The ASTM A453 Grade 660 specification describes the standards of studs, bolts, nuts and other fasteners that are used in high-temperature bolting. This material is grouped in four types of properties (A, B, C, and D) that have certain tensile and stress rupture characteristics. Grade 660 bolts are commonly utilized to secure elements in boilers, pressure vessels, gasketed pipeline flanges and valves that are to be used in high temperature service. ASTEM A453 Grade 660 material has the same chemical composition as ASTM B638 Grade 660 stainless steel alloy but is heat-treated to obtain the mechanical properties of Grade 660 described in the ASTM A453 standard. These requirements are defined to assure uniform quality and performance under a well-known ASTM standard that regulates the mechanical and the chemical properties that are used reliably in a harsh environment.
ASTM A453 Gr 660 Stud Bolt, UNS S66286 Half Threaded Stud Bolt, DIN 1.4944 Double End Threaded Rod, Grade 660 Full Threaded Rod, ASME SA453 Gr.660 Full Threaded Stud Bolt Supplier
A453 Gr 660 Bolts are high-temperature fasteners manufactured from Alloy A286 (UNS S66286 / DIN 1.4944) — the ASTM A453 Gr 660 material equivalent designed for continuous service in boilers, pressure vessels, valve flanges, and gasketed pipeline assemblies at temperatures up to 700°C (1292°F). The ASTM A453 Grade 660 specification covers four tensile classes A, B, C, and D each heat-treated to distinct mechanical and stress rupture thresholds.
Jade Alloys is a Mumbai-based manufacturer, supplier, and exporter of ASTM A453 Gr 660 bolts certified to ASTM, ASME SA453, NACE MR0175/MR0103, ISO 15156, and PED 97/23/EC. We supply stud bolts, hex bolts, heavy hex bolts, and socket head cap screws in imperial sizes 3/8″ to 4″ and metric M10 to M100 available ex-stock with EN 10204 Type 3.1 Mill Test Certificates. Custom sizes and drawings accepted. Jade Alloys has supplied high-performance fasteners for 20+ years to clients in oil & gas, aerospace, and power generation across 50+ countries.
Table of Contents
- Types of ASTM A453 Gr 660 Fasteners
- ASTM A453 Gr 660 Stud Bolt Specification
- ASTM A453 Gr 660 Equivalent Grades
- Class A vs B vs C vs D — Comparison
- ASTM A453 Grade 660 Bolts Chemical Composition
- Mechanical Properties ASTM A453 Gr 660 Bolts
- ASTM A453 Gr 660 Stud Bolt Dimensions Chart
- Dimensions of A453 Gr 660 Heavy Hex Bolts
- ASTM A453 Grade 660 Bolts Size Chart
- A453 Gr 660 Socket Head Cap Screw Dimensions
- ASTM A453 Gr. 660 Bolts Inventory
- Applications of ASTM A453 Gr. 660 Fasteners
Types of ASTM A453 Gr 660 Fasteners
ASTM A453 Gr 660 Stud Bolts
ASTM A453 Gr 660 Hex Bolts
ASTM A453 Gr 660 Heavy Hex Nuts
ASTM A453 Gr 660 Hex Cap Screws
ASTM A453 Gr 660 Socket Head Cap Screws
ASTM A453 Gr 660 Heavy Hex Bolts
ASTM A453 Gr 660 U-Bolts
ASTM A453 Gr 660 Washers
ASTM A453 Gr 660 Bolts
ASTM A453 Gr 660 Stud Bolt Specification
| Property | Details |
|---|---|
| Dimensions | ASME B18.2.1, B18.3 |
| Size Range | 3/8″ to 4″ (Imperial) | M10 to M100 (Metric) — larger sizes on request |
| Melt Origin | East Europe / South America / Korea / Japan |
| Product Origin | Made in India |
| Thread Configuration | ASME B1.1 2A/3A Inch Unified Threads and B1.13M 6h Metric Coarse Threads |
| Certification | Dual Certified as per ASTM & ASME Codes |
| MTC Type | EN 10204 Type 3.1 Mill Test Certificate supplied with all orders |
| Additional Certifications | PED 97/23/EC Certified | Merkblatt AD 2000 W2 Certified |
| NACE Compliance | NACE MR0103 / MR0175 / ISO 15156 |
| Mandatory Requirements | Free from Mercury & Radioactive Contamination |
| Metric Companion Spec | ASTM A453M — metric-sized stud bolts, hex bolts, and nuts |
| Offshore / API | Class D certified under API 20F (BSL-2 & BSL-3) and NORSOK M630 (MDS S39 Rev.1) |
ASTM A453 Gr 660 Equivalent Grades
The ASTM A453 Gr 660 equivalent designations include UNS S66286, AISI 660, DIN 1.4944, BS HR 51, AMS 5726, JIS SUS 660, and EN X6NiCrTiMoV26-15. All are precipitation-hardened austenitic alloys chemically and mechanically equivalent to Alloy A286 — the ASTM A453 Gr 660 material base alloy.
| AISI | UNS | BS | W. Nr. | EN Name | DIN EN | JIS | AMS | ASTM | Other Names |
|---|---|---|---|---|---|---|---|---|---|
| 660 | S66286 | HR 51 | 1.4944 | X6NiCrTiMoV26-15 | 10269 | SUS 660 | 5726 | ASTM A453 Grade 660A | Incoloy A286, Alloy A286 |
ASTM A453 Gr 660 Class Comparison — A vs B vs C vs D
Each class of ASTM A453 Grade 660 is produced by a distinct heat treatment cycle, resulting in different mechanical thresholds and compliance requirements. Use this table to select the correct class for your application.
| Feature | Class A | Class B | Class C | Class D |
|---|---|---|---|---|
| Heat Treatment | Solution anneal + age harden | Solution anneal + cold work + age harden | Solution anneal + age harden | Single age harden |
| Min Yield Strength | 85 ksi (585 MPa) | 85 ksi (585 MPa) | 85 ksi (585 MPa) | 105 ksi (725 MPa) |
| Tensile Strength | 130 ksi (895 MPa) | 130 ksi (895 MPa) | 130 ksi (895 MPa) | 130 ksi (895 MPa) |
| Stress Rupture Test | Required (100 hrs @ 650°C) | Required (100 hrs @ 650°C) | Required (100 hrs @ 650°C) | Not required |
| NACE MR0175 (max HRC) | ≤ 35 HRC | ≤ 35 HRC | ≤ 35 HRC | ≤ 35 HRC |
| API 20F Certification | — | — | — | BSL-2 & BSL-3 |
| Fatigue Resistance | Standard | Enhanced (cold worked) | Standard | High (high-yield) |
| Typical Application | Pressure vessels, boilers | Offshore, fatigue-loaded joints | High-temp flanges | Sour service, offshore CRA |
Stress Rupture Test: ASTM A453 Gr 660 Class A, B & C bolts are stress rupture tested for 100 hours at 650°C in finished condition per ASTM E139. Class D is exempt from stress rupture testing per specification. Jade Alloys maintains in-house stress rupture test facility for sufficient quantity orders.
ASTM A453 Grade 660 Chemical Composition
| Element | Content (%) |
|---|---|
| Carbon | 0.08 max |
| Manganese | 2.00 max |
| Phosphorus | 0.040 max |
| Sulfur | 0.030 max |
| Silicon | 1.00 max |
| Nickel | 24.0 – 27.0 |
| Chromium | 13.5 – 16.0 |
| Molybdenum | 1.00 – 1.50 |
| Titanium | 1.9 – 2.35 |
| Aluminum | 0.35 max |
| Vanadium | 0.10 – 0.50 |
| Boron | 0.001 – 0.010 |
Mechanical Properties — ASTM A453 Gr 660 Bolts
| Grade | Class | Tensile Strength (ksi) | Tensile Strength (MPa) | Yield Strength (ksi) | Yield Strength (MPa) | Elongation 4D min % | Reduction of Area min % | Brinell Hardness | Rockwell min | Rockwell max |
|---|---|---|---|---|---|---|---|---|---|---|
| Grade 660 | A, B and C | 130 | 895 | 85 | 585 | 15 | 18 | 248–341 | 24 HRC | 37 HRC |
| Grade 660 | D | 130 | 895 | 105 | 725 | 15 | 18 | 248–341 | 24 HRC | 35 HRC |
Stress Rupture Test (per ASTM E139): Class A, B & C — tested for 100 hours at 650°C in finished condition. Class D — stress rupture test not required per ASTM A453 specification.
ASTM A453 Gr 660 Stud Bolt Dimensions Chart
| Nominal Size (D) inch | Tap End Full Thread Length (BM) | Umax = 2P | Min Nut End Full Thread Length (Bmin) | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Nominal | Min | Max | UNC & NC-5 | UNF | 8UN | L ≤ 10 | 10 < L ≤ 16 | L > 16 | |
| 1/4 | 0.375 | 0.350 | 0.400 | 0.100 | 0.071 | — | 0.750 | 1.000 | 1.500 |
| 5/16 | 0.469 | 0.440 | 0.498 | 0.111 | 0.083 | — | 0.875 | 1.125 | 1.625 |
| 3/8 | 0.563 | 0.532 | 0.594 | 0.125 | 0.083 | — | 1.000 | 1.250 | 1.750 |
| 1/2 | 0.750 | 0.708 | 0.792 | 0.154 | 0.100 | — | 1.250 | 1.500 | 2.000 |
| 5/8 | 0.938 | 0.892 | 0.983 | 0.182 | 0.111 | — | 1.500 | 1.750 | 2.250 |
| 3/4 | 1.125 | 1.075 | 1.175 | 0.200 | 0.125 | — | 1.750 | 2.000 | 2.500 |
| 7/8 | 1.313 | 1.258 | 1.368 | 0.222 | 0.143 | — | 2.000 | 2.250 | 2.750 |
| 1 | 1.500 | 1.438 | 1.562 | 0.250 | 0.167 | — | 2.250 | 2.500 | 3.000 |
| 1 1/4 | 1.875 | 1.813 | 1.938 | 0.286 | 0.167 | 0.250 | 2.750 | 3.000 | 3.500 |
| 1 1/2 | 2.250 | 2.188 | 2.313 | 0.333 | 0.167 | 0.250 | 3.250 | 3.500 | 4.000 |
| 2 | 3.000 | 2.925 | 3.075 | 0.444 | — | 0.250 | 4.250 | 4.500 | 5.000 |
| 2 1/2 | 3.750 | 3.675 | 3.825 | 0.500 | — | 0.250 | 5.250 | 5.500 | 6.000 |
| 3 | 4.500 | 4.425 | 4.575 | 0.500 | — | 0.250 | — | 6.500 | 7.000 |
| 4 | 6.000 | 5.900 | 6.100 | 0.500 | — | 0.250 | — | 8.500 | 9.000 |
Dimensions of A453 Gr 660 Heavy Hex Bolts
| Diameter (D) | Body Diameter (D) | Across Flats (F) | Across Corners (C) | Head Height (H) | Thread Length (T) | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| MAX | MIN | MAX | MIN | MAX | MIN | MAX | MIN | < 6″ | > 6″ | |
| 1/2 | 0.515 | 0.482 | 0.875 | 0.85 | 1.010 | 0.969 | 0.364 | 0.302 | 1.25 | 1.5 |
| 5/8 | 0.642 | 0.605 | 1.062 | 1.031 | 1.227 | 1.175 | 0.444 | 0.378 | 1.5 | 1.75 |
| 3/4 | 0.768 | 0.729 | 1.250 | 1.212 | 1.443 | 1.383 | 0.524 | 0.455 | 1.75 | 2 |
| 1 | 1.022 | 0.976 | 1.625 | 1.575 | 1.876 | 1.796 | 0.700 | 0.591 | 2.25 | 2.5 |
| 1 1/4 | 1.277 | 1.223 | 2.000 | 1.938 | 2.309 | 2.209 | 0.876 | 0.749 | 2.75 | 3 |
| 1 1/2 | 1.531 | 1.470 | 2.375 | 2.300 | 2.742 | 2.622 | 1.036 | 0.902 | 3.25 | 3.5 |
| 2 | 2.039 | 1.964 | 3.125 | 3.025 | 3.608 | 3.449 | 1.388 | 1.175 | 4.25 | 4.5 |
| 2 1/2 | 2.559 | 2.461 | 3.875 | 3.750 | 4.474 | 4.275 | 1.708 | 1.479 | 5.25 | 5.5 |
| 3 | 3.081 | 2.961 | 4.625 | 4.475 | 5.340 | 5.102 | 2.060 | 1.815 | 6.25 | 6.5 |
ASTM A453 Gr 660 Socket Head Cap Screw Dimensions Chart
| Nominal / Basic | Body D max | Body D min | Head A max | Head A min | Head H max | Head H min | J Hex Socket | T Key Engagement min |
|---|---|---|---|---|---|---|---|---|
| 1/4 | 0.2500 | 0.2435 | 0.375 | 0.365 | 0.250 | 0.244 | 3/16 | 0.120 |
| 5/16 | 0.3125 | 0.3053 | 0.469 | 0.457 | 0.312 | 0.306 | 1/4 | 0.151 |
| 3/8 | 0.3750 | 0.3678 | 0.562 | 0.550 | 0.375 | 0.368 | 5/16 | 0.182 |
| 1/2 | 0.5000 | 0.4919 | 0.750 | 0.735 | 0.500 | 0.492 | 3/8 | 0.245 |
| 5/8 | 0.6250 | 0.6163 | 0.938 | 0.921 | 0.625 | 0.616 | 1/2 | 0.307 |
| 3/4 | 0.7500 | 0.7406 | 1.125 | 1.107 | 0.750 | 0.740 | 5/8 | 0.370 |
| 1 | 1.0000 | 0.9886 | 1.500 | 1.479 | 1.000 | 0.988 | 3/4 | 0.495 |
Contact Jade Alloys today with your requirement for ASTM A453 Gr 660 Bolts — we respond within 24 hours with a best-price quote and EN 10204 Type 3.1 MTC.
ASTM A453 Gr. 660 Bolts Inventory
ASTM A453 Gr. 660 Bolts
ASTM A453 Gr. 660 Stud Bolts
ASTM A453 Gr. 660 Hex Bolts
Applications of ASTM A453 Gr. 660 Fasteners
ASTM A453 Gr 660 bolts are selected for high-temperature environments where standard alloy or stainless steel fasteners fail under creep or stress relaxation. The Alloy A286 base material retains tensile strength in continuous service up to 700°C (1292°F), making it the industry standard for the following applications:
- Power Generation
- Petrochemicals
- Gas Processing
- Heat Exchangers
- Pressure Vessels & Boilers
- Aircraft Exhaust Manifolds
- Jet Engines & Turbocharger Components
- Off-Shore Oil Drilling
- Specialty Chemicals
- Sea Water Equipment
-
- Pharmaceutical Equipment
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Frequently Asked Questions About ASTM A453 Gr. 660 Bolts
What is ASTM A453 GR 660 material?
ASTM A453 Grade 660 is a precipitation-hardened austenitic stainless steel fastener material, also known as Alloy A286 (UNS S66286 / DIN 1.4944). It is age-hardenable and designed for high-temperature, high-pressure service with excellent corrosion resistance, tensile strength, and yield strength — retaining properties at continuous service temperatures up to 700°C.
What is the difference between ASTM A453 GR 660 Class A and Class B Studbolts?
The fundamental distinction is heat treatment. Both Class A and Class B are solution annealed and precipitation hardened. Class B undergoes additional cold working followed by hardening, resulting in higher fatigue resistance and superior resistance to stress corrosion cracking compared to Class A. Class B is preferred for offshore and cyclic-load applications.
What is ASTM A453 GR 660 equivalent to?
ASTM A453 Grade 660 is functionally and chemically equivalent to Alloy A286 and UNS S66286 stainless steel. Other equivalent designations include AISI Grade 660, BS HR 51, DIN 1.4944 (W. Nr. 1.4944), JIS SUS 660, and AMS 5726. All are precipitation-hardened austenitic stainless steels designed for high-temperature service.
What is the maximum service temperature of ASTM A453 Grade 660 bolts?
ASTM A453 Gr 660 bolts (Alloy A286 / UNS S66286) maintain their full mechanical properties in continuous service up to 700°C (1292°F). This high-temperature capability makes them the preferred fastener material for gas turbines, jet engines, pressure vessels, and boiler flanges.
What is the difference between ASTM A453 Gr 660 and ASTM A193 B7 bolts?
ASTM A453 Gr 660 (Alloy A286) is a precipitation-hardened austenitic alloy designed for continuous service above 500°C with superior stress rupture resistance. ASTM A193 B7 is a chromium-molybdenum alloy steel typically used below 450°C. A453 Gr 660 is the correct specification where creep and stress relaxation resistance at elevated temperatures are critical design requirements.
Does ASTM A453 Grade 660 comply with NACE MR0175?
Yes. ASTM A453 Gr 660 Class A, B, and D bolts can be certified to NACE MR0175 / ISO 15156 for sour service, provided hardness does not exceed 35 HRC. Class D is also certified under API 20F qualification requirements (BSL-2 and BSL-3) and NORSOK M630 (MDS S39 Rev.1) for offshore applications.
