I,m gonna go out on a limb here and play devils advocate. If welding machines are not checked to insure the set amperage is correct, then what good is the PQR? What have you got if your "set" amperage isnt what you really have and the only way to make sure of that is calibrated machines. If welders are allowed to set their machine any way they want, why do we bother with Procedure Quals? Some welders have enough experiece to set their machines and be within the tolerances of the WPS and make good welds. There are others out there that belive that "the hotter, the better" with no knowledge of whats happening in the weld and to the base metal. When I was still witnessing PQR's I used a multi-tester to verify amps and volts. If the settings on the machine were off from the actual readings I would tell the fabricator. Just my thoughts.
Well, while your points certainly contain elements of validity there are also gaping holes too. Yes, we must qualify WPS' in many if not most industries but using your logic, what's to keep the engineer or whomever is actually writing the WPS variables from going too far to one extreme or another? Yes, there are rules in most Codes but how often have we all seen less than competent engineers running the show? Or, perfectly comeptent civil engineers preparing WPS' for piping applications? Also, there is added credence for specifying in-process inspections and other examinations by many codes... monitoring things while work progresses is and should be a shared function of management, quality control and competent engineering. I reiterate, an experienced welder will tell the engineer he/she is all wet if the WPS is written incorrectly. Similarly, if there's 200 feet of lead streaming from the equipment, the equipment readings may be way higher than the output at the stinger / torch / gun.
Nobody is advocating welders setting their machines wherever they want. At least not what I've read to date that I remember. They still have to set them to the parameters on a WPS. And these parameters still have to be verified by QC. What I am arguing is the realization that its the puddle/arc characteristics that determine where the gages will end up, not the gages that determine the puddle/arc. Even a pre-WPS for qual purposes relies on someones experience as to the proper range of settings. If not, you will quickly find it.
Some minimum verification is needed. But where? That's the question.
Ask yourself this, why is it ASME Section IX does not dictate ranges in which volts and amps are to be set, even with a qualification (in fact voltages for certain processes are often only stated on the WPS for information purposes only-it is not required to dictate voltage). Somewhere in the answer to this question is an understanding that is consistent with this debate. I do not believe the Section IX guys are overlooking something. I believe we are.
js55, as usual, your insight is marvelous. I'm certainly not advocating setting welding machines wherever the welder wishes them to be set, even if he/she may be among the best suited to determine whether or not sound weld metal is being deposited. I am simply reluctant to have this type issue mandated by codes / standards. There was good reason D1.1 decided to remove this requirement and also why ASME has decided not to include it. If AISC, WABO or other jurisdictions wish to bog themselves down in the minutia of audit trail then so be it. For me, I will continue performing "reasonable verification" on a voluntary basis.
Hello dmilesdot, I agree with the logic of your post, where I have issues with it would have to do with the many machines that do not have meters to read volts/amps and the like. There are tons of machines that don't have this capability, Miller's 8PAKs, 6PAKs, SRH444s, Lincoln SAE 400s, 200s, 250s, etc. I believe you get the idea. I contacted Miller directly to inquire on calibration of their machines, they essentially told me that you could calibrate the meters on machines that are so equipped but that any machines that didn't have meters could not be "calibrated". They also went on to say that a true machine calibration scenario can only be be done by using a load bank and the associated calibrated electronics for verification and getting accurate readings. They also went on to say that you could calibrate the machine but when you throw variables into the mix such as lead length, cable size, ground clamp condition, stinger condition, arc length, and a host of other things they can all affect machine output and performance. That's why I put more credence into weld inspection of finished welds and a bit less into the machine calibration issue. My $.02 Regards, Allan
Very well said Allan and I completely agree with your position on this matter.
Dave
You have hit the nail on the head. Why do we need PQRs and WPSs if nobody is going to follow them? How can they be sure what they are doing, if they don't have some way of checking that the machins is running at the desired parameters. Perhaps "Calibrated" in the NIST sense of the word is not necessary. Perhaps the parameters just need to be "Checked" or "Verified" against a standard, even if it is just the in-shop clamp-probe that was used when the PQR was welded. However, What process would be used to require the Oxy-Acetylene Gages to be "Calibrated"? If you are doing some sort of powder spraying, or some sort of Zinc spray galvanizing, you need some assurance that the process is working at the optimum, and the Oxy-Acetylene gages need to be checked.
If anyone gets to see the NIST Calibration requirements for Steel Tape measures they woul die laughing. Nobody could build a building with the allowances they permit. Yet, because the tape measure is used for measuring in the process, it has to be calibrated traceable to NIST.
Parameter settings on the welding machine are set in the morning, but then, the welder decides to change from back hand to fore hand welding. The welder changes his stickout, and that is something that the inspector will not readily catch. So even if everything was properly calibrated the actions of the welder throw a wrench in the process. So, what good did your "Calibration" system do?
Hello Joseph P. Kane, my take on calibration and all the associated components of it is one that brings out the vast variability of all of the factors that make up these requirements. PQRs and WPSs are definitely needed to verify the correctness of a given welding application and it's use. They are there to show that this process will work and accomplish the intended purpose the engineers have set forth in a given welding design and manufacture method. I also believe environmental issues dictate a different use and application of these standards as required. When I say that I mean to differentiate between shop fabrication practices and field practices. I don't feel you can apply the same set of rules for these two very different scenarios. Shops have the latitude of a greater amount of control over welding processes and other associated environmental factors. Hence it makes sense to look to control these parameters more closely. Field conditions on the other hand have a different set of parameters and I don't feel that you can attempt to impose the same set of controls on the welding that occurs in that case. That is why I feel that inspection of finished welds is more critical to attaining proper quality levels especially in the field sense. This is a view that I have on the subject. I always try to consider everyones input on a topic and this is no different, that is why I am following this thread with interest. Best regards, Allan
Joe, does it seem somewhat bizzarre that AISC work should be held to a higher standard than nuclear work? I'm not one to answer that question but can tell you over the past 27 years of being more into than out of the nuclear field, tape measures and certain other measuring devices are excluded from the "Measuring & Test Equipment" category... how about squares, are those also required to be calibrated? Are levels also? I can see some things falling under the NIST umbrella but a lot that should not.
I have to say that as far as laughable is concerned the whole AISC verification of squares, tapes, etc. is laughable (not to necessrily hijack the thread). It should be absolutely amazing to anybody defending this practice how so much structural, vessel, boiler, piping, and whatever-in fact, the vast, vast majority-of metal fabrication is ever even accomplished without a single bit of third party verification over verification of these tools. And ner a piping or vessel failure in history because the the hook on the end of a tape was a bit loose or a square was slightly out of square.
The idea is, we can verify stuff because we have a logic that we work hard to convince ourselves is important, or we can verify stuff because we have evidence that it is a real service problem.
Accuracy in measurement is most assuredly important. But to have it as a auditing point in third party verification? Nah.
If ASME is so wrong in this I await the evidence to the contrary.
Sadly, this entire third party verification bit has completey lost focus of technical merit. I think a few of us know the whole bit is simply to create "programs" which force constructors into paying big $$$$ for audits and auditors. The technical benefit? Perhaps in the end it may create better constructors but like most quality systems the pendulum has swung way too far to one side....
By rsx-s-02 
Date 05-24-2007 14:28
Edited 06-06-2007 15:50
Jon, we just completed our annual AISC audit and calibration of squares was listed as a concern.
Concerning D1.1 or an AISC audit requiring calibration of the welding machines....even though I don't recall seeing it written, I still think that the reason that they can hold us to the task of calibration is because we have written WPSs and we even have essential variables listed in Table 4.5 of D1.1. So for an auditor to ask if the welder(person) is welding within a WPS's permissible ranges listed in Table 4.5, you would have to KNOW that the machine is reading correctly or that the gages are close enough to say.... "yes this welder(person) is welding within the WPS's ranges". 
