RapidBoltCarbon Steel Bolts, Stud Bolts & Nuts for Pressure and Structural Duty
ASTM A193 B7 and B7M, A307, Grade 8.8 and 10.9 carbon steel bolting supplied to project specification with EN 10204 3.1 certification and full heat traceability.
Material Characteristics
Carbon steel bolts are the most widely specified fastener material in industrial plant. In bolting terms, "carbon steel" covers low-carbon grades such as ASTM A307, medium-carbon quenched and tempered grades such as ISO 898-1 Grade 8.8 and 10.9, and the chrome-moly A193 family (B7, B7M, B5, B6) used for pressure-containing flanged joints.
We supply carbon steel stud bolts, hex and heavy hex bolts, threaded rod, nuts and washers in imperial sizes from 1/4in to 6in and metric M5 to M150, in standard and cut-to-length options. Quenched and tempered ASTM A193 B7 delivers 860 MPa tensile and 720 MPa yield, making it the default selection for ASME B16.5 and B16.47 flange bolting, pressure vessels, valves and pipe supports.
Because carbon steel has limited inherent corrosion resistance, project bolting is usually supplied coated — hot dip galvanising to AS/NZS 4680, zinc plating, Xylan or PTFE — to the coating system nominated in the client specification.
Every line item ships with EN 10204 3.1 material certification and heat number traceability as standard, with 3.2 third-party inspection available on request. Stock is held in Brisbane and supplied Australia-wide and across Asia-Pacific.
Key Properties
Available Grades & Specifications
We stock and supply the following grades. All materials supplied with EN 10204 3.1 mill test reports and full chemical and mechanical certification.
| Designation | Description |
|---|---|
| ASTM A193 B5 | 5% Chromium Steel |
| ASTM A193 B6 | 13% Chromium Steel (410 SS) |
| ASTM A193 B7 | Chrome-Moly Steel, Q&T |
| ASTM A193 B7M | Chrome-Moly Steel, Reduced Hardness |
| ASTM A307 Grade A | Low Carbon Steel |
| ASTM A307 Grade B | Low Carbon Steel (Flanged) |
| Grade 8.8 (ISO 898-1) | Medium Carbon Steel, Q&T |
| Grade 10.9 (ISO 898-1) | Medium Carbon Alloy, Q&T |
| ASTM A325 Type 1 | Structural Bolt, Medium Carbon |
| ASTM A490 Type 1 | Structural Bolt, Alloy Steel |
Typical Applications
- ASME B16.5 flanged connections in process piping
- Pressure vessel and heat exchanger bolting
- Structural steel connections (bridges, buildings, towers)
- General purpose mechanical assembly
- Pipeline construction and maintenance
- Valve and pump assembly
- Storage tank construction
- Mining and materials handling equipment
Available Fastener Types
NACE MR0175 / ISO 15156
B7M grade (max 22 HRC / 235 HBW) is compliant with NACE MR0175 for sour service environments. We supply B7M with full hardness certification for H₂S-containing applications.
Hot Dip Galvanising
Carbon steel fasteners can be hot-dip galvanised to AS/NZS 4680 or ASTM A153 for outdoor and coastal applications. We carry extensive HDG stock in common sizes.
High Temperature Service
B5 and B6 grades contain chromium additions for elevated temperature oxidation resistance up to 566°C, commonly used in refinery heater and boiler applications.
Standards & Documentation
All carbon steel fasteners are supplied with full documentation, EN 10204 3.1 mill test reports, and compliance with relevant industry standards.
EN 10204 3.1 Certification
Third-party verified material test reports with full chemical and mechanical data.
Heat Number Traceability
Complete material traceability from mill source through to final delivery.
PMI Testing
Positive Material Identification for critical alloy verification.
ISO 9001 Quality
Quality management ensuring consistent product quality and compliance.
Related Materials & Products
Frequently Asked Questions
Common questions about carbon steel fasteners, specifications, and applications.
What is the difference between ASTM A193 B7 and B7M?
B7 is the standard quenched and tempered chrome-moly grade with 860 MPa tensile strength. B7M is a reduced-hardness variant (max 235 HBW / 22 HRC) specifically designed for sour service compliance with NACE MR0175/ISO 15156 in H₂S-containing environments.
What temperature range can carbon steel fasteners operate in?
Standard ASTM A193 B7 is suitable for service from -29°C to +450°C. For sub-zero applications below -29°C, impact-tested alloy grades like ASTM A320 L7 are recommended. For temperatures above 450°C, upgrade to ASTM A193 B16 or high-temperature alloys.
Do carbon steel fasteners need a protective coating?
Carbon steel has limited inherent corrosion resistance and typically requires protective coatings for outdoor or corrosive environments. Common options include hot-dip galvanising (AS/NZS 4680), zinc plating, Xylan fluoropolymer, and PTFE coatings.
What is the most common carbon steel bolt grade?
ASTM A193 Grade B7 with A194 Grade 2H nuts is the most widely used high-strength carbon steel combination in industrial applications, particularly for ASME B16.5 flanged connections in process piping, pressure vessels, and valves.
What sizes of carbon steel bolts do you supply?
Imperial 1/4in to 6in diameter and metric M5 to M150, in standard lengths or cut to length. Stud bolts, hex and heavy hex bolts, threaded rod, nuts and washers are all available in carbon steel grades.
A307 or Grade 8.8 — which carbon steel bolt should I use?
ASTM A307 is a low-carbon, non-heat-treated grade (415 MPa tensile) suited to general purpose and non-critical duty such as light anchoring and low-pressure flanges. ISO 898-1 Grade 8.8 is quenched and tempered to 800 MPa tensile and is the metric equivalent for structural and higher-load bolted joints.
Are carbon steel bolts supplied with material certification?
Yes. All carbon steel bolting is supplied with EN 10204 3.1 certification and heat number traceability as standard, with EN 10204 3.2 third-party witnessed certification available where the project specification requires it.
Need a Quote for Carbon Steel Bolting?
Tell us the grade, size and quantity you need in carbon steel — we'll confirm availability, certification level and lead time to your site.
Phone
+61 (0)7 4055 6928Emergency Support
24/7 availability for critical projects