Chain Breaking Strength

When it comes to ratchet straps winch straps and just about any other type of strap in the cargo industry the words working load limit wll and breaking or break strength are commonly seen.

Chain breaking strength.

It is unclear why the wll definition is different for grade 40 chain. The most common measure of roller chain s strength is tensile strength. Chain grades are determined by calculating newtons per square millimeter using the formula n mm 2. Chain is graded based on the ultimate breaking strength of the chain measured in n mm 2 the american society of testing materials astm has published safety standards and regulations for these chain grades.

Chain grades are a standard method for showing the ultimate breaking strength tensile strength of a chain. What is break strength vs. Chain grades what does g30 g43 g70 g80 g100 and g120 mean. Chain is embossed with both the grade and size so you can determine.

The wll is a quarter or a fifth of the chain s breaking strength. The critical factors in a chain s fatigue strength is the quality of steel used to. The higher the grade the greater the break strength. This number is what we see today g30 g43 g70 g80 g100 and the common chain grades.

Chains must be inspected regularly to make sure it is safe to use. One of the safety measures implemented was to place chain in grades based on the ultimate breaking strength of that chain. Lower chain grades g30 and g43. The wll of a chain is determined by both the grade and the diameter.

Just as important as tensile strength is a chain s fatigue strength. Grade 43 aka grade 40 has higher tensile strength and abrasion resistance and comes with a higher price tag. The wll is different from the tensile or breaking strength. See chart for astm specification number.

How to determine a chain s working load limit. The wll wroking load for chain is usually defined of the ubs ultimate breaking strength expressed in pounds for all chain types except g4 grade 40 htchain has the wll defined as 1 3 of the ubs. Chains have a working load limit or wll of approximately one third of their break strengths the amount of force the chains can withstand before they break. Grade 30 aka proof coil has less carbon and is good service duty chain.

Chain manufacturers set the wll to determine the maximum force that can be used on the product. With galvanized chain it basically boils down to how much carbon is in the steel. Grades help determine what sort of applications are appropriate for a given chain. Tensile strength represents how much load a chain can withstand under a one time load before breaking.

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