What is the difference between 8.2 and 8.5 10 bolts?
There is no widely recognized standard meaning for “8.2” versus “8.5” when referring to 10 bolts in common bolt catalogs. Those numbers are not part of the official ISO/SAE/A SAE or ASTM strength classifications for fasteners. If you encounter them, they’re most likely manufacturer-specific designations or internal part numbers, and you should consult the exact datasheet from the supplier to understand their mechanical properties, coatings, and intended applications.
In practice, engineers often rely on established strength classes and grades (for example ISO metric classes such as 8.8 or 10.9, or SAE grades like Grade 5 and Grade 8) to compare bolts. The labels 8.2 and 8.5 do not map to those standard categories in a universal way, which can lead to confusion when sourcing parts across brands or industries. This article explains how to interpret such labels and what to check to ensure the correct fastener is used for a given application.
What the numbers might refer to in practice
Before selecting bolts, it helps to understand how labels are typically used in the industry. The following possibilities are common when you see nonstandard numbers like 8.2 or 8.5 on a 10‑bolt kit or catalog:
- Nonstandard manufacturer designations that do not correspond to a universal strength class.
- Internal part numbers or catalog codes used by a supplier to differentiate variants (for example, different coatings, thread pitches, or lengths).
- Potential mislabeling or transcription errors where the intended reference was a standard class such as 8.8, 10.9, or a Grade 5/Grade 8 equivalent.
To avoid ambiguity, always verify the exact mechanical properties and specifications with the supplier’s datasheet or product drawing, rather than relying on the numeric label alone.
How to verify bolt specifications and ensure the right choice
Follow these steps to compare bolts reliably when confronted with nonstandard labels like 8.2 and 8.5:
- Identify the governing standard and the actual class or grade listed on the datasheet (for example, ISO 898‑1 class 8.8 or SAE Grade 8).
- Check the tensile strength, yield strength, and proof load specified by the supplier, and confirm the units (MPa for metric, ksi for imperial).
- Confirm thread size, length, pitch, and whether the bolt is fully threaded or partially threaded to ensure proper engagement with the nut or tapped hole.
- Verify coating or finish (zinc plating, black oxide, stainless, etc.) and any corrosion resistance requirements for the environment.
- Ensure compatibility with mating components (nut type, washer, flange, or weld surfaces) and the intended torque range using the correct torque chart.
In practice, documenting the exact properties from the supplier’s datasheet is essential. A label like “8.2” or “8.5” without cross-reference can lead to under- or over-engineering, which may compromise joint integrity and safety.
Summary
In short, 8.2 and 8.5 are not standard bolt strength classes you’ll reliably find in universal catalogs. They are more likely to be supplier-specific designations or potential labeling errors. When sourcing bolts, always refer to the product datasheet or an official standard classification (such as ISO 8.8/10.9 or SAE Grade 5/8) and verify tensile strength, yield, coating, thread details, and installation torque to ensure the fastener meets the application’s requirements. If in doubt, contact the supplier for a corrected specification sheet to avoid mismatches.
