#gradeb8

Overview

ASTM A193 Grade B8 fasteners are extensively used and are widely known for their dependability. These fasteners are produced from AISI 304 stainless steel and possess exceptional corrosion resistance, durable strength in high-temperature and high-pressure applications, and long-term durability. They find important applications in industries such as oil and gas, power generation, petrochemical, food processing, etc.

Available in a wide array of types such as bolts, nuts, washers, studs, screws, and threaded rods, Grade B8 fasteners conform to stringent mechanical and chemical standards laid out by ASTM.

What Is ASTM A193?

The ASTM A193 standard specifies alloy and stainless steel materials used in bolting for pressure vessels, valves, flanges, and fittings. This specification is specifically engineered to perform in high-temperature and high-pressure environments.

Key Attributes of Grade B8:

Based on AISI 304 stainless steel.

Exhibits excellent corrosion and oxidation resistance.

Heat-treated for enhanced strength and performance.

Supports service temperatures up to 593°C (1100°F).

It is categorized into Class 1 (annealed) and Class 2 (strain-hardened) based on the heat treatment process.

Chemical Composition of Grade B8

The blend of chromium and nickel ensures long-term performance in corrosive settings such as chemical processing plants and marine environments.

Mechanical Properties of Grade B8 Fasteners

Class 2 fasteners are particularly suitable for demanding environments due to their higher strength achieved through strain-hardening.

Available Types of Grade B8 Fasteners

Hex Head Bolts

Nuts

Threaded Rods

Stud Bolts

Screws

Washers

They are typically used in assemblies where both mechanical strength and corrosion resistance are essential.

Class 1 vs. Class 2

Choosing between Class 1 and Class 2 depends on the specific mechanical requirements of your application.

Grade B8 vs. Grade B8M

B8M fasteners are more suited for aggressive environments due to improved resistance to pitting and crevice corrosion.

Marking & Identification

Every Grade B8 fastener shall be clearly marked to indicate:

Grade (e.g., B8)

Class (e.g., CL1 or CL2)

Manufacturer's symbol or logo

These markings provide proper traceability and compliance with ASTM specifications.

Typical Uses of ASTM A193 Grade B8 Fasteners

Pressure Vessels

Heat Exchangers

Flanges & Valves

Petrochemical Equipment

Food Processing Machinery

Pharmaceutical Plants

Water Treatment Facilities

Boilers and High-Temperature Piping

Advantages of Grade B8 Fasteners

Outstanding corrosion resistance in oxidizing environments.

Durable under high-stress conditions.

Excellent mechanical integrity at elevated temperatures.

Non-magnetic when annealed.

Cost-effective and widely available.

Manufacturing Process

The production of Grade B8 fasteners involves:

Selection of AISI 304 stainless steel.

Forging or cold-forming the desired fastener type.

Heat treatment (solution annealing).

Optional strain-hardening (for Class 2).

Thread cutting or rolling.

Testing and certification.

Marking for identification.

Strict quality checks are applied throughout the process to ensure conformity with ASTM A193.

Quality Assurance and Testing

To ensure that Grade B8 fasteners meet industry standards, they undergo:

Tensile Testing

Hardness Testing

Dimensional Verification

Intergranular Corrosion Testing

Non-Destructive Testing (NDT) (if specified)

Conclusion

ASTM A193 Grade B8 fasteners are a preferred solution for industries requiring high-strength, corrosion-resistant bolting components. With their proven reliability under pressure and heat, they are a cornerstone in sectors ranging from energy to food processing. Whether in standard or strain-hardened form, these fasteners consistently deliver performance, longevity, and safety.

When you're seeking fasteners that combine strength, durability, and resistance to harsh environments, ASTM A193 Grade B8 is the standard to trust.

Frequently Asked Questions (FAQs)

Q1. Are B8 fasteners suitable for marine environments?

While they offer good corrosion resistance, B8M (AISI 316) is preferred in marine environments due to better resistance to salt and chlorides.

Q2. How are B8 fasteners marked?

They are marked with the grade (B8), class (CL1 or CL2), and manufacturer’s identification.

Q3. What industries commonly use B8 fasteners?

Introduction

ASTM A193 Grade B8 is one of the most commonly used specifications for high-temperature and high-pressure fasteners, especially in petrochemical, power generation, and marine industries. These fasteners are crafted from AISI 304 stainless steel, delivering an optimal blend of corrosion resistance, mechanical strength, and long-lasting durability.

This guide provides a comprehensive look at ASTM A193 B8 fasteners, including their chemical and mechanical properties, types, applications, equivalent grades, and why they are essential in demanding environments.

What is ASTM A193 Grade B8?

Grade B8 fasteners are manufactured from AISI 304 stainless steel and are strain-hardened to improve mechanical strength. These fasteners are commonly used in chemical processing, oil & gas, petrochemical, nuclear power plants, and marine environments due to their excellent corrosion resistance and mechanical performance.

Grade B8 under this specification refers to fasteners made from 304 stainless steel (or its variants), with or without carbide solution treatment depending on the class.

Class 1: Carbide solution treated

Class 2: Strain-hardened

These classes affect the mechanical properties of the fasteners and are selected based on the application's requirements.

Chemical Composition of ASTM A193 Grade B8

The chemical composition is based on AISI 304 stainless steel, which provides excellent corrosion resistance and good mechanical strength.

Mechanical Properties

Mechanical properties vary based on the class (Class 1 vs. Class 2):

The choice between Class 1 and Class 2 depends on whether the application prioritizes ductility or strength.

Types of ASTM A193 B8 Fasteners

Ananka Group specializes in manufacturing and supplying an extensive range of ASTM A193 B8 fasteners, including:

Hex Bolts

Stud Bolts

Heavy Hex Nuts

Threaded Rods

Cap Screws

Washers

All these fasteners are available in both Class 1 and Class 2 conditions, depending on project specifications.

Heat Treatment

Class 1 Fasteners: Undergo carbide solution treatment to eliminate residual stress and improve corrosion resistance.

Class 2 Fasteners: Strain-hardened to increase tensile strength and load-bearing capacity.

Applications of ASTM A193 Grade B8 Fasteners

Due to their excellent corrosion resistance and strength at high temperatures, ASTM A193 B8 fasteners are widely used in:

Oil & Gas Industry

Chemical Processing Plants

Petrochemical Equipment

Power Generation (Thermal & Nuclear)

Marine Environments

Food Processing Equipment

Pharmaceutical Plants

They are ideal for flanged connections, reactors, heat exchangers, and pressure vessels.

ASTM A193 B8 vs B8M: What’s the Difference?

B8M is preferred where chloride exposure is high, while B8 is sufficient for standard high-temperature services.

Advantages of ASTM A193 B8 Fasteners

High resistance to oxidation and corrosion

Durable under thermal cycling

Strong under high pressure

Non-magnetic in annealed condition

Cost-effective for a wide range of applications

ASTM Standards & Certifications

All ASTM A193 Grade B8 fasteners are produced in strict accordance with the following standards:

ASTM A193 for mechanical and chemical requirements

ASME B1.1 (Unified Inch Screw Threads)

ASME B18.2.1 / B18.2.2 for dimensions

NACE MR0175 (if required for sour service)

Ananka Group – Premier Manufacturer and Supplier of ASTM A193 B8 Fasteners

Ananka Group is a globally recognized manufacturer and exporter of ASTM A193 Grade B8 fasteners. Our fasteners are made using premium stainless steel with strict adherence to ASTM standards. We supply fasteners with full traceability, test certifications, and custom packaging for international delivery.

We serve a wide range of industries in USA, Canada, Germany, UAE, Australia, Singapore, and beyond.

Conclusion

ASTM A193 Grade B8 fasteners are vital components for applications requiring a combination of corrosion resistance and high tensile strength. From chemical processing plants to marine environments and power generation facilities, these fasteners deliver dependable, long-lasting performance while meeting stringent industry standards. At Ananka Group, we are committed to manufacturing top-quality B8 fasteners with a focus on precision, reliability, and customer satisfaction.

FAQs

How does B8 differ from B8M?

B8 is made from 304 stainless steel, while B8M is made from 316 stainless steel, which has better corrosion resistance due to added molybdenum.

What is the distinction between Class 1 and Class 2 in ASTM A193 B8?

Class 1 refers to fasteners that have been annealed through carbide solution treatment. Class 2 refers to strain-hardened fasteners with higher tensile strength.

Can B8 fasteners be used in chloride environments?

For better resistance in chloride-rich environments, B8M is preferred over B8.

Are B8 bolts magnetic?

B8 bolts are typically non-magnetic in their annealed condition; however, they may exhibit slight magnetic properties after undergoing strain hardening.

Is certification available for ASTM A193 B8 fasteners?

Introduction

Fasteners play a crucial role in ensuring the integrity and safety of structures, equipment, and machinery. ASTM A193 is a widely recognized standard that specifies alloy and stainless steel bolting materials for high-temperature or high-pressure service. Among the most commonly used grades within this specification are Grade B7 and Grade B8. While both grades serve critical fastening applications, they have distinct differences in terms of composition, mechanical properties, applications, and corrosion resistance.

In this blog, we will compare ASTM A193 Grade B7 and Grade B8 in detail, highlighting their unique characteristics and key differences.

What is ASTM A193 Grade B7?

ASTM A193 Grade B7 is a high-strength, heat-treated chromium-molybdenum steel fastener. It is primarily used in high-pressure and high-temperature applications, making it a popular choice in industries such as oil and gas, power plants, and refineries.

Chemical Composition of Grade B7

Carbon (C): 0.37 - 0.49%

Manganese (Mn): 0.65 - 1.10%

Phosphorus (P): ≤ 0.035%

Sulfur (S): ≤ 0.040%

Silicon (Si): 0.15 - 0.35%

Chromium (Cr): 0.75 - 1.20%

Molybdenum (Mo): 0.15 - 0.25%

Mechanical Properties of Grade B7

Tensile Strength: 125 ksi (860 MPa) minimum

Yield Strength: 105 ksi (725 MPa) minimum

Elongation: 16% minimum

Hardness: HRC 35 maximum

Applications of Grade B7

Pressure vessels and boilers

High-temperature pipelines

Oil and gas drilling equipment

Power plants

Structural applications requiring high strength

What is ASTM A193 Grade B8?

ASTM A193 Grade B8 fasteners are made from AISI 304 stainless steel, offering excellent corrosion resistance. Unlike Grade B7, B8 fasteners undergo a carbide solution treatment to enhance their mechanical properties.

Chemical Composition of Grade B8

Carbon (C): ≤ 0.08%

Manganese (Mn): ≤ 2.00%

Phosphorus (P): ≤ 0.045%

Sulfur (S): ≤ 0.030%

Silicon (Si): ≤ 1.00%

Chromium (Cr): 18.00 - 20.00%

Nickel (Ni): 8.00 - 11.00%

Mechanical Properties of Grade B8

Tensile Strength: 75 ksi (515 MPa) minimum

Yield Strength: 30 ksi (205 MPa) minimum

Elongation: 30% minimum

Hardness: HRB 92 maximum

Applications of Grade B8

Marine environments

Chemical processing industries

Food and beverage industries

Pharmaceutical industries

Applications requiring corrosion resistance

Key Differences Between Grade B7 and Grade B8

Grade B7 and Grade B8 fasteners differ mainly in material composition, mechanical properties, and applications. ASTM A193 Grade B7 is made from chromium-molybdenum steel and is heat-treated to achieve high tensile strength, making it ideal for high-pressure and high-temperature applications such as in petrochemical and power plants. In contrast, ASTM A193 Grade B8 is manufactured from austenitic stainless steel, typically 304 stainless steel, offering excellent corrosion resistance but lower tensile strength compared to B7. 

Due to its corrosion-resistant properties, B8 is commonly used in environments exposed to moisture, chemicals, and extreme temperatures, such as in marine, food processing, and chemical industries. While B7 fasteners require additional coatings or treatments for corrosion resistance, B8 fasteners naturally resist oxidation and rust.

Which One Should You Choose?

The choice between Grade B7 and Grade B8 depends on the application requirements:

If your project requires high strength and the environment does not pose corrosion risks, Grade B7 is the ideal choice.

If your project involves corrosive environments such as marine or chemical applications, Grade B8 is the better option due to its stainless steel composition.

Conclusion

ASTM A193 Grade B7 and Grade B8 fasteners serve distinct purposes in industrial applications. While B7 fasteners provide excellent strength and high-temperature resistance, B8 fasteners offer superior corrosion resistance with moderate strength. Understanding their differences ensures you choose the right fastener for your specific needs, enhancing the durability and reliability of your equipment or structure.

FAQs

1. Can Grade B7 fasteners be used in corrosive environments?

Grade B7 fasteners have limited corrosion resistance. To enhance their longevity in corrosive environments, they are often coated or plated (e.g., zinc, PTFE, or hot-dip galvanized).

2. Are Grade B8 fasteners stronger than Grade B7?

No, Grade B7 fasteners have higher tensile and yield strength compared to Grade B8 fasteners, making them more suitable for high-stress applications.

3. Is Grade B8 equivalent to stainless steel?

Yes, Grade B8 is made from AISI 304 stainless steel, which is widely used for its corrosion resistance properties.

4. What coatings can be applied to Grade B7 bolts?

Common coatings for Grade B7 bolts include zinc plating, PTFE (Teflon), hot-dip galvanizing, and cadmium plating to improve corrosion resistance.

5. Which industries commonly use Grade B7 and Grade B8 fasteners?

Grade B7 is commonly used in power plants, oil and gas, and high-temperature applications.

Introduction

The ASTM A193 Grade B8 specification is widely recognized in the fastener industry for its exceptional performance in high-temperature and corrosive environments. Grade B8 fasteners, made from austenitic stainless steel (typically Type 304), are essential components in various industries, including petrochemical, power generation, and marine applications. This blog explores the characteristics, chemical and mechanical composition, applications, and manufacturing details of Grade B8 bolts, nuts, and washers.

What is ASTM A193 Grade B8?

ASTM A193 Grade B8 refers to a standard specification for austenitic stainless steel bolts, nuts, and washers designed for high-pressure or high-temperature services. These fasteners are made from stainless steel Type 304, offering excellent corrosion resistance, durability, and strength.

Characteristics of Grade B8 Fasteners

Corrosion Resistance: Grade B8 fasteners exhibit excellent resistance to corrosion and oxidation, making them suitable for harsh environments.

High-Temperature Strength: These fasteners retain their mechanical properties at elevated temperatures, making them ideal for high-temperature applications.

Durability: The material’s austenitic structure enhances toughness and longevity.

Non-Magnetic Properties: While Grade B8 fasteners are generally non-magnetic, slight magnetism may develop due to cold working.

Chemical Composition

The chemical composition of Grade B8 fasteners aligns with Type 304 stainless steel. The primary elements include:

Carbon (C): Max 0.08%

Manganese (Mn): Max 2.00%

Phosphorus (P): Max 0.045%

Sulfur (S): Max 0.030%

Silicon (Si): Max 1.00%

Chromium (Cr): 18.00 - 20.00%

Nickel (Ni): 8.00 - 11.00%

Iron (Fe): Balance

Mechanical Properties

Grade B8 fasteners provide the following mechanical properties:

Tensile Strength: Min 75 ksi (515 MPa)

Yield Strength (0.2% Offset): Min 30 ksi (205 MPa)

Elongation: Min 30%

Hardness: Max 223 HB or 96 HRB

Applications of Grade B8 Fasteners

Grade B8 bolts, nuts, and washers are employed in various industries, such as:

Petrochemical Industry: Used in piping systems, heat exchangers, and pressure vessels.

Power Generation: Ideal for boilers, turbines, and high-temperature equipment.

Marine Applications: Suitable for shipbuilding and offshore platforms due to their corrosion resistance.

Construction: Utilized in structural components exposed to corrosive environments.

Manufacturing and Processing

Grade B8 fasteners are manufactured using high-quality Type 304 stainless steel. The process includes:

Cold Working: To enhance mechanical properties such as tensile strength.

Threading: Rolled threads ensure smooth installation and removal.

Heat Treatment: Some Grade B8 fasteners may undergo heat treatment to achieve specific mechanical properties.

Surface Finishing: Options include passivation or electro-polishing to improve corrosion resistance.

Benefits of ASTM A193 Grade B8 Fasteners

Long-lasting performance in challenging environments.

Resistance to rust and oxidation.

High strength-to-weight ratio.

Versatility in various industrial applications.

Conclusion

ASTM A193 Grade B8 bolts, nuts, and washers are a reliable choice for industries requiring durable and corrosion-resistant fasteners. Their superior mechanical and chemical properties make them suitable for demanding applications, ensuring longevity and performance under challenging conditions.

When sourcing Grade B8 fasteners, partnering with a reputable manufacturer ensures compliance with international standards and consistent quality. Ananka Group is a trusted name in the fastener industry, offering a wide range of Grade B8 fasteners tailored to meet specific industrial needs.

Frequently Asked Questions (FAQ)

1. What is the difference between Grade B8 and Grade B8M? 

Grade B8 fasteners are made from Type 304 stainless steel, while Grade B8M fasteners are manufactured using Type 316 stainless steel, offering enhanced corrosion resistance due to the addition of molybdenum.

2. Are Grade B8 fasteners suitable for marine applications? 

Yes, Grade B8 fasteners exhibit excellent corrosion resistance, making them suitable for certain marine applications, though Grade B8M may be preferred for environments with high chloride exposure.

3. What is the temperature range for Grade B8 fasteners? 

Grade B8 fasteners can withstand temperatures up to 815°C (1500°F), making them ideal for high-temperature applications.

4. Can Grade B8 fasteners be used in acidic environments? 

Grade B8 fasteners resist corrosion in mildly acidic environments. For highly acidic conditions, consider using fasteners made from Type 316 or other specialized alloys.

5. Why choose Ananka Group for Grade B8 fasteners? 

Introduction

Fasteners play a critical role in a wide range of industries, ensuring the structural integrity and performance of machinery, equipment, and infrastructure. Among the many grades of fasteners, ASTM A193 Grade B7 and Grade B8 are widely used due to their unique properties and performance characteristics. Understanding the differences between these two grades is crucial for selecting the right fasteners for specific applications.

Understanding Grade B7 Fasteners

ASTM A193 Grade B7 fasteners are alloy steel fasteners known for their high tensile strength and excellent performance in high-temperature environments. These fasteners are commonly used in industries such as oil and gas, power generation, and petrochemical industries.

Key Features of Grade B7 Fasteners:

Material Composition: Grade B7 fasteners are made from chromium-molybdenum (Cr-Mo) alloy steel.

Tensile Strength: They have a minimum tensile strength of 125 ksi, making them suitable for heavy-duty applications.

Temperature Resistance: Grade B7 fasteners can withstand temperatures up to 450°C (842°F).

Corrosion Resistance: While they offer moderate corrosion resistance, they are often coated or treated for enhanced durability in corrosive environments.

Applications: Commonly used in pressure vessels, flanges, valves, and fittings.

Understanding Grade B8 Fasteners

ASTM A193 Grade B8 fasteners are stainless steel fasteners designed for applications requiring excellent corrosion resistance. These fasteners are made from austenitic stainless steel, which provides superior performance in corrosive environments.

Key Features of Grade B8 Fasteners:

Material Composition: Grade B8 fasteners are manufactured using stainless steel 304 or its equivalent.

Tensile Strength: They have a minimum tensile strength of 75 ksi.

Temperature Resistance: These fasteners are suitable for both high and low-temperature environments.

Corrosion Resistance: Exceptional resistance to corrosion, making them ideal for marine and chemical applications.

Applications: Used in chemical processing, marine environments, food and beverage industries, and more.

Key Differences Between Grade B7 and Grade B8 Fasteners

Choosing Between Grade B7 and Grade B8 Fasteners

The selection between Grade B7 Bolts and Grade B8 Bolts fasteners depends on several factors, including the application, environmental conditions, and budget. Here are some guidelines:

Choose Grade B7: For high-strength applications in high-temperature environments where moderate corrosion resistance is sufficient. Ideal for use in oil refineries, power plants, and other industrial settings.

Choose Grade B8: When corrosion resistance is a top priority, such as in marine environments, chemical processing plants, and food and beverage industries.

Common Coatings and Treatments

To enhance their performance, both Grade B7 and Grade B8 fasteners can be treated or coated with materials such as:

Zinc Plating: Provides additional corrosion resistance.

PTFE Coating: Reduces friction and enhances resistance to chemicals.

Hot-Dip Galvanizing: Improves corrosion resistance, especially for outdoor applications.

Ananka Group: Your Trusted Partner for Grade B7 and Grade B8 Fasteners

At Ananka Group, we specialize in manufacturing, supplying, and exporting high-quality fasteners, including Grade B7 and Grade B8. Our products are crafted to meet international standards such as ASTM, ASME, and DIN, ensuring reliability and performance in the most demanding environments.

Why Choose Ananka Group?

Extensive Inventory: A wide range of fasteners in various sizes, materials, and finishes.

Custom Solutions: Tailored fasteners to meet specific project requirements.

Global Reach: Supplying to industries worldwide with timely delivery.

Quality Assurance: Stringent quality checks to ensure compliance with international standards.

Conclusion

Both ASTM A193 Grade B7 and Grade B8 fasteners offer distinct advantages, making them suitable for different applications. Grade B7 is ideal for high-temperature, high-pressure environments, while Grade B8 is preferred for its superior corrosion resistance. Understanding their properties, differences, and applications can help you make an informed decision for your projects.

For premium quality Grade B7 and Grade B8 fasteners, contact Ananka Group today. We’re here to assist you with all your fastening needs.

FAQs

1. What is the main difference between Grade B7 and Grade B8 fasteners? 

The primary difference lies in their material composition and application. Grade B7 is made of chromium-molybdenum alloy steel for high strength, while Grade B8 is made of austenitic stainless steel for superior corrosion resistance.

2. Can Grade B7 fasteners be used in corrosive environments? 

Grade B7 fasteners offer moderate corrosion resistance but can be coated or treated for enhanced durability in corrosive environments.

3. Are Grade B8 fasteners magnetic? 

No, Grade B8 fasteners are generally non-magnetic due to their austenitic stainless steel composition.

4. Which industries commonly use Grade B7 fasteners? 

Industries such as oil and gas, petrochemicals, and power generation frequently use Grade B7 fasteners.

5. Are Grade B8 fasteners more expensive than Grade B7? 

Yes, due to the stainless steel composition and superior corrosion resistance, Grade B8 fasteners are typically more expensive.

6. Can Ananka Group provide customized fasteners? 

Fasteners play a crucial role in industrial applications, and selecting the right material is essential for ensuring safety, durability, and performance. ASTM A193 Grade B8M and ASTM A193 Grade B7M are two commonly used fastener grades, each with distinct properties tailored for specific applications. In this blog, we'll explore their chemical composition, mechanical properties, and key differences.

1. Understanding ASTM A193 Grade B8M

ASTM A193 Grade B8M refers to fasteners made from austenitic stainless steel, specifically Type 316. These fasteners are widely used in environments where corrosion resistance is critical.

Chemical Composition of B8M

Carbon (C): ≤ 0.08%

Chromium (Cr): 16.0 - 18.0%

Nickel (Ni): 10.0 - 14.0%

Molybdenum (Mo): 2.0 - 3.0% (enhances corrosion resistance)

Manganese (Mn): ≤ 2.0%

Silicon (Si): ≤ 1.0%

Phosphorus (P): ≤ 0.045%

Sulfur (S): ≤ 0.030%

Mechanical Properties of B8M

Tensile Strength: ≥ 75 ksi

Yield Strength: ≥ 30 ksi

Elongation: ≥ 30%

Hardness: ≤ 223 HB

Key Features

Exceptional resistance to corrosion, especially in marine and chemical environments.

Retains strength at high temperatures.

2. Understanding ASTM A193 Grade B7M

ASTM A193 Grade B7M fasteners are made from chromium-molybdenum alloy steel, specifically heat-treated for enhanced strength and toughness. These fasteners are commonly used in high-pressure and high-temperature applications.

Chemical Composition of B7M

Carbon (C): 0.28 - 0.45%

Chromium (Cr): 0.75 - 1.20%

Molybdenum (Mo): 0.15 - 0.25%

Manganese (Mn): 0.60 - 1.00%

Silicon (Si): 0.15 - 0.35%

Phosphorus (P): ≤ 0.035%

Sulfur (S): ≤ 0.040%

Mechanical Properties of B7M

Tensile Strength: 100 - 115 ksi

Yield Strength: ≥ 65 ksi

Elongation: ≥ 20%

Hardness: ≤ 235 HB

Key Features

High strength and excellent resistance to heat and pressure.

Typically used in petrochemical, refinery, and power generation industries.

3. Key Differences Between B8M and B7M

4. Applications

B8M Applications

Marine environments.

Chemical processing plants.

Food and beverage industries.

B7M Applications

Pressure vessels.

High-temperature pipelines.

Refinery and petrochemical industries.

Conclusion

ASTM A193 Grade B8M and B7M fasteners cater to different industrial needs. While B8M is the go-to choice for corrosion resistance and long-term durability in harsh environments, B7M stands out for its high strength and performance in extreme pressure and temperature conditions. Choosing the right grade depends on the specific requirements of your project.

FAQs

1. Which is more corrosion-resistant, B8M or B7M?

ASTM A193 Grade B8M is more corrosion-resistant due to its austenitic stainless steel composition and added molybdenum content.

2. Can B7M be used in marine environments?

B7M is not ideal for marine environments as it lacks the corrosion resistance provided by B8M.

3. What are the typical industries using B8M fasteners?

Industries like marine, food processing, and chemical plants frequently use B8M fasteners.

4. Are B7M fasteners heat-treated?

Yes, B7M fasteners undergo heat treatment to enhance their strength and toughness.

5. How do I decide between B8M and B7M for my project?

Choose B8M for corrosion resistance and B7M for high-pressure or high-temperature requirements.

High-stress connections with secure and durable results are precisely what industries demand, and fasteners are crucially important in this regard. Among the popular grades found in the ASTM A193 standard, Grade B8 and Grade B7 are two extensively used grades to make bolts, nuts, washers, and studs. Although both are high-strength materials, their chemical and mechanical properties address other needs in the industrial sector. This blog highlights an in-depth comparison of ASTM A193 Grade B8 vs. B7 to assist you in making the right material choice for your application.

Overview of ASTM A193 Grade B8

ASTM A193 Grade B8 is an austenitic stainless steel alloy which contains 18 percent chrome and 8 percent nickel with excellent resistance to corrosion along with high-temperature strength. This grade finds its application wherever extreme temperatures and corrosive environment conditions are concerned. 

Pressure vessels

Valves

Flanges

Power generation equipment

Key Characteristics of ASTM A193 Grade B8

Material Type: Austenitic stainless steel (based on 304 SS)

Corrosion Resistance: Excellent in atmospheric and chemical environments

Temperature Range: Suitable for both cryogenic and elevated temperatures

Applications: Preferred in industries requiring high corrosion resistance and durability

Overview of ASTM A193 Grade B7

ASTM A193 Grade B7 is a chromium-molybdenum alloy steel known for its high tensile strength and excellent resistance to high temperatures. Grade B7 is commonly used in applications that require superior strength but are not exposed to extreme corrosive environments, such as:

Petrochemical facilities

High-pressure pipelines

Boiler equipment

Key Characteristics of ASTM A193 Grade B7

Material Type: Alloy steel

Strength: Superior tensile and yield strength compared to Grade B8

Temperature Range: Effective in high-temperature applications up to 450°C

Applications: Best suited for non-corrosive high-pressure and high-temperature environments

Chemical Composition

Mechanical Composition

Comparison: Grade B8 vs Grade B7

Applications of ASTM A193 Grade B8 and B7 Bolts, Nuts, and Washers

ASTM A193 Grade B8

Ideal for industries requiring corrosion resistance such as:

Chemical processing

Food and beverage

Power plants

ASTM A193 Grade B7

Suited for high-strength applications in less corrosive environments:

Oil and gas

High-pressure steam pipelines

Industrial machinery

Choosing the Right Fastener: Key Considerations

When selecting between Grade B8 and Grade B7, consider:

Environmental Conditions: Choose Grade B8 for corrosive environments; Grade B7 for non-corrosive settings.

Strength Requirements: Grade B7 offers higher tensile and yield strength.

Temperature Extremes: Grade B8 is versatile for cryogenic and elevated temperatures, whereas Grade B7 is effective in high heat.

Conclusion

Both ASTM A193 Grade B8 and B7 are excellent materials typically made for specific industrial purposes. Grade B8 is preferred for corrosion resistance and good high-temperature performance, while Grade B7 is preferred for strength in non-corrosive and high-pressure conditions. The grade depends on your application's environment and mechanics.

Ananka Group is a leading bolt, nut, and washer manufacturer and supplier based on ASTM A193 Grade B8 and B7 in India. All of these are made to withstand different tests and have rigorous quality standards, meaning they offer more reliability and durability in each application. Call today to order your fasteners!

FAQs

1. What is the difference between ASTM A193 Grade B8 and B7?

Grade B8 is made of austenitic stainless steel, providing excellent corrosion resistance, whereas Grade B7 is a chromium-molybdenum alloy steel that is known to provide strength.

2. Is Grade B7 suitable for corrosive environments?

Grade B7 cannot be used in highly corrosive environments because Grade B7 is not as corrosion-resistant as Grade B8 is.

3. Which industries typically use Grade B8 fasteners?

Grade B8 fasteners are used in chemical processing, power generation, and more, where materials have to exhibit resistance to corrosion.

4. Which grade would be considered superior for high-pressure applications?

B7 would be recommended for high-pressure applications as it possesses higher strength.

5. Does Ananka Group manufacture custom fasteners?