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
Nitronic 60 Fasteners, Anti-Galling Bolts, Studs, Nuts, Washers
Nitronic 60 fasteners (UNS S21800) are specified wherever sliding contact between threaded surfaces would cause 316L or 304 to gall. The high-manganese, high-silicon, nitrogen-strengthened austenite resists the adhesive cold-welding step that seizes stainless bolts during makeup-breakout cycles, locks valve stems mid-stroke, and rounds threads on dry-installed fasteners. TorqBolt manufactures the full Nitronic 60 fastener portfolio with EN 10204 3.1 and 3.2 MTC documentation traceable to mill source through final inspection.
Why Nitronic 60 for Bolting
316L bolting fails by galling, not by tensile overload. Threshold galling stress for self-mated Nitronic 60 in standard ASTM G98 testing is many times higher than for self-mated 304 or 316L, and stays high even when paired against dissimilar austenitic counterfaces. Combined with 380 MPa minimum yield (vs 170 MPa for 304/316L), Nitronic 60 lets engineers spec a smaller bolt diameter, install without anti-seize, and disassemble after long service without thread damage.
Fastener Variants Manufactured
| Variant | Primary Spec | Typical Size Range |
|---|---|---|
| Hex bolts | ASTM A193 Gr B8R / B8RA | 1/4-20 through 3 inch dia; M6 through M76 |
| Stud bolts | ASTM A193 Gr B8R / B8RA | 3/8-16 through 4 inch dia; lengths to 60 inch |
| Double-end stud bolts | ASTM A193 Gr B8R / ASME B16.5 | 1/2-13 through 2-1/2 inch dia, ASME B16.5 flange lengths |
| Anchor bolts | ASTM A193 / F1554 | 1/2-13 through 2 inch dia |
| Socket cap screws (SHCS) | ASTM F837 / ASME B18.3 | #10 through 1 inch; M5 through M30 |
| Hex cap screws | ASME B18.2.1 | 1/4-20 through 2 inch dia |
| Set screws | ASME B18.3 (cup, flat, cone, dog points) | #10 through 1 inch; M5 through M24 |
| Threaded rod (all-thread) | ASTM A276 / A580 | 1/4-20 through 1-1/2 inch dia, lengths to 12 ft |
| Hex nuts | ASTM A194 Gr 8R / 8RA | 1/4-20 through 4 inch; M6 through M100 |
| Heavy hex nuts | ASTM A194 Gr 8R / ASME B18.2.2 | 1/2-13 through 4 inch dia |
| Lock nuts | ASTM A194 + DIN 985 / DIN 980 (nyloc, all-metal) | 1/4-20 through 1-1/2 inch dia; M6 through M36 |
| Jam nuts (thin hex) | ASTM A194 + ASME B18.2.2 | matched to bolt size |
| Washers (flat, lock, bevel) | ASTM F436 / DIN 125 / DIN 127 | matched to bolt size |
| Helicoil thread inserts | NASM21209 / MS21209 / MS124 | UNC #2-56 through 1-1/2 inch; M2 through M48 |
| Anti-galling fastener selection guide | (application engineering) | any of the above |
Specification Coverage
Nitronic 60 bolting is covered by ASTM A193 Grade B8R (solution-annealed) and B8RA (hot-strain-hardened, higher proof load). The matching nut grades are ASTM A194 Grade 8R and 8RA. Bar stock for fasteners is ordered to ASTM A276 or ASTM A479 (pressure-part bar). Forging stock for heavy hex nuts and large studs is per AMS 5848 or ASTM A314. Wire for spring components and welding filler is per ASTM A580.
Sour-Service & API 6A Compliance
Annealed Nitronic 60 falls inside the NACE MR0175 / ISO 15156-3 hardness window (95 HRB max per ASTM A276) for sour-service exposure. API 6A subsea wellhead and Christmas-tree trim applications use Nitronic 60 valve stems and trim hardware where galling under pressure cycling and H2S exposure rule out 316L. PSL-3 and PSL-4 documentation is supported with EN 10204 Type 3.2 MTCs traceable through final inspection.
Marine, Cryogenic & Sliding-Contact Service
Common service envelopes for Nitronic 60 fasteners include marine and seawater bolting (anti-galling under salt-fog wet-dry cycles), cryogenic service to -196 C (austenite stable; no martensitic transformation), nuclear reactor internals (low magnetic permeability + non-galling under reactor-cycling makeup), FDA-acceptable food-grade hardware, and oil and gas downhole tools where Stellite is too expensive and 316L galls under pressure.
Matched-Pair Pairing Logic
Galling between mated threaded surfaces is governed by the lower-galling-resistance counterface. To get the full anti-galling benefit, both bolt and nut must be Nitronic 60 (or one Nitronic 60 + one cobalt or PH wear alloy with a documented galling-test pair). Mating Nitronic 60 hex bolts with 316L nuts gives 316L's galling behaviour. Standard pairing patterns: hex bolt + heavy hex nut (matched class B8R / 8R), stud bolt + heavy hex nut x 2 for ASME B16.5 flange service, SHCS + tapped hole or helicoil insert, threaded rod + jam-nut + heavy hex nut for adjustable assemblies.
Quality Documentation, 3.1 vs 3.2 MTC
EN 10204 Type 3.1 certificates (manufacturer's mechanical and chemical results, traceable to heat number) are standard on every TorqBolt Nitronic 60 fastener order. Type 3.2 certificates (independent third-party endorsement, required for API 6A and most NACE-critical service) are issued on request with TPI witness during final inspection. Heat-treatment time-temperature charts and hardness traverses are supplied on request for cold-worked HS-condition orders.
TorqBolt Fastener Network
For other alloy-specific fastener catalogs, see hex-bolt.com (TorqBolt's hex-bolt hub across all alloys), 12pointbolt.com (12-point variant), alloya286.com (A286 PH-strength fasteners), duplex2507.com (super duplex sour-service), and nitronic60.com (Nitronic 60 marine alternative).
Request a Quote
For Nitronic 60 fasteners in any of the variants above, with EN 10204 3.1 or 3.2 MTC documentation, Contact the TorqBolt QA-QC team at info@torqbolt.com or +91-22-66157017. We respond within 24 hours with sized stock availability, lead time, and 3.1 / 3.2 MTC documentation samples.
Frequently Asked Questions
Why use Nitronic 60 for fasteners?
Highest galling resistance among austenitic stainless steels, 2x the yield of 304 and 316L. Resists adhesive cold-welding during sliding contact, which is the dominant failure mode of 316L bolting in marine and subsea service.
Which ASTM specs cover Nitronic 60 fasteners?
ASTM A193 Gr B8R / B8RA for bolts, ASTM A194 Gr 8R / 8RA for matching nuts. Bar stock per ASTM A276 / A479; forging stock per AMS 5848 / ASTM A314.
Is Nitronic 60 NACE MR0175 compliant?
Yes, in the annealed condition (95 HRB max per ASTM A276) within the NACE MR0175 / ISO 15156-3 hardness window. Cold-worked condition may exceed the limit; verify with end-user spec.
What sizes are stocked?
Inch UNC / UNF from #10 through 4 inch diameter; metric M6 through M100. Special diameters and lengths quoted on request.
Can Nitronic 60 fasteners be cold-worked for higher proof load?
Yes. ASTM A193 Gr B8RA (hot-strain-hardened) and the HS strain-hardened condition reach yield ~830 MPa with reduced ductility. Mind the NACE hardness window for sour service.
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