ASTM A193 B8 Stainless Steel — Specs, Uses & Applications

When it comes to fasteners in industrial and infrastructure projects, corrosion resistance is often the deciding factor. That’s where ASTM A193 Grade B8 comes in. Based on 304 stainless steel, B8 is one of the most widely used specifications in the A193 family, trusted for its balance of strength, availability, and corrosion resistance.

From chemical plants and refineries to food processing and pharmaceutical facilities, A193 B8 fasteners provide the durability needed to maintain long-term performance. In this blog, we’ll explore what the spec covers, how its classes differ, and why it remains one of the most specified stainless fastener grades worldwide.

What Is ASTM A193 B8?

ASTM A193 B8 defines austenitic stainless steel fasteners manufactured from 304 stainless. These include studs, threaded rods, and heavy-duty fasteners for high-pressure, high-temperature, and corrosive service.

ASTM A193 B8 Key features:

• 18% chromium, 8% nickel stainless composition.

• Excellent general corrosion resistance across many environments.

• Good strength for industrial service, enhanced further in Class 2.

• Non-magnetic in the annealed state, with slight magnetism possible after cold working.

Because of this versatility, B8 fasteners are specified across multiple industries where corrosion resistance is essential.

Class 1 vs. Class 2

The B8 specification is divided into two classes:

• Class 1: Carbide solution treated for maximum corrosion resistance. Best for food, beverage, and pharmaceutical applications, where cleanliness and chemical resistance matter most.

• Class 2: Strain-hardened for higher tensile strength. Common in chemical plants and structural applications requiring both strength and corrosion protection.

Choosing the correct class ensures the fastener system aligns with project performance needs.

Properties & Heat Treatment

B8 fasteners combine the corrosion resistance of 304 stainless with reliable strength.

• Tensile strength: 75–100 ksi for Class 1; up to 125 ksi for Class 2.

• Yield strength: 30–95 ksi depending on class.

• Heat treatment: Carbide solution treatment reduces carbide precipitation and enhances corrosion resistance.

• Limitations: Susceptible to chloride stress corrosion cracking; for marine or chloride-heavy applications, B8M (316 stainless) is preferred.

By balancing cost, availability, and durability, B8 has become the “workhorse” stainless spec across multiple industries.

Compatible Nuts: ASTM A194

B8 fasteners are paired with ASTM A194 Grade 8 nuts, manufactured from 304 stainless. This ensures:

• Material compatibility, avoiding galvanic corrosion.

• Consistent preload and torque under stress.

• Reduced galling during installation.

Correct nut/fastener pairing is essential for spec compliance and reliable joint performance.

Applications of ASTM A193 B8

The widespread use of A193 B8 reflects its adaptability. Common applications include:

• Chemical processing plants: piping, valves, and pressure vessels.

• Food & beverage facilities: sanitary fasteners resistant to cleaning agents.

• Pharmaceutical manufacturing: corrosion-resistant and hygienic fasteners.

• General construction: assemblies in high-humidity or corrosive environments.

• Industrial equipment: systems requiring both moderate strength and corrosion defense.

B8 fasteners support safe, long-lasting performance in environments where carbon and alloy steels would fail prematurely.

California Fastener’s Offering

At California Fastener, we maintain a deep inventory of ASTM A193 B8 fasteners, including:

• Both Class 1 and Class 2 options with full certification.

• Matching ASTM A194 Grade 8 nuts.

• Studs, threaded rods, and heavy-duty fasteners in multiple sizes and thread pitches.

• Pre-kitted packaging for efficient installation and inspection.

• Dependable fulfillment timelines for construction and maintenance projects.

We help contractors and facility managers reduce project risk with on-spec, traceable fasteners delivered on time.

FAQs About ASTM A193 B8

Q: What is the difference between Class 1 and Class 2 B8?
A: Class 1 maximizes corrosion resistance, while Class 2 provides higher strength through strain hardening.

Q: Where is B8 commonly used?
A: Chemical plants, food & beverage facilities, pharmaceutical production, and general construction.

Q: What nuts pair with B8 fasteners?
A: ASTM A194 Grade 8 nuts should always be used for compatibility.

Q: Is B8 magnetic?
A: Non-magnetic when annealed; slight magnetism may occur after strain hardening.

Q: When should I choose B8M instead of B8?
A: In marine or chloride-heavy environments, B8M (316 stainless) offers superior resistance.

Securing Projects with Stainless Confidence

ASTM A193 B8 remains one of the most specified fastener standards because it balances strength, corrosion resistance, and availability at scale. From refineries to food plants, it ensures reliable performance in environments where carbon steels can’t hold up.

At California Fastener, we provide A193 B8-compliant fasteners that are fully certified, traceable, and delivered on time.

Contact us today to source ASTM A193 B8 fasteners—trusted for their reliability and ready for your next project.