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العربية Stainless steel fasteners are ordered in both metric and inch sizes, depending on the equipment standard, project market, and mating parts. For buyers, the main risk is not choosing stainless steel itself. The risk is ordering the wrong diameter, pitch, length, or thread system.
A fastener may look close by eye, but metric and inch threads are not interchangeable. Size confirmation should always come before price comparison.
Metric Stainless Steel Fastener Sizes
Common Metric Size Format
Metric fasteners are described in millimeters. A typical bolt size such as M10 × 40 means a 10 mm nominal thread diameter and 40 mm length. If pitch is important, it should be written clearly, such as M10 × 1.5 × 40.
| Metric Item | Example | Meaning |
|---|---|---|
| Diameter | M8, M10, M12 | Nominal thread diameter |
| Pitch | 1.25, 1.5, 1.75 mm | Distance between threads |
| Length | 30, 50, 100 mm | Measured according to fastener type |
| Material | A2, A4, 304, 316 | Stainless steel grade |
| Strength | A2-70, A4-80 | Mechanical property class |
Metric stainless steel fasteners are common in European, Asian, and global machinery projects. Buyers can review stainless steel fasteners when comparing material grades.
Inch Stainless Steel Fastener Sizes
UNC and UNF Threads
Inch fasteners use fractional diameters and threads per inch. For example, 1/2”-13 UNC × 2” means a 1/2 inch diameter, 13 threads per inch, and 2 inch length.
| Inch Thread Type | Example | Typical Use |
|---|---|---|
| UNC | 1/2”-13 | General coarse thread |
| UNF | 1/2”-20 | Fine thread applications |
| Fractional diameter | 1/4”, 3/8”, 5/8” | U.S. standard sizing |
| Inch length | 1”, 2”, 3” | Common U.S. purchasing format |
Inch stainless steel fasteners are common in U.S. machinery, maintenance, marine equipment, and replacement projects.
Size Matching Rules for Buyers
Confirm the Mating Part
A stainless steel bolt must match the nut, tapped hole, washer, or assembly component. Do not convert metric to inch by approximate diameter only.
Check these items before ordering:
- Metric or inch system
- Coarse or fine thread
- Pitch or TPI
- Overall length
- Thread length
- Head type or drive type
- Material grade, such as 304 or 316
- Required standard, such as DIN, ISO, ASTM, or ASME
For standard items, buyers can compare standard fasteners and the full fastener products range.
When Custom Sizes Are Needed
Custom stainless steel fasteners may be required for special thread length, non-standard head shape, shoulder diameter, fine pitch, or drawing-based equipment parts. In these cases, use custom non-standard fasteners and provide drawings or measured samples.
Final Advice
For stainless steel fastener sizes, accuracy matters more than appearance. Define the thread system, pitch, length, material grade, and standard before ordering. A clear RFQ prevents wrong-thread delivery, assembly failure, and unnecessary replacement cost.