weep rings at pipe penetrations through conc walls

huangyhg

weep rings at pipe penetrations through conc walls
i was wondering if anybody can tell me what the minimum weep ring size that needs to be welded ontop steel pipes to achieve a tight water-seal. i heard a 2" steel ring is all that is required to achieve a water tight penetration. is this true? for my project, i have pipes ranging from 8" to 60" in size and these will be running through a bunch of liquid tanks. i need to know the minimum size required because space is tight in a bunch of places and welding a flange on the pipe will not work.
thanks guys!
there are other ways to seal around pipes passing thru concrete wall. bentonite water stop is one - see this simplified detail