Bolt design tips
According to International Standard ISO4347 any anchor bolt (also known as a clevis) must be at least as strong as the chain to which it is fitted in its ultimate tensile strength. Any additional safety factor applying to the chain will, therefore, also apply to the bolt. These safety factors vary according to application.
When designing a leaf chain anchor bolt (clevis) it is vital to select the appropriate steels for the particular application. The bolt must achieve the breaking strength required and in some cases it may need to be welded (only certain materials can be welded).
The application must be carefully analysed to determine the types of stresses that the anchor bolt will need to withstand. Most normal applications are simple to review but occasionally unusual stresses such as tension, compression, shear and bending affect the clevis in use.
Anchor bolts should ideally be designed so that the chain pull passes directly through the axial centre line of the bolt. This is to avoid any problems with bending or shearing stresses in the threaded portion of the bolt as these will eventually lead to fatigue.
In terms of the dimensions, certain areas of the bolt require specific calculation to determine adequate strength of the anchor, namely the root diameter of the thread and the tensile and shear areas in the vicinity of the anchor pin.
The slot dimensions are given in the International Standard ISO4347 and ensure complete interchangeability with the leaf chain.
For some applications leaf chain anchor bolts will need to be corrosion-resistant. However, some surface treatments can lead to hydrogen embrittlement which will weaken the anchor bolt. To ensure the correct surface treatment for your application please speak to one of our specialist advisors, who can recommend a different solution with optimal outcome.