A couple of things. You have to be more precise when talking about properties. In most cases properties are generally either considered as mechanical, electrical, thermal, or physical, etc., none of which ferrite belongs to. Ferrite is more of a result than a property since that result can change due to a variety of variables, including chemistry, heat input, preheat, dilution, material thickness, electrode diameter, polarity, flux coating, flux burden, volts, amps, travel speed, gas shielding, etc., even testing methods, testing tolerances and human error or disagreement.
Any time you get into testing regimes beyond those involving code required regimes you may find that things such as brand names can be important.
You will find the same situation, as you indicated, with corrosion testing of nickel base alloys, etc.
So the brand name allowance under the code (Section IX specifically)is intended to be applicable to code testing regimes, and is based upon mountains of emperical data.
js 55,
thanks and really appreciate on your explaination.
i understand all the welding parameters u mentioned even testing or other tolerances.
lets say if i hold all essential variables unchanged or within the range qualified that ASME VIII/IX permitted.
will you expect the weld deposit give u the same mechanical and corrosion resistance by just changing the brand name of the consumable with the same ASME classification? even the properties when components are service at elevated and/or extremely low temperature.
frankly speaking, different manufacturer has different level of technology, QA/QC control and etc.
if there are too many "things" to considered when we change the brand name and always... most people think (even myself) brand is non essential variable means by changing the brand and keep the classification will not affect anything and why special care to be taken? and how to control if we wanted?
just feel that it is too difficult to control, imaging if your small sub-contractor is doing the job for you without proper qualified/certified personnel only base on what the code mentioned in a superfacial view. "Code says this is non essential and why u not allow me do change?"
Best Regards,
Noel Tan
I have never seen trade name listed as an essential in any American Standard however I was familiar with it in British Standards specifically BS4515 1984 for overland and subsea pipelines. I suppose it all comes down to risk management. In the vast majority of cases it does not matter whose consumables or base materials you use but in critical applications it can. With regard to welding consumables do not believe that if a manufacturer gives an analysis that meets the AWS requirements that it ends there. Consumable manufacturers are constantly developing their products to remain competitive. For this reason many company's will not accept procedures that were qualified over a certain period (Maersk Denmark allows 3 years before requalification). Similarly with base materials. How much emphasis does ASME place on manufacturing routes. A/R, N, Q/T, TMCR. Do you see this clearly listed as essential variables in American standards? No not really. The American standards are, in my opinion, a world institution as far as I am concerned for the Oil and Gas industry and so many other fields (and quite rightly so) however the problem as I see it is that it is vey easy to end up in a sitaution where, if by misconception, you follow the guide by numbers, as most inspectors will do, everything wil be all right. I do not believe this is the case. In Europe there is greater emphasis placed on the "Welding Engineer" who must have recognised welding engineering qualifications and a set amount of experience. Inspectors never write procedures or make engineering decisions on welding. Inspectors and Welding Engineers work hand in hand as either cannot cover the full scope. I get the impression this is not the casefrom this forum. Interested to here how it works in America, correct me if I am wrong.
John,
I fully agreed with you becasue i'm working in subsea pipelay of an european company, DNV even asking for batch testing under same manufactorer/trade name and classificaiton (of course only required when some criteria are met). i only said i "wonder" why american standards do not normally address nor consider the criticality of consumable manfacturer/trade, and i cannot see why? for example: refinery application is not critical. of course American Standard may have different considerations which i do not know.
Best Regards,
Noel Tan
As mentioned by a couple of members of the forum, ASME codes and other welding standards such as AWS Welding Codes and API try to limit the essential variables to minimize the "burden" the contractor has to bear when qualifying their welding procedures. In most cases the selection of manufacturer or the specific tradename of the electrode or filler metal is based on availability and price. For the bulk of the welding being done by industry it makes no difference provided the mechanical requirements of the applicable welding standard are met.
A manufacturer may make several electrodes that are qualified and are listed as meeting a particular classification, E7018, E9018-C3, E71T-1, etc. They are differentiated by the manufacturer's tradename and each has a different balance of alloying chemistry that meets the mechanical properties of a classification. In those situation where a particular chemistry is required, careful selection of the electrode by specification, classification, and tradename is warranted. When this is the case it is up to the welding engineer or the person saddled with the responsibility for such matters to include the appropriate information in the WPS.
WPSs can be written for general applications or they can be job specific. Again, it is the responsibility of the individual tasked with this responsibility to know which type of WPS is best suited for the work at hand.
I agree with the statement that the tradename can be important factor in the success of certain jobs. Some of my work involves the repair of large presses. I have a chemical analysis of the casting done to find out what chemistry is present. If the chemistry indicates a potential problem with sulfur, i.e., the sulfur content is on the high side, I am very selective of which filler metal is used. I review the published information on deposited weld chemistry of the electrodes produced by several manufacturers and select the one that has "high manganese" to counter the affects of the sulfur. In order to ensure the contractor uses the correct filler metal, I list the filler metal specification, classification, manufacturer, and the specific tradename of the wire I want them to use. It is then the inspector's responsibility to verify the proper electrode, by tradename, is used.
The welding standards list the "minimum" requirements that have to be met. It is the "responsible individual's" responsibility to meet the minimum "code" requirement and any additional requirements that affect the success of a project/product. An example that comes to mind are consumer products; not only do they have to meet the requirements of the "code", but they also have to have "visual" appeal and meet the customer's expectations.
Best regards - Al
This discussion is another example of the minimum standard/cookbook argument. And not only would I NOT expect it to go away any time soon. I think its ligitimate and important discussion, and in my experience an implicit part of virtually every Section IX Code Week meeting.
Having said that, when using the very terminology of 'essential variable', etc., you are referring, in the case of ASME, to Section IX. and the variables are intended to be tied into the testing regimes. Which in ASME IX is exclusively room temperature tensiles, bends, and impacts (except for hardnesses in the new temper bead stuff of course).
Therefore the intent is to limit variables to those things that consistently influence those specific mechanical test results. There is, of course, some dispute over some variables as to whether or not they need to be more stringent or not. And certainly everybody has anecdotes that argue for exceptions. But the consensus decisions, though often messy and sometimes influenced by certain special interests, are based upon mountains, as I said earlier, of emperical data.
And even if an argument can be made that any particular variable application could be made more stringent, I think those situations are limited, and it still does not excuse anybody from their due diligence responsibility.
The third paragraph of the ASME Section IX Forward says it clearly and concisely.
Its just that nobody ever reads the Forward.
And if, you are going to argue to the committee (a process that everyone is more than welcome and encouraged to do-4 times a year) that tradenames should be imposed as an essential variable for tensile, bend, and impact testing regimes over a global industry, not just specific applications, you better bring data. Lots and lots of data. Because only conflicting data will move opinion based upon data.
Noel, I have worked to DNV Rules for Submarine Pipelines and that is one tough specification, really elevates the importance of the Welding Engineer on the project.
JS55 I am aware of the third paragraph of the foreword and I agree most people are not. It probably deserves a page on it's own, something maybe like a government health warning on a pack of cigarettes!
Forum
