Whether you are doing welding at home, workshop or at site for a company, you will need a good welder. Performance Qualification of Welders (WPQ) or a Welder Qualification Test (WQT) is to prove that a welder can do a sound weld.
A qualitative test gives an assurance that the output job done by the welder is a satisfactory one.
Every industry or clientele have their own set of specifications to which welders must be qualified. For example, if you are a steel fabricator, then you will likely need a different welding reference than you would if you were a home builder.
How to Welder Qualification Test to ASME Section IX?
Firstly, go through the client scope or agreement. Here, we are discussing in general, how to qualify a welder to ASME BPVC Section IX. And, we will consider welder testing on piping. This code, consequently, the most widely practiced in my experience.
Secondly, a WPQ Test should follow an approved WPS. A successful pre-WPS or PQR Qualification Test is also acceptable for a Welder to Qualify to the approved limitations.
The basic steps for qualifying welders have outlined here in brief. For more detailed insight into the sections, visit ASME Section IX documents.
Basic steps for Welder Qualification on Piping
General
To illustrate, reference Section IX Welder Performance Qualification Record (WPQR) form QW-484 shall be followed, if there are no specific WQT documents from the client. Whenever a reference is made, the procedures needs to comply with the ASME Section IX standards.
The Test Coupons
The test coupons may be in plate, pipe or other product forms, and with each individual welding process in separate test coupons, or with a combination of welding processes in a single test coupon.
Similar procedure applies for the qualifying combination of welders using a single test coupon. So, failing test on one of the coupons fails the entire test coupon with their weld process and welders.
What is the Role of Contractor in a welder qualification test or WQT?
Welder Qualification Tests are to conduct under the direct supervision of the contractor. The client has to engage a full-time monitoring representative from an independent lab or technical consultant.
The contractor (executor), shall oversee the operations and sign the initial WPQR form. He will ensure all required manpower, materials, resources and testing are available for the job.
What is the Role of Third Party Inspection in WQT?
The role of the authorized independent representative is to monitor the work that complies with the code. Moreover, the representative needs to sign off verifying that the process is done by an authorized welder. The test coupon, filler metal, their sizes, the welding techniques do comply with the Welding Procedure Specification document.
Based on successful final weld visual examination (cracks, incomplete penetration, fusion), the representative shall approve the welder qualification test specimen for testing, or even terminate the welder test based on the skill established during welding the coupon.
Non Destructive Examination Procedure for Specimen Welds
A welder can be qualified by testing the coupon on any of the below methods;
- Visual Testing
- Mechanical Testing.
- Volumetric NDE.
- Volumetric NDE of initial production weld.
Provided, the visual examination acceptance (QW-194) criteria over the entire circumference, inside and outside is complied and cleared for further testing by examiner as noted in the previous section.
Who approves test specimens to ASME Section IX?
Both the Qualification Specimens and the Test Results from Qualification have to be approved by the Third Party Inspection Personnel (an Independent Observer).
Testing shall be carried out by an approved testing laboratory (witnessed by third party) and involves, among other things, ensuring the weld is produced to required specifications.
What are essential variables in Welder Qualification Test?
Article IV Section IX QW-350 lists for each processes, the essential variables, are that when changed required re-qualification.
As per QW-401.2 The ability of a welder to deposit sound weld metal will be affected by a change in welding condition. (such as a change in welding process, deletion of backing, electrode, F‐Number, technique, etc.).
Refer QW-350 Welding Variables for Welders of BPVC ASME Section IX for complete description of essential variables.
Reference Table QW-353 lists applicable essential variable for Shielded Metal‐Arc Welding (SMAW);
QW-402.4 Joints – without Backing, QW-403.16 Base metals – ϕ Pipe diameter & QW-403.18 – ϕ P‐Number, QW-404.15 Filler – ϕ F‐Number & QW-404.30 – ϕ t Weld deposit, QW-405.1 Positions – + Position and QW-405.3 Position – ϕ ↑↓ Vertical welding
And, the Table QW-356 lists essential variables for Manual and Semiautomatic Gas Tungsten‐Arc Welding (GTAW);
QW-402.4 Joints – without Backing, QW-403.16 Base metals – ϕ Pipe diameter & QW-403.18 – ϕ P‐Number, QW-404.15 Filler – ϕ F‐Number QW-404.22 ± Inserts, QW-404.23 ϕ Filler metal product form & QW-404.30 – ϕ t Weld deposit, QW-405.1 Positions – + Position and ϕ ↑↓ Vertical welding, QW-408 Gas − Backing gas & QW-409.4 Electrical – ϕ Current or polarity.
Similarly the essential variables for other welding process for welder qualification test is noted as under, refer ASME Section IX for full description.
QW-352 Oxyfuel Gas Welding (OFW)
QW-354 Semiautomatic Submerged‐Arc Welding (SAW)
QW-355 Semiautomatic Gas Metal‐Arc Welding (GMAW)
QW-357 Manual and Semiautomatic Plasma‐Arc Welding (PAW)
Essential Variables in brief for Piping with SMAW and GTAW Process
As we are only looking into the aspect of piping with Shielded Metal Arc Welding and Gas Tungsten Arc Welding process, other processes have not been discussed here.
In correlation to above, the brief details are as under:
QW-402.4 – Denotes without backing ring for single groove welds.
QW-403.16 – Change in pipe diameter beyond the range permitted.
QW-403.18 – Change from one P‐Number to any other P‐Number or to a unlisted base metal in Sec IX.
QW-404.15 – Change from one F‐Number to any other F‐Number or to any other filler metal
QW-404.22 – Omission or addition of consumable inserts
QW-404.23 – Change in type of filler metal product forms to another
QW-404.30 – Change in deposited weld metal thickness
QW-405.1 – Addition of other welding positions than those already qualified
QW-405.3 – Change from upward to downward, or from downward to upward, in the progression
QW-408.7 – Change in the type of fuel gas
QW-409.4 – Change from AC to DC, or vice versa
Each sections and sub-sections have specific limitations defined, refer the Code for detailed understanding related to the job.
What is the Procedure to Qualify Welders?
No matter which type of industry you work in, be confident with the requirements, specifications, and standards that pertain to that industry. They are often industry-specific and are used for quality control and verification.
Outlined steps here briefly elaborates the procedure to qualifying welder to ASME BPVC Section IX Codes and Standards.
Procedure for Testing Test Coupons
Welding Procedure
Reference ASME Section IX, the performance qualification test (WPQR) shall be welded in accordance with qualified Welding Procedure Specifications (WPS), or Standard Welding Procedure Specifications (SWPS), where PWHT requirements, if any, may be omitted.
Welding Test Coupons
Firstly, welder qualification test specimens to the Welding Procedure Specifications technical document. It is recommended to prepare two sets of bevelled test pieces and tack them, correlating with the WPS requirements. Ensure the filler metals are from unopened containers or that are properly baked and free from any moisture.
Piping Test Positions
Mostly, welding of piping test coupons are done in the 2G & 5G, or 6G positions as per requirements to QW-122 and illustrations in QW-461.4
Testing Pipe Diameter
Table QW-452.3, especially, defines the qualification parameters for pipe diameters. Generally, 6″ O.D. piping are preferred for qualifications that applies to piping O.D 2 7/8″ (NPS 2 1/2″) and over. Therefore, qualifying piping diameters below O.D. 2 7/8″ qualifies welders upto the 1″ piping O.D. In addition, qualifying piping diameters below O.D. 1″ qualified welders to the actual piping O.D. The maximum diameter is unlimited in any case.
Weld Thickness Qualified
Reference Table QW-452.1, for groove welds, the thickness that qualify is 2 times the coupon weld thickness, where, thickness welded is less than 3/4″, and is unlimited for weld thickness 3/4″ and above.
Moreover, table QW-452.6 for test specimen on 6″ Groove welds qualifies for Fillet welds on any sizing, for pipes, plates or socket welds.
Welder Performance Qualification Tests (QW-452)
Types of Performance Qualification Test Required
Bend Tests
The specimen weld thickness (without reinforcement), determines the type of bend tests required for welder qualification. For instance, reference to Table 462.1 (a), for 3/8″ (10mm) weld thickness the 2 bend tests (one face and one root) is required. However, the tests required become four for 5G or 6G positions, and six tests, if it is a combination of 2G & 5G.
In case of 3/4″ (10mm) to less than 3/8″ (19mm) weld thickness, one face and one root bend test or two side bends. However, the tests required becomes four for 5G or 6G positions, and six tests, if it is a combination of 2G & 5G.
Moreover, for 3/8″ (19mm) and more, two side bend tests are required. For that reason, the tests required become four for 5G or 6G positions, and six tests, if it is a combination of 2G & 5G.
Fillet-Weld Test
In general, the fillet weld performance test carried out as per Figure QW-462.4(c) of ASME Section IX for piping. Therefore, for Tee fillets 3/16″ (5mm) or greater the test qualifies for all base materials, all sizes and for piping O.D 2 7/8″ or more
For Tee joint thickness less than 3/16″ (5mm), performance qualified from T to 2 T base material thickness, T maximum fillet size, and all diameters 2 7/8″ (73) O.D. and over.
Consequently, all thicknesses of as welded test coupons require one Macro test & one Fillet Fracture test.
Volumentric NDE (Radiographic Test)
Volumetric NDE (QW-191) describes in detail various methods of NDE tests. That includes QW-191.1 Radiographic Examination as per procedure outlined in QW-142. The QW-191.2 Ultrasonic Examination as per procedure in QW-142 with their acceptance criteria defined in the Code. This mostly has to follow as per written practice of the client and should meet the requirements of ASME Sec V, Article 1.
Though QW-304 recommends Volumetric NDE as an alternative to guided-bend tests, it has been widely used with the bend tests for most groove weld Performance Testing for SMAW, GTAW, GMAW(except short circuiting) or the combination processes.
What is the Validity of WQT Certificate
Best of all, no re-qualification compliance requirement, if no more than 6 months have passed for the qualified welding process. Moreover, a re-qualification may be required if there is a question on the welder’s ability to make sound welds.
Moreover, the authorized independent authority has to stamp the certificate (Refer QW-484 A). Consequently, this document confirms that the values of essential variables in test, range qualified for production welding, the type of tests and their results are as required for welder performance qualification requirements of ASME Section IX.
Moreover, the failure of any test specimen taken from a combination test coupon constitutes failure of every welding process. Every welder involved in making coupon, and so on. Likewise, the failure of any of visual, mechanical or NDE tests will require the welder to do a complete retest. This have to confirm to the same testing procedures as initial test.
Conclusion
The article in general, addresses in practical for Welder Performance Tests as per ASME Section IX. Brief outline of the steps are provided here for general guidance.
ASME BPVC Section IX Qualification Requirements for Welders and Welding Operators involves reference to various criteria and technical requirements. That includes the specimen dimensions for testing, not covered in this article. Do refer to technical document ASME Section IX (latest editions) for complete details.
Do let us know your comments or suggestions or improvisations to this article.
