Austenitic Stainless Steel Stud Bolts for Low Temperature Service
ASTM A320 B8 Stud Bolt
ASTM A320 Grade B8 stud bolts are austenitic stainless steel fasteners designed for low-temperature and cryogenic pressure service.
They are commonly used in flanged joints, valves, pressure vessels, and piping systems where corrosion resistance and low-temperature toughness are required.
ASTM A320 B8 stud bolts are widely applied in LNG facilities, petrochemical plants, offshore platforms, and low-temperature process piping systems.
What Is ASTM A320?
ASTM A320 is a standard specification covering alloy steel and stainless steel bolting materials intended for low-temperature service.
The specification defines requirements for:
- Chemical composition
- Mechanical properties
- Heat treatment
- Impact testing (where applicable)
ASTM A320 is commonly specified for bolting used at temperatures below ambient, where ASTM A193 may not be suitable.
What Is Grade B8?
ASTM A320 Grade B8 corresponds to an austenitic stainless steel bolting grade equivalent to Type 304 stainless steel.
Key characteristics of A320 B8:
- Excellent corrosion resistance
- Good ductility and toughness at low temperatures
- Non-magnetic in solution-annealed condition
- Suitable for cryogenic service
Equivalent Grades
| Standard | Grade |
|---|---|
| ASTM | A320 B8 |
| UNS | S30400 |
| ASTM A193 Equivalent | B8 |
| EN | 1.4301 |
| DIN / EN | X5CrNi18-10 |
| AISI | 304 |
Chemical Composition (Typical – ASTM A320 B8)
| Element | Content (%) |
|---|---|
| Carbon (C) | ≤ 0.08 |
| Chromium (Cr) | 18.0 – 20.0 |
| Nickel (Ni) | 8.0 – 11.0 |
| Manganese (Mn) | ≤ 2.00 |
| Silicon (Si) | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.045 |
| Sulfur (S) | ≤ 0.030 |
Mechanical Properties
| Property | Requirement |
|---|---|
| Tensile Strength | ≥ 515 MPa |
| Yield Strength (0.2% Offset) | ≥ 205 MPa |
| Elongation | ≥ 30% |
| Hardness | ≤ 223 HB |
⚠️ Mechanical properties apply after solution annealing.
Heat Treatment Requirements
ASTM A320 B8 stud bolts must be supplied in the solution-annealed condition, followed by rapid cooling.
This heat treatment ensures:
- Maximum corrosion resistance
- Stable austenitic microstructure
- Excellent low-temperature toughness
Low Temperature Performance
ASTM A320 B8 stud bolts are suitable for sub-zero service, including:
- Cryogenic piping
- LNG processing
- Low-temperature pressure vessels
Impact testing may be specified by the purchaser depending on design temperature and project requirements.
Dimensions & Threading
- Thread Standard:
- ASME B1.1 (UNC / UNF)
- Metric threads on request
- Stud Length:
- As per ASME B16.5 / B16.47 flange requirements
- Custom lengths available
Inspection & Certification
ASTM A320 B8 stud bolts are typically supplied with:
- Chemical composition analysis
- Mechanical property testing
- Heat treatment verification
- Dimensional inspection
- Visual examination
- Certification: EN 10204 3.1
Typical Applications
- LNG and cryogenic systems
- Petrochemical plants
- Offshore and marine environments
- Low-temperature piping systems
- Stainless steel flanged connections
ASTM A320 Grade B8 stud bolts provide a reliable solution for low-temperature stainless steel bolting applications.
With excellent corrosion resistance, stable mechanical properties, and compliance with ASTM A320 requirements, B8 stud bolts are widely trusted in critical cryogenic and low-temperature pressure systems.
Related Products
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ASTM A193 B8 / B8M Stud Bolts
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