STANDARD · ASME-B16-5

ASME B16.5 Flange Dimensions

ASME B16.5-2025 · ASME B16.5

ASME B16.5-2025North America, Middle East, South-East Asiapressure class

ASME B16.5 is the baseline American flange standard for pipe sizes NPS 1/2 to NPS 24 in pressure classes 150 through 2500. It defines outside diameter, flange thickness, raised-face diameter and height, bolt circle, bolt count, bolt hole diameter and hub geometry for weld neck, slip-on, blind, socket-weld, threaded and lap-joint flanges.

Because B16.5 is organised by nominal pipe size and class, a flange is only interchangeable with another B16.5 flange of the same size, class and facing. Class sets the wall thickness, bolt count and bolt size; the actual allowable pressure is read from the B16.5 pressure–temperature tables for the material group and design temperature. Above NPS 24, ASME B16.47 takes over — the two standards are not interchangeable. Coverage limits are part of the standard: Class 2500 runs only to NPS 12 and has no slip-on flanges, Class 1500 slip-on flanges stop at NPS 2-1/2, and Classes 900, 1500 and 2500 have no NPS 3-1/2.

Base materialASTM A105

Size notationNPS (inch)

Material options5 groups

Reference data5 topics

DIMENSIONS

Dimension tables

One row per specification. Open a size for the drawing, pressure ratings and printable A4 sheet.

Weld Neck 136 Slip-On 110 Blind 136

Blind: A solid disc bolted over a line end or vessel opening for isolation, testing and future tie-ins. 136 specifications.

136 specifications

Size	Rating	Outside Ø D	Thickness C	Raised face D2	Bolt circle K	Bolting	Hub A	Length H	Weight
6″DN150	Class 2500	482.6	108	215.9	368.3	8 × Ø54	—	—	156 kg	Spec sheet
8″DN200	Class 150	342.9	28.4	269.7	298.5	8 × Ø22.2	—	—	20.4 kg	Spec sheet
8″DN200	Class 300	381	41.1	269.7	330.2	12 × Ø25.4	—	—	36.7 kg	Spec sheet
8″DN200	Class 400	381	47.8	269.7	330.2	12 × Ø28.6	—	—	45.4 kg	Spec sheet
8″DN200	Class 600	419.1	55.6	269.7	349.3	12 × Ø31.8	—	—	63.5 kg	Spec sheet
8″DN200	Class 900	469.9	63.5	269.7	393.7	12 × Ø38.1	—	—	90.7 kg	Spec sheet
8″DN200	Class 1500	482.6	91.9	269.7	393.7	12 × Ø44.5	—	—	136 kg	Spec sheet
8″DN200	Class 2500	552.5	127	269.7	438.2	12 × Ø54	—	—	240 kg	Spec sheet
10″DN250	Class 150	406.4	30.2	323.9	362	12 × Ø25.4	—	—	31.8 kg	Spec sheet
10″DN250	Class 300	444.5	47.8	323.9	387.4	16 × Ø28.6	—	—	56.2 kg	Spec sheet
10″DN250	Class 400	444.5	53.8	323.9	387.4	16 × Ø31.8	—	—	70.3 kg	Spec sheet
10″DN250	Class 600	508	63.5	323.9	431.8	16 × Ø34.9	—	—	104 kg	Spec sheet
10″DN250	Class 900	546.1	69.9	323.9	469.9	16 × Ø38.1	—	—	132 kg	Spec sheet
10″DN250	Class 1500	584.2	108	323.9	482.6	12 × Ø50.8	—	—	231 kg	Spec sheet
10″DN250	Class 2500	673.1	165.1	323.9	539.8	12 × Ø66.7	—	—	465 kg	Spec sheet
12″DN300	Class 150	482.6	31.8	381	431.8	12 × Ø25.4	—	—	49.9 kg	Spec sheet
12″DN300	Class 300	520.7	50.8	381	450.9	16 × Ø31.8	—	—	83.9 kg	Spec sheet
12″DN300	Class 400	520.7	57.2	381	450.9	16 × Ø34.9	—	—	102 kg	Spec sheet
12″DN300	Class 600	558.8	66.5	381	489	20 × Ø34.9	—	—	134 kg	Spec sheet
12″DN300	Class 900	609.6	79.2	381	533.4	20 × Ø38.1	—	—	188 kg	Spec sheet
12″DN300	Class 1500	673.1	124	381	571.5	16 × Ø54	—	—	313 kg	Spec sheet
12″DN300	Class 2500	762	184.2	381	619.3	12 × Ø73	—	—	590 kg	Spec sheet
14″DN350	Class 150	533.4	35.1	412.8	476.3	12 × Ø28.6	—	—	63.5 kg	Spec sheet
14″DN350	Class 300	584.2	53.8	412.8	514.4	20 × Ø31.8	—	—	113 kg	Spec sheet
14″DN350	Class 400	584.2	60.5	412.8	514.4	20 × Ø34.9	—	—	132 kg	Spec sheet
14″DN350	Class 600	603.3	69.9	412.8	527.1	20 × Ø38.1	—	—	161 kg	Spec sheet
14″DN350	Class 900	641.4	85.9	412.8	558.8	20 × Ø41.3	—	—	236 kg	Spec sheet
14″DN350	Class 1500	749.3	133.4	412.8	635	16 × Ø60.3	—	—	442 kg	Spec sheet
16″DN400	Class 150	596.9	36.6	469.9	539.8	16 × Ø28.6	—	—	81.6 kg	Spec sheet
16″DN400	Class 300	647.7	57.2	469.9	571.5	20 × Ø34.9	—	—	134 kg	Spec sheet
16″DN400	Class 400	647.7	63.5	469.9	571.5	20 × Ø38.1	—	—	168 kg	Spec sheet
16″DN400	Class 600	685.8	76.2	469.9	603.3	20 × Ø41.3	—	—	225 kg	Spec sheet
16″DN400	Class 900	704.9	88.9	469.9	616	20 × Ø44.5	—	—	272 kg	Spec sheet
16″DN400	Class 1500	825.5	146.1	469.9	704.9	16 × Ø66.7	—	—	590 kg	Spec sheet
18″DN450	Class 150	635	39.6	533.4	577.9	16 × Ø31.8	—	—	99.8 kg	Spec sheet
18″DN450	Class 300	711.2	60.5	533.4	628.7	24 × Ø34.9	—	—	179 kg	Spec sheet
18″DN450	Class 400	711.2	66.5	533.4	628.7	24 × Ø38.1	—	—	206 kg	Spec sheet
18″DN450	Class 600	743	82.6	533.4	654.1	20 × Ø44.5	—	—	286 kg	Spec sheet
18″DN450	Class 900	787.4	101.6	533.4	685.8	20 × Ø50.8	—	—	386 kg	Spec sheet
18″DN450	Class 1500	914.4	162.1	533.4	774.7	16 × Ø73	—	—	794 kg	Spec sheet
20″DN500	Class 150	698.5	42.9	584.2	635	20 × Ø31.8	—	—	129 kg	Spec sheet
20″DN500	Class 300	774.7	63.5	584.2	685.8	24 × Ø34.9	—	—	229 kg	Spec sheet
20″DN500	Class 400	774.7	69.9	584.2	685.8	24 × Ø41.3	—	—	266 kg	Spec sheet
20″DN500	Class 600	812.8	88.9	584.2	723.9	24 × Ø44.5	—	—	367 kg	Spec sheet
20″DN500	Class 900	857.3	108	584.2	749.3	20 × Ø54	—	—	488 kg	Spec sheet
20″DN500	Class 1500	984.3	177.8	584.2	831.9	16 × Ø79.4	—	—	1009 kg	Spec sheet
22″DN550	Class 150	749.3	46	641.4	692.2	20 × Ø28.6	—	—	—	Spec sheet
22″DN550	Class 300	838.2	66.5	641.4	743	24 × Ø41.3	—	—	—	Spec sheet
22″DN550	Class 400	838.2	73.2	641.4	743	24 × Ø44.5	—	—	—	Spec sheet
22″DN550	Class 600	870	95.3	641.4	777.7	24 × Ø47.6	—	—	—	Spec sheet
24″DN600	Class 150	812.8	47.8	692.2	749.3	20 × Ø34.9	—	—	195 kg	Spec sheet
24″DN600	Class 300	914.4	69.9	692.2	812.8	24 × Ø41.3	—	—	358 kg	Spec sheet
24″DN600	Class 400	914.4	76.2	692.2	812.8	24 × Ø47.6	—	—	404 kg	Spec sheet
24″DN600	Class 600	939.8	101.6	692.2	838.2	24 × Ø50.8	—	—	567 kg	Spec sheet
24″DN600	Class 900	1041.4	139.7	692.2	901.7	20 × Ø66.7	—	—	919 kg	Spec sheet
24″DN600	Class 1500	1168.4	203.2	692.2	990.6	16 × Ø92.1	—	—	1644 kg	Spec sheet

REFERENCE

Pressure ratings, materials and tolerances

Transcribed from ASME B16.5-2025 with table and page references.

Pressure-temperature ratings

ASME B16.5-2025 pressure ratings by material group

Tables 2-1.1 (SI units, bar) and 2-1.1C (U.S. Customary units, psig) of ASME B16.5-2025 give the maximum allo…

Open reference Material groups

ASME B16.5-2025 material groups and bolting tables

Table 1.1-1 is the master material list of ASME B16.5-2025. For every accepted material it gives four things:…

Open reference Tolerances

ASME B16.5-2025 flange tolerances (Section 7)

Section 7 of ASME B16.5-2025 sets the manufacturing and inspection tolerances for flanges and flanged fitting…

Open reference Marking

ASME B16.5-2025 marking requirements (Section 4)

Section 4 of ASME B16.5-2025 defines the identification markings that must be applied to flanges and flanged …

Open reference Edition changes

ASME B16.5-2025: what changed from the 2020 edition

ASME B16.5-2025 is the current edition of the American pipe-flange and flanged-fitting standard, covering NPS…

Open reference

How to read the pressure class

ASME classes are not fixed pressures. For ASTM A105 (material group 1.1) the ASME B16.5-2025 ambient rating is 285 psi (19.6 bar) at Class 150, 740 psi (51.0 bar) at Class 300, 985 psi (68.0 bar) at Class 400, 1,480 psi (102.0 bar) at Class 600, 2,220 psi (153.1 bar) at Class 900, 3,705 psi (255.1 bar) at Class 1500 and 6,170 psi (425.1 bar) at Class 2500 at 38 °C (100 °F), derating as temperature rises. The 2025 edition revised the rating tables (record 23-2509); these are the 2025 values and the full temperature tables are on the ASME B16.5 pressure-ratings page.

Edition and verification

Dimension values on this page have been checked cell by cell against ASME B16.5-2025, using both the SI and U.S. Customary tables. The 2025 edition revised the bore (B) dimension figures and the minimum hub-height method, neither of which is a field published in these tables; outside diameter, thickness, hub, length, bolt circle and bolt-hole values match the 2025 edition. Raised-face height follows the 2025 rule: 1.5 mm for Classes 150 and 300, 6.4 mm for Classes 400 to 2500.

Data imported 2026-11-05 08:05.