In welding, we have different types of grooves like V-shaped groove, U-shaped groove, Double V, Double U, J and Double J. What is the advantage of each kind over the other?
Edge preparation is required for joining thick plates for proper welding joint. Its always preferable less volume of groove size. Less volume of groove gives less HAZ and having good mechanical properties. Double V, Double U joints are there but we need to follow certain welding sequence like first layer on one side and second layer on second groove which leads to less distortions. Single V can be used most of the cases because of easy edge preparation instead of U. J joint can be used in specific purposes like one material is weldable another is not weldable. Then due to J joint we have prepared J on only non weldable plate another plate is without edge preparation. It is also depends on the thermal conductivity of the material
Mostly a function of thickness. It is expensive to fill a groove with weld metal so try to use a low volume but simple groove. Such a ( simple) V groove at 1/2 " thickness and a U groove at 3" thickness.