ABOUT THE BLEND:
a simple metal shader applied on a T shaped pipe
a curve around the connection for the welding part
a curve's profile for the bevel shape.
a node's group for tweeking the welding aspect
Welding Curve Is Material node's group to apply on UV based curves extracted from edge topology or created from scratch.
How to use it?
select the edges you want to be converted to bezier curve. Duplicate in place . Separate.
convert the new object to bezier curve.
set your curve interpolation type in the W menu Set Spline Type (Bezier)
Create another bezier Spline from scratch (on top view), to be used as bevel curve on the
extracted edge spline . it ll be used for profiling your welding joint
Apply the ;appended material from the file to your main curve or buid your own with "welding bourlet" node's group
Once you have it applied as bevel curve on extracted edge's curve. Play with Tilt to correctly orient the welding joint.
Push away curve's vertices on there local axis to match closely as possible the welded's surfaces. (Better use occlusion to see how far you are from surfaces)
Repeat: Number of welding rings regarding your scene scale.
Torsion: How much the rings are bended
Consistance: How much" material" there is for the welding joint
Irregularity Size: the scale of the ring's variations
Irregularity Details: The amount of noise on those irregularitys
Alpha Propagate: How close is the Alpha mask from the edge of the welding mesh border