SPECIFICATION LIBRARY

ASTM A193

ASTM A193 encompasses a broad range of high-strength alloy steel and stainless steel materials used for bolts, screws, studs, and other externally threaded fasteners in high-temperature or high-pressure environments. This standard is pivotal in sectors like petrochemical, oil and gas, power plants, and structural engineering, where reliability and performance under extreme conditions are paramount.

Overview of ASTM A193 Standard

The ASTM A193 standard specifies the mechanical properties, chemical composition, and testing requirements for fasteners. These materials are selected for their ability to withstand harsh environments, including elevated temperatures and pressures, without compromising integrity.

Detailed Analysis of Selected ASTM A193 Grades

B7: Comprising chromium-molybdenum steel, grade B7 is renowned for its high strength and is often used in the manufacture of bolting for flanges and pressure vessels.
B16: A chromium-molybdenum-vanadium alloy, B16 is known for its enhanced strength at higher temperatures, making it ideal for high-pressure and high-temperature applications.
B7M: Similar to B7 but with controlled hardness requirements, B7M is used in applications where resistance to stress corrosion cracking is essential.
B8: Made of 304 stainless steel, B8 grade fasteners are used in environments requiring corrosion resistance and moderate strength at high temperatures.
B8M: With 316 stainless steel construction, B8M fasteners offer superior corrosion resistance, especially in chloride-containing environments, compared to B8.
B6: Fabricated from 410 stainless steel, B6 is utilized where high strength and moderate corrosion resistance are required.

Chemical Composition of Selected ASTM A193 Grades

The chemical composition of these grades varies to meet different mechanical and environmental demands:

ASTM A193: The Backbone of Industrial Fastening

  
    
  
      Grade
      C
      Mn
      P
      S
      Si
      Cr
      Ni
      Mo
    

  
      B7
      0.38–0.48%
      0.75–1.00%
      0.035% max
      0.040% max
      0.15–0.35%
      0.80–1.10%
      —
      0.15–0.25%
    

      B16
      0.36–0.47%
      0.45–0.70%
      0.035% max
      0.040% max
      0.15–0.35%
      0.80–1.15%
      —
      0.50–0.65%
    

      B7M
      0.38–0.48%
      0.75–1.00%
      0.035% max
      0.040% max
      0.15–0.35%
      0.80–1.10%
      —
      0.15–0.25%
    

      B8
      0.08% max
      2.00% max
      0.045% max
      0.030% max
      1.00% max
      18.0–20.0%
      8.0–11.0%
      —
    

      B8M
      0.08% max
      2.00% max
      0.045% max
      0.030% max
      1.00% max
      16.0–18.0%
      10.0–14.0%
      2.00–3.00%
    

      B6
      0.15–0.20%
      1.00% max
      0.040% max
      0.030% max
      1.00% max
      11.5–13.5%
      —
      —
    


  

Grade	C	Mn	P	S	Si	Cr	Ni	Mo
B7	0.38–0.48%	0.75–1.00%	0.035% max	0.040% max	0.15–0.35%	0.80–1.10%	—	0.15–0.25%
B16	0.36–0.47%	0.45–0.70%	0.035% max	0.040% max	0.15–0.35%	0.80–1.15%	—	0.50–0.65%
B7M	0.38–0.48%	0.75–1.00%	0.035% max	0.040% max	0.15–0.35%	0.80–1.10%	—	0.15–0.25%
B8	0.08% max	2.00% max	0.045% max	0.030% max	1.00% max	18.0–20.0%	8.0–11.0%	—
B8M	0.08% max	2.00% max	0.045% max	0.030% max	1.00% max	16.0–18.0%	10.0–14.0%	2.00–3.00%
B6	0.15–0.20%	1.00% max	0.040% max	0.030% max	1.00% max	11.5–13.5%	—	—

Mechanical Properties of Selected ASTM A193 Grades

  
    
  
      Grade
      Diameter
      Tensile Strength
      Yield Strength
      Elongation
      Hardness
    

  
      B7
      Up to 2-1/2"
      125 ksi min
      105 ksi min
      16% min
      321 HB max
    

      
      2-1/2" – 4"
      115 ksi min
      95 ksi min
      16% min
      321 HB max
    

      B16
      Up to 2-1/2"
      130 ksi min
      115 ksi min
      18% min
      321–352 HB
    

      
      2-1/2" – 4"
      120 ksi min
      100 ksi min
      17% min
      321–352 HB
    

      B7M
      Up to 4"
      100 ksi min
      80 ksi min
      18% min
      235 HB max
    

      B8 Class 1
      Up to 4"
      75 ksi min
      30 ksi min
      30% min
      223 HB max
    

      B8 Class 2
      Up to 3/4"
      125 ksi min
      100 ksi min
      12% min
      321 HB max
    

      
      3/4" – 1"
      115 ksi min
      80 ksi min
      15% min
      321 HB max
    

      
      1" – 1-1/4"
      105 ksi min
      65 ksi min
      20% min
      321 HB max
    

      
      1-1/4" – 1-1/2"
      100 ksi min
      50 ksi min
      28% min
      321 HB max
    

      B8M Class 1
      Up to 4"
      75 ksi min
      30 ksi min
      30% min
      223 HB max
    

      B8M Class 2
      Up to 3/4"
      110 ksi min
      95 ksi min
      15% min
      321 HB max
    

      
      3/4" – 1"
      100 ksi min
      80 ksi min
      20% min
      321 HB max
    

      
      1" – 1-1/4"
      95 ksi min
      65 ksi min
      25% min
      321 HB max
    

      
      1-1/4" – 1-1/2"
      90 ksi min
      50 ksi min
      30% min
      321 HB max
    

      B6
      Up to 4"
      110 ksi min
      85 ksi min
      15% min
      217–248 HB
    


  

Grade	Diameter	Tensile Strength	Yield Strength	Elongation	Hardness
B7	Up to 2-1/2"	125 ksi min	105 ksi min	16% min	321 HB max
	2-1/2" – 4"	115 ksi min	95 ksi min	16% min	321 HB max
B16	Up to 2-1/2"	130 ksi min	115 ksi min	18% min	321–352 HB
	2-1/2" – 4"	120 ksi min	100 ksi min	17% min	321–352 HB
B7M	Up to 4"	100 ksi min	80 ksi min	18% min	235 HB max
B8 Class 1	Up to 4"	75 ksi min	30 ksi min	30% min	223 HB max
B8 Class 2	Up to 3/4"	125 ksi min	100 ksi min	12% min	321 HB max
	3/4" – 1"	115 ksi min	80 ksi min	15% min	321 HB max
	1" – 1-1/4"	105 ksi min	65 ksi min	20% min	321 HB max
	1-1/4" – 1-1/2"	100 ksi min	50 ksi min	28% min	321 HB max
B8M Class 1	Up to 4"	75 ksi min	30 ksi min	30% min	223 HB max
B8M Class 2	Up to 3/4"	110 ksi min	95 ksi min	15% min	321 HB max
	3/4" – 1"	100 ksi min	80 ksi min	20% min	321 HB max
	1" – 1-1/4"	95 ksi min	65 ksi min	25% min	321 HB max
	1-1/4" – 1-1/2"	90 ksi min	50 ksi min	30% min	321 HB max
B6	Up to 4"	110 ksi min	85 ksi min	15% min	217–248 HB

Manufacturing Process and Heat Treatment

ASTM A193 fasteners are typically produced through various processes like forging, rolling, and machining, followed by heat treatment (quenching and tempering) to achieve the desired mechanical properties. The specific heat treatment process depends on the grade and the properties required.

Applications and Design Considerations

Each ASTM A193 grade is designed for specific applications, considering factors like temperature, pressure, and corrosive environment. For example, B7 is widely used in the petrochemical industry for flanged joints, while B8 and B8M are preferred in marine and acidic environments.

Real-world applications of ASTM A193 grades illustrate their performance and reliability. For instance, grade B7 fasteners are commonly used in high-temperature steam lines, while B8M fasteners are chosen for their superior corrosion resistance in chemical processing plants.

Quality Assurance and Compliance Testing

Adherence to ASTM A193 standards is ensured through rigorous testing, including tensile testing, hardness testing, and impact testing. These procedures guarantee that the fasteners meet the specified mechanical and chemical requirements.

Recommended Hardware

  
      ASTM A193 Grade
      Recommended Nuts
      Recommended Washers
    
      B7
      ASTM A194 Grade 2H
      ASTM F436
    
      B16
      ASTM A194 Grade 7
      ASTM F436
    
      B7M
      ASTM A194 Grade 2HM
      ASTM F436
    
      B8
      ASTM A194 Grade 8
      304 SS / 316 SS
    
      B8M
      ASTM A194 Grade 8M
      316 SS
    
      B6
      ASTM A194 Grade 6
      316 SS / 410 SS

ASTM A193 Grade	Recommended Nuts	Recommended Washers
B7	ASTM A194 Grade 2H	ASTM F436
B16	ASTM A194 Grade 7	ASTM F436
B7M	ASTM A194 Grade 2HM	ASTM F436
B8	ASTM A194 Grade 8	304 SS / 316 SS
B8M	ASTM A194 Grade 8M	316 SS
B6	ASTM A194 Grade 6	316 SS / 410 SS

ASTM A194 Grade 2H, 2HM: These are carbon or alloy steel nuts, quenched and tempered, recommended for use with ASTM A193 Grade B7 fasteners.

ASTM A194 Grade 7: Specifically chosen for high-temperature service, these grades are compatible with B16 fasteners, providing the necessary mechanical properties and temperature resistance.
ASTM A194 Grade 8 and 8M: Made of austenitic stainless steel, these nuts are used with B8 and B8M fasteners, respectively, offering excellent corrosion resistance and strength at high temperatures.
ASTM A194 Grade 6: This grade is suitable for use with ASTM A193 Grade B6 fasteners and is made of martensitic stainless steel, offering good mechanical properties and resistance to high temperatures.

Request A Quote

With California Fastener, you’re not just purchasing hardware— you’re gaining a partner dedicated to your projects success.

Take action today—submit your quote request and secure the strength and reliability that only California Fastener can deliver.

Two metallic thread rods on a flat surface in front of a machine with a yellow and black striped cutting blade, and parts of a blue machine with a yellow and black license plate reading 'CINCINNATI' at the top.