ASME B16.5 : Complete Guide to Blind Flange Dimensions

ASME B16.5 is an important standard for “Pipe Flanges and Flange Fittings” that specifies the dimensions, tolerances, materials, pressure-temperature ratings, testing, and marking of blind flange from 1/2-inch to 24-inch NPS (Nominal Pipe Size).

A blind flange is a solid disc that does not have a bore or a hub. Its primary function is to seal off the end of a piping system, valve opening, or pressure vessel opening.

ZIZI is committed to professionally manufacturing and exporting various types of blind flanges. We are well aware that blind flanges play a vital role in industrial piping and pressure vessel systems – they are not only the end points of connection and sealing, but also key components to ensure safe operation, maintenance or future expansion of the system.

With years of industry experience and persistent pursuit of quality, ZIZI ensures that every blind flange we produce meets strict international standards and meets the specific needs of global customers through precise manufacturing processes.

Common pressure levels (Class)

According to ASME B16.5, blind flanges are divided into the following seven pressure levels:

150#

300#

400#

600#

900#

1500#

2500#

The higher the pressure level, the thicker the flange wall and the stronger the pressure bearing capacity.

BL Class 150 lb

Blind Flange Dimensions (ASME B16.5) in Millimeter.

Norminal Pipe Size		A	C	G	H	I	J	Weight
	mm	mm	mm	mm	Number of Holes	mm	mm	kg/piece
1/2	21.3	88.9	11.2	35. 10	4	15.7	60.45	0.42
3/4	26.7	98.6	12.7	42.9	4	15.7	69.85	0.61
1	33.4	108	14.2	50.8	4	15.7	79.25	0.86
11/4	42.2	117.3	15.7	63.5	4	15.7	88.9	1.17
11/2	48.3	127	17.5	73. 15	4	15.7	98.6	1.53
2	60.3	152.4	19. 10	91.9	4	19.1	120.7	2.42
21/2	73.0	177.8	22.4	104.6	4	19.1	139.7	3.94
3	88.9	190.5	23.9	127	4	19.1	152.4	4.93
31/2	101.6	215.9	23.9	139.7	8	19.1	177.8	6.17
4	114.3	228.6	23.9	157.2	8	19.1	190.5	7.00
5	141.3	254	23.9	185.7	8	22.4	215.9	8.63
6	168.3	279.4	25.4	215.9	8	22.4	241.3	11.3
8	219.1	342.9	28.4	269.7	8	22.4	298.5	19.6
10	273.0	406.4	30.2	323.9	12	25.4	362	28.8
12	323.8	482.6	31.75	381	12	25.4	431.8	43.2
14	355.6	533.4	35. 10	412.8	12	28.4	476.3	58.1
16	406.4	596.9	36.6	469.9	16	28.4	539.8	76.0
18	457.2	635	39.6	533.4	16	31.75	577.9	93.7
20	508.0	698.5	42.9	584.2	20	31.75	635	122
24	609.6	812.8	47.8	692.2	20	35.1	749.3	185

BL Class 300lb

Blind Flange Dimensions (ASME B16.5) in Millimeter.

Nominal Pipe Size		A	C	G	H	I	J	Weight
	mm	mm	mm	mm	Number of Holes	mm	mm	kg/piece
1/2	21.3	95.2	14.2	35.1	4	15.7	66.55	0.64
3/4	26.7	117.3	15.7	42.9	4	19	82.5	1.11
1	33.4	123.9	17.5	50.8	4	19	88.9	1.39
11/4	42.2	133.3	19	63.5	4	19	98.5	1.79
11/2	48.3	155.4	20.6	73.15	4	22.3	114.3	2.66
2	60.3	165. 1	22.3	91.9	8	19. 10	127	3.18
21/2	73.0	190.5	25.4	104.6	8	22.3	1.493	4.85
3	88.9	209.5	28.4	127	8	22.3	168.1	6.81
31/2	101.6	228.6	30.2	139.7	8	22.3	184.1	8.71
4	114.3	254	31.7	157.2	8	22.3	200.1	11.5
5	141.3	279.4	35	185.7	8	22.3	234.9	15.6
6	168.3	317.5	36.5	215.9	12	22.3	269.7	20.9
8	219. 1	381	1.620 41.10	269.7	12	25.4	330.2	34.3
10	273.0	444.5	47.7	323.9	16	28.4	387.3	53.3
12	323.8	520.7	50.8	381	16	31.7	450.8	78.8
14	355.6	584.2	53.8	412.8	20	31.7	514.3	105
16	406.4	647.7	57.15	469.9	20	35	571.5	137
18	457.2	711.2	60.45	533.4	24	35	628.6	175
20	508.0	774.7	63.5	584.2	24	35	685.8	221
24	609.6	914.4	69.85	692.2	24	41. 10	812.8	339

BL Class 400lb

Blind Flange Dimensions (ASME B16.5) in Millimeter.

Nominal Pipe Size		A	C	G	H	I	J	Weight
	Outside Diameter	Overall Diameter	Flange Thickness min	Face Diameter	Number of Holes	Bolt Hole Diameter	Diameter of Circle of Holes	kg/piece
	mm	mm	mm	mm		mm	mm
1/2	21.3	95.2	14.2	35. 10	4	15.7	66.55	0.76
3/4	26.7	117.3	15.7	42.9	4	19.1	82.6	1.28
1	33.4	123.9	17.5	50.8	4	19.1	88.9	1.60
11/4	42.2	133.3	20.6	63.5	4	19.1	98.6	2.23
11/2	48.3	155.4	22.3	73. 15	4	22.4	114.3	3.25
2	60.3	165.1	25.4	91.9	8	19.1	127	4.15
21/2	73	190.5	28.4	104.6	8	22.4	149.4	6.13
3	88.9	209.5	31.7	127	8	22.4	168.1	8.44
31/2	101.6	228.6	35	139.7	8	25.4	184.2	11.0
4	114.3	254	35. 10	157.2	8	25.4	200.2	13.7
5	141.3	279.4	38. 10	185.7	8	25.4	235	18.5
6	168.3	317.5	41. 10	215.9	12	25.4	269.7	25.5
8	219.1	381	47.8	269.7	12	28.4	330.2	42.6
10	273	444.5	53.8	323.9	16	31.75	387.4	64.5
12	323.8	520.7	57. 15	381	16	35.1	450.9	94.30
14	355.6	584.2	60.45	412.8	20	35.1	514.4	124
16	406.4	647.7	63.5	469.9	20	38.1	571.5	162
18	457.2	711.2	66.55	533.4	24	38.1	628.7	205
20	508	774.7	69.85	584.2	24	41.1	685.8	254
24	609.6	914.4	76.2	692.2	24	47.8	812.8	386

BL Class 600lb

Blind Flange Dimensions (ASME B16.5) in Millimeter.

Nominal Pipe Size		A	C	G	H	I	J	Weight
	Outside Diameter	Overall Diameter	Flange Thickness min	Face Diameter	Number of Holes	Bolt Hole Diameter	Diameter of Circle of Holes	kg/piece
	mm	mm	mm	mm		mm	mm
1/2	21.3	95.2	14.2	35.1	4	15.7	66.55	0.76
3/4	26.7	117.3	15.7	42.9	4	19. 10	82.6	1.28
1	33.4	123.9	17.5	50.8	4	19. 10	88.9	1.60
11/4	42.2	133.3	20.6	63.5	4	19. 10	98.6	2.23
11/2	48.3	155.4	22.3	73.15	4	22.4	114.3	3.25
2	60.3	165. 1	25.4	91.9	8	19. 10	127	4.15
21/2	73	190.5	28.4	104.6	8	22.4	149.4	6.13
3	88.9	209.5	31.7	127	8	22.4	168.1	8.44
31/2	101.6	228.6	35	139.7	8	25.4	184.2	11.0
4	114.3	273. 1	38.1	157.2	8	25.4	215.9	17.3
5	141.3	330.2	44.5	185.7	8	28.4	266.7	29.4
6	168.3	355.6	47.8	215.9	12	28.4	292.1	36.1
8	219. 1	419. 1	55.6	269.7	12	31.75	349.3	58.9
10	273	508	63.5	323.9	16	35. 10	431.8	97.5
12	323.8	558.8	66.55	381	20	35. 10	489	124
14	355.6	603.3	69.85	412.8	20	38. 10	527.1	151
16	406.4	685.8	76.2	469.9	20	41. 10	603.3	214
18	457.2	743	82.6	533.4	20	44.5	654.1	272
20	508.0	812.8	88.9	584.2	24	44.5	723.9	349
24	609.6	939.8	101.6	692.2	24	50.8	838.2	533

BL Class 900lb

Blind Flange Dimensions (ASME B16.5) in Millimeter.

Nominal Pipe Size		A	C	G	H	I	J	Weight
	Outside Diameter	Overall Diameter	Flange Thickness min	Face Diameter	Number of Holes	Bolt Hole Diameter	Diameter of Circle of Holes	kg/piece
	mm	mm	mm	mm		mm	mm
1/2	21.3	120.6	22.3	35. 10	4	22.3	82.5	1.77
3/4	26.7	130	25.4	42.9	4	22.3	88.9	2.42
1	33.4	149.3	28.4	50.8	4	25.4	101.6	3.57
11/4	42.2	158.7	28.4	63.5	4	25.4	111.2	4.15
11/2	48.3	177.8	31.7	73. 15	4	28.4	123.9	5.75
2	60.3	215.9	38. 10	91.9	8	25.4	165.1	10.1
21/2	73	244.3	41. 10	104.6	8	28.4	190.5	14.0
3	88.9	241.3	38. 10	127	8	25.4	190.5	13.1
4	114.3	292.1	44.5	157.2	8	31.7	234.9	26.9
5	141.3	349.2	50.8	185.7	8	35	279.4	36.5
6	168.3	381	55.6	215.9	12	31.7	317	47.40
8	219.1	469.9	63.5	269.7	12	38.1	393.7	82.5
10	273	546.1	69.85	323.9	16	38.1	469.9	122
12	323.8	609.6	79.25	381	20	38.1	533.4	173
14	355.6	641.3	85.8	412.8	20	41.1	558.8	206
16	406.4	704.8	88.9	469.9	20	44.4	615.9	259
18	457.2	787.4	101.6	533.4	20	50.8	685.8	367
20	508	857.2	107.9	584.2	20	53.8	749.3	463
24	609.6	1041.4	139.7	692.2	20	66.55	901.7	876

BL Class 1500lb

Blind Flange Dimensions (ASME B16.5) in Millimeter.

Nominal Pipe Size		A	C	G	H	I	J	Weight
	Outside Diameter	Overall Diameter	Flange Thickness min	Face Diameter	Number of Holes	Bolt Hole Diameter	Diameter of Circle of Holes	kg/piece
	mm	mm	mm	mm		mm	mm
1/2	21.3	120.6	22.3	35.1	4	22.3	82.5	1.77
3/4	26.7	130	25.4	42.9	4	22.3	88.9	2.42
1	33.4	149.3	28.4	50.8	4	25.4	101.6	3.57
11/4	42.2	158.7	28.4	63.5	4	25.4	111.2	4.15
11/2	48.3	177.8	31.7	73.15	4	28.4	123.9	5.75
2	60.3	215.9	38.1	91.9	8	25.4	165.1	10.1
21/2	73	244.3	41.1	104.6	8	28.4	190.5	14.0
3	88.9	266.7	47.7	127	8	31.7	203.2	19.1
4	114.3	311.1	53.8	157.2	8	35	241.3	29.9
5	141.3	374.6	73.15	185.7	8	41.1	292.1	58.4
6	168.3	393.7	82.5	215.9	12	38.1	317.5	71.8
8	219. 1	482.6	91.9	269.7	12	44.4	393.7	122
10	273	584.2	107.9	323.9	12	50.8	482.6	210
12	323.8	673. 1	123.9	381	16	53.8	571.5	316
14	355.6	749.3	133.3	412.8	16	60.45	635	420
16	406.4	825.5	146	469.9	16	66.55	704.8	558
18	457.2	914.4	162	533.4	16	73. 15	774.7	760
20	508	984.2	177.8	584.2	16	79.25	831.8	965
24	609.6	1168.4	203.2	692.2	16	91.9	990.6	1558

BL Class 2500lb

Blind Flange Dimensions (ASME B16.5) in Millimeter.

Nominal Pipe Size		A	C	G	H	I	J	Weight
	Outside Diameter	Overall Diameter	Flange Thickness min	Face Diameter	Number of Holes	Bolt Hole Diameter	Diameter of Circle of Holes	kg/piece
	mm	mm	mm	mm		mm	mm
1/2	21.3	133.4	30.2	35. 10	4	22.4	88.9	2.99
3/4	26.7	139.7	31.7	42.9	4	22.4	95.3	3.50
1	33.4	158.8	35. 10	50.8	4	25.4	108	4.96
11/4	42.2	184.2	38. 10	63.5	4	28.4	130	7.35
11/2	48.3	203.2	44.5	73. 15	4	31.75	146.1	10.4
2	60.3	235	50.8	91.9	8	28.4	171.5	15.6
21/2	73	266.7	57. 15	104.6	8	31.75	196.9	22.6
3	88.9	304.8	66.55	127	8	35.1	228.6	34.8
4	114.3	355.6	76.2	157.2	8	41.1	273.1	53.9
5	141.3	419.1	91.9	185.7	8	47.88	323.9	90.8
6	168.3	482.6	108	215.9	8	53.8	368.3	141
8	219.1	552.5	127	269.7	12	53.8	438.2	214
10	273	673.1	165.1	323.9	12	66.55	539.8	411
12	323.8	762	184.2	381	12	73.15	619.3	592

7 7 月, 2025