Cupronickel 70-30 U Bolts manufactured at TorqBolt are seawater resistant,crevice resistant,stress corrosion crack resistant & hydrogen embrittlement resistant.
Dimensional standards as per DIN 3599 are provided.
The raw material of these fasteners is classified as copper based nickels. Being a PED certified Fasteners Manufacturer by TUV Rheinland,our fasteners are accompanied with EN 10204 3.1/3.2 certification. Cupronickel 70-30 U Bolts are available in hot forged,cold forged and bar stock machined conditions depending upon the order quantity.
Cupronickel 70 30 U Bolts — Specifications & Dimensions
Cupronickel 70 30 U bolts are externally threaded fasteners with an integral head, manufactured per ASME B18.2.1, ISO 4014/4017, and DIN 933/931. TorqBolt produces Cupronickel 70 30 U bolts in metric (M6–M100) and imperial (1/4"–4") diameters with custom lengths from 10 mm up to 3000 mm.
Head Styles Available
Hex head — ASME B18.2.1, the workhorse for general bolting
Heavy hex head — thicker head for high-load joints, ASTM A325 / A490 patterns
Socket head cap (SHCS) — ASME B18.3 / DIN 912, ideal where space is limited
Cupronickel 70 30 U bolts are supplied with full or partial threading. Full-thread (UNC, UNF, ISO metric coarse/fine) for tension-only joints; partial-thread shank for shear loads where the unthreaded grip carries the load. Thread fits per ASME B1.1 (Class 2A) or ISO 965 (6g) by default; tighter Class 3A / 4h6h fits available on request. Engagement length follows the 1.5×D rule for tapped holes; 1.0×D minimum on through-bolting.
Mechanical Performance
Cupronickel 70 30 U bolts achieve characteristic tensile strength, yield, and elongation per the source-material spec, with proof-load testing and hardness verification per ASTM F606 / ISO 898-1. Torque-tension calibration is published per ASME PCC-1 for critical joints. Each lot ships with EN 10204 3.1 (or 3.2 on request) certificates listing chemistry, mechanicals, hardness, and dimensional inspection.
Custom Configurations
TorqBolt can produce Cupronickel 70 30 U bolts to drawing, with non-standard heads, drilled-shank variants, double-end, captive, or matched-set configurations. Coatings include zinc, PTFE, Xylan, hot-dip galvanized, and electroless nickel. NACE MR0175 / ISO 15156 sour-service certification on request.
Copper-Nickel & Cupronickel Alloys
Copper-nickel (cupronickel) alloys combine copper's bio-fouling resistance with nickel's strength and corrosion enhancement. The two production grades dominate marine + desalination service where titanium is too costly: 90/10 Cu-Ni (~90% Cu, 10% Ni) and 70/30 Cu-Ni. Cu-Ni alloys are the only commercial materials inherently resistant to marine bio-fouling, eliminating the need for antifouling coatings on heat-exchanger tubes and ship hulls.
C70600 (90/10 Cu-Ni) is the high-volume marine alloy: yield ~105 MPa, used for desalination tubing, condenser tubes, hull cladding, and offshore piping fasteners. C71500 (70/30 Cu-Ni) increases nickel for higher strength (~160 MPa yield) and better seawater erosion-corrosion at higher flow velocities — the choice for naval condensers and high-pressure desalination. C71640 (70/30 + Fe + Mn) extends service to even higher flow rates.
Cu-Ni fasteners ship per ASTM B151 (rod/bar) and B171 (plate/forging) with EN 10204 3.1 / 3.2 certificates. Welding uses ERCuNi or ENiCu-7 filler with low-heat-input technique to avoid hot cracking. NACE MR0175 sour-service application is limited; ammoniacal stress-corrosion can occur if exposed to NH₃ in service.
