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
Hiduron Stress-Corrosion Cracking Resistance
Hiduron 191 (UNS C72420, NES 835, DEF STAN 02-835, DOD-C-24676) is qualified to NACE MR0175 / ISO 15156 for sour-service bolting on the standard solution-anneal plus age cycle, with the hardness controlled at or below 286 HBW (28 HRC). The Cu-Ni-Al matrix is immune to hydrogen embrittlement through the operating envelope of subsea hydraulic and naval bolting service, which is the property that separates Hiduron 191 from precipitation-hardened nickel-base alloys (Monel K-500, Inconel 718) at their NACE hardness limits. The chloride-SCC resistance in flowing seawater and in splash-zone exposure is qualified through over 15 years of in-service performance on North Sea and Gulf of Mexico offshore platform riser bolting. The data table below summarises the SCC and HE behaviour against the design envelopes that the standards control.
SCC Resistance Against Service Environment
| Environment | Hiduron 130 | Hiduron 191 | Comment |
|---|---|---|---|
| Chloride SCC in flowing seawater (RT to 80 deg C) | Immune | Immune | Cu-Ni-Al passive film stable through service envelope |
| Sour H2S service (NACE MR0175) | Not qualified | Qualified at <=286 HBW | Hiduron 191 is the NACE-listed grade |
| Hydrogen embrittlement (cathodic protection) | Immune | Immune | FCC Cu-Ni matrix; no H trap sites in service envelope |
| Caustic SCC (NaOH up to 50 percent, 80 deg C) | Resistant | Resistant | Cu-Ni-Al film stable against alkaline attack |
| Ammoniacal SCC (Mattsson solution) | Susceptible above 50 percent of yield | Susceptible above 50 percent of yield | Avoid ammonia-bearing service; specify cupronickel-free grade if unavoidable |
| Mercury SCC | Susceptible | Susceptible | Avoid mercury contamination; standard caveat on all copper alloys |
NACE MR0175 Qualification on Hiduron 191
NACE MR0175 / ISO 15156 lists Cu-Ni-Al precipitation-hardened cupronickels on the qualified materials list for sour-service bolting, with the controlling hardness limit of 22 HRC or, on hardness-controlled product, 28 HRC (286 HBW). Hiduron 191 in the standard solution-anneal plus age condition reads 270 to 320 HV (260 to 295 HBW), so the NACE compliance is checked at the bolting product level by hardness measurement on every test piece. The certificate reports the hardness reading as the NACE evidence. The mechanism is that the gamma-prime Ni3Al precipitate strengthens the matrix without raising the chloride-SCC susceptibility, because the matrix remains FCC copper-nickel rather than the BCC or martensitic structures that drive H2S cracking on high-strength steel bolting.
Hydrogen Embrittlement Immunity
The Cu-Ni-Al FCC matrix has no hydrogen-trap sites of the kind that drive embrittlement on high-strength steel bolting under cathodic protection in subsea service. Hydrogen diffuses through the matrix without accumulating at grain boundaries or precipitate interfaces, which is why Hiduron 191 does not suffer the delayed-failure mechanism that limits the use of high-strength steel and precipitation-hardened nickel-base alloys in CP-protected subsea bolting. This immunity is the operational reason the alloy is specified into subsea hydraulic connectors and splash-zone bolting on platforms with impressed-current cathodic protection.
Field Performance Record
Hiduron 191 splash-zone bolting on North Sea and Gulf of Mexico offshore platform risers has over 15 years of in-service performance without SCC failure or HE failure recorded on the standard inspection schedule. Subsea hydraulic connector bodies in Hiduron 130 have a comparable record on flying-lead and stab-plate applications in the same operating envelopes. The standards (NES 835, DEF STAN 02-835, DOD-C-24676) reference this field record as the qualification basis for naval and offshore procurement.
Hiduron 130 + 191 Designation Chain
| Designation system | Hiduron 130 | Hiduron 191 |
|---|---|---|
| UNS (Unified Numbering System) | C72400 | C72420 |
| Werkstoff (German register) | 2.1504 | not formally assigned |
| Chemical-symbol designation | CuNi14Al3Fe1 | CuNi14Mn4AlFe |
| UK Air Ministry | DTD 900/4805 | not applicable |
| UK Naval Engineering Standard | not applicable | NES 835 |
| UK Ministry of Defence | not applicable | DEF STAN 02-835 |
| US Department of Defense | not applicable | DOD-C-24676 |
| Originator and brand | Langley Alloys (UK) | Langley Alloys (UK) |
Related Hiduron Property Pages
- Chemical Composition: Element ranges for both grades with role notes for each addition.
- Mechanical Properties: Yield, tensile, elongation and hardness at room and elevated temperature.
- Heat Treatment: Solution-anneal plus age cycle for gamma-prime Ni3Al precipitation.
- Seawater Corrosion: Cu-Ni-Al passive film behaviour in flowing seawater.
- SCC Resistance: Stress-corrosion cracking and hydrogen embrittlement immunity.
- Magnetic Permeability: Non-magnetic naval and aerospace qualification.
- Machinability: Cu-Ni-Al cutting parameters and tooling notes.
- Density and Physical Properties: Density, modulus, thermal expansion, conductivity.
Hiduron Forms TorqBolt Supplies
| Form factor | Standard sizes | Page |
|---|---|---|
| Round bar (raw stock) | OD 16 to 250 mm | Round Bar |
| Stud bolts | M12 to M100, 50 to 600 mm | Stud Bolts |
| Hex bolts (DIN 931 / ISO 4014) | M12 to M64 | Hex Bolts |
| Heavy hex bolts (ASME B18.2.1) | 1/2 to 3 inch | Heavy Hex Bolts |
| Nuts and heavy hex nuts | M12 to M100 | Nuts |
| Washers (flat, spring, locking) | M12 to M48 | Washers |
| Forgings (subsea connector blank) | up to 600 kg piece | Forgings |
| Machined components (custom) | to project drawing | Machined Components |
Where Hiduron Is Specified
- Subsea Connectors: Hiduron 130 flying-lead, stab-plate and umbilical termination bodies.
- Riser Bolting: Hiduron 191 splash-zone bolting on North Sea and Gulf of Mexico platforms.
- Splash Zone Bolting: Hiduron 191 fasteners for the wet-dry tidal band.
- Naval Fasteners: NES 835 and DEF STAN 02-835 procurement on Royal Navy and allied bolting.
- Pump Shafts and Valve Spindles: Marine pump shafts and subsea valve spindles.
- Mechanical Seals: Seal-face bodies against tungsten-carbide running faces.
- Propeller Shafts: Naval and commercial marine propeller shafts.
- Sour Service (NACE): NACE MR0175 qualified bolting for sour oil and gas service.
Hiduron Controlling Standards
| Standard | Scope | Relevance |
|---|---|---|
| NES 835 | UK Naval Engineering Standard for Cu-Ni-Al bolting | Hiduron 191 controlling spec |
| DEF STAN 02-835 | UK Ministry of Defence adoption of NES 835 | Hiduron 191 MoD procurement |
| DOD-C-24676 | US Department of Defense Cu-Ni-Al spec | Hiduron 191 US Navy procurement |
| DTD 900/4805 | UK Air Ministry specification | Hiduron 130 original spec |
| NACE MR0175 | Sour service materials qualification | Hiduron 191 qualified to 286 HBW limit |
EN 10204 Certification and Inspection
Every Hiduron 130 and Hiduron 191 stock and finished fastener ships with EN 10204 type 3.1 mill test certificate as standard. Type 3.2 third-party witness by Lloyd's Register, DNV, BV, SGS or TUV is supplied on call-out and is standard practice on naval and subsea procurement orders. The certificate carries the melt heat number, full chemical analysis to the controlling specification, solution-anneal plus age cycle parameters, tensile and yield results, hardness, Charpy V impact result where called out, and the dimensional report. For Hiduron 191 sour-service orders, an additional NACE MR0175 hardness certificate confirms that every test piece reads below the 286 HBW (28 HRC) limit.
Request a Quote on Hiduron Bolting
TorqBolt supplies Hiduron 130 (UNS C72400, DTD 900/4805) and Hiduron 191 (UNS C72420, NES 835, DEF STAN 02-835, DOD-C-24676) in round bar, stud bolts, hex bolts, heavy hex bolts, nuts, washers, forgings and machined components. Standard fastener lead time is 4 to 8 weeks from order, subsea machined components quote project-specific lead time. Send an enquiry through TorqBolt Contact with the controlling specification, the form factor, the size envelope and the certification level (3.1 default, 3.2 on call-out, NACE on call-out).
Request a Quote on Hiduron 130 and Hiduron 191 Bolting Stock and Fasteners
Reference and Downloads
- Hiduron 130 Datasheet: Consolidated chemistry, mechanicals and heat treatment.
- Hiduron 191 Datasheet: NACE-qualified naval and subsea grade datasheet.
- Bolt Dimensions: Imperial and metric thread, head and stress-area tables.
- Torque Chart: Cu-Ni-Al fastener torque values, dry and lubricated.
- FAQ: Consolidated questions on Hiduron specification, certification and supply.
Hiduron SCC and HE FAQ
Q. Is Hiduron 191 immune to hydrogen embrittlement?
Yes. The Cu-Ni-Al FCC matrix has no hydrogen-trap sites of the kind that drive embrittlement on high-strength steel bolting under cathodic protection. Hydrogen diffuses through the matrix without accumulating at grain boundaries or precipitate interfaces.
Q. Is Hiduron 191 NACE MR0175 compliant?
Yes. Hiduron 191 is qualified to NACE MR0175 / ISO 15156 for sour-service bolting on the standard solution-anneal plus age cycle, with the hardness controlled at or below 286 HBW (28 HRC). The certificate reports the hardness reading as the NACE evidence.
Q. Does Hiduron suffer chloride SCC in seawater?
No. The Cu-Ni-Al passive film is stable in flowing seawater and splash-zone exposure through the operating envelope of subsea and naval bolting. Over 15 years of in-service performance on North Sea and Gulf of Mexico risers confirms the immunity.
Q. Can Hiduron be used with cathodic protection?
Yes. The hydrogen-embrittlement immunity makes Hiduron 191 the preferred bolting on subsea platforms with impressed-current cathodic protection, where high-strength steel and precipitation-hardened nickel-base alloys are at risk of delayed failure.
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