Nuts · Trade series (Bollhoff RIVKLE stainless-steel series)
Property Class 12.9 Steel Stainless Knurled Countersunk Blind Rivet Nuts
Mechanical properties, corrosion behaviour and the full dimensional range for this grade.
Property Class 12.9 Steel Stainless Knurled Countersunk Blind Rivet Nuts are supplied to ISO 898-1 property class 12.9. Corrosion behaviour is requires plating or black-oxide protection, the material is magnetic, and the usable service range is commonly limited to approx. +300 °C; confirm against the coating and the load. In practice this grade is the highest common strength class, for high-load machine assembly.
Grade
ISO 898-1 property class 12.9
Corrosion resistance
Requires plating or black-oxide protection
Magnetic response
Magnetic
Service temperature
commonly limited to approx. +300 °C; confirm against the coating and the load
Property values are typical for the grade. Certified mechanical test data is available on request for production orders.
Stainless Knurled Countersunk Blind Rivet Nuts manufactured in Property Class 12.9 Steel (ISO 898-1 property class 12.9) are dimensioned to Trade series (Bollhoff RIVKLE stainless-steel series). The sections below give the mechanical and physical properties of the grade, its behavior in corrosive and elevated-temperature service, and the full size table.
Why Choose Property Class 12.9 Steel for Stainless Knurled Countersunk Blind Rivet Nuts
The highest common strength class, for high-load machine assembly. For stainless knurled countersunk blind rivet nuts, this matters when requires plating or black-oxide protection is the primary requirement.
Mechanical & Physical Properties
Grade designation
ISO 898-1 property class 12.9
Magnetic response
Magnetic
Service temperature
commonly limited to approx. +300 °C; confirm against the coating and the load
Corrosion characteristic
Requires plating or black-oxide protection
Corrosion Behavior in Service
Carbon and alloy steel stainless knurled countersunk blind rivet nuts require a coating for corrosion protection. Zinc plating (with or without passivation) is the most common; hot-dip galvanizing is used for outdoor structural service; black-oxide is mainly a tarnish-prevention finish for tool-room use.
Comparable Grades
For Stainless Knurled Countersunk Blind Rivet Nuts, class 8.8 is the comparable strength step. Move up when the joint preload approaches the proof load of the current class; move down when the joint is over-specified. For corrosion-critical service, switch to stainless A2 or A4.
Sizes of Stainless Knurled Countersunk Blind Rivet Nuts Available in Property Class 12.9 Steel
Thread size
Body diameter (mm)
Body length (mm)
Grip range (mm)
Hole diameter (mm)
Countersink thickness (mm)
End options
M3
8.8
7.0
1.3~2.0
5.0
0.9
open / closed
M3
9.9
7.0
2.0~3.0
5.0
0.9
open / closed
M4
9.3
8.0
1.3~2.0
6.0
0.9
open / closed
M4
10.3
8.0
2.0~3.0
6.0
0.9
open / closed
Technical Drawing
Customize the parameters below — every spec field is editable, and the drawing redraws to match the values you choose. Changing the size will snap the other fields to that size's standard values; you can then override any individual value.
Sends the selected values to the quote form below.
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Dimensions & Specifications (Trade series (Bollhoff RIVKLE stainless-steel series))
Thread size
Body diameter (mm)
Body length (mm)
Grip range (mm)
Hole diameter (mm)
Countersink thickness (mm)
End options
M3
8.8
7.0
1.3~2.0
5.0
0.9
open / closed
M3
9.9
7.0
2.0~3.0
5.0
0.9
open / closed
M4
9.3
8.0
1.3~2.0
6.0
0.9
open / closed
M4
10.3
8.0
2.0~3.0
6.0
0.9
open / closed
Applications & Industries
Where Stainless Knurled Countersunk Blind Rivet Nuts are used, and what decides the specification in each case. Stocked from M3 to M4.
Industries that specify Stainless Knurled Countersunk Blind Rivet Nuts
Automotive interiorsFlush threaded mounting points behind trim and finished panels.
Laboratory equipmentStainless blind threads in cleanable covers and guards.
Electronic housingsServiceable threads in thin sheet where insert rotation must be controlled.
Precision fabricationCountersunk blind inserts that remain below the finished panel face.
Automotive & transportVibration-prone joints where the locking type is specified on the drawing.
Maintenance & MROReplacements matched to the existing bolt class, thread and finish.
Typical applications
leaving a countersunk insert flush with the parent sheet
resisting rotation through a knurled blind body
adding a reusable thread without reaching the rear of the panel
matching countersink depth, hole diameter and grip range
locking an adjustment so it cannot drift
joints re-torqued at a service interval
Service conditions to specify against
Marine and coastal
Available in A4 (316) stainless for chloride exposure — coastal structures, pool halls, water treatment and deck hardware, where A2 will eventually pit.
High load
Supplied in ISO 898-1 property classes, so the joint can be designed to a stated proof load and tightened to a calculated torque rather than by feel.
Match the class
A nut below the bolt property class strips before the bolt reaches its own limit — pair class 8 nuts with 8.8 bolts, class 10 with 10.9.
Where to use something else
Do not leave the countersink shallow; a proud flange can interfere with the mating panel or finish.
Third-party video, selected automatically for this topic. It is not produced by Engineering Hardware and is not a specification source — use the tables on this page for dimensional data.
Inside the plant
Manufactured in our own plant
This part is cold-formed, threaded, heat-treated and finished in-house. The stages below are where its class and finish are actually decided.
01
Cold heading
Wire rod is drawn to size and cold-formed into blanks. Forming rather than cutting keeps the grain flow continuous around the head, which is where a bolt is most likely to fail.
Head dimensions and under-head radius checked at set-up and per shift.
02
Thread rolling
Threads are rolled between hardened dies rather than cut. Rolled threads are stronger in fatigue than cut threads and hold pitch and flank angle far more consistently across a batch.
Go / no-go ring gauges to ISO 965 tolerance class 6g.
03
Heat treatment
Quench-and-temper brings carbon and alloy steel to the property class ordered — 8.8, 10.9 or 12.9 — with the furnace charge tracked so a finished lot can be traced back to it.
Core hardness and tensile tested per lot to ISO 898-1.
04
Surface treatment
Zinc, zinc-nickel, hot-dip galvanizing, black oxide, phosphate and Dacromet, selected against the service environment rather than against the price list.
Coating thickness and neutral salt spray hours to ISO 9227.
Frequently Asked Questions
What's the service temperature limit for Property Class 12.9 Steel?
The practical service range is commonly limited to approx. +300 °C; confirm against the coating and the load.
Can Property Class 12.9 Steel replace stainless steel structurally?
No — stainless A2/A4 cannot match class 10.9 / 12.9 strength. Stainless is selected for corrosion, not raw strength.
Are Property Class 12.9 Steel Stainless Knurled Countersunk Blind Rivet Nuts magnetic?
Property Class 12.9 Steel Stainless Knurled Countersunk Blind Rivet Nuts are magnetic.
What corrosion resistance do Property Class 12.9 Steel Stainless Knurled Countersunk Blind Rivet Nuts offer?
Property Class 12.9 Steel Stainless Knurled Countersunk Blind Rivet Nuts provide requires plating or black-oxide protection with a service range of commonly limited to approx. +300 °C; confirm against the coating and the load.
How do I request a quotation?
Use the technical drawing on this page to pick the exact configuration, then submit it with the quote form. We respond within one business day.
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