TYPE III STRUCTURAL FASTENERSTECHNICAL DATA SHEET

NUCOR FASTENER

Nucor Type III Structural Fasteners are made using a special chemistry, corrosion resistant (weathering) steel. The steel has to meet the chemistry requirements as specified in the applicable ASTM standards such as A325, A490 or A563. Type III fasteners, nuts and washers are commonly used in outdoor structures such as bridges or stadiums, where the steel is exposed to the outdoor environment. When weathering steel is specified, such as ASTM A242, A588, or A709, then Type III Structural Fastener Products are used to complete the connections.

Structural Fasteners meeting the Type III requirements are made from alloy steel containing copper, chromium, and nickel. As the surface of the steel corrodes, instead of forming coarse, flaky rust, the Type III material forms a fine-textured oxide coating that tightly adheres to the base metal. This oxide coating seals the surface of the base metal from further corrosion. The surface appears to be a uniform fine grained, deep brownish-red rust color. The protection of this oxide coating works well in moderate environments such as normal outdoor weather, but, if exposed to more concentrated corrosive conditions, such as heavy industrial fumes, the oxide may not form sufficiently to protect the base metal. The weathering steel should also not be used in applications where the fasteners will be subject to rapidly-flowing water (which might disrupt the oxide layer) or where some discoloration around the fastener (from “bleeding” of the reddish oxide) cannot be tolerated.

Structural Fastener Grades A325 Type III and A490 Type III; A563 Structural Nut Grades C3 and DH3; F436 Washers made from weathering steel; and Twist-off Tension Control F1852 Type III and F2280 Type III Assemblies, all have mechanical properties identical to their corresponding type 1 steel counterparts, however, the grade marking requirements are different to distinguish Type III structural products. On structural fasteners the grade identification (i.e., A325, A325TC, A490 or A490TC) is underlined to identify the fastener as Type III material. DH3 Nuts must have “DH3” on one nut face, and C3 Nuts and F436 Type III Structural Washers must have a “3” stamped on one face.

TDS-003A 2-15-08

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Nucor Type III Structural Fasteners are 100% Made in the U.S.A. from American Steel. Our products are all formed on precision high speed formers, utilizing in-process quality systems with full traceability from raw material to each container of product we ship. Chemical and physical certifications are provided with every shipment. Nucor Fastener is TS16949 and ISO9001 Registered and our laboratory is A2LA Accredited.

Nucor Black Kegs are really “Green”! With an Average Recycled Content of 99%, Nucor Fastener products qualify for “Green Building” applications or LEED® rated projects. Just as you would expect from Nucor, the largest recycler in North America. It’s our Nature!

Nucor Fastener has the equipment, quality, systems, expertise, sources, people and distributor network to supply your Type III Fastener needs!

This Technical Data Sheet is subject to change without prior notification.

ASTM A325-3

head marks

ASTM A490-3 ASTM A563 Gr C3 ASTM A563 Gr DH3

TODAY, THAT LITTLE “n” MEANS BIG THINGS!