ASME Section IX permits covering multiple welder qualification through single test coupon. In this article, I will discuss various things that must be kept in mind when opting for qualifying multiple welding performance qualifications in a single coupon.
A welder must qualify for each of the processes that he intends to use in production welding. He can take his qualification test for each of these processes in separate test coupons, or in a single test coupon which covers multiple processes. The weld metal thickness for each of these processes must be planned beforehand to obtain qualified weld metal thickness in accordance with QW 452.1 (b).
If a single coupon is used, the thickness deposited with each of the processes must then be measured and recorded during the preparation of the test coupon (Interpretation IX-92-32 is contextual here).
Each of the processes is then counted as a separate qualification with its own qualified range for various essential variables. These qualifications can then be used individually or in any combination in production joints (Interpretation with record number 15-35 question 1, and interpretation IX-18-36 are contextual).
Likewise, multiple welders can be qualified on the same test coupon as well, for the same process or different processes. The thickness deposited by each welder should be planned beforehand, and then checked & recorded during preparation of the test coupon. Once the coupon passes the requisite testing of QW 304/ QW 305, each welder gets qualified for the process with which he deposited.
Each of the qualifications is then counted as a separate qualification with its own qualified ranges for the essential variables. These welders can weld on individual joints, or multiple welders can be deployed on a single production weld as well.
In a similar way, a single welder can do multiple performance qualifications with the same process, with different essential variables, in a single test coupon.
For example, he may deposit 10 mm weld thickness in a test coupon with a F-Number 4 electrode, and deposit another 10 mm with a F-Number 43 electrode in the same test coupon. He would then have two qualifications to his name, which would be treated individually.
The crux of the story is that multiple qualifications can be done on a single test coupon. Each qualification is treated as a standalone qualification which can be used singly or in combination with other qualifications, within the qualified limits of each qualification. Section IX expressly permits this, in QW 306.
Things To Keep In Mind When Performing Multiple Welder Qualifications Through Single Coupon
When a combination of qualifications is done in a single test coupon, there are few things that need to be taken note of:
- Per QW 306, “failure of any portion of a combination test in a single test coupon constitutes failure of the entire combination.”
- The thickness of test coupon must be minimum 19 mm when three or more welders (using the same or a different welding process) are qualified in a single test coupon.
- The weld metal thickness ‘t’ for each qualification must be determined and used individually in the table of QW 452.1 (b) to determine the qualified weld metal thickness for each qualification.
- The thickness of weld metal for determining the type and number of tests in QW 452.1 (a) is to be taken as the total weld metal thickness deposited by all welders and all processes exclusive of the weld reinforcement.
- Coupons tested by face and root bends shall be limited to weld deposit made by one welder with one or two processes or two welders with one process each. This is as per Note (2) under Table QW 452.1 (a).
Note (1): It is important to bear in mind that at any given time during production welding, only one performance qualification can be considered at a time. That means, the welder’s eligibility to weld on a production joint must be derived from only one qualification at any given instant. The article below explains this in detail.
Note (2): While preparing a test coupon, if a change occurs in any of the essential variables at any stage, it becomes a different qualification. That is, the portions of the coupon that are deposited with different essential variables must be counted as separate qualifications. The qualified weld deposition range for each such qualification should be reckoned individually, per QW-452.1(b). This has been given at QW-306, as well as in footnotes under QW-452.1(b).
Welding a Coupon in Multiple Positions to Qualify for All Positions
When we talk about why a fabricator would try to do multiple qualifications in a single test coupon, the reasons can be many. He may be short on the base metal pieces required to do separate qualifications. Or, the queue in the RT hall may be long, which would make him want to make least number of coupons. These are logistical reasons.
Sometimes, the reason may be a more of a technical one. When it is required to qualify a welder for all positions, the ideal way would be to make him take a test coupon in 6G position. However, there are other ways as well, to qualify him for all positions.
If the requirement is to make a welder ready for welding pipes in all positions, the welder can be made to take a pipe coupon (of suitable diameter) in 2G and 5G position. Three quarters of pipe circumference should be welded in 5G position, while one quarter in 2G position. The samples for mechanical testing should then be drawn in accordance with figures in QW-463.2 (f) or QW-463.2 (g).
If the requirement is to make a welder ready for welding plates in all positions, the welder can be made to take a plate coupon in 2G, 3G and 4G positions. Part of the coupon’s thickness should be filled in 2G position. Then the coupon should be shifted to 3G position, then part of the thickness should be deposited in this position. Then the coupon should be shifted to 4G position, and remaining thickness should be filled in 4G position.
The thickness to be deposited in each position should be carefully decided by the welding engineer based on the production requirements.
The coupon should be subjected to testing in accordance with QW-304. If it passes, such a coupon qualifies the welder to weld in all positions.
This information is contained in the table under QW-461.9. The interpretation 15-1730 also contains a pertinent query on the subject.
Combination of Multiple Performance Qualifications In a Weld
Can A Welder Use A Combination Of His Performance Qualifications In A Single Production Joint?
This is a very interesting question. Many variations of this question have occurred in my mind for many years, as I am sure, must be occurring in the minds of engineers the world over. ASME has issued a good number of Interpretations answering variations of this question.
The best way to explain would be to take up a few examples, and explain them individually. Keep reading.
OD And F-Number
- Consider the following.
A welder is qualified for GTAW process, with a pipe of OD 73 mm, and with a filler of F number 6. This makes him eligible to weld all pipes of OD 73 mm and above as per QW 452.3, and with fillers having F number 6 as per QW 433, with GTAW process.
He has another qualification with GTAW process, in which he was qualified with a pipe of OD 25 mm, with a filler of F number 43, which makes him eligible to weld on all pipes of OD 25 mm and above, with fillers of F number 43.
Now, there is a production job in his shop that is having OD 50 mm, and needs to be welded with GTAW process, using a filler of F number 6.
Can the welder having qualifications described above weld this job?
This exact scenario occurs in my shop. The problem seems quite commonplace.
The welder does have skill to weld pipes of OD 25 mm and above. It is another matter that his qualification on a pipe of this size was done with F number 43. Logically, one would think that the welder is qualified to weld the job.
But does Section IX permit it?
If this welder had only one of the qualifications described above, he would not be qualified to weld the production job. Because, that would mean a violation of the QW 404.15 or QW 403.16.
Neither of the qualifications on a standalone basis would definitively support a production job that requires skill with filler of F number 6 and on a pipe of OD 25 mm and above.
However, in this case – half of the required skill has been acquired from one qualification, and half from another. In such cases, what does Section IX stipulate?
As far as I know, Section IX has not addressed this anywhere. However, they did make it clear through an Interpretation. A very similar question to the situation described above was put to ASME by somebody. The reply given by ASME was ‘No’. The Interpretation number is IX-20-20.
This makes it clear that it is only allowed to apply the essential variables of QW 350 for one qualification at a time. One cannot mix some variables of one qualification with those of another.
OD And Consumable Insert
- Consider another example.
A welder has two qualifications, both with GTAW process.
First qualification is with a one inch OD pipe, with consumable insert. This makes him eligible to weld on pipes of OD one inch upwards, with consumable insert (and not without it).
Second qualification is on an open butt root, on a half inch OD pipe. This makes him eligible to weld on pipes of OD half inch upwards, with open root, or with backing (but not with a consumable insert).
There is a production job that is half inch OD pipe, and is required to be welded with a consumable insert. Can the welder weld this job?
There are two skills involved here. One skill is to weld on a pipe of half inch OD. Another skill is to weld with a consumable insert. The welder has acquired one skill from one qualification, and other skill from another qualification.
One would think that logic allows the welder to make the weld in question.
However, it is not so. Only one qualification can be considered at a time. If a job requires certain skills (or variables, in Section IX parlance), welder’s qualification to weld with those skills must have come from a single qualification. This is Code’s intent.
ASME makes it clear through an Interpretation IX-83-22, which addresses the scenario just described.
Position and thickness
- Consider another example.
A welder has two qualifications in a process, say GTAW. One of them makes him eligible to weld in all positions, up to a weld deposition thickness of half an inch. Another qualification makes him eligible to weld in flat position only, but up to a weld deposition thickness of 2 inches.
Can this welder weld production jobs up to 2 inch in deposition thickness, in all positions?
Now, there are two skills (or two variables) required to fulfil the specified production requirements. One skill is to deposit weld thicknesses of up to 2 inches. Another skill is to weld in all positions.
One skill has been acquired from one qualification, while the second skill has been acquired from another qualification.
As per Code rules, this welder is not eligible to weld the production jobs that require two inches weld deposit thickness, and are require to be welded in non-flat positions.
It is necessary that both skills should have come from a single qualification. Only one qualification can be considered at a time to determine the welder’s eligibility to weld a production joint.
An Interpretation IX-83-23 addressing this scenario was issued way back in 1982, by ASME. The Interpretations IX-89-24 and IX-18-37 also addressed pretty similar questions.
- Consider the following example.
A welder has two performance qualifications in a process, say GTAW. The first one makes him eligible to weld unlimited thickness in flat, vertical and overhead positions. The second one qualifies him to weld in horizontal position, but up to a thickness of only 15 mm.
Now, there is a production job that requires welding in horizontal position with a high deposition thickness, say 50 mm. Can the welder described above weld this job?
The answer is no.
There are two variables with respect to which welder‘s eligibility is required to be judged. Welder has qualified for one variable in one qualification, and has qualified for second variable in a separate qualification. This, like we saw in the examples above, is not permitted. Only one qualification has to be considered at a time.
A couple of Interpretations, that address a similar scenario, are IX-82-05 (qs3) and IX-86-30.
F-Number And Position
- Consider another example.
A welder has two performance qualifications to his name. In one of the qualifications, he used a F No. 4 electrode, and deposited a thickness of 10 mm. In second qualification, he welded with a F No. 5 electrode, and deposited 9 mm thickness. Both qualifications are with SMAW process.
A production job requires 20 mm deposition thickness with a F number 5 SMAW electrode. Is the welder described above eligible?
There are two essential variables that need to be considered here. One is F number, and deposition thickness. Welder’s eligibility for depositing 20 mm thickness comes from first qualification, while eligibility for welding with F number 5 electrode comes from second qualification.
In other words, one of the variables required for production weld is satisfied in one qualification, and another variable is satisfied in another qualification. This is against the understanding established by Section IX.
At a given time, for making a particular weld, all essential variables should have been supported by one qualification only.
The welder described above is NOT eligible to make the production weld in question. Similar questions were addressed by ASME in Interpretations IX-17-08 and IX-18-42.
OD, Position And Weld Thickness
- Consider the following example.
A welder has two qualifications. In one of them, he has qualified on a 3 in. OD pipe, wall thickness ½ in., in 1G position. In the second qualification, he has qualified on a 1 ¼ in. OD pipe, wall thickness 1/8 in., in 6G position.
Is this welder qualified to weld on a 1 ¼ in. OD pipe of wall thickness ½ in., in all positions?
The answer is No. Let’s see why.
Three variables have been specified here, viz. pipe diameter, wall thickness (assume that this is equal to deposition thickness), and position. The second performance qualification mentioned above qualifies the welder to weld on pipes of OD 1 ¼ in. in all positions. However, this qualification only qualifies him to weld up to deposition thicknesses of ¼ in.
The first performance qualification does qualify the welder to deposit thicknesses of up to 1 in., but only in 1G position, and in pipes of OD 73 mm and above only.
Similar to the preceding examples, part of the welder’s required skill has been acquired from one qualification, while another part comes from another qualification.
This, as we saw, is not good enough. At a given time, only one qualification has to be reckoned to determine welder’s eligibility to make a particular weld.
This example figured in an Interpretation, IX-92-53. The reply given by the Committee affirmed the above understanding. Interpretations IX-89-98 and IX-92-15 presents similar examples.
Another pertinent example involving F-No. and deposit thickness appears in interpretation IX-83-55.
OD and Thickness – An exception
There is, however, an exception to the above established understanding, when two different qualifications CAN be combined together to determine a welder’s eligibility to make a production weld.
This exception appears at Note (2) under the Table QW-452.1(b). This Note (2) goes like this: “Two or more pipe test coupons with different weld metal thickness may be used to determine the weld metal thickness qualified and that thickness may be applied to production welds to the smallest diameter for which the welder is qualified in accordance with Table QW-452.3.”
To understand about this provision, consider the following example.
Say, a welder has two qualifications. One, on a pipe of OD 2 inches (50 mm) and deposit thickness 1/4 inch (6 mm). Ordinarily, with this qualification – the welder can weld on pipes of OD from 1 inch (25 mm) to unlimited, and deposit thickness of up to 1/2 inches (13 mm) maximum.
The welder has a second qualification too: on a pipe of OD 2-7/8 inches (73 mm) and deposit thickness 1/2 inch (13 mm). Ordinarily, with this qualification – the welder can weld on pipes of OD from 2-7/8 inches (73 mm) to unlimited, and deposit unlimited thickness.
Now, consider that a production weld of OD 1-1/2 inches (38 mm) and wall thickness 3/4 inch (19 mm) needs to be welded. Can the welder described above make this weld?
Ordinarily, as we saw in the above paragraphs, only one qualification should be considered at a time. It is not acceptable that half of the skill needed to make a weld has been derived from one qualification, and half from another. With this understanding, the answer to the above question would normally be ‘No’. However, in this case – the answer is a ‘yes’.
This is due to the above mentioned special condition provided in Note (2) under Table QW-452.1(b). There are several interpretations that further confirm this. The interpretation IX-92-59 is one such example.
So, this was about the subject of multiple welder qualifications in single test coupon. In second half of the article, we have explored the question of applying multiple qualifications of a welder on a single production joint. Please do let us know your thoughts on this subject in the comments section below.