Amigo Impex, a Mumbai-based manufacturer, supplier and exporter since 2013, provides high-temperature Inconel 660A fasteners globally. One point deserves clarification at the outset: Inconel 660A is a market name used in the fastener trade for A-286, the iron-nickel-chromium precipitation-hardening alloy registered as UNS S66286 and supplied to ASTM A453 Grade 660 Class A. Special Metals Corporation markets the same alloy as Incoloy alloy A-286.
The 660A alloy carries 24.0 to 27.0% nickel and 13.5 to 16.0% chromium, with titanium forming the hardening phase during ageing. Class A material meets a minimum tensile strength of 895 MPa and a minimum 0.2% offset yield strength of 585 MPa at room temperature. Bolted joints keep useful preload at service temperatures up to approximately 704°C. Equivalent designations, W.Nr 1.4980 and SUH 660 among them, appear on international drawings for the same material.
We stock hex bolts, hex nuts, stud bolts, washers, screws, threaded rods, anchor bolts, socket head cap screws, U-bolts and eyebolts from M3 to M56 and 3/16 in to 2 1/4 in, with lengths from 3 mm to 200 mm and custom dimensions machined to order. Cutting, machining, threading, testing and packing are coordinated in-house with our manufacturing partners. Grade 660 bolting from our stock reaches oil and gas installations, petrochemical plants, power stations and aerospace assemblies. Amigo Impex is certified to AS 9120B, ISO 9001:2015 and ISO 45001:2018, with material approval under the Pressure Equipment Directive 2014/68/EU, and quotes per-kg rates in INR and USD. Every consignment ships with a mill test certificate to EN 10204 Type 3.1.
ASTM A453 splits Grade 660 into Classes A, B, C and D. Classes A, B and C share the same strength minima and differ by heat-treatment route, while Class D is supplied to a higher 725 MPa yield minimum. The specifications below apply to Class A, the standard supply condition for Inconel 660A fasteners stocked at our Mumbai works. Class D, at a 725 MPa minimum yield and controlled to 35 HRC maximum for NACE MR0175 service, is supplied to order for API 6A and API 20F flange bolting.
Material standards fix the alloy chemistry and heat-treated condition, while dimensional standards govern thread and head geometry. Both sets apply to A-286 fastener supply, and as Inconel 660A fasteners suppliers, we ensure that the specified material condition, dimensions and thread requirements are met, with the mill certificate recording the exact combination ordered.
| Standard | Scope |
|---|---|
| ASTM A453 / A453M Grade 660 Class A | High-temperature bolting material, the governing specification |
| ASME SA-453 Grade 660 | Boiler and Pressure Vessel Code adoption of A453 |
| ASTM F2281 | Stainless steel and nickel alloy bolts, hex cap screws and studs for heat resistance and high temperature applications; Alloy 660 (UNS S66286) is listed as Type III Class B |
| ASTM A638 Grade 660 | Precipitation-hardening iron-base superalloy bars and forgings |
| ASTM A962 / A962M | Common requirements for bolting, mandatory companion to A453: test methods, finish, thread dimensions, marking and certification |
| DIN 931, 933, 934 | Hex bolt and hex nut dimensions |
| ASME B18.2.1, B18.2.2, B18.3 | Bolt, nut and socket screw dimensions |
| ASME B16.5 | Stud bolt lengths for flange joints |
| ISO 4032, ISO 4033 | Hex nut dimensions |
Iron-nickel-chromium age hardening gives this alloy its bolt stress retention: titanium and aluminium combine with nickel to precipitate gamma prime during ageing, while boron strengthens the grain boundaries, so clamping force holds at temperatures that relax standard austenitic bolting. Limits below follow ASTM A453 Grade 660 for UNS S66286.
| Element | Composition (%) |
|---|---|
| Carbon (C) | 0.08 max |
| Manganese (Mn) | 2.00 max |
| Phosphorus (P) | 0.040 max |
| Sulphur (S) | 0.030 max |
| Silicon (Si) | 1.00 max |
| Nickel (Ni) | 24.0 – 27.0 |
| Chromium (Cr) | 13.5 – 16.0 |
| Molybdenum (Mo) | 1.00 – 1.50 |
| Titanium (Ti) | 1.90 – 2.35 |
| Aluminium (Al) | 0.35 max |
| Vanadium (V) | 0.10 – 0.50 |
| Boron (B) | 0.001 – 0.010 |
| Iron (Fe) | Balance |
Values apply to Grade 660 Class A fasteners solution treated at 900 °C, liquid quenched and aged at 720 °C for 16 hours. Room-temperature figures are minima under ASTM A453 / A453M. Stress-rupture testing is required where the design temperature exceeds 427 °C and is tested at 650 °C; material supplied without it is stamped NR.
| Property | Requirement (Class A) |
|---|---|
| Tensile Strength, min | 895 MPa (130 ksi) |
| Yield Strength, 0.2% offset, min | 585 MPa (85 ksi) |
| Elongation in 4D, min | 15% |
| Reduction of Area, min | 18% |
| Brinell Hardness | 248 to 341 HBW |
| Stress Rupture at 650 °C | 385 MPa (56 ksi), 100 h minimum life, 5% minimum elongation |
International drawings call the material out under several national designations. The table matches Inconel 660A fasteners against EN, DIN, AFNOR, JIS and GB equivalents, every one of them cross-referencing the same UNS S66286 chemistry.
| Country / Standard | Designation |
|---|---|
| USA (UNS) | S66286 |
| Europe (EN / W.Nr) | 1.4980 (X6NiCrTiMoVB25-15-2) |
| France (AFNOR) | Z5NCTDV25-15B |
| Japan (JIS) | SUH 660 |
| China (GB) | GH2132 |
Ten fastener forms are supplied in Alloy 660A from our works, each threaded and finished to the dimensional standards listed above.
A-286 fasteners leave from our Mumbai warehouse in cartons or boxes, with wooden cases for bulk consignments and export packing as agreed. As an Inconel 660A fasteners supplier, stockist and exporter, we despatch PAN India and ship to the USA, the Gulf, Europe and Asia. Urgent orders move within 1 to 2 days; made-to-order items carry a lead time of around 30 days.
Every lot ships with a mill test certificate to EN 10204 Type 3.1. Chemistry is confirmed by positive material identification, heat-treated condition by hardness testing to ASTM A453 Table 5, and room-temperature strength by tension testing. Stress-rupture testing to A453 Table 6 is carried out where the design temperature exceeds 427 °C. Ultrasonic examination and third-party inspection can be arranged on request. Amigo Impex is certified to AS 9120B, ISO 9001:2015 and ISO 45001:2018, with material approval under the Pressure Equipment Directive 2014/68/EU.
Inconel 660A fasteners are priced at approximately ₹1,200–₹3,800 per kg in India and US$14–US$44 per kg internationally. Prices vary with fastener type, diameter, length, head style, thread form, quantity, certification, and prevailing nickel-market rates.
Share a drawing or bill of materials to receive a firm price on Grade 660 bolting.
Request a Quote60–70 tonnes held in Mumbai, with urgent requirements dispatched within one to two days.
AS 9120B, PED, ISO 9001:2015 and ISO 45001:2018, with an MTC on every order.
Cutting, machining, threading, fabrication and testing all handled at our own Mumbai facility.
Original mill certificates plus our own test reports, so every batch can be traced back.
Non-standard sizes and specifications made to order.
Dispatched from Mumbai to every major Indian city, and exported to USA, Gulf, Europe, Asia
Inconel 660A fasteners are supplied to ASTM A453/A453M Grade 660 Class A, with ASME SA-453 covering pressure-vessel bolting.
Inconel 660A fastener material is equivalent to W.Nr 1.4980 (EN), SUH 660 (JIS) and GH2132 (GB), all cross-referencing UNS S66286.
Bolts run from M3 to M56 and 3/16" to 2-1/4", and nuts cover the same range. Custom sizes and lengths beyond 200 mm are machined to order.
704 °C (1300 °F) is the accepted practical ceiling where fasteners must retain strength. Oxidation resistance extends higher, so the limit is set by strength and stress relaxation rather than scaling. Stress-rupture strength is verified at 650 °C under ASTM A453.
No, Inconel 660A fasteners are austenitic, so they are essentially non-magnetic in the aged condition.
Choose Inconel 660A for static high-temperature bolting up to approximately 704 °C at lower cost, and move to Inconel 718 where joint stresses run higher or the environment carries chlorides or sour gas.
Inconel 660A fasteners cost around ₹1,200–₹3,800 per kilogram in India and US$14–US$44 per kg globally. Prices vary depending on fastener type, diameter, length, head style, thread form, quantity, certification, and current nickel market pricing. Contact Amigo Impex to confirm current stock and delivery schedules for Inconel 660A fasteners.
Please contact us with the grade, diameter, temper and quantity to confirm stock availability and to acquire a dated quotation.
Grade 660 fasteners serve sectors where bolting must hold preload at elevated temperature.
