The Slip-on flange has a low hub because the pipe slips into the flange prior to welding.
It is welded both inside and out to provide suffcient strength and prevent leakage.Slip-on flanges are all bored slightly larger than the O.D. of the pipe. They are preferred over welding neck flanges bu many users due to their lower intial cost, but final intallation cost is probably not much less than that of the welding neck flange because of the additional welding involved.
Advantages of slip on flanges:
Low cost installation
Less time needed to spent on ensuring the accuracy of the cut pipe
They are somewhat easier to align
The slip-on flanges have low hub because the pipe slips into the flange before welding
The flange is welded both inside and outside to provide sufficient strength
They prevent leakage
SOH Flange SO Flange Weight SO Flange Demensions SO Flange 150 Slip On Pipe Flange Slip On Flange Raised Face