QW 403.6 interpretation

Your Welding Procedure Specification (WPS) for the GTAW/SMAW processes will be qualified for a minimum base metal thickness of 5/8", according to QW-403.6. This is a supplementary essential requirement pertaining to GTAW and SMAW processes.

The Procedure Qualification Record (PQR) is not qualified, it is a record of welding to a specific welding procedure and is certified.

So if it is only a GTAW process then the thk qualified for WPS will be as per QW 451.1, which for a 1" thk will be a minimum of 3/16".

Merzi

First off, are you talking about a different weld coupon where the entire 1" thickness was welded with GTAW versus the combined welding processes and coupons you referenced in an earlier post? This has become confusing because you keep switching around between GTAW, SMAW/GTAW processes and weld coupons.

If a welding procedure is qualified with impact testing, the supplementary essential requirements are just as important as essential requirements. As such, the base metal minimum thickness supplementary essential variable QW-403.6 would apply, and QW-403.8 would be applicable for maximum base metal thickness, for each welding process.

I am sorry I did not phrase the question properly. I absolutely understand what you are saying, however if you look at QW 253 table for SMAW it clearly talks about T limits for impact. Subsequently if you look at QW 254, QW 255 and QW 256 403.6 it onlytalks about T limits. I need clarification on that .

Regards

Merzi

Merzi;
Ok. Lets try and work thru and example. For simplistic purposes, lets assume you have welded a 1” thick weld coupon using the SMAW process for the root and fill following a new WPS. You decide to have the coupon impact tested – weld metal, and HAZ (heat affected zone) in addition to the standard bend and tensile testing.

Bends, tensiles and impacts are all ok from the lab. You certify the PQR, and now comes time to use the WPS. To use in production welding of material that must be impact tested per Code requirements, the minimum qualified base metal thickness permitted by this welding procedure is 5/8” per QW-403.6. The reason is because the weld coupon T (1”) was greater than 5/8” and therefore, the minimum qualified base metal thickness for this welding procedure would be the lesser of T or 5/8”. The maximum thickness permitted by this procedure remains at 2” (2T) per QW-451.

Now you need to perform production welding on base material that requires impact testing per Code requirements and the base metal is only ½” in thickness. Under QW-403.6 for the SMAW process, you are outside of the base metal minimum thickness range as a supplementary essential welding variable for this procedure and, as such, you would need to re-qualify a new welding procedure. Alternatively, if you were going to use this same welding procedure for a production weld on base metal that did not require Code impact testing, the minimum base metal thickness would be 3/16”, per essential variable QW-403.8 for the SMAW process. The maximum base metal thickness qualified still remains at 2” for this procedure.

Again let me reiterate that I fully know what you have said but I have a very simple question regarding 430.6.

"Is T limits for impact only applicable for SMAW process or for all other welding processes also ( GTAW,GMAW,SAW).

Regards

Merzi

Here is a simple answer- Read QW-254, 255 and 256. QW403.6 is a supplementary essential welding variable for impact qualification of SAW, GMAW and GTAW processes.

Merzi

Reference to QW-403.6 in QW-254, QW-255, QW-256 are exactly identical in meaning as that in QW-253. They are all pertinent to supplementary essential variable that means impact testing is a requirement and the paragraph QW-403.6 should be applied to all those processes in identical way.

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