Tightening Procedure High strength structural bolts

Setup and installation of high-strength bolts tightening / nut, at least as expensive as the structural assembly of the bolt / nut itself, and the choice of nuts and bolts procedure is an important factor in the high-strength bolted structure of the economy.

Snug tightening
 Snug tight is defined in AS 4100, as the full force of a person with a key Podger standard, or where there is a change in recording speed, or when the key is the impact of solid pneumatic impact. Podger keys are evaluated with respect to the length of the bolt size and strength, and, for example, the order of 450 mm for M20 high strength structural bolts, and 600 mm for the M24 high strength structural bolts.Snug tightening in the following cases:

1. The final level of a structural tightening of the bolts in the general run of commercial bolts - category 4.6 / S. 
2. A final level of tightening bolts high strength structural bolts - category 8.8 / S. The values ​​of the different structures than the procedure should be applied 8.8/TB 8.8/TF and bolts, as described on page 52. 
3. mid-level gate voltage is applied as a first step in the process of tightening a full - Category 8.8/TF and 8.8/TB.

The growing popularity of high-strength structural bolts as a 1252 convenient to use in tough conditions leads to a situation in which the bolt may require full tightening with AS 4100 in one easy application, and only tightening in other countries. To avoid confusion and ensure the correct tightening the designer must clearly indicate the level of torque is required, as the drawings and specifications. Steps should be taken so that this information has been communicated to all concerned in the installation, tightening and inspection.