Reference API 1104 (2005).  Paragraph 6.2.2 (Single qualification scope) says a welder who passes the butt or branch test decribed in 6.2.1 is qualified within the limits of the essential variables listed.  Variable (d) lists three OD ranges, one of which is a 2.375 inches to 12.750 inches.  Section 6.2 on single qualification does not specify a pipe size for the test.

Section 6.3 (multiple qualification) requires a welder to pass both a butt test and a branch test.  Paragraph 6.2.1 requires a minimum pipe OD of 6.625 inches.  Paragraph 6.3.2 says a welder that passes both tests on a pipe less than 12.750 inches is qualified to weld on pipe sizes equal to or smaller than the pipe size used for the test.

It appears that a wlder that passes a single qualification for butt welds on a 6.625 inch pipe is qualified for 2.375 to 12.750 inch pipe.  But a welder that passes a multiple qualification test on a 6.625 inch pipe is only qualified for 6.625 inch and smaller.  This makes no sense to me.  Where am I going wrong with my interpretation of API 1104? 

Thanks

Flaguy,
I believe the wall thickness, diameter groups and joint design of the pipe limits the single qualification and requires requalification when change beyond limits, were as the multiple qualification the welder is not limited to wall thickness, diameter groups and joint design but to diameter if smaller than 12.750”.

Rey