Stainless Steel ASTM A 453 Gr.660 Class A Hex Bolts

A453 Gr660 Class A Bolts, Specifications & Dimensions

A453 Gr660 Class A bolts are externally threaded fasteners with an integral head, manufactured per ASME B18.2.1, ISO 4014/4017, and DIN 933/931. TorqBolt produces A453 Gr660 Class A bolts in metric (M6–M100) and imperial (1/4"–4") diameters with custom lengths from 10 mm up to 3000 mm.

Head Styles Available

Thread & Shank

A453 Gr660 Class A 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. Thread fits per ASME B1.1 (Class 2A) or ISO 965 (6g) by default; tighter Class 3A / 4h6h on request.

Mechanical & Certification

A453 Gr660 Class A bolts meet 130 ksi [895 MPa] min tensile, 85 ksi [585 MPa] min yield, 15% min elongation and 24–37 HRC, with tension and hardness testing per ASTM A962 / A370 (F606M full-size testing when SI units are specified). Each lot ships with EN 10204 3.1 (or 3.2) certificates listing chemistry, mechanicals, hardness, and dimensional inspection. NACE MR0175 / ISO 15156 sour-service certification on request; ISO 15156-3 Table A.26 limits UNS S66286 to 35 HRC max in the solution-annealed and aged or double-aged condition.

: specification facts on this page checked against ASTM A453/A453M, DIN 934, ISO 4032, ISO 4033, ASME B18.2.2, ASME B18.2.4.6M, ASME B18.2.3.6M, ISO 4014, ASTM A962/A962M, ISO 15156-3, AMS 5737.

A286, Iron-Nickel-Chromium Superalloy

A-286 (UNS S66286, ASTM A453 Grade 660) is a precipitation-hardened austenitic stainless steel for high-temperature bolting, with expansion coefficients comparable to austenitic stainless steels. Chemistry per ASTM A453 Table 3: 24.0–27.0% Ni, 13.5–16.0% Cr, 1.00–1.50% Mo, 1.90–2.35% Ti, 0.35% Al max, 0.10–0.50% V and 0.001–0.010% B.

ASTM A453 covers it for bolts, screws, nuts and studs for pressure vessel and valve flanges in high-temperature service. Class A is solution treated at 900°C (1650°F) for 2 h min, Class B at 980°C (1800°F) for 1 h min, both liquid quenched, then aged at 720°C (1325°F) for 16 hours and air cooled. Classes A, B and C require 895 MPa min tensile, 585 MPa min yield and 15% min elongation.

A-286 fasteners ship per ASTM A453 grade 660 (classes A/B/C/D) and AMS 5737 with EN 10204 3.1 / 3.2 certification. Classes A, B and C are stress-rupture tested at 650°C (1200°F) when the design temperature is above 427°C (800°F); Class D does not require it and is stamped NR. ISO 15156-3 Table A.26 accepts UNS S66286 for sour service at 35 HRC max in the solution-annealed and aged or solution-annealed and double-aged condition, up to 65°C and 100 kPa H2S partial pressure.

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