System Strength of Synthetic Cord Strap

Important Terms to Know When Working with Synthetic Cord Strap

When trying to determine the proper strength of synthetic cord strap needed in your load plan there are two types of measurements commonly referred to – Break Strength and System Strength – but what do these mean? Below are descriptions of each of these terms and why they are just some of the important terms to know when trying to decide which type of synthetic cord strap you need to secure your cargo.

Break Strength (also referred to as Tensile Strength):  The Break Strength of synthetic cord strap is the amount of force (commonly measured in pounds or dekanewtons) that a piece of strap can withstand before breaking and/or splitting. The Break Strength of strap is used to determine the strength of the synthetic cord strap alone, without the addition of a buckle (i.e. Joint Efficiency).

Joint Efficiency: Joint Efficiency is a percentage of the strap strength with the incorporation of a wire buckle or ladder buckle. The Joint Efficiency is critical when trying to calculate the System Strength.

System Strength: System Strength is the force (commonly measured in pounds or dekanewtons) required to break a unit of strap. This consists of one loop of strap and one buckle used to connect the ends of the strap, forming a “belt loop”. The System Strength can be found by multiplying two times the Break Strength of the strap by the Joint Efficiency of the buckle (Ex. System Strength = (Break Strength x 2) x Joint Efficiency).

Below is a diagram of the different types of measurements being tested.

When trying to obtain the proper System Strength of your strap, it is important that the same strap and compliant buckle combo are being used that was originally tested to achieve the AAR approval. Using an unapproved strap and buckle combination can lead to a different System Strength and cause your load to be non-compliant. The approved strap and their corresponding buckle can be found on the AAR’s website in Table 19.2 of the AAR’s Open Top Loading Rules. The list of AAR approved strap for doorway protection can be found in the AAR’s publication “Nonmetallic Strap Substitution for Steel Strap as Doorway Protection in Boxcars”.

Please note, not all the factors that need to be considered when choosing a strap for your load plan were mentioned in this blog. Understanding Break Strength, Joint Efficiency and System Strength will provide you with a good start on your search for your cargo strap. For more information about the strength of synthetic cord strapping and the corresponding buckles, speak to one of our knowledgeable technical sales and services representatives by calling us toll free at 866-858-8800.

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