ANSI B16.5 is a standard established by the American National Standards Institute (ANSI) that specifies the dimensions, pressure-temperature ratings, materials, tolerances, marking, and testing of flanges for use in piping systems. It covers pipe flanges and flanged fittings with nominal sizes ranging from 1/2 inch to 24 inches.
Type of ANSI/ASME B16.5 Flange
ANSI B16.5 Welding Neck Flange
ANSI B16.5 Threaded Flange
ANSI B16.5 Socket Welding Flange
ANSI B16.5 Slip-on Flange
ANSI B16.5 Blind Flange
ANSI B16.5 LAP Joint Flange
ANSI/ASME B16.5 Flange Class 150 Dimensions in mm
Nom. Pipe Size
O
T
TJ
R
X
#/Dia of Holesa
Bolt Circle Dia
B
B2b
B3
H
L
L2
L3c
r
D
Thr
½
3.50
0.38
0.44
1.38
1.19
4-0.62
2.38
0.88
0.62
0.90
0.84
0.56
1.81
0.62
0.12
0.38
0.62
¾
3.88
0.44
0.50
1.69
1.50
4-0.62
2.75
1.09
0.82
1.11
1.05
0.56
2.00
0.62
0.12
0.44
0.62
1
4.25
0.50
0.56
2.00
1.94
4-0.62
3.12
1.36
1.05
1.38
1.32
0.62
2.12
0.69
0.12
0.50
0.69
1¼
4.62
0.56
0.62
2.50
2.31
4-0.62
3.50
1.70
1.38
1.72
1.66
0.75
2.19
0.81
0.19
0.56
0.81
1½
5.00
0.62
0.69
2.88
2.56
4-0.62
3.88
1.95
1.61
1.97
1.90
0.81
2.38
0.88
0.25
0.62
0.88
2
6.00
0.69
0.75
3.62
3.06
4-0.75
4.75
2.44
2.07
2.46
2.38
0.94
2.44
1.00
0.31
0.69
1.00
2½
7.00
0.81
0.88
4.12
3.56
4-0.75
5.50
2.94
2.47
2.97
2.88
1.06
2.69
1.12
0.31
0.75
1.12
3
7.50
0.88
0.94
5.00
4.25
4-0.75
6.00
3.57
3.07
3.60
3.50
1.12
2.69
1.19
0.38
0.81
1.19
3½
8.50
0.88
0.94
5.50
4.81
8-0.75
7.00
4.07
3.55
4.10
4.00
1.19
2.75
1.25
0.38
0.88
1.25
4
9.00
0.88
0.94
6.19
5.31
8-0.75
7.50
4.57
4.03
4.60
4.50
1.25
2.94
1.31
0.44
0.94
1.31
5
10.00
0.88
0.94
7.31
6.44
8-0.88
8.50
5.66
5.05
5.69
5.56
1.38
3.44
1.44
0.44
0.94
1.44
6
11.00
0.94
1.00
8.50
7.56
8-0.88
9.50
6.72
6.07
6.75
6.63
1.50
3.44
1.56
0.50
1.06
1.56
8
13.50
1.06
1.12
10.62
9.69
8-0.88
11.75
8.72
7.98
8.75
8.63
1.69
3.94
1.75
0.50
1.25
1.75
10
16.00
1.12
1.19
12.75
12.00
12-1.00
14.25
10.88
10.02
10.92
10.75
1.88
3.94
1.94
0.50
1.31
1.94
12
19.00
1.19
1.25
15.00
14.38
12-1.00
17.00
12.88
12.00
12.92
12.75
2.12
4.44
2.19
0.50
1.56
2.19
14
21.00
1.31
1.38
16.25
15.75
12-1.12
18.75
14.14
13.25
14.18
14.00
2.19
4.94
3.12
0.50
1.63
2.25
16
23.50
1.38
1.44
18.50
18.00
16-1.12
21.25
16.16
15.25
16.19
16.00
2.44
4.94
3.44
0.50
1.75
2.50
18
25.00
1.50
1.56
21.00
19.88
16-1.25
22.75
18.18
17.25
18.20
18.00
2.62
5.44
3.81
0.50
1.94
2.69
20
27.50
1.62
1.69
23.00
22.00
20-1.25
25.00
20.20
19.25
20.25
20.00
2.81
5.62
4.06
0.50
2.13
2.88
22
29.50
1.75
1.81
25.25
24.25
20-1.38
27.25
22.22
21.25
22.25
22.00
3.07
5.82
4.25
0.50
2.38
3.13
24
32.00
1.81
1.88
27.25
26.12
20-1.38
29.50
24.25
23.25
24.25
24.00
3.19
5.94
4.38
0.50
2.50
3.25
leo.
Pressure Rating
Pressure (psi)
Temperature (𐩑F)
150#
300#
400#
600#
900#
1500#
2500#
-20 to 100
285
740
985
1480
2220
3705
6170
200
260
680
905
1360
2035
3395
5655
300
230
655
870
1310
1965
3270
5450
400
200
635
845
1265
1900
3170
5280
500
170
605
805
1205
1810
3015
5025
600
140
570
755
1135
1705
2840
4730
650
125
550
730
1100
1650
2745
4575
700
110
530
710
1060
1590
2655
4425
750
95
505
675
1015
1520
2535
4230
800
80
410
550
825
1235
2055
3430
850
65
320
425
640
955
1595
2655
900
50
230
305
460
690
1150
1915
950
35
135
185
275
410
685
1145
1000
20
85
115
170
255
430
715
Tolerance
Flange Type
Tolerance Type
Standard Tolerance
Weld Neck
Hub Length, Bevel Angle
±0.03 inches, ±2°
Slip-On
Bore Diameter, Thickness
±0.02 inches, ±0.06 inches
Blind
Thickness, Flatness
±0.06 inches, 0.1-0.5 mm flatness
Threaded
Thread Alignment
Per ASME B1.20.1 standards
Socket Weld
Socket Depth, Bore
±0.03 inches, ±0.02 inches
Lap Joint
Bolt Hole, Outer Diameter
±0.03 inches, ±0.06 inches
Ring Type Joint
Groove Dimensions
±0.005 inches
Key Features of ANSI/ASME B16.5 Flange
Pressure Classes:
Accessible in pressure classes of 150, 300, 400, 600, 900, 1500, and 2500.
It is extensively utilized in the oil and gas, petrochemical, power generating, water treatment, and other industries.
Suitable for both high-temperature and low-temperature applications.
Standards for Compatibility:
Designed for compatibility with ASME B31.1 and B31.3 piping codes.
Materials: ANSI B16.5 flanges are manufactured from a variety of materials to suit different operational requirements:
Carbon Steel: Cost-effective and widely used for general applications.
Stainless Steel: Offers excellent corrosion resistance and durability.
Alloy Steel: High strength and toughness for demanding applications.
Duplex and Super Duplex Steel: Exceptional mechanical strength and corrosion resistance.
Nickel Alloys and Other Special Materials: For highly corrosive or high-temperature environments.
High-Temperature Applications
ANSI B16.5 Flanges are ideal for high-temperature applications due to their robust design and material composition. Key characteristics for high-temperature use include:
Heat Resistance: Materials like alloy steel and stainless steel are commonly used to withstand elevated temperatures without deforming or losing strength.
Pressure Handling: Designed to endure high pressures associated with high-temperature operations, such as in petrochemical and power generation industries.
Corrosion Resistance: Specialty alloys like Inconel and Monel resist oxidation and scaling, ensuring longevity.
Low-Temperature Applications
For low-temperature environments, these flanges are optimized to maintain integrity under freezing conditions. Key features include:
Low-Temperature Toughness: Materials like carbon steel with low-temperature ratings (LTCS) and austenitic stainless steel ensure ductility and resistance to brittle fracture.
Cryogenic Suitability: Used in industries such as LNG and chemical processing where cryogenic temperatures are prevalent.
Impact Resistance: Designed to withstand mechanical shocks even at sub-zero temperatures.
ANSI/ASME B16.5 Flange Face Types
Flat Face (FF): For low-pressure systems.
Raised Face (RF): Enhances gasket sealing under pressure.
Ring Type Joint (RTJ): For high-pressure applications.
Male & Female (M&F): For precise alignment and sealing.