ASTM A193 Specification
ASTM A193 is the standard for alloy steel and stainless steel bolting , bolting under ASTM A193 can be used for pressure vessels, valves, flanges and fittings for high-temperature or high-pressure service.
Grade B7,B7M, B16 Stainless steel B8,B8M, are the most common grade and widely used for flange and valves connection.
You would find the gerneral induction for the chemical composition,mechanical property ,Heat treatment,testing requirement certificate for those materials according to ASTM A193 standard.
Heat Treatment
Heat treatment requirement for B7 and B7M(quenching and tempering)
According to ASTM A193 standard,
Grade B7 and B7M Bolt shall be firstly heat treated by quenching in aliquid medium and then tempering. While for B7M Bolts, The Final tempering heat treatment if conducted at 1150 °F [620 °C] minimum, shall be done after all machining and forming operations, including thread rolling and any type of cutting. Surface preparation for hardness testing, nondestructive evaluation, or ultrasonic bolt tensioning is permitted
Heat treatment requirement for B16 (tempering and Quenched)
Material Grade B16 Bolt shall be heated to a temperature range from 1700 to 1750 °F [925 to 955 °C] and then oil quenched.
Heat requirement for A193 B8 ,B8M
Stainless steel bolting has different heat treatment method from the alloy steel bolts.
All austenitic stainless steels shall receive a carbide solution treatment,In the case of. Classes 2, Material shall be strain hardened to achieve the required properties.
B7 B7M B16 B8 B8M Chemical Composition under ASTM A193
Mechnical Property under ASTM A193
| Grade | Description and UNS Diameter, in. | Minimum Tempering Temperatur, F | Tensile Strength, | Yield Strength, | Elongation in 4D, | Reduction of Area, | Hardness, |
| min, | min, | min, | min, | max | |||
| ksi | 0.2 % offset, | % | % | ||||
| ksi | |||||||
| B7 Chromium-molybdenum | 2 1/2 and under | 1100 | 125 | 105 | 16 | 50 | 321 HBW or 35 HRC |
| over 2 1/2 to 4 | 1100 | 115 | 95 | 16 | 50 | 321 HBW or 35 HRC | |
| over 4 to 7 | 1100 | 100 | 75 | 18 | 50 | 221 HBW or 35 HRC | |
| B7MA Chromium-molybdenum | 4 and under | 1150 | 100 | 80 | 18 | 50 | 235 HBW or 99 HRB |
| over 4 to 7 | 1150 | 100 | 75 | 18 | 50 | 235 HBW or 99 HRB | |
| B16 Chromium-molybdenum-vanadium | 2 1/2 and under | 1200 | 125 | 105 | 18 | 50 | 321 HBW or 35 HRC |
| over 2 1/2 to 4 | 1200 | 110 | 95 | 17 | 45 | 321 HBW or 35 HRC | |
| over 4 to 8 | 1200 | 100 | 85 | 16 | 45 | 321 HBW or 35 HRC |
Stud Bolt Thread requirment
Length of studs and stud bolts shall be measured from first thread to first thread (Effective Length)
If Imperial Thread is required for Stud bolt, the thread specificaiton should follow ASME B18.31.2 Continuous Thread Studs
Imperial inch threated bars with rolled thread. Thread up to 1″ UNC, over 1″ 8UN. Fine thread UNF on request. Common tolerance ANSI/ASME B1.1 2A
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