In general, the parts of a groove weld all work together to increase/decrease weldablility, increase/decrease volume of weld, and increase/decrease weld joint prep time.
There are standard joint designs that are preferred and typical for many situations. I have welded 10" Schedule 160 with a 3/32" gap at the top and a 3/4" or so gap at the bottom. Techniques and settings all had to be varied during every part of the weld to get an RT Quality Root for B31.1 requirements.
With SMAW, the joint geometry will come into play sooner than with processes with smaller diameter electrodes. Because of the larger diameter electrode and the fact that the flux is on the outside, the ability for a joint with an narrow root opening, narrow groove angle, or thick root face may be more difficult than one with a more "open" joint. On the other extreme, wide root opening, larger groove angle, or thinner root face may cause excessive welding/distortion, and make controlling the root profile difficult.
All of the "parts" of a groove play a role in how easy it is to weld. As your skill grows as a welder the "perfect" fitup will grow in tolerances and you will gain some preferences when you are in a situation that allows some variation.
As welders, we may or may not have any options but to weld what was put in front of us or go home and let someone else that can handle it, weld it up. (Not a good cjhoice IMO).
Your numbers you provided are not firm. A CJP groove with a 1/16 root opening, 1/8" Root Face, and a 45 degree included angle would be tough in most positions and most processes. Take that same joint and either open the root opening to 5/16"or reduce the root face to 0 with a 70 degree included angle and it becomes more weldable.
There are "standards" in many industries and the structural world has AWS D1.1 for prequalified joint details or restricted amounts that geometry can change before a WPS must be requalified .
For piping situations, there are standards that address the preparation on the ends of fittings but those are almost always altered in the field because of inconsistencies, WPS requirements, or welder preference.
I hope you continue to chase welding related knowledge.
Have a great day.
Gerald Austin
