ASME B16.5 Scope
ASME B16.5 covers pressure–temperature ratings, materials, dimensions, tolerances, marking, testing, and methods of designating openings for pipe flanges and flanged fittings.
ASME B16.5 pdf 2020 free download
Flange Rating Classes Flanges with rating class designations 150, 300, 400, 600, 900, 1500, and 2500
Sizes Covered for Flanges
- – Rating classes 150, 300, 400, 600, 900, and 1500: NPS 1/2 through NPS 24
- – Rating class 2500: NPS 1/2 through NPS 12
Flanged Fittings Rating Classes Flanged fittings with rating class designations 150, 300, 400, 600, 900, 1500, and 2500
- Sizes Covered for Flanged Fittings
- – Rating classes 150 and 300: NPS 1/2 through NPS 24
- – Rating classes 400, 600, 900, 1500, and 2500: NPS 1/2 through NPS 24
Measurement Units Requirements given in both metric and U.S. Customary units with diameter of bolts and flange bolt holes expressed in inch units
Materials Covered
- – Flanges and flanged fittings made from cast or forged materials
- – Blind flanges and certain reducing flanges made from cast, forged, or plate materials
Additional Requirements Includes requirements and recommendations regarding flange bolting, gaskets, and joints.
Multiple Material Grades
ASME B16.5 Flange Dimensions in Inches & mm
ASME B16.5 Flange Dimensions Tolerances
For the purpose of determining conformance with ASME B16.5, the conventionfor fixing significantdigitswhere limits, maximum or minimum values, are specified shall be rounded as defined in ASTM Practice E29. This requires that an observed or calculated value shall be rounded to thenearest unitinthe last right-hand digit used for expressing the limit. The listing of decimal tolerances does not imply a particular method of measurement.
1.Center-to-Contact Surfaces and Center-to-End Tolerances
| Required tolerances for various flanges and flanged fitting elements are as follows: | Size | Tolerance, mm (in.) |
| Center-to-Contact Surfaces Other Than Ring Joint | NPS ≤ 10 | ±1.0 (±0.04) |
| NPS ≥ 12 | ±1.5 (±0.06) | |
| Center-to-End (Ring Joint) | NPS ≤ 10 | ±1.0 (±0.04) |
| NPS ≥ 12 | ±1.5 (±0.06) | |
| Contact Surface-to-Contact Surface Other Than Ring Joint | NPS ≤ 10 | ±2.0 (±0.08) |
| NPS ≥ 12 | ±3.0 (±0.12) | |
| End-to-End (Ring Joint) | NPS ≤ 10 | ±2.0 (±0.08) |
| NPS ≥ 12 | ±3.0 (±0.12) |
2.Facings
Inside and outside diameter of large and small tongue and groove and female, ±0.5 mm (±0.02 in.).
Outside diameter, 6.4 mm (0.25 in.) raised face, ±0.5 mm (±0.02 in.).
Ring joint groove tolerances are shown in Table 5 (Table 5C).
| Tolerances that apply to flanges are as follows: Perpendicularity of the face with the bore | Size | Tolerance, deg |
| NPS ≤ 5 | 1 | |
| NPS ≥ 6 | 0.5 |
3.Flange Thickness
| Required tolerances for flange thickness are as follows: | Size | Tolerance, mm (in.) |
| NPS ≤ 18 | +3.0, −0.0 (+0.12, −0.00) | |
| NPS ≥ 20 | +5.0, −0.0 (+0.20, −0.00) |
4.Welding End Flange Ends and Hubs
| Outside Diameter. Required tolerances for the nominal outside diameter dimension A of Figures 7 and 8 of welding ends of welding neck flanges are as follows: | Size | Tolerance, mm (in.) |
| NPS ≤ 5 | +2.0, −1.0 (+0.08, −0.04) | |
| NPS ≥ 6 | +4.0, −1.0 (+0.16, −0.04) |
| Inside Diameter. Required tolerances for the nominal inside diameter of welding ends of welding neck flanges and smaller bore of socket welding flanges (dimension B in the referenced figures) are as follows: | Size | Tolerance, mm (in.) |
| For Straight Hub Welding Flanges, Welding Neck Flange Hub and Welding End Profiles for Wall Thicknesses t From 5 mm (0.19 in.) to 22 mm (0.88 in.), and Welding Neck Flange Hub and Welding End Profiles for Wall Thicknesses t Greater Than 22 mm (0.88 in.), the tolerances are | NPS ≤ 10 | ±1.0 (±0.04) |
| 12 ≤ NPS ≤ 18 | ±1.5 (±0.06) | |
| NPS ≥ 20 | +3.0, −1.5 (+0.12, −0.06) | |
| For Inside Contour for Use With Rectangular Backing Ring, the tolerances are | NPS ≤ 10 | +0.0, −1.0 (+0.0, −0.04) |
| NPS ≥ 12 | +0.0, −1.5 (+0.0, −0.06) |
| Backing Ring Contact Surface. | Size | Tolerance, mm (in.) |
| Required tolerances for the bore of the backing ring contact surface of welding neck flanges, dimension C of Inside Contour for Use With Rectangular Backing Ring and Inside ContourforUse With Taper Backing Ring are as follows: | 2 ≤ NPS ≤ 24 | +0.25, −0.0 (+0.01, −0.0) |
Hub Thickness.
Despite the tolerances specified for dimensions A and B, the thickness of the hub at the welding end shall not be less than 871∕2% of the nominal thickness of the pipe, having an under-tolerance of 12.5% for the pipe wall thickness to which the flange is to be attached or the minimum wall thickness as specified by the purchaser.
5.Length Through Hub on Welding Neck Flanges
| The required tolerances for the length through hubs on welding neck flanges are as follows: |
Size | Tolerance, mm (in.) |
| NPS ≤ 4 | ±1.5 (±0.06) | |
| 5 ≤ NPS ≤10 | +1.5, −3.0 (+0.06, −0.12) | |
| NPS ≥ 12 | +3.0, −5.0 (+0.12, −0.20) |
6.Flange Bore Diameter
| Lapped and Slip-On Flange Bores. The required tolerances for lapped and slip-on flange bore diameters are as follows: | Size | Tolerance, mm (in.) |
| NPS ≤ 10 | +1.0, −0.0 (+0.04, −0.0) | |
| NPS ≥ 12 | +1.5, −0.0 (+0.06, −0.0) | |
| Counterbores, Threaded Flanges. The required tolerances for threaded flange counterbores are as follows: | NPS ≤ 10 | +1.0, −0.0 (+0.04, −0.0) |
| NPS ≥ 12 | +1.5, −0.0 (+0.06, −0.0) | |
| Counterbores, Socket Welding Flanges. The required tolerance for socket end counterbores is as follows: | 1/2 ≤ NPS ≤3 | ±0.25 (±0.010) |
7.Drilling and Facing
Bolt Circle Diameter. The required tolerance for all bolt circle diameters is as follows: ±1.5 mm (±0.06 in.)
Bolt Hole to Bolt Hole. The required tolerance for the center-to-center of adjacent bolt holes is as follows: ±0.8 mm (±0.03 in.)
| Bolt Circle Concentricity. The required toler ances for concentricity between the flange bolt circle diameter and machine facing diameters are as follows: | Size | Tolerance, mm (in.) |
| NPS ≤ 2 1/2 | 0.8 (0.03) | |
| NPS ≥ 3 | 1.5 (0.06) |
