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
DEF STAN 02-835 Hiduron 191
DEF STAN 02-835 is the UK Ministry of Defence Defence Standard that controls procurement of Hiduron 191 (UNS C72420) Cu-Ni-Al-Mn precipitation-hardened cupronickel bolting for Royal Navy, Royal Fleet Auxiliary and allied naval service. The standard is the Defence Standardisation adoption of the original Naval Engineering Standard NES 835 and carries the same technical content. DEF STAN 02-835 fixes chemistry, heat treatment, mechanical floor, hardness ceiling for sour-service compliance, magnetic permeability ceiling for naval qualification, EN 10204 inspection categories and marking.
Scope of DEF STAN 02-835
DEF STAN 02-835 specifies technical delivery conditions for the Hiduron 191 grade in round bar, forging stock, finished forgings, finished fasteners and machined components for UK Ministry of Defence procurement. The scope covers the full Cu-Ni-Al-Mn precipitation-hardened cupronickel grade family used in Royal Navy surface ship and submarine bolting where the combination of seawater corrosion resistance, hydrogen-embrittlement immunity, NACE MR0175 hardness ceiling compliance and non-magnetic response is required in a single material.
Latest Revision and Sister Standards
DEF STAN 02-835 is maintained under the UK Ministry of Defence Defence Standardisation programme. The standard is the formal Defence Standards adoption of the original Naval Engineering Standard NES 835, with the same technical content. The US Department of Defense maintains the sister specification DOD-C-24676 for US Navy procurement of the same Hiduron 191 grade. Cross-procurement orders commonly cite all three documents on the same purchase order to ensure acceptance on both sides of the Atlantic.
Grade Matrix Relevant to Hiduron
| Designation | UNS | Family role | Use case in scope of DEF STAN 02-835 |
|---|---|---|---|
| Hiduron 191 | C72420 | Mn-modified Cu-Ni-Al, highest strength | Royal Navy bolting, sour service, splash zone |
| Hiduron 130 | C72400 | Base Cu-Ni-Al, mid strength | Cross-reference (controlled by DTD 900/4805) |
Chemistry to DEF STAN 02-835 (Hiduron 191)
DEF STAN 02-835 fixes the Hiduron 191 chemistry to the identical windows as NES 835: nickel 14.0 to 15.5 percent, manganese 4.0 to 5.0 percent, aluminium 1.5 to 2.5 percent, iron 0.5 to 1.5 percent, balance copper. Tight tramp limits on lead at 0.02 percent, sulphur as a residual, and carbon at 0.05 percent maintain hot workability and weldability. The detailed element-by-element table is in the shared Chemistry block below.
Mechanical-Property Floor (DEF STAN 02-835)
The mechanical floor for Hiduron 191 in the solution-annealed plus aged condition is identical to NES 835: tensile strength 820 to 1000 MPa, 0.2 percent proof stress at least 580 MPa, elongation A5 at least 15 percent, Charpy V impact at least 40 J at room temperature. Hardness controlled below 286 HBW (28 HRC) for NACE MR0175 compliance. Magnetic permeability controlled below 1.005 mu_r for Royal Navy mine-countermeasures qualification. Detailed property table is in the shared Mechanicals block below.
Inspection Categories to EN 10204
DEF STAN 02-835 inspection follows EN 10204: type 3.1 mill test certificate issued by the manufacturer with heat-level traceability is the TorqBolt default; type 3.2 inspection certificate with Lloyd's Register, DNV, BV, SGS or TUV witness is supplied on call-out and is standard practice on UK Ministry of Defence procurement. The witness body is named on the purchase order and joins the heat at solution-anneal plus age stage with stamped acceptance through to dispatch.
Cross-References to Other Standards
DEF STAN 02-835 cross-references the Naval Engineering Standard NES 835, the US Department of Defense sister specification DOD-C-24676, the sour-service hardness rule from NACE MR0175, and the Hiduron 130 base-grade procurement specification DTD 900/4805.
Frequently Asked Questions
Q. What is DEF STAN 02-835?
DEF STAN 02-835 is the UK Ministry of Defence Defence Standard for Hiduron 191 (UNS C72420) Cu-Ni-Al-Mn precipitation-hardened cupronickel bolting for Royal Navy and allied naval service. It is the formal Defence Standardisation adoption of NES 835 with identical technical content.
Q. How does DEF STAN 02-835 relate to NES 835?
DEF STAN 02-835 is the Defence Standards series adoption of the Naval Engineering Standard NES 835. The two documents carry identical technical content covering chemistry, heat treatment, mechanical floor, hardness ceiling for NACE compliance, magnetic permeability ceiling for naval qualification, and EN 10204 inspection categories.
Q. What is the US equivalent of DEF STAN 02-835?
DOD-C-24676 maintained by the US Department of Defense is the sister specification for US Navy procurement of the same Hiduron 191 grade. UK and US naval cross-procurement orders commonly cite both DEF STAN 02-835 and DOD-C-24676 on the same purchase order.
Q. Is Hiduron 191 to DEF STAN 02-835 NACE compliant?
Yes when supplied to the 286 HBW (28 HRC) maximum hardness ceiling. DEF STAN 02-835 explicitly captures the hardness limit so the same bolt lot is acceptable for naval and for NACE MR0175 sour oil and gas service.
Q. Do you supply DEF STAN 02-835 material with type 3.2 certification?
Yes. EN 10204 type 3.1 mill test certificate by default; type 3.2 with Lloyd's Register, DNV, BV, SGS or TUV witness on call-out and standard practice for Royal Navy and UK MoD procurement.
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