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 Sour Service Components
Hiduron 191 (UNS C72420, NES 835, DEF STAN 02-835) is qualified to NACE MR0175 / ISO 15156 for sour-service bolting in oil and gas duty containing wet H2S. The Cu-Ni-Al matrix carries hydrogen embrittlement immunity at the gamma-prime precipitate interfaces, holds the controlling hardness ceiling of 286 HBW / 28 HRC at full strength specification, and develops yield strength above 580 MPa for primary structural bolting. The grade closes the gap that excludes high-strength carbon steel, Inconel 718 and Monel K-500 from sour-service duty at full strength.
Sour-service bolting on subsea production trees, sour-gas Christmas trees, well-stream isolation valves, sour-gas pipeline flanges and refinery sour-water system bolting moves to Hiduron 191 when the design must hold full yield strength below the NACE MR0175 hardness ceiling. Operators including Saudi Aramco, ADNOC, Petrobras and TotalEnergies specify NACE MR0175 / ISO 15156 compliance across the sour-service portfolio; EPCs including Saipem, McDermott and Worley deliver the bolting packages. The mill test certificate carries the hardness reading on every stud or bolt as the compliance evidence, with EN 10204 type 3.2 third-party witness on call-out.
Hiduron Chemical Composition (Cu-Ni-Al Family)
Hiduron 130 (UNS C72400) is a copper-nickel-aluminium-iron precipitation-hardened cupronickel with roughly 14 to 15.5 percent nickel, 2.7 to 3.4 percent aluminium and 1 to 2 percent iron in a copper matrix. Hiduron 191 (UNS C72420) carries the same nickel envelope with a manganese addition of 4 to 5 percent and a lower aluminium and iron level, which lifts the strength response while preserving NACE MR0175 compliance. The aluminium is the gamma-prime former: it pairs with the nickel during age to precipitate the Ni3Al strengthening phase that is the entire reason both grades carry yield strengths above any conventional cupronickel.
| Element | Hiduron 130 typical, percent | Hiduron 191 typical, percent | Role |
|---|---|---|---|
| Copper (Cu) | balance (~80 to 82) | balance (~76 to 78) | Matrix; seawater corrosion resistance |
| Nickel (Ni) | 14.0 to 15.5 | 14.0 to 15.5 | Strengthening partner for gamma-prime Ni3Al |
| Aluminium (Al) | 2.7 to 3.4 | 1.5 to 2.5 | Gamma-prime former; precipitation hardening |
| Iron (Fe) | 1.0 to 2.0 | 0.5 to 1.5 | Grain refinement; corrosion modifier |
| Manganese (Mn) | up to 0.75 | 4.0 to 5.0 | Solid-solution strengthening (191) |
| Silicon (Si) | up to 0.10 | up to 0.10 | Deoxidation residual |
| Lead (Pb) | up to 0.02 | up to 0.02 | Tramp limit for hot workability |
| Carbon (C) | up to 0.05 | up to 0.05 | Tramp limit |
Hiduron Mechanical Properties (Solution Annealed + Aged)
Both Hiduron grades are supplied in the solution-annealed-plus-aged condition. Hiduron 130 develops tensile 740 to 850 MPa with 0.2 percent proof stress at least 480 MPa and elongation A5 at least 18 percent. Hiduron 191 develops tensile 820 to 1000 MPa with 0.2 percent proof stress at least 580 MPa and elongation A5 at least 15 percent. Both grades hold hardness below the NACE MR0175 sour-service limit of 286 HBW / 28 HRC when the age is controlled correctly. Magnetic permeability stays below 1.005 mu_r in both grades, which is the value that qualifies them for naval mine-countermeasures and submarine applications where stainless steels and standard Monel grades are excluded.
| Property | Hiduron 130 | Hiduron 191 | Test condition |
|---|---|---|---|
| Tensile strength (Rm) | 740 to 850 MPa | 820 to 1000 MPa | RT, SA+aged |
| 0.2 percent proof stress (Rp0.2) | ≥480 MPa | ≥580 MPa | RT, SA+aged |
| Elongation A5 | ≥18 percent | ≥15 percent | RT, longitudinal |
| Hardness (HV) | 240 to 280 | 270 to 320 | RT, Vickers |
| NACE MR0175 hardness ceiling | n/a (not NACE) | ≤28 HRC / ≤286 HBW | Sour-service limit |
| Charpy V impact (RT) | ≥60 J | ≥40 J | RT, longitudinal |
| Magnetic permeability | <1.005 mu_r | <1.005 mu_r | Non-magnetic, naval qualified |
| Density | 8.85 g/cm3 | 8.65 g/cm3 | Calculated |
Why Hiduron Beats Standard Cupronickel and Monel K-500
The Hiduron family combines seawater corrosion and biofouling resistance of conventional 70/30 cupronickel with the strength response of gamma-prime precipitation hardening. The decisive value drivers are: NACE MR0175 sour-service compliance at high yield strength, hydrogen embrittlement immunity in cathodically protected subsea service, non-magnetic response below 1.005 mu_r for naval qualification, anti-galling behaviour against stainless and tungsten-carbide running faces, and anti-biofouling response that suppresses marine growth on long-immersion components. Standard Monel K-500 carries higher hardness than NACE MR0175 will allow at the strength levels that subsea connector and platform bolting require, which is the gap Hiduron 191 fills.
- NACE MR0175 sour-service compliance: Hiduron 191 is qualified to the 286 HBW / 28 HRC ceiling at full yield-strength specification.
- Hydrogen embrittlement immunity: Cu-Ni-Al matrix does not trap hydrogen at the precipitate interfaces, so cathodically protected subsea bolting holds capacity through service life.
- Non-magnetic, below 1.005 mu_r: Qualified for UK Royal Navy mine-countermeasures hulls, submarine fittings and non-magnetic instrument bays.
- Anti-galling: The Cu-Ni-Al matrix runs against austenitic stainless, super duplex, tungsten carbide and silicon carbide without surface seizure.
- Anti-biofouling: Copper-nickel matrix releases trace copper ions that suppress barnacle, mussel and tube-worm attachment to long-immersion components.
Hiduron Heat Treatment (Solution Anneal + Age, Gamma-Prime Precipitation)
The standard cycle is solution-anneal at 900 to 950 deg C, hold one hour every 25 mm of section, then water quench to freeze the gamma-prime formers in solid solution. The age follows at 475 to 525 deg C for 3 to 6 hours then air cool. The age develops the Ni3Al strengthening precipitate that lifts the yield strength to the specification floor. Age temperature is the controlling variable: below 475 deg C the precipitate is under-developed and room-temperature yield falls below specification; above 525 deg C the precipitate over-coarsens and tensile drops. For NACE MR0175 sour-service bolting the age cycle is controlled to land hardness below 286 HBW / 28 HRC, and the hardness reading on the mill test certificate is the compliance evidence.
Hiduron Welding Notes
Hiduron 130 and Hiduron 191 are welded with matched-composition Cu-Ni-Al filler under inert-gas shielding using gas tungsten arc with argon shield. Preheat is 100 to 150 deg C and inter-pass temperature is controlled below 250 deg C to protect the heat-affected-zone toughness. The filler chemistry matches the parent gamma-prime response so the joint develops comparable strength after a post-weld age at 475 to 525 deg C. On naval and subsea bolting, post-weld solution-anneal followed by full age is standard to restore parent properties through the weld. Inspection follows ISO 5817 quality level B visual, dye-penetrant on cap and root, and ultrasonic on butt joints above 25 mm. On Hiduron 191 sour-service welds, hardness traverse across weld plus HAZ plus parent verifies hardness stays below 286 HBW / 28 HRC at every point.
Hiduron 130 vs 191 vs Monel K-500 vs Nickel Aluminium Bronze
Hiduron 130 is the mid-strength Cu-Ni-Al grade specified into subsea hydraulic connectors and general marine bolting to DTD 900/4805. Hiduron 191 steps up the strength envelope and adds NACE MR0175 sour-service compliance, which is why it is the controlling spec on naval and splash-zone bolting. Monel K-500 carries the same gamma-prime mechanism in a nickel-copper matrix but exceeds the NACE MR0175 hardness ceiling at full strength specification. Nickel Aluminium Bronze (UNS C95400) is a different alloy family (Cu-Al-Ni-Fe casting alloy) with a different strengthening mechanism; it is not interchangeable with Hiduron.
| Grade | UNS | Service envelope | When to specify |
|---|---|---|---|
| Monel K-500 | N05500 | Subsea instruments, gauges | Step UP to Hiduron 191 when NACE MR0175 hardness limits exclude K-500 |
| Hiduron 191 | C72420 | Naval, subsea, splash zone, sour service | Highest-strength NACE-compliant Cu-Ni-Al; non-magnetic |
| Hiduron 130 | C72400 | Subsea hydraulic connectors, marine | Mid-strength Cu-Ni-Al; subsea connector flagship grade |
| Nickel Aluminium Bronze (NAB) | C95400 | Propellers, marine valves | Different alloy family; not interchangeable with Hiduron |
| 70/30 Cupronickel | C71500 | Seawater piping | Lower strength; Hiduron replaces it where structural load matters |
Hiduron Applications by Industry
The Hiduron family is specified into eight primary service areas across subsea, naval and marine sectors. Each application page below sets out the selection drivers, fastener form-factor mix, governing standards and inspection regime for that service.
- Subsea Connectors: Hiduron 130 flying-lead, stab-plate and umbilical termination bodies for subsea hydraulic and electrical control systems.
- Riser Bolting: Hiduron 191 splash-zone bolting on North Sea and Gulf of Mexico offshore platform risers.
- Splash Zone Bolting: Hiduron 191 fasteners for the wet-dry tidal band where stainless steels suffer chloride crevice attack.
- Naval Fasteners: NES 835, DEF STAN 02-835 and DOD-C-24676 procurement on Royal Navy, US Navy and allied surface and submarine bolting.
- Pump Shafts and Valve Spindles: Marine pump shafts and subsea valve spindles where anti-galling and corrosion fatigue performance are decisive.
- Mechanical Seals: Seal-face bodies that need anti-galling against tungsten-carbide and silicon-carbide running faces.
- Propeller Shafts: Naval and commercial marine propeller shafts and drive bushes.
- Sour Service (NACE): NACE MR0175 / ISO 15156 qualified bolting for sour oil and gas service.
Related Hiduron Forms and Fasteners
TorqBolt supplies Hiduron 130 and Hiduron 191 across the bolting and machined-component form range that the Cu-Ni-Al alloy class is commercially available in. Plate, sheet, tubing, seamless pipe, fittings and flanges are not commercial Hiduron forms and are not supplied. Every order is supplied with EN 10204 type 3.1 mill test certificate by default, with type 3.2 third-party witness on call-out.
- Round Bar: hot-worked stock OD 16 to 250 mm
- Stud Bolts: M12 to M100, lengths 50 to 600 mm, flange bolting
- Hex Bolts + Heavy Hex Bolts: DIN 931 / ISO 4014 / ASME B18.2.1
- Anchor Bolts + U-Bolts + Threaded Rod
- Nuts + Heavy Hex Nuts + Washers: matched-grade companion hardware
- Forgings: subsea connector blanks up to 600 kg piece
- Machined Components: subsea connector bodies, valve spindles, pump shafts to project drawing
Request a Quote on Hiduron Bolting and Machined Components
TorqBolt supplies Hiduron 130 (UNS C72400) and Hiduron 191 (UNS C72420) bolting and machined components worldwide from Mumbai head office and Rajkot production plant. EN 10204 type 3.1 mill test certificate by default; type 3.2 with Lloyd's Register, DNV, BV, SGS or TUV witness inspection on call-out. NACE MR0175 hardness certificate on call-out for Hiduron 191 sour-service orders. Send your enquiry →
Hiduron Sour Service Frequently Asked Questions
Q. Why is Hiduron 191 qualified to NACE MR0175 / ISO 15156?
Hiduron 191 holds hardness below the NACE MR0175 ceiling of 286 HBW / 28 HRC at the standard solution-anneal plus age cycle while developing yield strength above 580 MPa. The Cu-Ni-Al matrix is immune to hydrogen embrittlement at the gamma-prime precipitate interfaces in wet H2S environments. The two characteristics together qualify the grade for sour-service bolting at primary-structural load levels.
Q. Where does Hiduron 191 outperform Monel K-500 in sour service?
Monel K-500 exceeds the NACE MR0175 hardness ceiling at the yield strengths needed for sour-service structural bolting. Hiduron 191 holds the hardness ceiling at higher yield strength, which closes the gap between K-500 capacity and structural-bolting demand on sour packages.
Q. Do you supply NACE MR0175 hardness certification on every stud?
Yes. Hardness reading per stud or bolt is on the EN 10204 type 3.1 mill test certificate by default for Hiduron 191 sour-service orders. EN 10204 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 operator-side sour-service procurement.
Q. Which sour-service components use Hiduron 191 bolting?
Subsea production trees, sour-gas Christmas trees, well-stream isolation valves, sour-gas pipeline flanges, sour-water injection valve bolting, sulphur recovery unit bolting, amine regenerator bolting and refinery sour-water system flanges all use Hiduron 191 where NACE MR0175 / ISO 15156 compliance is mandatory.
Q. Is Hiduron 191 a substitute for Inconel 718 in sour service?
Inconel 718 carries higher yield strength but exceeds the NACE MR0175 hardness ceiling at full age. Hiduron 191 substitutes Inconel 718 on sour-service bolting at the yield strengths where the NACE ceiling excludes 718, which is the primary sour-service structural bolting envelope.
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