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M21 x 69mm 304 Stainless Steel Hex Cap Screw

Expert Overview

Engineered for exceptional strength and corrosion resistance, this M21 x 69mm Hex Cap Screw is manufactured from high-grade 304 stainless steel. Its robust design ensures reliable fastening in challenging environments.

StandardISO 9001
Material304 Stainless Steel
FinishZinc Plated
GradeN/A
SizeM21
Length69mm
Head Width33mm

Detailed Engineering Specifications

Trusted by engineers across multiple sectors, this M21 x 69mm Hex Cap Screw offers superior performance due to its construction from 304 stainless steel, renowned for its excellent resistance to corrosion and pitting, even in marine or chemical-intensive environments. The M21 diameter ensures significant tensile strength, while the 69mm length provides ample thread engagement for secure assemblies. The 33mm hex head allows for high torque application with standard tooling, making it ideal for structural, mechanical, and outdoor infrastructure projects where durability and longevity are paramount.

🧊 Download 3D CAD Model (.STEP)

Verified Global OEM Partners

This component strictly adheres to the tolerances, material specifications, and quality benchmarks set by the world's leading industrial manufacturers.

BossardEst. 1831
Switzerland🇨🇭
"Global leader in fastening technology."
Market Rank
🏆 Top 3 Global Fastener Network
Industry Approvals
🚀 Aerospace & Tesla Approved
Warranty & Support
🛡️ Lifetime Traceability
Green Manufacturing
🌱 Carbon Neutral by 2030
Certified:ISO 9001, RoHS, REACH
Würth GroupEst. 1945
Germany🇩🇪
"Premium assembly and fastening materials."
Market Rank
🏆 #1 Global Assembly Supplier
Industry Approvals
🚀 VW & BMW OEM
Warranty & Support
🛡️ 5-Year Industrial Warranty
Green Manufacturing
🌱 100% Recyclable Packaging
Certified:ISO 9001, DIN EN
Brighton-BestEst. 1925
USA🇺🇸
"Master distributor of industrial fasteners."
Market Rank
🏆 Largest Distributor in NA
Industry Approvals
🚀 Boeing Approved
Warranty & Support
🛡️ Global Replacement Guarantee
Green Manufacturing
🌱 Green Steel Initiative
Certified:ISO 9001, A2LA

Certifications & Compliance

RoHS Compliant:Yes
REACH Compliant:Yes
Material Traceability:Available on Request
DFARS Compliant:Yes

Installation Procedure

1. Select the appropriate wrench or socket size (33mm) for the hex head. 2. Ensure the mating threads are clean and free from debris. 3. Thread the screw into the desired component, applying consistent torque until snug, then tighten to the specified torque value for the application.

Equivalent Standards (Cross-Reference)

Standard SystemDesignation
ISO EquivalentISO 898-1 / ISO 4014
DIN EquivalentDIN 931 / DIN 933
Primary StandardISO 9001

Mechanical Properties

Tensile Strength75,000 psi (515 MPa)
Yield Strength30,000 psi (205 MPa)
Elongation in 2 in.40% min
HardnessRockwell B95 max

Chemical Composition

Carbon (C)0.08% max
Chromium (Cr)18.0 - 20.0%
Nickel (Ni)8.0 - 10.5%
Manganese (Mn)2.00% max

Temperature & Environment Rating

Min Operating Temp
-320°F (-195°C)
Max Continuous Temp
1400°F (760°C)
Thermal Expansion
Typical for Material Class

Recommended Torque Values

Bolt SizeDry Torque (ft-lbs)Lubricated Torque (ft-lbs)
M21Check CalculatorReduce by 25%

Weight Reference Table

Size / TypeEst. Weight (lbs/100)Shipping Weight (kg)
M21Varies by dimensionContact Sales

Corrosion Resistance Guide

EnvironmentRating
Indoor / DryExcellent
Outdoor / ExposedExcellent
Marine / SaltwaterGood
Chemical / AcidicNot Recommended

Common Mistakes & How to Avoid Them

❌ Mistake✅ Correct Approach
Using undersized or incorrect tooling, leading to cam-out and potential damage to the fastener head.Always use a correctly sized 33mm hex socket or wrench to ensure proper engagement and optimal torque transfer.
Cross-threading the screw, which can strip the threads of both the screw and the mating component.Start threading the screw by hand to confirm it engages smoothly. If resistance is met, back it out and realign.

Common Applications

  • Structural steel connections
  • Marine and offshore equipment
  • Industrial machinery and equipment
  • Outdoor infrastructure and signage

⚠️ Engineering Warnings

  • Ensure the mating components are designed to accommodate the M21 thread size and the required clamping force.
  • Avoid over-tightening, which can lead to thread stripping or fastener failure. Consult engineering specifications for proper torque values.

Alternative Products to Consider

Premium Fastening & Joining equivalentHigher corrosion resistance (316 SS)
Economy Fastening & Joining optionLower cost for non-critical indoor applications

Frequently Asked Questions

Q: What is the Hex Head Cap Screw, 304 Stainless Steel made from?

A: This Hex Head Cap Screw, 304 Stainless Steel is manufactured from 304 Stainless Steel.

Q: What are the main applications?

A: Structural steel connections, Marine and offshore equipment, Industrial machinery and equipment, Outdoor infrastructure and signage.

Technical Schematic

HEX BOLT DIAGRAMSAE J429 / ASME B18.2.1HEXHEADLENGTH = 69mmAF33mm1/2"-13TIGHTEN →MECHANICAL PROPERTIESTensile Strength: 150,000 psiThread: 1/2"-13 UNCTorque Direction: Clockwise (CW)Head Marking: 6 radial lines (Grade 8)

Torque Specifications

⚡ UNIT CONVERTER

Conversion factor: 1 ft-lb ≈ 1.356 Nm

Verified Compatibility

StatusMating ComponentStandardTorque SpecEngineering Notes
No verified compatibility data found for this component.