API std says, each U-tube shall be formed from a single length and shall have no circumferential welds.
What if the code is B31.1 or B31.3? I know that this a designer's call if no code restriction.
Any idea on why some engineers will not allow to have the splice joint at U bend? let say the pipe size is 2"dia below, P1 material.

Appreciate your input.

Dear experts,
Can we weld CS NPS 4" XXS elbow with 6" SCH160 CS pipe as per reference from ASME B31.3 and / or ASME B16.25.

I'm trying to develop a procedure for welding 9 Cr. pipe (P-5B) with GMAW spray transfer using a ER80S-B8 wire in the 1G rolled position. We are using a 90/10 AR/CO2 gas mix, a preheat of 400 degree F and 650 max. interpass temp. Does anyone have any tips/experience with this material?