American Welding Society Forum
Case: Combination of GTAW,SMAW & SAW in one test coupon.
Coupon thickness: 25 mm
Root run & 2nd run : GTAW Deposited thickness : 5 mm
Further 10mm deposit by SMAW
Remaining 10mm by SAW
Querry: 1. What is the base metal thickness qualified by each process?
2. What is the weld deposit qualified by each process?
1.) The entire weldment performed by the 3 processes would qualify the joint at 1/8" [3 mm] to unlimited thickness.
Comment: I don't think each process is qualified individually unless I've missed a provision in this code. Otherwise I would perform 3 seperate tests to qualify individual thicknesses.
2.) For a specific weld deposit thickness, I would recommend the 1/8" [3 mm] to 2T maximum for the process qualified. Because the weld deposit is < the full thickness of the joint (or thinner member joined), per this code it would be defined as a PJP deposit.
Out of curiosty, what is the application that requires a GTAW/SMAW/SAW combination?
Would'nt this be similar to qualifying a pipe test where you place the root with one process and then fill and cap with another?
Interesting mix of processes, isn't it?
The required combination is GTAW root and SMAW for remaining thickness, of course to avoid back gouging in a pipe cir seam.
I had assumed this to be a tubular application. I also worded my question incorrectly; Why use the GTAW in lieu of SMAW for the root pass?
(In your last post you noted: "...SMAW for the remaining thickness,...")
It is understood why welding from one side of the joint to be ideal. SMAW would provide sufficient root penetration (assuming again proper electrode and technique are implemented) and "backing" with an increase in layer thickness (preventing melt through) and higher deposition rates vs. GTAW for subsequent SAW passes.
Is this to achieve a specific alloy content in the weld deposit?
Additional: For the tubular welds I have qualified in the past and recently in Taiwan, it is often a design requirement to specify the number of passes used to perform the weld (this includes qualification to the 2004 edition of the code). Specifying the number, placement, width and thickness of weld passes and layers on the WPS is quite common, particularly here in CA.
BTW, what material specification(s) are you joining?
"...number, placement, width and thickness of weld passes and layers..."
I know this is a reqirement in D1.1 and D1.5 to specify on the WPS and there are limits. But can someone tell me why there should be limits on these variables for the base metals listed in these two codes? I do understand that increases in heat input can affect notch toughness properties, but why should these limits be imposed for applications where notch toughness properties are not a concern? And I can see where it is an issue in bridges where dynamic loading occurs and the temperatures can get low enough to drop below the transition temperature. It just seems unrealistic to apply such limits on all WPS's, regardless of application, and increases the burden on fabricators to implement them and inspectors to ensure they are met. D1 needs to get real. Why not just have one variable that requires the WPS to be requalified if a heat input greater than that used in qualification is used?
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