Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
Incoloy 800H Lock Nuts
Incoloy 800H lock nuts are prevailing-torque nuts that resist loosening under vibration, machined from ASTM B408 round bar in two variants: DIN 985 nylon-insert lock nuts for service below 120 deg C (250 deg F) and DIN 980 all-metal lock nuts for service to 815 deg C (1500 deg F). The nylon-insert variant uses a deformable polyamide ring to grip the bolt thread; the all-metal variant uses a controlled top-section deformation to grip without an insert. For high-temperature Incoloy 800H service the all-metal DIN 980 variant is the only suitable option; the nylon-insert variant is restricted to ambient-temperature secondary fastening (instrument panels, junction boxes). TorqBolt manufactures all-metal lock nuts in diameter range M12 to M48, with prevailing torque per DIN 980 schedule. Every lock nut ships with EN 10204 type 3.1 mill test certificate documenting heat number, ASTM B408 chemistry, solution-anneal cycle and ASTM grain size 5 verification, with prevailing-torque test result logged on each batch.
Lock Nut Dimensions (DIN 980 All-Metal Variant)
| Size designation | Across flats / OD | Head / nut height | Thread pitch | Standard reference |
|---|---|---|---|---|
| M12 | 12.0 mm thread | A/F 19 mm; Nut height 14 mm (incl. lock section) | 1.75 mm | DIN 980 |
| M16 | 16.0 mm thread | A/F 24 mm; Nut height 17 mm | 2.0 mm | DIN 980 |
| M20 | 20.0 mm thread | A/F 30 mm; Nut height 21 mm | 2.5 mm | DIN 980 |
| M24 | 24.0 mm thread | A/F 36 mm; Nut height 25 mm | 3.0 mm | DIN 980 |
| M30 | 30.0 mm thread | A/F 46 mm; Nut height 31 mm | 3.5 mm | DIN 980 |
| M36 | 36.0 mm thread | A/F 55 mm; Nut height 37 mm | 4.0 mm | DIN 980 |
| M42 | 42.0 mm thread | A/F 65 mm; Nut height 43 mm | 4.5 mm | DIN 980 |
| M48 | 48.0 mm thread | A/F 75 mm; Nut height 49 mm | 5.0 mm | DIN 980 |
Manufacturing Route at TorqBolt
Lock nut manufacture extends the standard hex nut process with a controlled top-section deformation step to create the locking action:
- Receive Incoloy 800H bar to ASTM B408; PMI verification.
- Cut bar into nut-height slugs (nut height plus lock section).
- CNC mill the 6-sided hex profile per DIN 980 across-flats.
- Drill the through-hole; tap the internal thread to class 6H per ISO 965.
- Solution anneal at 1149 deg C plateau followed by rapid quench.
- Cold-form the top section: controlled radial deformation to create thread-grip prevailing torque per DIN 980.
- Post-form stress-relief anneal: 870 deg C for 2 hours (does NOT undo cold-form prevailing torque).
- Prevailing-torque test on first piece and one per batch; results logged on EN 10204 cert.
- Visual + dimensional + PMI inspection; pack matched with bolt or stud.
Lock Nut Sizes Stocked and Lead Times
| Diameter range | Length range | Stock status | Lead time |
|---|---|---|---|
| M12 - M20 | Per DIN 980 | Made-to-order from stock bar | 10 to 14 working days |
| M24 - M30 | Per DIN 980 | Made-to-order from stock bar | 14 to 21 working days |
| M36 - M42 | Per DIN 980 | Made-to-order, large bar | 3 to 4 weeks |
| M48 | Per DIN 980 | Made-to-order | 4 to 6 weeks |
Inspection and Heat Marking
Lock nut specific inspections cover prevailing-torque test, deformed-section integrity and thread compliance:
- Prevailing torque tested on first piece and one per batch per DIN 980 schedule; results logged.
- Deformed top-section visual inspection for cracking after cold-form.
- Internal thread verified with class 6H plug gauge full-traverse.
- Across-flats verified per DIN 980 schedule.
- Hardness band 120-184 HB on first piece and one per batch.
- ASTM E112 grain-size etch verification (grain size 5 or coarser; post-form anneal applied).
- PMI by X-ray fluorescence on first piece and one per batch.
- Heat number traceable to bar.
Typical Service Conditions
All-metal lock nuts are specified where vibration or thermal cycling would loosen a standard nut:
- ASME Section VIII pressure-vessel internal-component bolting subject to fluid-flow vibration.
- Heat exchanger baffle and tube-support bolting subject to thermal cycling.
- Ethylene cracker burner-tile retainer bolting subject to combustion vibration.
- Reformer pigtail bracket fastening on cyclic-temperature service.
- Furnace component hearth-plate fixing on cyclic furnace service.
- Steam superheater support-clip bolting on cyclic-pressure service.
Incoloy 800H Alloy Considerations on This Fastener Form
Companion Fasteners and Related Pages
- Hex Nuts: standard hex nut without prevailing torque.
- Heavy Hex Nuts: heavy-pattern alternative for high-load bolting.
- Castle Nuts: cotter-pin retention alternative.
- Coupling Nuts: extended hex variant for threaded-rod joining.
- Washers: spring and locking washers as alternative loose-prevention.
Frequently Asked Questions
Q. Can nylon-insert lock nuts be used on Incoloy 800H bolts above 120 deg C?
No. The polyamide insert in DIN 985 nylon-insert lock nuts degrades above 120 deg C (250 deg F). For high-temperature service the all-metal DIN 980 variant is the only suitable option.
Q. How is prevailing torque verified?
Per DIN 980 / ISO 2320 prevailing-torque test schedule. The nut is run onto a calibrated test mandrel and the running torque is measured at first installation and after multiple cycles. Results are logged on the EN 10204 certificate.
Q. Are lock nuts re-usable?
DIN 980 all-metal lock nuts are limited-cycle re-usable (typically 5 to 10 cycles before prevailing torque drops below the DIN 980 minimum). Single-use applications are preferred where re-installation reliability is critical.
Q. What is the difference between DIN 980 and DIN 6925?
DIN 980 (DIN 980V) is the older series; DIN 6925 is the newer series with extended diameter range and tighter prevailing-torque tolerance. Both use the same cold-form all-metal locking principle.
Q. Can lock nuts be re-annealed after install?
No. Re-annealing after install undoes the cold-form prevailing torque and converts the lock nut back into a standard hex nut. Service temperature must not exceed the post-form stress-relief temperature (870 deg C).
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