Weldoflange vs. Flangeolet

You can use both for this branch connection, but is better if you talk about "Flanged Olet". Normally are forged flanges integrally reinforced outlet fitting. They are more expensives but reduces the welding and installation times. Quality increasse also. Good solution for hot taps. For instruments, like thermowelds the use of "Thermalets" give good results (Moves the joint weld away from the instrument top)

Go here:

http://www.bonneyforge.com/OletCat.PDF

or Here:

http://wfi-intl.com/WFI_catalog05.pdf

To see the fifferent types of "O-Let fittings available and some claims about benefits of each.