If you are referring to 1G,2G,3G etc. Then I could help you by telling you those are designations for the position used during welder or welding procedure qualification testing.

These designations are often used by individuals to refer to the position in which actual welding is performed however I am unable to find this in the two codes I worked with most often. In industry welders and others often use these terms to refer to the position that production welding is performed in.

Here is a poster by lincoln electric showing the welding protons and their corresponding designations. http://marcomcentral.app.pti.com/printone/ClickEventTracker.ashx?CompanyID=16631&ProductID=37&SKUID=9112330&UserID=-1&Description=&SaveIDToSession=0&EventType=2

Here is a page briefly describing the difference between test position and welding position. http://www.weldingdata.com/testpositionsVSWeldPositions.htm

If you are referring to the 1d, 2d etc. I am at a loss.

Gerald Austin

The only place I can think of offhand where these designations are used is in pipe bending where the designation establishes the radius of the bend through reference to the diameter of the pipe. In other words if you are bending an 18" pipe with a 54" radius it is a 3D bend. This is critical when considering the compressive stresses of the intrados  which can cause wrinkling and the tensile stresses of extrados which can cause thinning. But they have nothing to do with position.