Blind Flange

What is Blind Flange

Blind flange is a solid flange the purpose of these is to block off a section of pipe. Unlike other types of flange that are used to connect pipes or components, it is used to close off a pipe or an opening in a system. They are serve a crucial role in maintaining the integrity of piping systems, preventing leaks, and enabling safe pressure testing.

Similar to other type flanges, blind flange has mounting holes around the perimeter and the gasket sealing rings are machined into the mating surface. The difference is that a blind flange has no opening for fluids to pass through.

ASME B16.5 Forged Blind Flange

ASME B16.5 is American standard for manufacturing cast and forged steel pipe flange. This standard included flanges and flange fittings made from cast or forged materials, and blind flanges and certain reducing flanges made from cast, forged, or plate materials. Also included in this standard are requirements and recommendations regarding flange bolting, flange gaskets, and flange joints. B16.5 cover the dimension, tolerance,weight of the flanges.

Sealing Face	RF, FF, FTJ
Size Range	1/2″ – 60″ / DN15 – DN1500
Pressure Rating	Class 150, 300, 600, 900, 1500, 2500lb
Standard	ASME / ANSI B16.5, ASME B16.47 Series A/B

Sealing Face for Blind Flange

The raised face (RF) is the most common type of flange facing used. These flanges are widely used in oil and gas pipelines.

RF Blind Flange

Flat face (FF) flanges are similar to the RF flanges. But they do not have the raised area like the RF flange. Instead, the whole surface is flat.

FF BL Flange

A Ring type joint flange(RTJ) is a machined metallic ring with a deep groove cut into its face. This groove rests a metal ring which gets compressed when the connecting bolts of the flange are tightened.

RTJ BL

Face Finish

However, the common objective of any type of flange face finish is to create the desired roughness on the face of a flange to ensure a strong match between the flange, the gasket, and the mating flange thus provide a high-quality seal.

The roughness are different for different face finish. It is available for various gasket for different roughness.

Surface Types	Maximum Roughness Value
Ring-type joint flanges	63 µin AARH (1.6 µm AARH)
Spiral wound gaskets	125 to 250 µin AARH (3.2 to 6.3 µm AARH)
Soft gaskets.	250 to 500 µin AARH (6.3 to 12.6 µm AARH)
Tongue and Groove	125 µ.in. or 3.2 µ.m AARH

Material for Forged Steel Flange

We are specialized in various steel flanges, the materials including carbon steel, alloy steel and stainless steel.

Carbon Steel	ASTM A105 / A105N, ASTM A350 LF2/LF3, ASTM A694 F42 / 46 / 56 / 60 / 65, P235GH, P265GH, P280GH, P355GH
Alloy Steel	ASTM A182 F11 / 12 / 5 / 9 / 91 / 92
Stainless Steel	ASTM A182 F304/304L/304H, 316/316L, 321, 310S, 317,347,904L， 1.4404, 1.4437.
Duplex Stainless Steel	ASTM A182 F51, F53, F55

Carbon steel flange, that is, the body material is carbon steel plate or end flange connection. Stainless steel flange, also called SS flange, it means the material of flange is stainless steel. Common material standards and Grades are ASTM A182 Grade F304/L and F316/L. It used in more industries than carbon steel. Stainless steel has better resistant performances on corrosion environment and always provides with a good appearance.

Advantages of Forged Blind Flange

There is no hole in the center of the blind flange, so it can seal the pipeline. Without blind flanges, shutdowns and repairs would be incredibly difficult to handle. Stainless steel blind flange have the following advantages.

Resistant to corrosion and staining

Low maintenance

Bright familiar luster

Steel Strength

Dimension and Weight

Dimension of ASME B16.5 blind flanges are in 1/2″ to 24″ nominal sizes. The pressure of Class 150#, 300#, 400#, 600#, 900#, 1500#, and 2500# . There are many seal facing as raised face (RF), flat face (FF), ring type joint (RTJ) , tongue-and-groove (T&G) and male-and-female (M&F).

CLASS150
Norminal Pipe Size		A	C	G	H	I	J	Weight
Norminal Pipe Size	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

Class 300
Nominal Pipe Size		A	C	G	H	I	J	Weight
Nominal Pipe Size	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	11.50
5	141.3	279.4	35	185.7	8	22.3	234.9	15.60
6	168.3	317.5	36.5	215.9	12	22.3	269.7	20.9
8	219. 1	381	41.1	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	105.0
16	406.4	647.7	57.15	469.9	20	35	571.5	137.0
18	457.2	711.2	60.45	533.4	24	35	628.6	175.0
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

CLASS400
Nominal Pipe Size	Outside Diameter	Overall Diameter	Flange Thickness min	Face Diameter	Number of Holes	Bolt Hole Diameter	Diameter of Circle of Holes	kg/piece
Nominal Pipe Size	mm	mm	mm	mm	Number of Holes	mm	mm	kg/piece
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	11.00
4	114.3	254	35. 10	157.2	8	25.4	200.2	13.70
5	141.3	279.4	38. 10	185.7	8	25.4	235	18.50
6	168.3	317.5	41. 10	215.9	12	25.4	269.7	25.50
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	94.3
14	355.6	584.2	60.45	412.8	20	35.1	514.4	124.0
16	406.4	647.7	63.5	469.9	20	38.1	571.5	162.0
18	457.2	711.2	66.55	533.4	24	38.1	628.7	205.0
20	508	774.7	69.85	584.2	24	41.1	685.8	254.0
24	609.6	914.4	76.2	692.2	24	47.8	812.8	386

CLASS600
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	Number of Holes	mm	mm	kg/piece
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

Class 900 lb
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	Number of Holes	mm	mm	kg/piece
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

Class 1500 lb
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	Number of Holes	mm	mm	kg/piece
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

Class 2500 lb
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	Number of Holes	mm	mm	kg/piece
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

ASME B16.5 STANDARD

What is Blind Flange

ASME B16.5 Forged Blind Flange

Sealing Face for Blind Flange

Face Finish

Material for Forged Steel Flange

Advantages of Forged Blind Flange

Dimension and Weight