Slip-on flanges, abbreviated as SOF, are designed to slip over the outside of pipe, long-tangent elbows, reducers, and swages. The flange has poor resistance to shock and vibration. It is easier to align than a weld neck flange.
A variation of the Slip On flange also exists. This is the Slip-On Reducing Flange. This is simply a larger (say a 14″) Slip-On flange blank that, instead of the Center (pipe) hole being cut out (or drilled out) for 14″ pipe it is cut out for a 6″ (or some other size) pipe. The SO Reducing flange is basically used for reducing the line size where space limitations will not allow the length of a weld neck flange and reducer combination. The use of the Slip-On Reducing Flange should only be used where the flow direction is from the smaller size into the larger size.
Slip On flanges or SO flanges are commonly lower in price than weld-neck flanges, and to this effect are a popular choice for our customers.
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