What is Burst Strength?

Learn the facts on burst strength and the importance of your cold chain packaging

Burst strength is the strength of material in pounds per square inch. Burst strength can be used to monitor the quality of cold chain packaging.

Often called the Mullen Burst Test, burst strength is an industry standard that measures the amount of force required to burst corrugated boxes and flexible packaging.

This test is typically used to understand how much force the corrugated or flexible packaging can manage during shipping, delivery, and handling and how much weight these packages can hold.

Your thermal packaging has an important role in maintaining the integrity, quality, and safety of your cold chain products. Tests including the burst strength test, edge crush test (ECT), and others are used to determine which packaging and corrugated materials are right for your cold supply chain.

Just as your products are unique, your cold supply chain is unique. How your cold chain products are manufactured, stored, packaged, shipped, delivered, and displayed determines what you need your thermal packaging to withstand.

For example, if your corrugated boxes are exposed to a lot of rough handling, you need to be confident that these boxes can stand up to drops, pressure, and other environmental and human impacts of shipping, transit, and delivery.

How is Burst Strength Measured?

Burst strength is measured in kilograms per square centimeter. The burst factor of a corrugated or flexible package is calculated using the burst strength and the grammage (density) of the packaging material.

Burst factor = Burst Strength (kg/cm2) x 1000/Grammage (gm/m2)

To measure this, the package is expanded, using a rubber diaphragm or other method until the package or its seals burst.

How to Test Cold Chain Packaging

To test cold chain packaging, packaging engineers and manufacturers may use one or more of the following packaging tests:

• Burst Strength Test or Mullen Burst Strength Test: the package is expanded until the package, or its seals burst. This test is useful in determining how well the package can sustain pressure during storage, transit, or delivery.

• Edge Crush Test (ECT): used to measure the strength of corrugated boxes when stacked. This is particularly useful when choosing packaging that is stacked and shipped on pallets.

• Drop Test: measures the impact strength of cold chain packaging when dropped from a variety of heights. It’s important to know this when thinking about the conditions your cold chain products endure throughout the cold supply chain.

• Seal Tests: several different testing methods are used to measure the strength, quality, flexibility, and integrity of packaging seals. For example, measuring the strength of the adhesive bonds in the package or the tear resistance of the package.

The type of packaging test data you need to know is based on your cold chain products. For example, if you specialize in food products such as milk and milk alternatives, you should know the amount of force needed to open bottles, jars, or closures. Or if you specialize in pharmaceutical products, you need to know the burst strength of packaging for any gels, liquids, or creams...

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