During my service, I have reviewed a great number of Welding Procedure Specifica>ons (WPS) and their suppor>ng Procedure Qualifica>on Records (PQR) in various shops. I have no>ced that there are common errors in the entries made in WPS & PQR forms. Here, I will be focusing on some of those common errors. 1. Revision Status:It is the normal prac>ce to include "Revision Status" in the Form of WPS, whenever there is a change in a non essen>al variable the WPS may be revised, since the WPS is a set of instruc>ons issued to welders. However, I have no>ced in some case the PQR is assigned a revision status. The PQR is a record of actual test, that cannot be revised. Therefore, the PQR Form shall NEVER include a revision status. In case an entry has been entered by error, the Code permits editorial correc>ons or addenda to PQR (Please refer to ASME Sec. IX, QW-200.2 (c)). Any corrected PQR shall be recer>fied. 2. Sketch of Joint in PQR: One of the widely spread errors no>ced in some shops, is that the sketch made in the PQR is having dimensions with a range or tolerances (such as bevel angle 60° ±5°; root gap 3 mm ±1). We must always remember that PQR is a record of an actual test, therefore actual nominal dimensions as measured at the >me of the test must be entered. 3. Sketch of Joint in WPS: The WPS includes the joint with dimensions with a range or tolerances (which is correct), but for produc>on welding, which joint shall be followed? Is it that on the WPS or that on the fabrica>on drawing? Of course the sketch according to the fabrica>on drawings must be followed. Therefore, it is advisable to enter a note in the WPS such as "In case of conflict between the joint details shown in the WPS and that on fabrica>on drawing, those on fabrica>on drawings shall be followed". 4. There are welding variables that apply to a welding process, but do not apply to a par>cular WPS such as PWHT, the entry in the WPS & PQR no>ced to be in several cases "Not Applicable" or abbreviated by "N/A". The term "Not Applicable" when used, it causes confusion as it does not iden>fy whether it refers to the process or to the par>cular WPS or PQR. So we need to use two different terms to reflect the exact meaning. Example: For SMAW, the entry for the variable "Gas" shall be "Not applicable" as it does NOT apply to the process. While for "PWHT" , the entry "None" shall be made to iden>fy that it is applicable to the welding process, but does not apply to the specific WPS or PQR. 5. One of the variables that is causing confusion is variable QW-404.50 "Flux" for GTAW. In many cases the entry made is "N/A". While the entry shall be "None" when not used. FYI, this is a paste flux which is mixed to form a gel. The gel is applied by a brush to the weld groove, and when it becomes dry, welding starts. That tends to improve the penetra>on. 6. Deposited weld metal thickness: When NO PWHT is applied, in some cases, the upper limit of deposited weld metal thickness exceeds the limit of exemp>on from PWHT specified by the construc>on Code (e.g. Test coupon having base metal thickness 25 mm, and deposited weld metal is 5 mm for first process (SMAW) & 20 mm for second process (SAW), the upper range qualified for deposited weld metal for SMAW is entered as 10 mm (2t according to Table QW-451.1), which is below the exemp>on limit, and it does not represent any problem. However, the upper limit of deposited weld metal for SAW is entered as 50 mm (2T according to Table QW-451.1). Since PWHT is not applied, the deposited weld metal thickness upper range must be limited to the maximum permihed thickness without PWHT (e.g. for Sec. VIII, div.1, for P No. 1 base metal is up to 38 mm. In addi>on the entry for preheat shall address the minimum preheat (e.g. 15°C) for thickness up to 32 mm, and 200°F (95°C) for thickness over 32 mm up to 38 mm. 7. Preheat: One of the most common errors is that, the PQR Form refers to "Preheat temperature (min.)" and "Interpass temperature (max.)". Again, I would like to remind you that the PQR is a record of an actual test. Another error I no>ced is that the preheat temperature is entered in the PQR as "ambient" and in some other cases the entry is "N/A". We need always to remember that the entry of the actual preheat temperature as measured during the test shall be entered in the PQR, as it is the basis of establishing the qualified range according to welding variable QW-406.1. 8. Gas: For GTAW: The variable QW-408.2 "Change single, mixture or %". It has been noted that a common error is made by entering "Argon 99.98%" in both WPS & PQR. The entry required for this variable is simply for single gas, the name of the gas "Argon". If mixture, the name of gases and mixture percentage of each e.g. "Argon 98%, Nitrogen 2%". During discussions with Welding Engineers, I asked what does the "99.98%" represent, the answer was "Purity level of Argon". I clarified that purity level is NOT a welding variable in Sec. IX. Anyhow, purity level is important and this is normally specified when ordering welding gas (such as Argon) and the purity level is verified during receiving inspec>on. 9. Filler metal product form: (Variable QW-404.23), One of the errors no>ced when a PQR is made using flux cored filler metal and the WPS is revised, without qualifica>on, to metal cored. Please note that solid filler metal and metal cored may replace each other without re-qualifica>on, but changing from flux cored to either solid or metal cored, requires re-qualifica>on.
