Hello All,
First time posting here and I was wondering if someone could provide some clarification on a single qualification to API 1104. Normally we require all of our welders to multi-qualify in order to make sure and cover all types of sizes, and walk thicknesses, but due to the nature of the situation time/costs are tight and we are trying to move forward by eliminating the branch (if we can). So my question is that the 1104 states that if an essential variable changes inside the size group then the welder "using the new procedure" must be re qualified.

"d. A change from one outside diameter group to another. These groups are defined as follows:
1. Outside diameter less than 2.375 in. (60.3 mm).
2. Outside diameter from 2.375 in. (60.3 mm) through 12.750 in. (323.9 mm).
3. Outside diameter greater than 12.750 in. (323.9 mm)."

Ive tested these welders in a 6G position on 12.750 pipe and currently thats what they are welding on. Do they have to retest in order to weld on 16"? Also, if they do retest on 16" pipe does that cover them for all sizes above 12.750" or does the standard assume that they will be retested for every size welded on above 12.750"?

Any help would be greatly appreciated, thanks.

You may be able to RT one of the 16" production welds and qualify them, depending on the service of the pipe.

API 1104
6.6.1
General
At the company’s option, the qualification butt weld may be examined by radiography in lieu of the tests specified in 6.5.

Watch out now , because:

49 CFR 192.229  
Limitations on welders.
(a) No welder whose qualification is based on nondestructive testing may weld compressor station pipe and components.