Heavy-Duty Hard Rigging

Our conversation about rigging and Working Load Limits starts with hard rigging. Hard rigging typically has a design factor of 4:1, meaning hard rigging can be used at 1/4 of its breaking strength. 

Generally shackles with synthetic components have a design factor of 5:1. Let’s take an example of hard rigging such as the 3/8 grade 8 chain. It has a Working Load Limit of 7,100 lbs. To identify the theoretical breaking strength of that 3/8 grade 100 chain, you would multiply it’s Working Load Limit by 4. So the breaking strength of a 3/8 grade 100 chain is going to be 28,400 lbs. 

Synthetic rigging generally carries a Working Load Limit based upon a design factor of 5:1. That theoretical reserve of 5:1 means that the working load limit is 1/5 of the breaking strength of that piece of synthetic rigging. 

Wire rope on the other hand, has many different design factors and those design factors are based upon the industry using it. In the towing and recovery industry, the design factor of wire rope is generally at a 3.55:1 design factor at WrackMaster, we choose to observe a design factor of 4:1 for wire rope.