BLIND FLANGE

Contrary to all the flange types seen above, blind flanges do not have a center hole, and are used to blind or seal a pipeline, a valve/pressure vessel and block the flow of the fluid.

Blind flanges allow easy access to the pipeline, as they can be easily unbolted to let the operator execute activities inside the terminal end of the pipe (this is also the reason why the blind flange type is used as manhole for pressure vessels, at times).

It is maybe interesting to observe that, while this flanges type is easier to manufacture, they are sold at a premium average cost per kilogram compared to the other flange types.

Blind flange dimensions are covered in ASME B16.5 – which covers Pipe Flanges and Flanged Fittings for size NPS ½” to 24” for above NPS 26” to 60” it should be as per ASME B16.47.

During dimensional inspection of flange, you should check for following;

Outer Diameter of body
Bolt Circle & Bolt hole Diameter
Straightness and alignment of the bolt hole
Thickness of the Blind

blind flange dimensions

Class 150 Blind Flange Dimensions

Size in Inch	Size in mm	Outer Dia.	Flange Thick.	RF Dia.	RF Height	PCD	No of Bolts	Bolt Size UNC	Machine Bolt Length	RF Stud Length	Hole Size	ISO Stud Size	Weight in kg
		A	B	C	D	E
1/2	15	90	9.6	34.9	2	60.3	4	1/2	50	55	5/8	M14	0.9
3/4	20	100	11.2	42.9	2	69.9	4	1/2	50	65	5/8	M14	0.9
1	25	110	12.7	50.8	2	79.4	4	1/2	55	65	5/8	M14	0.9
1 1/4	32	115	14.3	63.5	2	88.9	4	1/2	55	70	5/8	M14	1.4
1 1/2	40	125	15.9	73	2	98.4	4	1/2	65	70	5/8	M14	1.8
2	50	150	17.5	92.1	2	120.7	4	5/8	70	85	3/4	M16	2.3
2 1/2	65	180	20.7	104.8	2	139.7	4	5/8	75	90	3/4	M16	3.2
3	80	190	22.3	127	2	152.4	4	5/8	75	90	3/4	M16	4.1
3 1/2	90	215	22.3	139.7	2	177.8	8	5/8	75	90	3/4	M16	5.9
4	100	230	22.3	157.2	2	190.5	8	5/8	75	90	3/4	M16	7.7
5	125	255	22.3	185.7	2	215.9	8	3/4	85	95	7/8	M20	9.1
6	150	280	23.9	215.9	2	241.3	8	3/4	85	100	7/8	M20	11.8
8	200	345	27	269.9	2	298.5	8	3/4	90	110	7/8	M20	20.5
10	250	405	28.6	323.8	2	362	12	7/8	100	115	1	M24	32
12	300	485	30.2	381	2	431.8	12	7/8	100	120	1	M24	50
14	350	535	33.4	412.8	2	476.3	12	1	115	135	1 1/8	M27	64
16	400	595	35	469.9	2	539.8	16	1	115	135	1 1/8	M27	82
18	450	635	38.1	533.4	2	577.9	16	1 1/8	125	145	1 1/4	M30	100
20	500	700	41.3	584.2	2	635	20	1 1/8	140	160	1 1/4	M30	130
24	600	815	46.1	692.2	2	749.3	20	1 1/4	150	170	1 3/8	M33	196

Class 300 Blind Flange Dimensions

Size in Inch	Size in mm	Outer Dia.	Flange Thick.	RF Dia.	RF Height	PCD	No of Bolts	Bolt Size UNC	Machine Bolt Length	RF Stud Length	Hole Size	ISO Stud Size	Weight in kg
		A	B	C	D	E
1/2	15	95	12.7	34.9	2	66.7	4	1/2	55	65	5/8	M14	1.4
3/4	20	115	14.3	42.9	2	82.6	4	5/8	65	75	3/4	M16	1.4
1	25	125	15.9	50.8	2	88.9	4	5/8	65	75	3/4	M16	1.4
1 1/4	32	135	17.5	63.5	2	98.4	4	5/8	70	85	3/4	M16	1.8
1 1/2	40	155	19.1	73	2	114.3	4	3/4	75	90	7/8	M20	2.7
2	50	165	20.7	92.1	2	127	8	5/8	75	90	3/4	M16	3.7
2 1/2	65	190	23.9	104.8	2	149.2	8	3/4	85	100	7/8	M20	5.5
3	80	210	27	127	2	168.3	8	3/4	90	110	7/8	M20	7.3
3 1/2	90	230	28.6	139.7	2	184.2	8	3/4	95	110	7/8	M20	9.6
4	100	255	30.2	157.2	2	200	8	3/4	95	115	7/8	M20	12.3
5	125	280	33.4	185.7	2	235	8	3/4	110	120	7/8	M20	15.9
6	150	320	35	215.9	2	269.9	12	3/4	110	120	7/8	M20	22.7
8	200	380	39.7	269.9	2	330.2	12	7/8	120	140	1	M24	36
10	250	445	46.1	323.8	2	387.4	16	1	140	160	1 1/8	M27	57
12	300	520	49.3	381	2	450.8	16	1 1/8	145	170	1 1/4	M30	84
14	350	585	52.4	412.8	2	514.4	20	1 1/8	160	180	1 1/4	M30	113
16	400	650	55.6	469.9	2	571.5	20	1 1/4	165	190	1 3/8	M33	134
18	450	710	58.8	533.4	2	628.6	24	1 1/4	170	195	1 3/8	M33	181
20	500	775	62	584.2	2	685.8	24	1 1/4	185	205	1 3/8	M33	230
24	600	915	68.3	692.2	2	812.8	24	1 1/2	205	230	1 5/8	M39	359

Class 400 Blind Flange Dimensions

Size in Inch	Size in mm	Outer Dia.	Flange Thick.	RF Dia.	RF Height	PCD	No of Bolts	Bolt Size UNC	RF Stud Length	Hole Size	ISO Stud Size	Weight in kg
		A	B	C	D	E
1/2	15	95	14.3	34.9	7	66.7	4	1/2	75	5/8	M14	1.5
3/4	20	115	15.9	42.9	7	82.6	4	5/8	90	3/4	M16	1.5
1	25	125	17.5	50.8	7	88.9	4	5/8	90	3/4	M16	1.8
1 1/4	32	135	20.7	63.5	7	98.4	4	5/8	95	3/4	M16	2.3
1 1/2	40	155	22.3	73	7	114.3	4	3/4	110	7/8	M20	3.7
2	50	165	25.4	92.1	7	127	8	5/8	110	3/4	M16	4.6
2 1/2	65	190	28.6	104.8	7	149.2	8	3/4	120	7/8	M20	6.8
3	80	210	31.8	127	7	168.3	8	3/4	125	7/8	M20	9.1
3 1/2	90	230	35	N/A	7	184.2	8	7/8	140	1	M24	13.2
4	100	255	35	157.2	7	200	8	7/8	140	1	M24	15
5	125	280	38.1	185.7	7	235	8	7/8	145	1	M24	20
6	150	320	41.3	215.9	7	269.9	12	7/8	150	1	M24	28
8	200	380	47.7	269.9	7	330	12	1	170	1 1/8	M27	46
10	250	445	54	323.8	7	387.4	16	1 1/8	190	1 1/4	M30	71
12	300	520	57.2	381	7	450.8	16	1 1/4	205	1 3/8	M33	102
14	350	585	60.4	412.8	7	514.4	20	1 1/4	210	1 3/8	M33	132
16	400	650	63.5	469.9	7	571.5	20	1 3/8	220	1 1/2	M36	168
18	450	710	66.7	533.4	7	628.6	24	1 3/8	230	1 1/2	M36	207
20	500	775	69.9	584.2	7	685.8	24	1 1/2	240	1 3/4	M39	266
24	600	915	76.2	692.2	7	812.8	24	1 3/4	265	1 7/8	M45	405

Class 600 Blind Flange Dimensions

Size in Inch	Size in mm	Outer Dia.	Flange Thick.	RF Dia.	RF Height	PCD	No of Bolts	Bolt Size UNC	RF Stud Length	Hole Size	ISO Stud Size	Weight in kg
		A	B	C	D	E
1/2	15	95	14.3	34.9	7	66.7	4	1/2	75	5/8	M14	1.4
3/4	20	115	15.9	42.9	7	82.6	4	5/8	90	3/4	M16	1.4
1	25	125	17.5	50.8	7	88.9	4	5/8	90	3/4	M16	1.8
1 1/4	32	135	20.7	63.5	7	98.4	4	5/8	95	3/4	M16	2.3
1 1/2	40	155	22.3	73	7	114.3	4	3/4	110	7/8	M20	3.7
2	50	165	25.4	92.1	7	127	8	5/8	110	3/4	M16	4.6
2 1/2	65	190	28.6	104.8	7	149.2	8	3/4	120	7/8	M20	6.8
3	80	210	31.8	127	7	168.3	8	3/4	125	7/8	M20	9.1
3 1/2	90	230	35	N/A	7	184.2	8	7/8	140	1	M24	13.2
4	100	275	38.1	157.2	7	215.9	8	7/8	145	1	M24	18.7
5	125	330	44.5	185.7	7	266.7	8	1	165	1 1/8	M27	31
6	150	355	47.7	215.9	7	292.1	12	1	170	1 1/8	M27	39
8	200	420	55.6	269.9	7	349.2	12	1 1/8	190	1 1/4	M30	64
10	250	510	63.5	323.8	7	431.8	16	1 1/4	215	1 3/8	M33	105
12	300	560	66.7	381	7	489	20	1 1/4	220	1 3/8	M33	134
14	350	605	69.9	412.8	7	527	20	1 3/8	235	1 1/2	M36	161
16	400	685	76.2	469.9	7	603.2	20	1 1/2	255	1 5/8	M39	225
18	450	745	82.6	533.4	7	654	20	1 5/8	275	1 3/4	M42	286
20	500	815	88.9	584.2	7	723.9	24	1 5/8	285	1 3/4	M42	368
24	600	940	101.6	692.2	7	838.2	24	1 7/8	330	2	M48	568

Class 900 Blind Flange Dimensions

Size in Inch	Size in mm	Outer Dia.	Flange Thick.	RF Dia.	RF Height	PCD	No of Bolts	Bolt Size UNC	RF Stud Length	Hole Size	ISO Stud Size	Weight in kg
		A	B	C	D	E
1/2	15	120	22.3	34.9	7	82.6	4	3/4	110	7/8	M20	1.8
3/4	20	130	25.4	42.9	7	88.9	4	3/4	115	7/8	M20	2.7
1	25	150	28.6	50.8	7	101.6	4	7/8	125	1	M24	3.6
1 1/4	32	160	28.6	63.5	7	111.1	4	7/8	125	1	M24	4.1
1 1/2	40	180	31.8	73	7	123.8	4	1	140	1 1/8	M27	5.9
2	50	215	38.1	92.1	7	165.1	8	7/8	145	1	M24	10.1
2 1/2	65	245	41.3	104.8	7	190.5	8	1	160	1 1/8	M27	16
3	80	240	38.1	127	7	190.5	8	7/8	145	1	M24	13
4	100	290	44.5	157.2	7	235	8	1 1/8	170	1 1/4	M30	24.5
5	125	350	50.8	185.7	7	279.4	8	1 1/4	190	1 3/8	M33	39.5
6	150	380	55.6	215.9	7	317.5	12	1 1/8	190	1 1/4	M30	53
8	200	470	63.5	269.9	7	393.7	12	1 3/8	220	1 1/2	M36	91
10	250	545	69.9	323.8	7	469.9	16	1 3/8	235	1 1/2	M36	132
12	300	610	79.4	381	7	533.4	20	1 3/8	255	1 1/2	M36	189
14	350	640	85.8	412.8	7	558.8	20	1 1/2	275	1 5/8	M39	237
16	400	705	88.9	469.9	7	616	20	1 5/8	285	1 3/4	M42	273
18	450	785	101.6	533.4	7	685.8	20	1 7/8	325	2	M48	367
20	500	855	108	584.2	7	749.3	20	2	350	2 1/8	M52	463
24	600	1040	139.7	692.2	7	901.7	20	2 1/2	440	2 5/8	M64	875

Class 1500 Blind Flange Dimensions

Size in Inch	Size in mm	Outer Dia.	Flange Thick.	RF Dia.	RF Height	PCD	No of Bolts	Bolt Size UNC	RF Stud Length	Hole Size	ISO Stud Size	Weight in kg
		A	B	C	D	E
1/2	15	120	22.3	34.9	7	82.6	4	3/4	110	7/8	M20	1.8
3/4	20	130	25.4	42.9	7	88.9	4	3/4	115	7/8	M20	2.7
1	25	150	28.6	50.8	7	101.6	4	7/8	125	1	M24	3.7
1 1/4	32	160	28.6	63.5	7	111.1	4	7/8	125	1	M24	4.1
1 1/2	40	180	31.8	73	7	123.8	4	1	140	1 1/8	M27	5.9
2	50	215	38.1	92.1	7	165.1	8	7/8	145	1	M24	10.1
2 1/2	65	245	41.3	104.8	7	190.5	8	1	160	1 1/8	M27	15.9
3	80	265	47.7	127	7	203.2	8	1 1/8	180	1 1/4	M30	21.8
4	100	310	54	157.2	7	241.3	8	1 1/4	195	1 3/8	M33	33
5	125	375	73.1	185.7	7	292.1	8	1 1/2	250	1 5/8	M39	64
6	150	395	82.6	215.9	7	317.5	12	1 3/8	260	1 1/2	M36	75
8	200	485	92.1	269.9	7	393.7	12	1 5/8	290	1 3/4	M42	136
10	250	585	108	323.8	7	482.6	12	1 7/8	335	2	M48	232
12	300	675	123.9	381	7	571.5	16	2	375	2 1/8	M52	314
14	350	750	133.4	412.8	7	635	16	2 1/4	405	2 3/8	M56	443
16	400	825	146.1	469.9	7	704.8	16	2 1/2	445	2 5/8	M64	591
18	450	915	162	533.4	7	774.7	16	2 3/4	495	2 7/8	M72	795
20	500	985	177.8	584.2	7	831.8	16	3	540	3 1/8	M76	1022
24	600	1170	203.2	692.2	7	990.6	16	3 1/2	615	3 5/8	M90	1648

Class 2500 Blind Flange Dimensions

Size in Inch	Size in mm	Outer Dia.	Flange Thick.	RF Dia.	RF Height	PCD	No of Bolts	Bolt Size UNC	RF Stud Length	Hole Size	ISO Stud Size	Weight in kg
		A	B	C	D	E
1/2	15	135	30.2	34.9	7	88.9	4	3/4	120	7/8	M20	3.2
3/4	20	140	31.8	42.9	7	95.2	4	3/4	125	7/8	M20	3.7
1	25	160	35	50.8	7	108	4	7/8	140	1	M24	5
1 1/4	32	185	38.1	63.5	7	130.2	4	1	150	1 1/8	M27	7.8
1 1/2	40	205	44.5	73	7	146	4	1 1/8	170	1 1/4	M30	10.5
2	50	235	50.9	92.1	7	171.4	8	1	180	1 1/8	M27	18
2 1/2	65	265	57.2	104.8	7	196.8	8	1 1/8	195	1 1/4	M30	25.5
3	80	305	66.7	127	7	228.6	8	1 1/4	220	1 3/8	M33	39
4	100	355	76.2	157.2	7	273	8	1 1/2	255	1 5/8	M39	61.5
5	125	420	92.1	185.7	7	323.8	8	1 3/4	300	1 7/8	M45	102
6	150	485	108	215.9	7	368.3	8	2	345	2 1/8	M52	157
8	200	550	127	269.9	7	438.2	12	2	380	2 1/8	M52	241
10	250	675	165.1	323.8	7	539.8	12	2 1/2	490	2 5/8	M64	470
12	300	760	184.2	381	7	619.1	12	2 3/4	540	2 7/8	M72	575