Complete Size Guide for Grade 8.8 High-Strength Bolts – Metric & Inch Conversion for Industrial Buyers
When it comes to heavy-duty industrial applications, Grade 8.8 hex bolts are among the most reliable fasteners due to their high tensile strength and durability. These bolts are widely used in construction, machinery, automotive, and infrastructure projects, especially in demanding environments like those found in the Middle East, Southeast Asia, and Africa, where extreme temperatures and harsh conditions require robust fastening solutions.
Understanding Grade 8.8 Bolts: Performance & Standards
Grade 8.8 bolts are made from medium-carbon steel and are heat-treated through quenching and tempering to achieve their mechanical strength. Standardized under ISO 898-1 and commonly aligned with ASTM A325 for structural use, these bolts deliver consistent performance across a variety of industries.
Key Properties of Grade 8.8 Hex Head Bolts:
- Tensile Strength: ≥800 MPa
- Yield Strength: ≥640 MPa
- Hardness: 22–32 HRC
- Surface Treatments: Zinc-plated (electro or hot-dip), black oxide, or Dacromet for enhanced corrosion resistance
Compared to other common bolt grades:
| Property | Grade 8.8 | Grade 10.9 | Stainless Steel (A2-70) |
|---|---|---|---|
| Tensile Strength | 800 MPa | 1000 MPa | 700 MPa |
| Yield Strength | 640 MPa | 900 MPa | 450 MPa |
| Corrosion Resistance | Moderate (coated) | Moderate (coated) | High (naturally resistant) |
| Applications | Construction, machinery, automotive | Structural steel, heavy machinery | Marine, chemical, food industry |
While stainless steel hex head bolts like A2-70 provide excellent corrosion resistance, Grade 8.8 bolts remain the preferred choice for high-load, high-stress applications.
Grade 8.8 Bolt Size Chart – Metric & Inch Conversion
One common challenge in procurement is selecting the correct bolt size, especially when working across both metric and inch systems. Below is a detailed 8.8 bolt size chart in mm and inch equivalents, designed to assist global industrial buyers.
| Metric Size (mm) | Thread Pitch (mm) | Inch Equivalent (approx.) | Head Size (mm) | Typical Use Cases |
| M6 | 1.0 | 1/4″ | 10 mm | Electrical enclosures, control boxes |
| M8 | 1.25 | 5/16″ | 13 mm | Solar clamps, brackets, furniture |
| M10 | 1.5 | 3/8″ | 16 mm | Machinery frames, motor bases |
| M12 | 1.75 | 1/2″ | 18 mm | Steel structures, automotive chassis |
| M16 | 2.0 | 5/8″ | 24 mm | Agricultural machinery, supports |
| M20 | 2.5 | 3/4″ | 30 mm | Bridges, structural joints |
| M24 | 3.0 | 15/16″ | 36 mm | Foundations, towers, heavy steel |
Note: Always confirm thread pitch compatibility for international standards.
Application Scenarios by Region
Middle East – Oil & Gas, Steel Construction
- M16–M24 bolts are commonly used in pipelines, oil rigs, and large steel structures. These bolts are often coated with Dacromet or hot-dip zinc to withstand desert and coastal climates.
Southeast Asia – Marine & Infrastructure
- M12–M20 bolts are ideal for bridges, shipyards, and port installations. Given the high humidity, hot-dip galvanized or stainless steel alternatives are often recommended.
Africa – Mining & Heavy Machinery
- M10–M24 bolts are essential in mining operations, truck chassis, and agricultural implements. Black oxide finishes are often sufficient in dry inland environments.
These size and finish combinations are based on actual purchase preferences in markets like Dubai, Nairobi, Jakarta, and Cairo.
Why Size Accuracy Matters
Choosing the correct 8.8 bolt size ensures structural integrity and simplifies cross-border sourcing. For engineers and procurement teams, using an accurate 8.8 bolt size chart in mm and inch reduces project delays, especially in multi-standard environments.
Partner with Quanfan for Grade 8.8 Bolts
Handan Quanfan Metal Products Co., Ltd. is a trusted manufacturer of Grade 8.8 hex bolts, offering a complete range of sizes from M6 to M24 and their inch equivalents. We supply both full-thread and partial-thread variants with various coatings to suit different environments.
With export experience to the Middle East, Southeast Asia, and Africa, we provide reliable service, consistent quality, and competitive pricing for industrial buyers worldwide.
Contact us today to request a quote or discuss custom specifications for your next project.
