Some Pipefitters and Welders have only worked in the field while others have only experienced work in shop environments. In my experience the on site, field work positions, hire and implement two separate employees, a tradesman for each role, one is strictly a fitter, one is strictly a welder. I have experienced both of these roles, in the field, fitting and welding seperatly; my time working in a fabrication shop environment holds true to the same. In the two most recent positions I accepted, I held the title of both a fitter and a welder, that being "Journeyman Pipefitter/Welder Level II." Seventy percent of my time was spent in the shop, prefabricating pipe system subassemblies to the closest feasible and possible level of completion, eliminating the greatest number of field welds required by the field team. During the fitting process two hole, level, plumb, square, and high/low are the most important things to ensure correctness. By building a structure in our shop that had each size of RFWN flanges, ranging from 2.5" up to 18" fit up properly, and putting bolts one size larger than what would be used in normal circumstances (they should barely fit through the bolt holes, too much factory paint can make you hammer the bolts through). Using vice grips or any clamping you prefer, you can attach a new flange to your flange rail, face to face, and start building off of that. In some cases our fit inches (the quantity of fits multiplied by the diameter of the pipe in each fit) dramatically increased from a 150-200 inches in 8 hours up to 250-325 inches.