Hex Bolt

ASTM A320 L7 Stud Bolts are designed for low temperature performance. These fasteners are commonly used in valves, flanges, fittings and pressure vessels. The ASTM specification recommends a minimum impact value of 20-ft-lbf -150F for ASTM A320 L7 studs.

The A320 Gr L7 stud material will undergo the following parametric tests – Impact Test, Tensile Test and Hardness Test according to the mechanical specification of A320 Grade L7 Bolts. The specification of A320 Gr L7 Hdg covers several grades of stainless steel including austenitic and ferritic stainless steels.

ASTM A193 Grade B7 specification covers the requirements for high strength alloy steel bolting materials for high temperature or high pressure service and other special purpose applications. It is a standard specification that defines typical chemical composition, mechanical properties, hardness requirements, preferential heat treatment, product marking, certification, and other requirements for bolted connections used in pressure vessel service, valves, flanges, and fittings. ASTM A193 defines SI (metric) and inch-pound units.

Grade B7 is a heat treated chromium molybdenum low alloy steel with a minimum tensile strength requirement of 125 ksi (860 Mpa), a yield strength of 105 ksi (720 Mpa) and a maximum hardness of 35HRC. Boltport produces B7 headed and headless bolts from alloy steel AISI 4140 bar stock or forgings. A193 Grade B7 is the most commonly used bolting size, plus A194 Grade 2H nuts are used for bolting carbon steel pipe. A193 B7 bolts are available in metric sizes from M6 to M180 and imperial sizes from 1/4 to 7 inches in diameter.

ASTM A193 Grade B8M Grade 1 Fasteners are similar to Grade B8 but are made of AISI 316 stainless steel instead of AISI 304 stainless steel. Type 316 stainless steel has better corrosion resistance than type 304 stainless steel due to the addition of molybdenum.

B8M Grade 1 fasteners require carbide solution treatment, while Grade 2 fasteners require additional strain hardening operations to increase strength and reduce susceptibility to wear.

ASTM A194 specification covers carbon, alloy and stainless steel nuts for high pressure and/or high temperature service. American National Standard Heavy Duty Hex Series (ANSI B 18.2.2) shall be used unless otherwise specified. Nuts no more than 1 inch in nominal size shall conform to UNC Series Class 2B.