The definitive B2B procurement reference for Inconel 625, 718, 600, 601, and 725 bolts, stud bolts, and nuts designed for extreme temperature, high pressure, and severe corrosive environments.
Inconel 718 & 625 Bolting Solutions
Engineered to eliminate stress corrosion cracking (SCC), pitting, and hydrogen embrittlement in sour gas and subsea production environments.
Thermal Stability Up to 1000°C / 1832°F
Custom forging, CNC machining, thread rolling, and specialized anti-galling coatings delivered to 105+ countries worldwide.
Hot forged and precision machined hex bolts in Inconel 625 & 718. Engineered for exceptional fatigue strength, high pressure flange sealing, and severe chemical exposure.
Continuous thread and double-end stud bolts for high-pressure piping flanges, heat exchangers, and subsea Christmas trees. Available in age-hardened Inconel 718 and 725.
High-strength, pitch-matched heavy hex nuts manufactured in Inconel 625, 718, and 600. Tapped to ASME B18.2.2 and DIN 934 to ensure uniform clamp load distribution.
When industrial joint requirements exceed the physical limits of 316L stainless steel, duplex 2205, or high-tensile alloy steels, procurement teams and structural piping engineers turn to nickel-chromium superalloy fasteners—collectively known under the trademark family Inconel.
Inconel fasteners are non-magnetic, solid-solution or precipitation-strengthened nickel-base superalloys engineered to withstand operational conditions characterized by oxidation, carburization, high pressure, and intense thermal cycling ranging from cryogenic temperatures up to 1000°C (1832°F). Unlike carbon or stainless steel fasteners that experience rapid degradation, grain boundary oxidation, and loss of tensile yield strength above 550°C, Inconel alloys retain exceptional mechanical integrity and creep-rupture strength.
At Neelkamal Alloys LLP, based in Mumbai, India, we specialize in converting certified, vacuum-melted Inconel bar stock into high-precision hex head bolts, heavy hex nuts, stud bolts, socket head cap screws, threaded rods, and custom turned components. By adhering strictly to ASTM B166, ASTM B446, ASTM B637, ASME, DIN, and ISO standards, our manufacturing facility bridges the gap between raw metallurgical science and dependable industrial joint integrity.
Selection of the exact Inconel grade is critical to prevent catastrophic mechanical shear, stress corrosion cracking (SCC), or thread galling. Below is an engineering overview of the primary Inconel grades utilized across global EPC projects:
Engineers and technical procurement officers can utilize this comparative table to verify exact chemical tolerances and mechanical performance criteria per ASTM & ASME standards.
| Element (wt %) | Inconel 600 (N06600) | Inconel 601 (N06601) | Inconel 625 (N06625) | Inconel 718 (N07718) | Inconel 725 (N07725) |
|---|---|---|---|---|---|
| Nickel (Ni) | 72.0 min | 58.0 – 63.0 | 58.0 min | 50.0 – 55.0 | 55.0 – 59.0 |
| Chromium (Cr) | 14.0 – 17.0 | 21.0 – 25.0 | 20.0 – 23.0 | 17.0 – 21.0 | 19.0 – 22.5 |
| Molybdenum (Mo) | — | — | 8.0 – 10.0 | 2.80 – 3.30 | 7.0 – 9.5 |
| Niobium / Columbium (Nb) | — | — | 3.15 – 4.15 | 4.75 – 5.50 | 2.75 – 4.00 |
| Iron (Fe) | 6.0 – 10.0 | Balance | 5.0 max | Balance (17%) | Balance |
| Aluminum (Al) | — | 1.0 – 1.7 | 0.40 max | 0.20 – 0.80 | 0.35 max |
| Titanium (Ti) | — | — | 0.40 max | 0.65 – 1.15 | 1.0 – 1.7 |
| Carbon (C) | 0.15 max | 0.10 max | 0.10 max | 0.08 max | 0.03 max |
| Alloy Grade | Condition / Heat Tx | Tensile Strength (MPa / ksi) | 0.2% Yield Strength (MPa / ksi) | Elongation (%) | Hardness (HRC/HRB) | Max Temp (°C / °F) |
|---|---|---|---|---|---|---|
| Inconel 600 | Annealed | 550 / 80 min | 240 / 35 min | 30 min | 65 – 85 HRB | 1093 / 2000 |
| Inconel 601 | Annealed | 550 / 80 min | 205 / 30 min | 30 min | 65 – 85 HRB | 1250 / 2250 |
| Inconel 625 | Grade 1 (Annealed) | 827 / 120 min | 414 / 60 min | 30 min | 175 – 240 HB | 982 / 1800 |
| Inconel 718 | Solution + Aged | 1275 / 185 min | 1034 / 150 min | 12 min | 36 – 45 HRC | 704 / 1300 |
| Inconel 725 | Age Hardened | 1207 / 175 min | 965 / 140 min | 20 min | 36 – 44 HRC | 815 / 1500 |
Procuring prime ultrasonic-tested, vacuum induction melted (VIM-VAR) Inconel round bars with heat certificates.
Induction pre-heating and hot heading of bolt heads, followed by precision CNC turning and threading.
Controlled atmosphere solution annealing and double aging in calibrated furnaces to reach API 6A / NACE hardness specs.
PMI spectro-analysis, thread gauge tolerance checks, tensile testing, and EN 10204 3.1 certification packaging.
Why choose Inconel over Stainless Steel, Duplex, Hastelloy, or Titanium? Review the technical trade-offs below.
| Attribute | Inconel 625 / 718 | 316L Stainless Steel | Duplex 2205 | Hastelloy C276 | Titanium Grade 5 |
|---|---|---|---|---|---|
| Max Operating Temp | 704°C – 1000°C | 425°C | 300°C | 650°C | 400°C |
| Chloride Pitting (PREN) | > 45 (Extremely High) | ~25 (Moderate) | ~35 (High) | > 65 (Maximum) | Immune (via Oxide Film) |
| Tensile Strength (Aged) | Up to 1350 MPa | 485 MPa | 750 MPa | 750 MPa | 950 MPa |
| Yield Strength @ High Temp | Exceptional Retention | Severe Drop above 400°C | Embrittles above 300°C | Good Retention | Moderate Drop |
| Sour Gas (H2S) Resistance | NACE MR0175 Compliant | Susceptible to SCC | Limited by Temperature | Excellent | Limited in Dry Chlorine |
| Relative Cost Factor | High (Value-Engineered) | Economic / Baseline | Moderate | Very High | High |
Information Gain Insight: While Stainless Steel 316L or Duplex 2205 fasteners offer lower initial purchase costs, their structural yield strength collapses rapidly under high temperatures or in the presence of concentrated H2S and chlorides. In contrast, Inconel 718 fasteners maintain their pre-load tension without suffering from thermal relaxation, thread relaxation creep, or stress corrosion failure—eliminating un-planned refinery shutdowns and costly offshore flange leaks.
Engineering strategies for installing Inconel bolts and stud bolts in extreme pressure & temperature service.
Because nickel alloys exhibit high ductility and friction coefficients during torque application, untreated Inconel-on-Inconel thread engagements can gall and freeze permanently. Neelkamal Alloys LLP provides silver plating, molybdenum disulfide (MoS2), and specialized Xylan/PTFE coatings to maintain a controlled coefficient of friction (μ = 0.12–0.15).
Calculating proper bolt torque is paramount. Due to the high yield strength of precipitation-hardened Inconel 718 (150 ksi yield strength), under-torquing leads to gasket leakage while over-torquing can exceed flange rating. Hydraulic tensioning is recommended for studs larger than M30 (1-1/8") to achieve uniform bolt pre-load.
When joining dissimilar metals (e.g., Inconel stud bolts on carbon steel or 316 stainless flanges), engineers must account for differences in coefficient of thermal expansion (α). Differential thermal growth can alter joint clamp load, leading to flange face unloading during thermal cycling.
Manufactured to ASTM B166, B446, B637, ASME B18.2.1, B18.2.2, DIN 931, DIN 933, and custom client blueprints.
UNS N06625 / W.Nr. 2.4856 bolts, screws, nuts, and washers. High pitting resistance (PREN > 45) for chemical plant service.
Send an InquiryUNS N07718 / W.Nr. 2.4668 high-strength stud bolts for NACE MR0175 sour gas wells, subsea manifolds, and gas turbines.
Send an InquiryUNS N06600 & N06601 socket cap screws, set screws, and heavy nuts for industrial furnace and heat-treating equipment.
Send an InquiryMachined flat washers, Belleville spring washers, double-end studs, and drawing-based special fasteners in exotic alloys.
Send an InquiryHow shifting global energy transitions, environmental regulations, and advanced manufacturing technologies are reshaping the high-nickel alloy market.
As energy companies transition toward green hydrogen production and zero-emission sCO2 power cycles, operational temperatures and pressures are escalating beyond traditional steam turbine thresholds. High-purity Inconel 718 and Inconel 725 fasteners are increasingly specified for electrolyzer stack clamping and ultra-high temperature gas turbine casing joints due to their immunity to hydrogen embrittlement when heat treated under clean vacuum conditions.
Global EPC contractors in Europe, North America, and the Middle East now mandate full raw material traceability from origin melt to final thread. Procurement officers require EN 10204 3.1 certification integrated with digital heat batch tracking, 100% Positive Material Identification (PMI) verifying exact Nickel/Molybdenum ratios, and environmental footprint disclosures.
Historically, Inconel fasteners were exclusively turned from solid bar stock due to work hardening tendencies. Modern multi-station warm/hot forging technology allows high-volume production of Inconel 625 and 718 hex bolts with continuous grain flow through the head-to-shank junction, increasing fatigue life by over 35% while reducing raw material scrap rates.
Given the price fluctuations of LME Nickel and Molybdenum, forward-thinking procurement teams are establishing long-term stockholding agreements with qualified Indian manufacturers like Neelkamal Alloys LLP. Maintaining strategic inventories of certified Inconel round bars enables rapid 48-hour emergency dispatch during refinery turnarounds or offshore rig maintenance shutdowns.
Based in the manufacturing hub of Mumbai, India, Neelkamal Alloys LLP is a premier manufacturer, stockist, and exporter of high-grade alloy steel, stainless steel, duplex, and exotic nickel alloy fasteners. We provide mission-critical bolting solutions to over 350 major project sites across 105 countries.
From raw bar inspection to high-speed CNC turning, induction forging, thread rolling, and final surface treatment, our Quality Management System ensures 100% compliance with ASTM, ASME, DIN, ISO, and client-specific engineering drawings.
Proven track record of supplying exotic alloy fasteners to oil refineries, chemical plants, offshore platforms, and power stations globally.
Inconel fasteners are critical components in environments where joint failure would cause catastrophic environmental or financial damage.
Inconel 718 stud bolts for API 6A valves, wellheads, blowout preventers, and subsea trees compliant with NACE MR0175.
Inconel 625 hex bolts for hydrocracker units, catalyst regenerators, flare stacks, and high-temperature reactors.
Inconel 600 & 601 bolts and furnace anchor pins operating continuously under thermal cycling up to 1250°C.
Fasteners resistant to organic and inorganic acids, dry chlorine gas, acetic anhydride, and nitric acid solutions.
Inconel 625 hardware for high-pressure reverse osmosis pumps, seawater intake valves, and marine propulsion.
High-tensile Inconel 718 socket head screws and turbine housing tie rods for land-based and aviation gas turbines.
Answers to common questions asked by international buyers, piping engineers, and quality managers regarding Inconel fasteners.
Send an InquiryThe core difference lies in their strengthening mechanism, mechanical strength, and service temperature range. Inconel 625 (UNS N06625) is a solid-solution strengthened alloy relying on Molybdenum and Niobium within a Nickel-Chromium matrix; it delivers superior general corrosion and pitting resistance up to 982°C (1800°F). Inconel 718 (UNS N07718) is a precipitation-hardenable alloy heat treated to form gamma double prime (γ'') precipitates, yielding nearly double the yield strength (over 1000 MPa / 150 ksi) of 625. Inconel 718 is preferred for high-stress applications like subsea sour gas wellheads up to 704°C (1300°F).
Yes. Neelkamal Alloys LLP manufactures Inconel 718 stud bolts and nuts under strictly controlled solution annealing and precipitation aging treatments to comply with NACE MR0175 / ISO 15156 and API 6A CRA requirements. We enforce a maximum hardness limit of 35 HRC or 40 HRC (depending on environmental severity class) to prevent sulfide stress cracking (SSC) in sour gas environments.
Material composition and bar stock standards include ASTM B166 (Inconel 600/601/690 rod/bar), ASTM B446 (Inconel 625 rod/bar), and ASTM B637 (precipitation-hardened Inconel 718/725/X-750 bar). Dimensional standards follow ASME B18.2.1 for hex head bolts, ASME B18.2.2 for heavy hex nuts, ASME B18.3 for socket cap screws, and DIN 931 / DIN 933 / ISO 4014 for metric fasteners.
Nickel alloys tend to cold weld or gall under pressure. We mitigate galling by maintaining precise thread flank tolerances, utilizing rolled threads rather than cut threads, and applying specialized anti-galling coatings such as electroplated Silver plating (per AMS 2410), Molybdenum Disulfide (MoS2), or PTFE / Xylan coatings. Using extreme-pressure high-nickel lubricants during torqueing is also strongly recommended.
Every shipment from Neelkamal Alloys LLP is dispatched with a complete EN 10204 3.1 Mill Test Certificate (MTC). This includes chemical composition, mechanical tensile & yield test results, elongation, hardness values, heat treatment history, 100% Positive Material Identification (PMI) spectro-analysis, microstructural grain size evaluation, and ultrasonic testing reports. Third-party inspection (TPI) by TUV, SGS, DNV, Lloyd's, or Bureau Veritas can be provided upon request.
Yes. In addition to standard ASME, DIN, and ISO sizes, our Mumbai facility produces custom Inconel hardware including special length stud bolts, extra-heavy flange bolts, reduced shank bolts, Belleville washers, slotted nuts, and precision turned parts per client blueprints.
We maintain an extensive stockholding of certified Inconel 625 and 718 round bars in sizes from 6mm to 100mm. Standard fast-track items can be machined and dispatched within 3 to 7 working days. Custom forged or heat-treated orders typically take 2 to 3 weeks depending on quantity. We accommodate small prototype quantities as well as large EPC project bill of materials (BOM).
Neelkamal Alloys LLP exports fasteners to over 105 countries worldwide, including the United Arab Emirates (UAE), Saudi Arabia, Qatar, Oman, Kuwait, Bahrain, United Kingdom, Germany, Netherlands, Italy, United States, Canada, Singapore, Malaysia, Australia, Brazil, and South Africa.
Contact our engineering sales team in Mumbai today for competitive factory-direct pricing, material test reports, and fast international delivery lead times.
