The United Association of Plumbers and Pipefitters (UA) identifies their standard pipe welding tests with the letters UA, a dash, and then a number. Like UA-1, UA-2, etc.There is a list available that goes all the way to UA-92. That does not mean there are only 92 tests ever given. There are many more possibilities but the Pipe fitters Union (UA) had to go all the way to # 92 to identify the most common pipe tests. However, this does serve as kind of an example to how many possibilities exist for pipe welding certification tests.With 4 different welding processes used for pipe welding (Gas Metal Arc / GMAW, Flux Core Arc / FCAW, Shielded Metal Arc / SMAW, and Gas Tungsten Arc / GTAW) and several different metal groups being welded (like carbon steel, stainless steel, and even aluminum), its no wonder so many different pipe welding certification tests are required to certify welders for the scope of work being done on a job or job site.ASME Section IX is a commonly referred to document in pipe welding used to determine welder certification requirements as well as qualification limitations.Some of the common limitations are thickness, position, and diameter of pipe.For example a welder passing a tig welding certification test on 2 inch schedule 80 pipe in a 6G position is qualified to weld 1 inch and greater diameter pipe, up to 436″ thick and in all positions.But a welder passing a test on 6″ schedule 40 in a 6G position is qualified to weld in all positions but only up to.560″ thick and only down to 2.875″ pipe diameter.If you are reading this and are wonder what rectal database they pulled these numbers from, I am with you on that. Its seems kind of silly that once you have.560″ of filler metal deposited, that you are not qualified to put more.I am just saying.