Mr. Ibrahim,
As you note impact testing is required for the job, therefore supplementary essential variables are applicable. Per QW-256, QW-404.12 is a supplementary essential variable for GTAW. Therefore, you must comply with the requirements of QW-404.12. QW-404.12 states that requalification of the WPS is required if there is “A change in the filler metal classification within an SFA specification . . .” . Note that the subsequent paragraphs/exemptions contained in QW-404.12 do not apply to your situation. The bottom line is that if impact testing is required and you were to change filler metal from ER70S-3 to ER70S-2, you would have to perform a new procedure qualification test with ER70S-2.
I think that it is also important to point out that even though certain properties are listed for a classification, this is not an endorsement by the Code that the filler is suitable for any application. In fact, unless you specify (demand) heat/lot specific testing, all you are going to get is a “typical” or “representative” material test report. The manufacturer must only prove that his process has produced an acceptable filler metal and as long as the manufacturing methodology is unchanged, the manufacturer is not required to perform any additional testing. You as the purchaser may, at your expense, require additional testing – see SFA-5.01 for different levels of testing. You should not be using the Sec II testing as a guarantee of impact properties for your application as many factors may be significantly different such as heat input, PWHT, preheat, interpass etc. all of which can affect your impact results. Impact properties often are much better (transition temperature lower, absorbed energy higher) than that demonstrated by Section II testing and therefore filler metals, appropriately tested by your PQR, may be often be used at lower temperatures than the required values of Section II. Conversely, it is obvious that your process parameters could adversely affect the structure of the weld metal such that it cannot meet the properties of Section II. This is the exact reason you must perform procedure qualification testing and why some customers may require heat or lot specific testing for filler metals in critical applications.
Hope this helps.
John A. Henning
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Muhammed Ibrahim
Sent: Thursday, May 13, 2010 10:39 AM
To: materials-welding@googlegroups.com
Subject: [MW:5165] Change in welding consumable when impact is required
Dear Members,
Please provide a clarification on the following query.
One PQR is qualified with GTAW+SMAW, ER 70S-3+E7018-1 and impact tested at-46.
Impact testing is required for the job at -29 Deg.C. Can I use ER70S-2 instead of ER70S-3 ?.
As per ASME Sec.II C, ER 70S-3 supports up to -20 Deg C & ER 70S-2 Supports up to -30 Deg.C.
Is QW 404.12 applicable in this change?.
Thanks & Regards
Muhammed Ibrahim PK
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