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 |
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| Magnetic response | Magnetic |
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| Service temperature | commonly limited to approx. +300 °C; confirm against the coating and the load |
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| Corrosion characteristic | Requires plating or black-oxide protection |
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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 |
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
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Automotive interiors
Flush threaded mounting points behind trim and finished panels.
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Laboratory equipment
Stainless blind threads in cleanable covers and guards.
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Electronic housings
Serviceable threads in thin sheet where insert rotation must be controlled.
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Precision fabrication
Countersunk blind inserts that remain below the finished panel face.
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Automotive & transport
Vibration-prone joints where the locking type is specified on the drawing.
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Maintenance & MRO
Replacements 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.
Full application guide: where Stainless Knurled Countersunk Blind Rivet Nuts are used, how to specify them, and the cases they are wrong for
