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Up Topic Welding Industry / ASME Codes / Use of SWPS for ASME work
- - By jsdwelder (***) Date 05-10-2016 19:07
I have a question about SWPS in accordance with ASME IX code. QW 100.1 states that SWPS's listed in Appendix E are acceptable to use when adopted by a manufacturer or contractor in accordance with Article V. QW-510 states that the manufacturer or contractor must weld and test one groove weld and record almost every variable. Can someone please explain why this is needed? I was under the impression that every SWPS had one or more supporting PQR's already. Is the testing for performance purposes? I am a little fuzzy on this one. I know that most on here feel that the SWPS's are not the best for production use as they typically provide too wide of a range in many cases and I feel the same way. Do anyone have any experience with this? I am just trying to understand ASMS's stance with this testing. I am referencing the 2007 edition of section IX. Thanks
Parent - - By 803056 (*****) Date 05-11-2016 16:38
Why are you testing to the 2007 edition?

One does not question why, one simple does what is required by the code.

OK, the reason they require the contractor to demonstrate the use of the SWPS is to demonstrate they have control over the process and they can implement the SWPS as it is written.

One must also read the construction code to see if the construction code will accept the use of a SWPS. For instance, B31.3 for high pressure fluid service will not permit the use of SWPSs.

Parent - - By jsdwelder (***) Date 05-11-2016 19:08 Edited 05-11-2016 19:30
Not testing Al. I was just breezing through an older edition I have at home in the man cave the other night and saw this and did not understand the reason for it. I had just never noticed it before and wondered why the need to test something that already has a PQR but what you say makes sense now as although someone created a PQR, it was not your company and therefore really doesn't mean much.
Parent - - By js55 (*****) Date 05-16-2016 12:38
Actually I would argue just the opposite. I think the parameters of pre-quals and SWPS's are stupidly narrow in most cases.
Parent - - By 803056 (*****) Date 05-29-2016 14:15
I agree, why would one want to restrict the welding parameters and have the welding techniques so similar that one could not tell one welder's welds from another. Why would one want the welds to be deposited with similar heat input and similar mechanical properties. It is so much more interesting when one welder uses wide weaves, high amperage, higher voltage, slow travel and high heat input with soft ductile welds while others are deposited using low amperage, high travel speed, low voltage, low heat input, hard strong welds.

It is so much more challenging with there are wide variations in heat input and wide variations in the resulting mechanical properties.

Let's face it heat input, cooling rates, grain size, they are all over rated by those that have too little to do and other unimportant matters to concern themselves with. Real welders don't worry about such things.

Parent - - By js55 (*****) Date 05-31-2016 12:45
Your problem is twofold. First, you use the word 'strong' and the word 'ductile' without actually determining from an engineering standpoint what those are.
Second, and related, is that there is simply NO empirical evidence that wide amp or volt ranges, those within the capability of current electrodes for example, deteriorate mechanical properties below acceptable minimums. For example 60 ksi for carbon steel. Try as you might you will not reduce said mechanical properties to say 50 ksi, 55 ksi, etc, by running hot or cold, if the weld is sound. Won't happen. And the soundness of the weld, i.e., slag if you are running cold, is a characteristics of a welders ability, not the metal. This is the logic behind ASME's wide range allowances.
When concerned with 'mechanical' properties, as defined by tensiles and bends, the actual engineering functional definitions, the metal is the metal.
Also, historically the parameters established for prequals were arbitrary. There is no empirical evidence to suggest that the parameters as limited are somehow a magic threshold to 'strong' 'ductile' welds. The gentlemen involved simply swept all of the WPS's at hand into the round file and made the parameters up. Based upon vast years of experience to be sure.

Now, if we are talking low alloys such as X70 or Q and T's it is a different story. But then prequals don't apply to them. And it is also a different story when considering toughness properties.
And you make the point of heat input, cooling rates, grain size, etc. So, I would ask, why is it NONE of these things are a concern for carbon steels in tensile and bend regimes in either AWS, ASME, or API? Its because they will not reduce strength or ductility, and this is the important part, to below the specified minimums. But, as I mentioned, these things are essential for toughness, which is why those very things you mention are considered important in those regimes. AND empirically based.
Parent - - By js55 (*****) Date 05-31-2016 12:52
One other point I might add.
If, under ASME, you qualified a procedure well within those limited ranges as established by prequalified procedures, say, centered the amps and volts in the range and using a single value, for example 135 amps and 22 volts for SMAW, and then took the liberties of broad ranges of parameters, as ASME allows, for example, 80 to 160 amps and 19 to 25 volts, well beyond the percentages allowed, where are the failures that would demonstrate this is a problem.
The answer is simple. There are none.
Parent - - By js55 (*****) Date 05-31-2016 12:57
Oh, and one other point.
Prequals don't actually limit the parameters totally. All they do is make you write another piece of paper. Or multiple pieces of paper to do as you please. So, to address your argument about welders using wide ranges you could simply have one welder running at the lowest end, one welder running at the highest end, and another running high here and low there, anyway. You just have to have the piece of paper to say its OK. And we all know how paper is the best remedy for mechanical viability. That file of mine will go a long way towards making my shops welds stronger and more ductile.
Parent - - By 803056 (*****) Date 06-01-2016 19:45
We've had similar discussions in the past. We're diametrically opposed on the subject of the necessity of having welding controls in place to ensure predictable outcomes.

With my limited comprehension of ASME and past experience with WPSs written to meet Section IX that are completely useless, I can appreciate your position. For the most part, many of the WPSs I've reviewed to verify the requirements of Section IX are met are in fact written by individuals that were clueless about welding. They did however meet Section IX requirements. With that in mind the WPS listing voltage as 0 to 220V and amperage 0 to 400A were correct. They were unusable, but correct. As was the WPS listing the groove angle as 0 to 90 degrees and the root opening as 0 to 3 inches without backing. So, my friend, I see your point from an ASME perspective.

With regards to prequalified WPSs written in accordance with the New Farm Code, I again agree. At least earlier editions required the welding parameters to be in accordance with the manufacturer's recommendations. The New Farm Code is definitely wanting in several areas. All the more reasons for Engineers to think twice about adopting the 2015 edition of the New Farm Code. There is little I can say in defense of "pulp fiction".

Best regards - Al
Parent - By js55 (*****) Date 06-02-2016 15:43
I would rebut that control comes from the shop culture and welder training, not the WPS.
Take D1.1 for example: Table 3.7.
I don't see any voltage. I don't see any amperage minimums. Nothing at all about travel speed or gas flow. All things that are controlled rather tightly 'by percentage' in the prequals. Which means that all one has to do is generate another piece of paper and you can use in essence the exact same parameters as those liberal ASME WPS's.
So, where's the control?
Up Topic Welding Industry / ASME Codes / Use of SWPS for ASME work

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