Worldwide: (+65) 9648 5210
US: (+1) (985) 876-8147

ASTM A193

ASTM A193


Scope

Originally approved in 1936, this specification is heavily utilized in petroleum and chemical construction applications.  The ASTM standard covers alloy steel and stainless steel bolting materials for high temperature or high pressure service. This specification includes fasteners intended for use in pressure vessels, valves, flanges, and fittings. Although, this material is often available in national coarse (UNC) thread pitches, if being used in traditional applications, threads are specified 8 threads per inch (tpi) for diameters above one inch.

Below is a basic summary of a few of the common grades. ASTM A193 covers a number of other standard specifications not covered in this description including B5, B6, and B16.

Grades

B7Alloy steel, AISI 4140/4142 quenched and tempered
B8Class 1 Stainless steel, AISI 304, carbide solution treated.
B8MClass 1 Stainless steel, AISI 316, carbide solution treated.
B8Class 2 Stainless steel, AISI 304, carbide solution treated, strain hardened
B8MClass 2 Stainless steel, AISI 316, carbide solution treated, strain hardened

Mechanical Properties

GradeSizeTensile ksi, minYield, ksi, minElong, %, minRA % min
B7Up to 2-1/21251051650
2-5/8 – 4115951650
4-1/8 – 7100751850
B8 Class 1All75303050
B8M Class 1All75303050
B8 Class 2Up to 3/41251001235
7/8 – 1115801535
1-1/8 – 1-1/4105652035
1-3/8 – 1-1/2100502845
B8M Class 2Up to 3/4110951545
7/8 – 1100802045
1-1/8 – 1-1/495652545
1-3/8 – 1-1/290503045

Chemical Properties

ElementB7 (AISI 4140)B8 (AISI 304)B8M (AISI 316)
Carbon0.37 – 0.49%0.08% max0.08% max
Manganese0.65 – 1.10%2.00% max2.00% max
Phosphorus, max0.035%0.045%0.045%
Sulfur, max0.040%0.030%0.030%
Silicon0.15 – 0.35%1.00% max1.00% max
Chromium0.75 – 1.20%18.0 – 20.0%16.0 – 18.0%
Nickel8.0 – 11.0%10.0 – 14.0%
Molybdenum0.15 – 0.25%2.00 – 3.00%

Recommended Nuts and Washers

Bolt GradeNutsWashers
B7A194 Grade 2HF436
B8 Class 1A194 Grade 8SS304
B8M Class 1A194 Grade 8MSS316
B8 Class 2A194 Grade 8SS304
B8M Class 2A194 Grade 8MSS316