Premium A2 (304) and A4 (316) stainless steel flange nuts. Available in metric coarse threads and select UNC/BSW on request. Mill Test Certificates (MTC), strict dimensional tolerances, and fast dispatch from ready stock.
DIN 6923
Stainless Steel Flange Nuts
TRSUTED SS FLANGE NUT FOR DEMANDING APPLICATION
Key Specifications
Standards
DIN 6923
Grades (Material)
A2 (304), A4 (316)
Strength Classes
-
Threads
Metric coarse (default). Fine/UNC/BSW available on request
Sizes
M 5 to M 24, 1/4" to 1" (others on request)
Lengths
-
Head
-
Marking
Grade/class & manufacturer ID as applicable
Certificates
MTC 3.1 / chemical composition & mechanicals available
Compliance
RoHS/REACH; generally non-magnetic in solution-annealed state (slight magnetism possible after cold-work)
Choosing the Right Stainless Steel Flange Nuts
What is a flange nut & when to use it?
A flange nut is a hex nut with an integrated washer face (flange) at the bottom.
Use a flange nut when you want:
Larger bearing area without a separate washer
Faster assembly (no handling extra washers)
Better load distribution on soft or painted surfaces
Improved resistance to loosening (with serrated flange type)
Environment & corrosion
Indoors / general outdoor → A2 (304) flange nut
Marine / coastal / chloride / chemical → A4 (316) flange nut
Use A2 for general machinery, fabrication, indoor and standard outdoor applications.
Use A4 for marine hardware, coastal projects, chemical plants, cooling towers, or where pitting corrosion is a concern.
Match to your bolt material:
A2 flange nut with A2 bolts
A4 flange nut with A4 bolts
Plain flange vs serrated flange
Plain (smooth) flange nut
Flange spreads the load like a built-in flat washer
Ideal when you want to protect surfaces, especially painted, plated, or softer materials
Does not damage the base surface
Serrated flange nut
Flange has radial serrations that bite into the surface
Gives better anti-loosening performance under vibration
Not recommended on soft, visible, or painted surfaces where marks are not acceptable
Rule of thumb:
Visible / painted / soft surfaces → Plain flange nut
Hidden / robust steel surfaces + vibration → Serrated flange nut
Strength & matching with bolt grade
General purpose joints →
→ With A2-70 / A4-70 bolts → use A2-70 / A4-70 flange nuts
Higher clamp load / more critical joints →
→ Consider A4-80 bolts + matching high-strength nuts if available / specified
Rule:
Nut property class should match or exceed the bolt class in the same stainless family.
The flange does not increase tensile strength of the nut – it improves the bearing area and loosening resistance.
Thread form & compatibility
Default → Metric coarse (e.g., M8×1.25, M10×1.5, M12×1.75)
Use metric fine / UNC / UNF only when:
Matching existing bolts, studs, or tapped holes
Design/standard specifically calls for fine pitch
Always match diameter + pitch + thread standard between bolt and flange nut.
Mechanical Properties (Guide)
Flange nuts use the same property class system as standard stainless hex nuts (e.g., A2-70, A4-70).
The flange changes the bearing surface, not the basic tensile class.
A2-70 Flange nuts
Material: A2 (304) stainless steel
Property class: 70 (for use with A2-70 bolts)
Typical uses:
General machinery, structures, brackets, panels
Applications where you want faster assembly and built-in load spreading
A4-70 Flange nuts
Material: A4 (316) stainless steel
Property class: 70 (for use with A4-70 bolts)
Typical uses:
Marine, coastal, outdoor and chemical environments
Stainless fabrications where both corrosion resistance and clean clamping are important
For both A2-70 and A4-70 flange nuts, ensure proper thread engagement and torque based on bolt size and property class. The flange aids in load distribution and anti-loosening, but the overall joint capacity is still governed by the bolt and nut property class and clamp length.
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Frequently Asked Questions
What is a flange nut?
A flange nut is a hex nut with a built-in washer face (flange) at the bottom.
The flange:
Spreads the load over a larger area
Helps protect the surface
Speeds up assembly by eliminating a separate washer in many cases
What’s the difference between a plain flange nut and a serrated flange nut?
Plain flange nut
Smooth bearing surface
Acts like an integrated flat washer
Ideal on painted, plated, or soft surfaces where you don’t want marks
Serrated flange nut
Flange has radial serrations
Serrations bite into the surface for better resistance to loosening under vibration
Not recommended on visible, soft, or painted surfaces (it will leave marks)
When should I choose a flange nut instead of a normal hex nut with washer?
Choose a flange nut when:
You want faster assembly (one piece instead of nut + washer)
Space is tight and you want a more compact solution
You want consistent bearing area without worrying about washer misalignment
You need basic vibration resistance (serrated flange version)
Are flange nuts as strong as normal hex nuts?
Yes – flange nuts follow the same property class system (e.g., A2-70, A4-70).
The flange does not change the tensile class, it only changes the bearing surface.
Strength depends on:
Property class (70, 80, etc.)
Proper thread engagement
Correct bolt size and grade
Will serrated flange nuts damage the surface?
Yes, serrated flange nuts intentionally bite into the mating surface to prevent loosening.
This will:
Leave visible marks on the surface
Remove paint/zinc plating locally
Use serrated flange nuts only where such marking is acceptable (hidden joints, structural steel, non-decorative areas).
