Hi Niekie,
Forgot COMOANY opinion, I am not agree with this way but I want to know my TQ is correct or not?I mean after PQRs test sataisfaction is it posssible to use FCAW for any pressure retaining above 600lbs or not ?
Regards,
Omid
The codes do not specify which type of welding process are to be used. That is left up to the manufacturer, who can choose any process they want.
The codes do offer some pre-qualified procedures that specify process, but, the manufacturer is not limited to these.
What the code does specify is that the process and all applicable parameters that are chosen by the manufacturer are to first be qualified or tested to prove that the weldment will hold the loads it's designed for.
Contract documents often are more specific toward acceptable processes, but that is a whole different issue that can only be resolved by reading and understanding the contract before signing.
While there are professional engineers who participate in this forum, the American Welding Society has no official support or responsibility toward anything stated here. This is simply a chat room for anyone who wishes to participate.
That being said, my personal opinion, based on previous experience, is that yes FCAW weldments are perfectly able to hold pressures of 600 psi and above, if the welds are done in accordance with a qualified procedure. However, Globular Transfer needs to be strictly forbidden as it cannot be sucessful in this application.
Tim
Hi Omid
A good FCAW weld can do exactly what a good SMAW or GTAW weld can do. The issue is that some companies (due to past experience) do not like FCAW. Historically there have been some bad welds made with FCAW, but since then a lot has improved with the wires, and especially the gas assisted wires give deposits that are comperable with SMAW. The bad image is however still out there, and that is why some companies restrict the use of FCAW. The issue for the client company is not whether it is possible to perform a certain type of weld, but whether it will consistently deliver good results in the field. As an example, it is possible to perform a good weld with dip transfer GMAW, but a high percentage of such welds will have lack of fusion defects, so almost all end-user companies do not allow the use of dip transfer GMAW. The issue is not "what is possible", the issue is "what is probable".
Your approach to the client company (in your TQ) would have to be to address their concerns. For instance, you may offer additional NDT to be able to detect LOF defects if they are present. (Can't remember your exact application, so am not sure if UT is possible.)
I hope this makes sense.
Regards
Niekie
Hi Niekie,
I have provided some of the WPSs including Automatic FCAW and most of the process piping lines which are defined to welding with this procedure will be performed radiography examination (5%~100%),after viusal inspection over the profile of weldment it was accepted and it was not found any welding defects, finally we instruct to our subcontractors to execute RT over the some welded jonits and the result was accepted.
Hi
Generally client specifications will try to exclude processes or practices that will either result in a defective weld where the defects are difficult to detect (e.g. Radiography will not detect most lack of fusion defects. - I am involved with validation of phased array testing procedures, and from this it is clear that 80% of LOF defects are missed by radiography.) or the defect rate is unacceptably high, increasing the project risks in terms of quality and schedule. If the company has excluded FCAW from being used in higher risk applications, then if you want to convince them otherwise, then you need to address their concern. If their concern is LOF, then you need to offer something like UT to show that it is not present. If their concern is slag inclusions, then going for 100% RT should convince them. It all depends what is driving their reluctance to use the FCAW. Seeing as they were happy to accept RT, I assume that they were concerned about volumetric defects such as slag inclusions. (Or they do not understand the limitations of RT)
Regards
Niekie
Omid, the the thing that really jumps out to me is the fact that your Client has specifically required information on previous experience using FCAW, your TQ makes no mention of you using this process before on previous jobs and your statement indicates that qualifying a PQR, in your company's opinion, will satisfy this requirement which I do not think will be adequate. As posted from another member of the forum globular transfer is not really suitable. Most company's using this process will use a rutile wire and operate in spray transfer mode in all positions which will give you higher deposition rates and sounder welds. As to using three different wires this a nightmare to control. Not all of these wires can be PWHT'd and you should check that what you intend to use is, best double check with manufacturer. Do you have a sufficient number of suitably qualified and experienced welders to do this work? You have not addressed this.
Of course FCAW can be used for these higher ratings but I see the problem being that your TQ will not address your Clients concerns and that he will reject your proposal (I would to be honest).
Dear nantong,
I attached of the TQ some accepeted results of Automatic FCAW related previous projects,also we were qualified Automatic FCAW operators under COMPANY supervisoin,for your more information most of the PQRs result at mechanical & metallurgical test are accepted thus COMOANY permitted to using Automatic FCAW for most of the welding actvities only according to the mentined clause of our specification, COMPANY prevents to utilize Automatic FCAW for above 600lbs.I think with accepted result of PQRs it is possible to utilize Automatic FCAW for above 600lbs.What is your concept?
Omid, your TQ is unclear to say the least. Certainly from your first submission on this subject I read it that you were trying to justify the use of this process based upon qualifying FCAW procedures and that you had not used it before. You now say that you have previous experience but you fail to detail what it is and merely make reference to attachments. You now say "[url=]most[/url] of the PQRs result at mechanical & metallurgical test are accepted..." Most are accepted? What wasn't accepted and what mettalurgical tests did you do? Information is now coming out in dribs and drabs, perhaps it is better to ask your Client for his technical justification in his specification (you should have questioned this at the bid stage if you did not understand.
People here cannot help if you do not give them the full story in a clear concise and full manner.
Dear Nontong,
As per topic I have cleared that we need permission to work over 600lbs it means we have provided FCAW WPSs ,some of the WPSs including combination process (GTAW &FCAW) passsed the PQR test,according to our project piping material specification minimum design temperature is -29˚C therfore some of the PQRs have been failed at ipmact test.Also it was performed metallography test over all PQRs test coupon.
Topic Welding Industry / Inspection & Qualification / FCAW permission for pressure retaining above 600 lbs
