Full Thread Studs (Studbolts) · ASTM A453 / ASME SA-453

A453 660 (A-286) Stud Bolts

A-286 bolting for the hottest joints — 130 ksi at room temperature and rated by stress-rupture at 1200 °F, for gas and steam turbines, exhaust and high-temperature process equipment.

Threaded rod inserted through the holes of mating flanges, paired with heavy hex nuts. Available in every diameter and length, imperial and metric, for flanged connections in critical service. Supplied bare or coated, with full material traceability.

ASTM A453 Grade 660 covers bolting in A-286, an iron-nickel-chromium superalloy strengthened by titanium and aluminum precipitates. Unlike the A193 grades it is qualified by room-temperature tensile properties and, for design temperatures above 800 °F, by a stress-rupture test at 1200 °F, because its purpose is to hold clamp load at temperatures where B16 and the austenitic stainless grades have already relaxed.

A453 660 (A-286) Stud Bolts at a glance

Material specificationASTM A453 / ASME SA-453

UNSS66286

Tensile, Classes A–D (≤2½ in.)130 ksi min (Class D over 2½ in.: 120)

Yield, Classes A–C / D85 / 105 ksi min (≤2½ in.)

Hardness24–37 HRC (A, B, C) · 24–35 HRC (D)

Stress rupture (A, B, C)56 ksi at 1200 °F, 100 h min

Typical serviceUp to 1300 °F

Size rangeImperial 1/4" – 4" diameter · Metric M6 – M100 · lengths to customer requirement

Thread formsUNC · 8UN · UNF · Metric coarse & fine

FinishesPTFE coated (blue / green), zinc plated, hot-dip galvanized, plain

CertificationEN 10204 3.1 material test report with every lot, traceable to the heat

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Mechanical properties

What A453 660 (A-286) must meet.

Mechanical properties at room temperature — ASTM A453 Grade 660

Class and size	Tensile strength, min (ksi)	Yield strength 0.2% offset, min (ksi)	Elongation in 4D, min (%)	Reduction of area, min (%)	Hardness
Class A — all sizes	130	85	15	18	248–341 HBW / 24–37 HRC
Class B — all sizes	130	85	15	18	248–341 HBW / 24–37 HRC
Class C — all sizes	130	85	15	18	248–341 HBW / 24–37 HRC
Class D — 2½ and under	130	105	15	18	248–321 HBW / 24–35 HRC
Class D — over 2½	120	95	15	18	248–321 HBW / 24–35 HRC

Values per ASTM A453/A453M-17 (verified against the specification). Confirm the edition called out on your purchase order with our estimating team.

Heat treatment

Solution treated and precipitation hardened per the class ordered (see table). Hardness is checked after aging; stress-rupture specimens are tested per heat-treat lot.

Full A453 660 data sheet: chemistry, physical properties and standards →

Dimensions & standards