Flange Tolerance

Pipe flange is a method of connecting pipes, valves, pumps and other equipment to form a piping system. It also provides easy access for cleaning, inspection or modification.

Tolerance of Welding Neck Flanges
Outside DiameterWhen O.D. is 24" or less ±1.6mm﹡
Inside Diameter10" and smaller ±0.8mm
12" thru 18" ±1.6mm
20" and larger +3.2mm, -1.6mm
Outside Diameter of hub5" and smaller +2.4mm, -0.8mm﹡
6" and larger +4.0mm, -0.8mm
Diameter of contact face1/16" rasied face tongue and groove male, female ±0.8mm
1/4" rasied face tongue and groove male, female ±0.4mm
Diameter of hub at basewhen hub base is 24" or smaller ±1.6mm﹡
Diameter of hub at point of welding5" and smaller +2.4mm, -0.8mm
6" and larger +4.0mm, -0.8mm
DrillingBolt circle ±1.6mm
Bolt hole spacing ±0.8mm
Eccentricity of bolt circle with respect to facing2 1/2" and smaller: 0.8mm, max﹡
Eccentricity of bolt circle with respect to bore3" and larger: 1.6mm, max﹡
Thickness18" and smaller +3.2mm, -0mm
20" and larger +4.8mm, -0mm
Length of thru hub10" and smaller ±1.6mm
12" and larger ±3.2mm

Tolerance of Threaded Flanges, Socket Welding Flanges, Slip-On Flanges
Lap Joint Flanges and Blind Flanges
Outside DiameterWhen O.D. is 24" or less ±1.6mm﹡
Inside DiameterThreadedWithin limits on boring gauge
Socket welding, Slip-on and Lap joint, 10" and smaller +0.8mm, -0mm
Socket welding, Slip-on and Lap joint, 12" and larger +1.6mm, -0mm
Outside Diameter of hub5" and smaller +2.4mm, -0.8mm﹡
6" and larger +4.0mm, -0.8mm
Diameter of contact face1/16" rasied face tongue and groove male, female ±0.8mm
1/4" rasied face tongue and groove male, female ±0.4mm
Diameter of counterboresame as for inside diameter
DrillingBolt circle±1.6mm
Bolt hole spacing±0.8mm
Eccentricity of bolt circle with respect to facing2 1/2" and smaller: 0.8mm, max﹡
Eccentricity of bolt circle with respect to bore3" and larger: 1.6mm, max﹡
Thickness18" and smaller +3.2mm, -0mm
20" and larger +4.8mm, -0mm
Length of thru hub10" and smaller ±1.6mm
12" and larger ±3.2mm

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