[MW:14196] T 22 material welding

Dear experts, I am facing a problem during the welding of header stub with terminal tube SA213 T22 material. terminal tube size is 38NB and thickness is 4.59 mm. Our WPS suggest to use GTAW+SMAW process for this type of welding. During welding spatter and crown under cut arrived at surface during SMAW process .and weld bead is also not in good seem we had maintain root gap is 2.4 .we use TGS brand ceriated based 2.4 mm size filler wire for root run during GTAW process. normally this type of joint welded in shop but here we made in our project site. Please guide me how can I minimise these weld defect. I had checked argon gas purity , fit up, voltage, current ,gas flow rate (8-14 CFH). But unable to detect the root cause of this problem. Can we go throw full GTAW process. Our made WPS allowed only 4 mm maximum GTAW.and weld reinforcement is 1.6 mm to 2 mm. Vishwas kumar pathak. Jaypee power bara thermal. (660*5 MW)
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