The Slip-on flange has a low hub because the pipe slips into the flange prior to welding. Slip-On Flanges, SO Flange 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 Standards, Dimensions & Weight ASME/ANSI B16.5 Class 150 SO ASME/ANSI B16.5 Class 300 SO ASME/ANSI B16.5 Class 600 SO ASME/ANSI B16.5 Class 900 SO BS 3293 Class 150 SO BS 3293 Class 300 SO BS 3293 Class 600 SO DIN 86029 PN 10 Specifications of Slip-on flange: Size: 1/2 to 60, DN 12mm to DN 1500mm . Pressure class: Class 150 to Class 2,500, PN 2.5 to PN 250 Facing: RF / RTJ Material of Slip-on flange: Cabon steel: A105, A350 LF2 Stainless steel: A182 F304/F304L/F316/F316L/F321 Alloy steel: F11, F12 Packing: plywood case and plywood pallet