Engineered for superior performance in demanding environments, this M21 x 28mm hex cap screw is crafted from robust 304 stainless steel, ensuring exceptional corrosion resistance and lasting durability for critical fastening needs.
| Standard | ASME B18 |
| Material | 304 Stainless Steel |
| Finish | Passivated |
| Grade | N/A |
| Size | M21 |
| Length | 28mm |
| Head Width | 17mm |
Purpose-built for heavy-duty applications, this M21 x 28mm hex cap screw boasts a nominal diameter of M21 and a precise 28mm length. The head features a 17mm hex width for secure torque application. Constructed from premium 304 stainless steel, it offers excellent tensile strength, superior resistance to rust and corrosion, and a broad operating temperature range, making it ideal for marine, chemical processing, and outdoor infrastructure projects where reliability is paramount.
This component strictly adheres to the tolerances, material specifications, and quality benchmarks set by the world's leading industrial manufacturers.
1. Select the appropriate wrench or socket for the 17mm hex head. 2. Clean the mating threads to ensure smooth engagement and prevent galling. 3. Tighten the screw to the required torque specification, avoiding over-tightening which can damage threads or the fastener.
| Standard System | Designation |
|---|---|
| ISO Equivalent | ISO 898-1 / ISO 4014 |
| DIN Equivalent | DIN 931 / DIN 933 |
| Primary Standard | ASME B18 |
| Tensile Strength | 75,000 psi (515 MPa) |
| Yield Strength | 30,000 psi (205 MPa) |
| Elongation in 2 in. | 40% min |
| Hardness | Rockwell B95 max |
| Carbon (C) | 0.08% max |
| Chromium (Cr) | 18.0 - 20.0% |
| Nickel (Ni) | 8.0 - 10.5% |
| Manganese (Mn) | 2.00% max |
| Bolt Size | Dry Torque (ft-lbs) | Lubricated Torque (ft-lbs) |
|---|---|---|
| M21 | Check Calculator | Reduce by 25% |
| Size / Type | Est. Weight (lbs/100) | Shipping Weight (kg) |
|---|---|---|
| M21 | Varies by dimension | Contact Sales |
| Environment | Rating |
|---|---|
| Indoor / Dry | Excellent |
| Outdoor / Exposed | Excellent |
| Marine / Saltwater | Good |
| Chemical / Acidic | Not Recommended |
| ❌ Mistake | ✅ Correct Approach |
|---|---|
| Using standard steel screws in corrosive environments. | Always opt for 304 stainless steel or higher grades for applications exposed to moisture, chemicals, or saltwater. |
| Over-tightening the hex head screw. | Refer to torque charts for the specific application and material being joined to prevent thread stripping or fastener fatigue. |
A: This Hex Head Cap Screw, 304 Stainless Steel is manufactured from 304 Stainless Steel.
A: Marine hardware and rigging, Chemical processing equipment, Outdoor structural components.
Conversion factor: 1 ft-lb ≈ 1.356 Nm
| Status | Mating Component | Standard | Torque Spec | Engineering Notes |
|---|---|---|---|---|
| No verified compatibility data found for this component. | ||||