore elimiting the purpose for using the corrision resistant material like stainless steel. Furthermore, Table QW-256 which references QW-408.9 under Gas, says removal of backing gas is an essential variables. Hope that helps.
Thanks
Jim
I've always had an interest in Solar Flux. Here in the UK, we don't like using Solar Flux in power plant steam lines (550 C operation). Solar Flux themselves dont recommend it either for these conditions on their website.
There is an interesting article here:
http://www.sperkoengineering.com/html/Purge.pdf
on the residual flux and this is partly the issue that is of concern, plus the sodium flouride that is present (although this seems to be only in the Type I for high Ni alloys).
One query I have about mechanically removing this stuff, how do you know its gone if the butt weld is a long way from the free end? The residue can be pretty difficult to get off in my experience.
We typical mechanically remove with a power brush or some light sanding . We only use this solar flux when we are in a pickle and would never apply to joint we did have good access to.
Gentlemen: Thanks so much for your kind responses. Andy, the article by Walt Sperko is just what I needed to make the case that there are more reasons to avoid solar flux than try to use it. I personally have never seen it used to where it would meet even Visual inspection. My biggest concern is the residual mess unaccessible in piping ,and the impact on system performance. Demin water service for Ion Exchange I have always believed to be quite sensitive to contamination. I am not an engineer or a chemist, and if I am wrong in being apprehensive I'd appreciate it if someone would enlighten me. As far as Potable is concerned I think anyone could see that small particles of "glass like"
residue flaking off into eyewash service is unacceptable. Jon,my friend, I am anxious to hear why this is not an essential variable; please tell me this is errata, although the 2000 Edition of IX reads the same. I confess that my implicit faith in the code is a tiny bit shaken. Again thanks to all; and any input from others with thoughts on this would be greatly appreciated. Deb
Our welders are using Solar Flux successfully when we are doing applications when we are unable to provide a purge, typically for emergency boiler tube repairs (P1, P4 or P5 materials). Preferably, I would like to use a argon purge as a first choice, but we get fairly good results using the solar flux and it is better than nothing which is what was done previously. Just FYI we do qualify our WPS and the welders (ASME) for such conditions and haven't had an issue with anything not meeting the criteria.
I would be interested in anyone's experience with fluxed GTAW rods??
Chris
Gerold, see the link on this post from Andy. A very good comparison of available methods
I had some past experience with a flux-covered Tig wire (316L) which was introduced as a cost saving measure at a paper mill in New England over a dozen years ago. A few of us pipe welders were given samples of the rod where we ran 3 or 4 joints (apiece) on 4" and 6" stainless pipe (schedule 10). It was difficult to see the puddle (with the flux floating around and such) and the results were varied. Actually, a sound root pass was possible, however, the resulting flux covering on the interior of the pipe joint was undesirable by the Client and thus the "experiment" was scraped. As long as the flux (similar to stainless stick rods) remained intact through out the 2 pass weld....and then the flux was removed (it came off the welds easy enough)...I would have thought it would have been alright as heat settings were similar as if we were purging the pipes with argon.
The higher ups wouldn't go for it and there were miles of pipe lines to joined so we ended up purging every joint with argon. I think they called it "scuttle-root" but that was such a long time ago and I have never seen or heard about it being used since. If the flux was removed before the weld was capped off......sugaring was unavoidable, but if it stayed on, you really had a nice looking weld.
I am curious if anyone has used it recently too.
Thanks,
Hawk
Solar flux doesn't like to join with water once it's glassed from welding and that right there is a problem. It's difficult to clean if you can't get to the back to at least sandblast and the glass will flake off into your system.
If you can close your system off and gas purge I'd go with that. Solar Flux is wonderful stuff, so long as you either can clean the back or simply don't need to.
Mind if I ask why you can't just purge and weld the system you're doing (I mean why gas purge isn't appropriate or possible)?
Kalroy
Kalroy, My boss just got the bill for argon, and is in denial in re the cost of welding. I am trying to difuse the situation as best I can. I surely don't want solar flux on this project, but I am trying to keep an open mind about it, and find other opinions than mine that support the process (fluxes) or reject it. Argon is KING as far as I am concerned.
Ouch. I'm lucky, I've led a lucky life, it's never an issue in aerospace.
Can you get to the back of the weld at all? If so, you could try glass welding tape. The flux comes off readily, but you still need access to tape the back of the weld, and it has a drawback in that it has to stay pretty flush to the back of your weld.
You might try calling the Solar Flux guys and ask them if there is a chemical that can disolve it. But beyond that I'm at a loss.
By they way, how do you purchase your argon, by bottle or dewer(sp)?
Kalroy
We buy dewers, and smaller bottles as well. This is entirely a SS pipe application; relatively small diameter, 3" 4", 6", so mechanical cleaning is not possible. Any kind of chemical flush will be expensive, and that is whole reason ($$$) we are looking at it. I will purchase a small amount and set up some tests. Untill we can achieve a clean root that meets the Visual requirements of Section IX I will not qualify a procedure; I will be very surprized if that happens, so perhaps this is just exercize in futility to say we have tried it. Right now I am just discouraged.
I do not know how many welds are involved but have you thought of purge dams that are inflatable? We use them, it cuts the argon use down. I ordered ours from COB Industries 312-723-3200 there are other companies that make them. With the dams and purge sensor the argon cost could be cut if you are trying to purge the entire pipe. Save the cost of a new PQR.
Gary
We have been using purge dams up to the present, and we have looked at the inflatable dams from Cob, but there again the $$$ involved get the purchase rejected. We're using soluable paper & tape. Now flush is an issue where they had not planned to flush, for instance Instrument air. We are also considering chill rings, though I realize the inside of the ring will probably sugar to some extent, but no more so than what happens using Picor fittings without purge. Speaking of dams; I feel damned if I do, and damned if I don't. Thanks for your input, and anyone else keep it coming.
Deb; the customer is always right (so is the boss!). Just keep saying this over and over and over again... P/S: I'm still waiting to hear back re purging essential v. nonessential for P8's.
Jon,
did you look at QW-256 & QW-356
? I interpret purging as an essential varrible. Again passivity is also something to look at. We have tried the solar flux and do to the glass like residue on the back side we were concerned that it would impede passivity. Do you think this is something to consider.
Deb.
did you look at the cost differintial between argon and nitrogen? Could be a cost saver for you.
Thanks
Jim
Jim, Yes I did study QW-256; This is where the confussion starts. When you read the reference to QW-408.9 indicated as an essential variable; then go to QW-408.9 it reads that it pertains to P-41 thru P-49, P-10J, 10I, 10K, and P-51 thru P-53, and P-61 & 62. So I feel that applying this in general to QW-256 is taking it out of context . Am I wrong in refering back to the specifics of these variables. Jon is looking into this . We have considered nitrogen, but then in the field you have to set up two bottles, regulators & etc. The added work & equiptment involved sort of negates the savings. Passivity is a great concern; the client has purchased SS for a reason; we should (shall) not ruin it to save 10 cents. I am trying my best to communicate this.
Deb,
I think your reading to much into QW-408-9. QW-408.9 pertains to the P# listed. QW-408.8 is what you need to focus on. You have QW-256 and QW-408.8 indicating it is an essential variable.
Thanks
Jim
Jim, I am in total agreement that it should be an Essential Variable, and QW-408.8 quite clearly states that. Unfortunately QW-408.8 is not listed on QW-256 , but on QW-356 Performance. QW-408.11 covers all bases on this omission as well, but it is not listed on QW-256 either. Can I, in good faith, simply requalify welders without a valid WPS? I feel the answer is NO. Loaded question here: Is it the intent of Section IX to take at face value Variables called out in QW-252 thru QW-265? If it is then you are totally right, and I am reading too much into it. If it is not then to take them out of context, is a misinterpretation. I am just not sure, not trying to argue. However you have brought to my attention that the heart of the matter is interpretation; so I will research the Interprtation Volumes. Thank you for your help. Deb
Here is an "official" unofficial answer from the Vice Chair of ASME IX: "The criteria for an essential variable is that changing it affects mechanical properties. Lack of purge may make a stainless weld unsuitable for service, but it does not affect properties."
Having said that, if a WPS for P8 were qualified WITH purge, a welder couldn't use it WITHOUT purge since purge IS an essential variable for performance qualification and it's unlikely (in my own opinion) that a welder could make a weld suitable for passing ASME IX tests WITHOUT purge.
Thank you, thankyou. I agree with you about performance; so we will procede to testing and see where this goes. Many thanks to All. Deb
I know better than to argue with Walt Sperko but I did tell him it didn't make a lot of sense to me but then he knows more than I'll ever know about ASME Codes.....
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