ASTM A453 Grade 660 Studs Bolts Heavy Hex Nuts
ASTM A453 Grade 660 Fasteners | Studs, Bolts & Heavy Hex Nuts
Grade 660 / Alloy A-286 / UNS S66286 precipitation-hardening austenitic fasteners for demanding high-temperature bolting applications.
ASTM A453 Grade 660 Fasteners are used for critical bolted joints where high-temperature strength, controlled heat treatment and long-term load resistance are important. Aanuraj supplies studs, stud bolts, hex bolts and heavy hex nuts for oil & gas, petrochemical, refinery, valve, pump and pressure-equipment applications.
ASTM A453 Grade 660 Fasteners - Technical Overview
Where Grade 660 fits
- High-temperature and high-load bolted joints.
- Critical oil & gas, refinery and petrochemical equipment.
- Valve, pump, flange and pressure-equipment assemblies.
- Applications where controlled heat treatment and traceability are important.
Other names and designations
- ASTM A453 Grade 660
- Alloy A-286 / A286
- UNS S66286
- EN 1.4980
- X6NiCrTiMoVB25-15-2
- Commonly described as precipitation-hardening austenitic stainless steel
Key Features of ASTM A453 Grade 660 Fasteners
High-temperature strength
Designed for demanding bolting service where elevated temperature reduces the strength of conventional materials.
Age hardening
Controlled precipitation hardening develops the required mechanical properties after solution treatment.
Stress-rupture performance
Stress-rupture testing evaluates resistance to sustained tensile loading at elevated temperature.
Oil & gas suitability
Useful for refinery, petrochemical, valve, pump and pressure-equipment bolting where high-temperature performance matters.
Custom manufacturing
Studs, stud bolts, bolts and heavy hex nuts can be manufactured to project dimensions and documentation requirements.
Traceability
MTC, PMI and inspection documentation can be supplied according to the project requirement.
ASTM A453 Grade 660 Chemical Composition
| Element | Requirement / Range |
|---|---|
| Carbon (C) | 0.08% max |
| Manganese (Mn) | 2.00% max |
| Silicon (Si) | 1.00% max |
| Phosphorus (P) | 0.040% max |
| Sulfur (S) | 0.030% 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% |
| Vanadium (V) | 0.10 - 0.50% |
| Aluminium (Al) | 0.35% max |
| Boron (B) | 0.001 - 0.010% |
| Iron (Fe) | Balance |
ASTM A453 Grade 660 Mechanical Properties
| Property | Classes A / B / C | Class D |
|---|---|---|
| Tensile strength | 895 MPa min | 895 MPa min |
| Yield strength | 585 MPa min | 725 MPa min |
| Elongation | 15% min | 15% min |
| Reduction of area | 18% min | 18% min |
| Hardness | Refer to governing A453/A453M requirement | Refer to governing A453/A453M requirement |
ASTM A453 Grade 660 Heat Treatment Cycles
ASTM A453 Grade 660 Stress-Rupture Test
A stress-rupture test measures how long a specimen can carry a specified tensile stress at elevated temperature before rupture, while also checking elongation. It is particularly relevant to high-temperature bolting because a joint can remain loaded for long operating periods.
Grade 660 A / B / C Stress-Rupture Requirement
Minimum elongation: 5%. The cited Grade 660 stress-rupture requirement applies to Classes A, B and C. Class D should be checked directly against the governing specification for the project.
Grade 660 Metric & Inch Fastener Standards
Metric standards
- ISO 4014 / ISO 4017 for hexagon head bolts where applicable.
- ISO 898 dimensional conventions are not a substitute for ASTM A453 material/class requirements.
- ISO 965 thread system for metric threads where specified.
- Project drawings and purchase specifications govern final dimensions.
Inch standards
- ASME B18.2.1 for inch-series hex bolts and screws where applicable.
- ASME B18.2.2 for inch-series nuts.
- ASME B18.31.2 for continuous-thread and stud-bolt forms.
- ASME B1.1 for Unified inch threads.
ASTM A453 Grade 660 Applications in Oil & Gas
Valves
Valve bonnet, flange and pressure-boundary bolting where elevated-temperature strength is required.
Pumps
Pump casing, flange and high-temperature assembly bolting for refinery and process equipment.
Refineries
Critical bolted joints in high-temperature process and hydrocarbon service.
Petrochemical plants
Fasteners for process equipment, piping assemblies and high-temperature connections.
Pressure equipment
Bolting for pressure vessels and associated high-temperature equipment where specified.
Flanges & piping
Stud bolts and heavy hex nuts for critical flange connections subject to sustained load and heat.
5 Questions Engineers Ask About Grade 660 Fasteners
It is a specification for high-temperature bolting materials, including Grade 660, a precipitation-hardening austenitic alloy commonly associated with A286 / UNS S66286.
The classes use different solution-treatment, quenching and aging cycles and therefore provide different specified mechanical-property requirements. The applicable class should be selected from the governing project specification.
It evaluates resistance to rupture under sustained tensile stress at elevated temperature, making it relevant to bolted joints that remain loaded during long operating periods.
Grade 660 can be specified for high-temperature valve, pump, flange and pressure-equipment bolting when the equipment design and governing specification call for its properties.
Yes. Aanuraj can supply studs, stud bolts, bolts and heavy hex nuts in project-specific dimensions, with material traceability and inspection documentation as required.
Why Aanuraj for ASTM A453 Grade 660 Fasteners?
1. Grade knowledge
Focused experience with stainless, duplex and high-nickel industrial fastener materials.
2. Hot-forged manufacturing
Manufacturing capability for heavy-duty studs, bolts and special fastener configurations.
3. Controlled processing
Heat-treatment and machining requirements can be managed against the specified Grade 660 class.
4. Material traceability
MTC, PMI and inspection documentation can be coordinated for critical orders.
5. Custom dimensions
Metric, inch and project-specific dimensions can be produced according to approved drawings.
6. Technical support
Engineering assistance for grade selection, dimensions, heat treatment and documentation requirements.
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