Weld Neck Dimensional Tolerances : ASME B16.5


Welding Neck Flanges
Outside Diameter*When OD is 24” or less±1/16”
When OD is over 24”± 1/8”
Inside Diameter10” and smaller±1/32”
12” through 18”+ 1/16”
20” and larger+1/8”, -1/16”
Diameter of Contact Face1/16” Raised Face±1/32”
1/4” Raised Face Tongue and Groove or Male and Female±1/64”
Diameter of Hub at Point of Welding5” and smaller+3/32”, -1/32”
6” and larger+5/32”, -1/32”
Welding Bevel Standardssee drawings on Page 78
Diameter of Hub at Base*When Hub Base is 24” or less±1/16”
When Hub Base is over 24”±1/8”
Drilling*Bolt Circle±1/16”
Bolt hole spacing+1/32”
Eccentricity of Bolt Circle and Facing (with respect to bore)1/32” max
Length Thru Hub10” and smaller±1/16”
12” and larger±1/8”
Thickness18” and smaller+1/8”, -0”
20” and larger+3/16”, -0”
Where allowance has been left on face for finish. All sizes*+1/8”, -1/16”
In accordance with ANSIB16.5
 *Tolerance for these dimensions not covered by ANSIB16.5