ASTM A182 Flange Dimensions Table

ASTM A182 flanges are essential components in high-pressure piping systems. They are manufactured from forged alloy and stainless steel, offering excellent strength and corrosion resistance. While material requirements are defined by ASTM A182, flange dimensions are standardized by ASME B16.5 and ASME B16.47.

What is ASTM A182?

ASTM A182 is a material specification covering forged or rolled alloy and stainless steel pipe flanges, fittings, valves, and parts. It is commonly applied in industries such as oil & gas, petrochemical, power generation, and chemical processing.
The standard defines:
Mechanical properties
Chemical composition
Heat treatment requirements
Pressure-temperature ratings
However, it does not directly define flange dimensions. These are governed by other standards.

Flange Dimension Standards You Must Know

To correctly use ASTM A182 flanges, dimensional compliance must follow standards such as:
ASME B16.5 (NPS ½” to 24”)
ASME B16.47 (NPS 26” to 60”)
These standards define:
Outside diameter (OD)
Bolt circle diameter (BCD)
Number and size of bolt holes
Flange thickness
Raised face (RF) or flat face (FF) dimensions
Without these standards, flange interchangeability would not be possible.

Common ASTM A182 Flange Types

Flange Type	Description	Typical Application
Weld Neck (WN)	Long tapered hub	High pressure & temperature
Slip-On (SO)	Slides over pipe	Low to medium pressure
Blind (BL)	Solid, no bore	Pipe end closure
Socket Weld (SW)	Socket connection	Small bore, high pressure
Threaded (TH)	Internal threads	Non-weld systems

ASTM A182 Flange Dimensions Table (ASME B16.5 – Class 150)

Below is a commonly used reference table for Class 150 Weld Neck Flanges:

NPS (inches)	Outside Diameter (mm)	Bolt Circle (mm)	Bolt Holes	Bolt Size (mm)	Thickness (mm)
1/2	90	60	4	16	9.6
1	108	79	4	16	11.2
2	152	120	4	19	14.3
3	190	152	4	19	15.9
4	229	191	8	19	17.5
6	279	241	8	22	20.7
8	343	298	8	22	22.3

ASTM A182 Flange Dimensions Table (Class 300 Comparison)

NPS (inches)	Outside Diameter (mm)	Bolt Circle (mm)	Bolt Holes	Bolt Size (mm)	Thickness (mm)
1/2	95	66	4	16	12.7
1	124	89	4	19	14.3
2	165	127	8	19	19.1
3	210	168	8	22	23.9
4	254	200	8	22	28.6
6	318	270	12	22	31.8
8	381	330	12	25	36.6

How to Select the Correct Flange Dimensions ？

Choosing the right ASTM A182 flange involves:
1.Determine pipe size (NPS)
2.Select pressure class (150–2500)
3.Choose flange type (WN, SO, BL)
4.Match material grade (ASTM A182)
5.Verify dimensions using ASME B16.5 tables
6.Confirm compatibility with mating components

Conclusion

ASTM A182 flanges combine high-quality forged materials with standardized dimensions defined by ASME specifications. While ASTM A182 controls material properties, dimensional accuracy depends on standards like ASME B16.5 and B16.47. Understanding these relationships is essential for safe, efficient, and long-lasting piping systems.
By carefully selecting flange type, pressure class, and material grade—and verifying dimensions against recognized standards—engineers and buyers can ensure optimal performance and reliability in demanding industrial applications.