Bolt Threads

In North America there is the Unified Screw Thread, which come in both fine and coarse – the thread is measured in TPI (Threads per Inch) For metric bolts there is the ISO Metric Screw Thread, which also comes in both fine and coarse – the thread is measured according to its Pitch which is the spacing …

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Bolts – Preferred Lengths

Bolt lengths come in preferred sizes which generally are in regular production – these are indicated in the table below as X – while those denoted (X) refer to bolts which are available, but not considered to be in regular production. Availability of these bolts should be confirmed by the supplier. Bolt diameters have been …

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Introduction to Bolts

Just about every steel structure today will use bolts as the primary means of connecting the various parts together. For the uninitiated, the appropriate selection of suitable bolts can be somewhat intimidating – There are literally hundreds of possible bolt and nut combinations – not to mention, standards, material types, grades, classes etc. – add …

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Determine the Bolt Length

A structural bolt typically has a partial thread, the unthreaded portion is the shank, which when added to the thread length gives the overall bolt length. The thread length is a function of the bolt diameter and length, which for the most part is standardized across the range of bolts – but it’s always wise …

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Strength of Bolts

Bolt Standards In North America bolts are classified according to ASTM standards (American Society for the Testing of Materials) while in Europe, they are classified according to national standards of the individual states. Each state has its own national standards institute BSI, DIN, AFNOR, etc. with each operating independently. To establish common standards within the …

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Standard Bolt / Hole Diameters

Bolt Diameters In practice, the vast majority of bolts used for load bearing connections will be between M16 (5/8”) and M24 (1”). Anything less than M16 is unlikely to be certified and should be avoided. Greater than M24 would be used only in the most exceptional circumstances. The table below will provide some idea of …

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