A193-11a

Scope
1.1 This specification² covers alloy and stainless steel bolting for pressure vessels, valves, flanges, and fittings for high temperature or high pressure service, or other special purpose applications. Bars and wire shall be hot-wrought and may be further processed by centerless grinding or by cold drawing. Austenitic stainless steel may be carbide solution treated or carbide solution treated and strain-hardened. When strain hardened austenitic steel is ordered, the purchaser should take special care to ensure that Appendix X1 is thoroughly understood.
² – For ASME Boiler and Pressure Vessel Code applications, see related Specification SA-193 in Section II of that Code.
NOTE 2—For grades of alloy-steel bolting suitable for use at the lower range of high temperature applications, reference should be made to Specification A354.

1.2 Several grades are covered, including ferritic steels and austenitic stainless steels designated B7, B8, and so forth. Selection will depend upon design, service conditions, mechanical properties, and high temperature characteristics.

Table 1: Chemical Requirements - Ferritic Steels

GradeDescriptionUNS Designation
B6 & B6X12% ChromiumS41000 (41)
ElementRangeProduct Variation Over or Under ᴮ
Carbon0.08-0.150.01 over
Manganese max10.03 over
Phosphorus max0.040.005 over
Sulfur max0.030.005 over
Silicon1.00 max0.05 over
Chromium11.5-13.50.15
Molybdenum
GradeDescription
B7, B7MChromium-Molybdenum ᶜ
ElementRangeProduct Variation Over or Under ᴮ
Carbon0.37-0.49 ᴰ0.02
Manganese max0.65-1.100.04
Phosphorus max0.0350.005 over
Sulfur max0.040.005 over
Silicon0.15-1.200.02
Chromium0.75-1.200.05
Molybdenum0.15-0.250.02
Vanadium
Aluminum max % ᴱ
Source: ASTM A193-11a

Table 1: Chemical Requirements - Austenititc Steels

GradeUNS DesignationGradeUNS Designation
B8S304400 (304)B8MS31600 (316)
ElementRangeProduct Variation Over/Under ᴮRangeProduct Variation Over/Under ᴮ
Carbon max0.080.01 over0.080.01 over
Manganese max20.04 over20.04 over
Phosphorus max0.0450.010 over0.0450.010 over
Sulfur max0.030.05 over0.030.005 over
Silicon max10.05 over10.005 over
Chromium18.0-20.00.216.0-18.00.2
Nickel8.0-11.00.1510.0-14.00.15
Molybdenum2.00-3.000.1
Columbium + tantalum
Source: ASTM A193-11a

Table 2: Mechanical Requirements - Ferritic Steels

GradeDiameterMinimum Tempering Temp °FTensile Strength, min, ksiYield Strength, min 0.2% offset, ksiElongation in 4D, min, %Reduction of Area min, %Hardness, max
B6 13% Chromiumup to 4", inclusvie1100110851550
B6X 13% Chromiumup to 4", inclusvie11009070165026 HRC
B7 Chromium-Molybdenum2-1/2" and under11001251051650321 HBW or 35 HRC
B7 Chromium-Molybdenumover 2-1/2" to 4"1100115951650322 HBW or 35 HRC
B7 Chromium-Molybdenum4" to 7"1100100751850323 HBW or 35 HRC
Source: ASTM A193-11a

Table 2: Mechanical Requirements - Austentitic Steels

GradeDiameterHeat Treatment ᴮTensile Strength, min, ksiYield Strength, min, 0.2% offset, ksiElongation in 4 D, min %Reduction of Area, min %Hardness max
Classes 1 & D1 - B8 & B8MAll DiametersCarbide Solution Treated75303050223 HBW or 96 HRB ᶜ
Class 2 - B83/4" and UnderCarbide Solution Treated & Strain Hardened1251001235321 HBW or 35 HRC
Class 2 - B8Over 3/4" to 1" InculsiveCarbide Solution Treated & Strain Hardened115801535321 HBW or 35 HRC
Class 2 - B8Over 1 to 1-1/4" InculsiveCarbide Solution Treated & Strain Hardened105652035321 HBW or 35 HRC
Class 2 - B8Over 1-1/4 to 1-1/2" InclusiveCarbide Solution Treated & Strain Hardened100502845321 HBW or 35 HRC
Class 2 - B8M3/4" and UnderCarbide Solution Treated & Strain Hardened110951545321 HBW or 35 HRC
Class 2 - B8MOver 3/4" to 1" InculsiveCarbide Solution Treated & Strain Hardened100802045321 HBW or 35 HRC
Class 2 - B8MOver 1 to 1-1/4" InculsiveCarbide Solution Treated & Strain Hardened95652545321 HBW or 35 HRC
Class 2 - B8MOver 1-1/4 to 1-1/2" InclusiveCarbide Solution Treated & Strain Hardened90503045321 HBW or 35 HRC
Source: ASTM A193-11a

ASTM A193-11a was approved on Nov 1 2011.

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