ANSI B18.5 Round Bolt

This Standard covers the complete general and dimensional data for the various types of inch series bolts generally classified as round head bolts and recognized as an American National Standard.

The key types of bolts covered include:

Leader-Fastener® ANSI B18.5 Round Bolts are frequently used in rail, heavy equipment, and agricultural applications.  The bolts have a low profile head that does not interfere with many applications where a dramatic protrusion from a hex head or other style would.  There are a variety of styles that include underhead features to hold the bolt in place while a nut is being tightened.

Step bolts are of similar design to a round head, square-necked bolt but with a much larger head size.

Elevator bolts are of similar design to the round head bolts but with a comparatively flat head frequently used in agricultural applications such as grain and other such elevators

ASME B18.5-2012 requires the use of additional standards–published by ASTM, ASME, IFI, and SAE -- in reference to thread dimensions, materials, mechanical properties, and finishes.

Leader-Fastener® ANSI/ASME B 18.5 - 2012 Round head bolts,(Inch Series) [Table1] (A307, SAE J429, F468, F593)

Minimum Thread Length:

The minimum length of thread shall be equal to twice the basic bolt diameter plus 0.25 in. for nominal bolt lengths of 6 in. or shorter, and twice the basic bolt diameter plus 0.50 in. for longer nominal lengths.

Bolts of nominal lengths too short to accommodate the minimum thread lengths shall be threaded full length. The length from the head or neck to the first complete (full form) thread shall not exceed the length of 2-1/2 threads for sizes up to and including 1 in., and 3-1/2 threads for sizes over 1 in.