Of course, both methods of tightening will eventualy get the job done. However, on large flanges such as this one, tensioning is advantageous not only because of the reason outlined above but also because it is a faster process. When tensioning, one is able to tighten at least 50% of the stud population at the same time. In some cases it's even possible to tighten 100% simultaneoulsy. This is important because it ensures consistent gasket compression and thus reduces the risk of damage before the joint is even pressurized.
Torquing, as implied above, can also be utilized. However, then one foregoes the previously-described benefits. Furthermore, in order to deal with the inherent innacuracies of any torque-tightening procedure of critical flanges, the bolt bolt stress MUST be verified after tightening. This is imperative since it will enable the operator to "tune" the applied torque at each fastener so that it applies the necessary clamp load. In so doing, one will usually find that it's necessary to apply a different torque to each fastener in oredr to ensure that they are all equally "tight".
