Are you asking about welder performance qualification for a particular process?
Review QW-405.3. This applies to upward and downward weld progression changes during vertical welding, if the progression is specified. Vertical does not mean limited to any particular coupon position.
thank you metenger. in 5G position if we weld continuously , in half of the joint the weld is upward and in half of it the weld is downward. is my opinion correct?
Only if the welder does not understand uphill or downhill weld progression sequence because the pipe is not turned or rolled for the 5G position. Review QW-350 Welding Variables for Welders. If you intend to qualify a welder, it is best to qualify in an uphill progression because vertical-uphill progression qualifies for all other positions - see QW-405.2.
Unless you have a specific need for downhill welding, the welder(s) should qualify with uphill progression. For performance qualification, you must stick with either uphill or downhill progression for the entire coupon.