The fabrication of your 44-inch ASTM A234 WPB elbows using two plates, resulting in two welds per elbow, is acceptable under ASME B31.3 and ASTM A234 WPB standards, provided that:
The welding procedures and welders are properly qualified according to ASME Section IX.
The welds are inspected and tested to ensure they are free from defects and meet all mechanical property requirements.
The finished fittings comply with all other applicable requirements of ASTM A234 WPB and ASME B31.3.