
Monel K-500 Nylon-insert lock nuts
ISO 7040ASTM B865
Monel K-500 nylon-insert nuts combine a specified alloy body with polymer-generated prevailing torque. Insert temperature, chemical compatibility and reuse performance define the complete nut’s service, including when the body is selected for age-hardened strength in the nickel–copper alloy family.
- MOQ
- 100PCS
- Samples · typical
- ~20 days
- Production · typical
- 25–35 days
- Heat treatment
- Annealed / age hardened
EN 10204 3.1 MTC + heat-number traceability
Which standard is on your order?
Raw Material Specifications
Threads · Metric
Threads · Inch
Dimension Reference
Heat Treatment
Annealed or age hardenedAnnealing provides a workable starting condition, while controlled aging develops the higher strength specified for age-hardened K-500.
What we can make in Monel K-500
Nylon insert
Use where a prevailing-torque nut helps retain an adjustment or mounting connection without a separate locking part. The bolt must engage through the nylon ring for the insert to act.
Metal body
The metal threads carry the axial clamp load. Select the body pattern and strength for that load, then check the additional running torque from the insert when setting the tightening process.
Temperature & chemicals
Choose this form for equipment temperatures and chemicals compatible with the insert. A nickel-alloy body does not make nylon suitable for furnace service; use an all-metal locking arrangement for elevated-temperature joints.
- Locking element
- Nylon insert
- Drive
- External hex
- Threads
- Metric · Inch
- Service limit
- Controlled by the insert
- Final condition
- Annealed · age hardened
- Inspection
- Insert retention · Prevailing torque · Dimensions
Manufacturing route
Small lots use machined blanks. Volume nut blanks use a forming route compatible with the alloy before machining the bore and tapping.
Heat treatment & final condition
Solution treatment and the specified aging condition are recorded against the production lot; final dimensions are checked after thermal processing.
Finished geometry
The nylon insert is installed after metal heat treatment and finishing. Prevailing torque is checked on the complete nut, including the specified reuse requirement.
Where K-500 fits — and what matters

Offshore & Marine
Deck-equipment brackets and marine pump skidsMonel K-500 nylon-insert lock nuts retain the threaded mountings on deck-equipment brackets and marine pump skids using insert-generated prevailing torque. The nylon insert defines the temperature and reuse limits of the complete nut. The assembled contact is exposed to saltwater, deposits and neighbouring metals.

Water Treatment & Desalination
Membrane-skid and pump supportsMonel K-500 nylon-insert lock nuts retain the threaded mountings on membrane-skid and pump supports using insert-generated prevailing torque. The nylon insert defines the temperature and reuse limits of the complete nut. The water stream, cleaning cycle and retained liquid define exposure at the installed part.

Oil & Gas
Utility skids and instrument supportsMonel K-500 nylon-insert lock nuts retain the threaded mountings on utility skids and instrument supports using insert-generated prevailing torque. The nylon insert defines the temperature and reuse limits of the complete nut. Utility connections and pressure-boundary parts have separate acceptance requirements on the equipment drawing.
Same nylon-insert lock nut. Different material priorities.
Monel K-500 material dataInconel 625
Solid-solution strength and resistance to aggressive process liquids.
- Connection priority
- Metal-body load capacity and polymer-generated prevailing torque
- Annealed or solution-annealed 625
- The Inconel 625 body and the nylon insert need separate acceptance. Cleaner, moisture and temperature exposure reach the insert at the mating thread; its rated condition controls prevailing-torque service.
Super Duplex 2507
Super-duplex strength and resistance to chloride pitting.
- Connection priority
- Metal-body load capacity and polymer-generated prevailing torque
- Final duplex structure
- The Super Duplex 2507 body and the nylon insert need separate acceptance. Cleaner, moisture and temperature exposure reach the insert at the mating thread; its rated condition controls prevailing-torque service.
Duplex 2205
Duplex strength and chloride-corrosion resistance.
- Connection priority
- Metal-body load capacity and polymer-generated prevailing torque
- S31803 or S32205
- The Duplex 2205 body and the nylon insert need separate acceptance. Cleaner, moisture and temperature exposure reach the insert at the mating thread; its rated condition controls prevailing-torque service.
From drawing to documented delivery




- 01Drawing & BOMForm, dimensions and quantity
- 02Material & formingGrade, heat and manufacturing route
- 03Final inspectionGeometry, threads and ordered tests
- 04Documents & dispatchLot records and identified packing
Order documents
- Material identity
- UNS N05500 · heat number · ordered condition
- Final-part acceptance
- Lot-linked aging record and mechanical acceptance in the final condition. Insert identity and complete-nut prevailing-torque results.
- Dimensional record
- Insert retention · Prevailing torque · Dimensions
- Traceability
- EN 10204 3.1 material certificate · production lot · identified packing
Build your K-500 nylon-insert lock nut enquiry
Questions about K-500 nylon-insert lock nuts
Can a heat-resistant body make the nylon nut suitable for a hot joint?
The nylon remains the temperature-limiting part. Use the actual insert rating and required prevailing-torque performance; a hot-service metal grade does not extend the polymer’s limit.