Burst Strength: Definition, Testing, Application, and Types

Burst strength is a measure of how well a material can resist pressure. It helps manufacturers ensure that their products can withstand the rigors of use, transportation, and storage. It is a vital metric in ensuring the durability and safety of a product or material.

In this article, we look at burst strength and discuss what it is, why it’s important, and how to measure it.

What Is Burst Strength?

Burst strength is a measure of how resistant materials are to bursting. It describes the amount of pressure that packaging can withstand before it ruptures. It is an important metric for understanding the strength and durability of packaging materials, pipelines, and other products that are subject to internal pressures. Burst strength testing is applied to a wide range of materials, such as paper, plastics, metals, textiles, leathers, foil, and cardboard.

How Does Burst Strength Work?

Burst strength is a direct measure of how resistant a material is to tearing or bursting. It is tested by applying hydrostatic pressure to a material until it bursts. Burst strength is determined by a variety of factors, including: material composition, thickness and density of the material, and the manufacturing process used to produce the material.

How Different Is Burst Strength Test From Other Strength Testing?

Burst strength testing measures the pressure required to rupture material under pressure. It is relevant to materials such as: paper, cardboard, metals, and textiles. Burst strength testing produces biaxial stress on the sample piece.

Tensile strength testing measures the amount of stress a material can withstand before breaking while being stretched. It is relevant to any materials that are subject to tensile forces. In tensile strength testing, the stress produced is uniaxial.

Meanwhile, compression strength testing evaluates how well a material can withstand loads that compress the material. This is relevant to any products that are subjected to compressions, such as corrugated boxes which are stacked on top of each other, or metals used for structural purposes.

Tear testing evaluates how well a material can resist failure perpendicular to the direction of an applied stress. Here the stress applied is biaxial.

What Applications Need Burst Strength?

The following types of applications require burst strength testing:

1. Packaging Materials: The packaging industry uses burst strength testing to determine how well their materials can handle pressure before rupturing. It is a crucial metric for them to understand, to ensure their products remain intact during use.
2. Paper: Paper product manufacturers use burst strength testing as a quality control measure. It is used to assess the durability and strength of paper products.
3. Textiles: The textile industry uses burst strength testing to evaluate the durability of fabrics. Manufacturers need to understand how well products like jeans, clothes, and upholstery can withstand bursting pressures.
4. Medical Packaging: The integrity of the packaging of medical devices and products is critical. It ensures that these products remain sterile and safe to use. Burst strength testing is a vital measure for manufacturers to ensure that medical packaging maintains its integrity.

How Is Burst Strength Measured?

Burst strength is measured using a hydraulic burst strength tester. A sample is first prepared by cutting a circular piece of the material to be tested. The sample is then placed on the rubber diaphragm of the burst strength tester. After this, pressure is gradually applied until the sample bursts. The pressure at which the sample bursts is the burst strength of the material.

To learn more, see our full guide on Tear Strength.

What Are the Requirements of Burst Strength Testing?

Valid and repeatable burst strength testing has the following requirements:

1. Equipment: A burst strength tester is required.
2. Technical Expertise: Testing operators must have adequate training and knowledge of testing standards and equipment.
3. Calibration: The equipment used in burst strength testing needs to be calibrated correctly to ensure accurate readings.
4. Standards Compliance: The equipment and methodology of the burst strength testing must adhere to the relevant standards.
5. Environmental Condition: The testing environment must be controlled. Temperature and humidity can have a significant effect on the burst strength of materials like paper.

What Types of Products Require Burst Strength Testing?

Burst testing is commonly performed on the following products:

1. Paper and Cardboard: Paper, paperboard, and cardboard are often used as packaging materials. They undergo burst strength testing to measure the amount of pressure they can withstand during transportation, use, and storage. By measuring the burst strength, manufacturers can ensure that the packaged product has adequate protection. Packaging manufacturers can also ensure that their products meet industry standards.
2. Textiles: The burst strength of fabrics is often tested to assess their resistance to pressure. This is especially useful for fabrics such as clothing or furniture upholstery.
3. Plastics: Plastic films, bottles, and containers usually undergo burst strength testing to understand the maximum pressures they can withstand. Measuring their burst strength helps manufacturers understand the durability and limitations of their products.
4. Pipes: Metal and plastic pipes undergo a special type of burst test, where internal pressure is increased until the sample ruptures or leaks. This test is crucial for oil and gas pipelines, and the chemical industry.

What Standards Govern Burst Strength Testing?

There are numerous international standards governing burst strength testing. These standards describe how the burst strength for various materials should be measured. Some of these standards include:

1. ISO 2758:2014: Describes the method of measuring the burst strength of paper.
2. ISO 13938-1:2019: Describes how to measure the bursting strength, of certain fabrics using hydraulic pressure
3. ISO 13938-2:2019: Describes how to measure the bursting strength of certain fabrics using pneumatic pressure.
4. ISO 2759:2014: Describes a method of determining the bursting strength of paperboards, including corrugated cardboard.
5. ASTM F2054: Describes a testing method to measure the burst strength of flexible packaging seals.
6. ASTM F1140: Describes methods for testing packaging material’s resistance to pressure, including a burst strength test.
7. ASTM D3786: Describes a testing standard for measuring the bursting strength of textiles.

To learn more, see our guide on What is ASTM.

What Are the Benefits of Burst Strength Testing?

Some benefits of burst strength testing are:

1. Quality Control: Burst strength testing helps ensure that materials are up to the required standards. It can be an effective way of picking up defective materials that would otherwise have failed in the field.
2. Product Safety: By testing the burst strength of materials, manufacturers can ensure that they will withstand the rigors of transportation, use, or storage. They can also ensure that the product is not exposed to pressures in service that exceed the design limits.
3. Regulatory Compliance: Certain industries have regulations that specify minimum burst strength requirements. Burst strength testing helps ensure compliance with these regulations.
4. Cost Savings: By verifying that a product meets its design specifications for maximum pressure, manufacturers can ensure that products do not fail after production. Sudden failures in the field would lead to costs associated with warranty and reputation damage. Materials can also be optimized to reduce excess material use, further reducing costs.
5. Material Selection: Burst strength testing helps in the material selection process. By measuring the burst strength, manufacturers can ensure that materials are optimized for the requirements.

What Are the Challenges of Burst Strength Testing?

Some challenges of burst strength testing include:

1. Equipment Calibration: Burst strength testing equipment needs to be regularly calibrated and maintained to ensure accurate measurements. This can be complex and costly.
2. Costs: Both the test equipment and maintenance of equipment can be prohibitively expensive for smaller companies.
3. Technical Expertise: Burst strength testing requires a certain level of technical expertise to perform correctly. This results in extra training requirements for staff who perform the testing.
4. Sample Preparation: Samples need to be prepared consistently to ensure accurate results.

What Machine Is Used for Burst Strength Testing?

A burst strength tester is used to perform burst strength tests. These machines are widely available and contain everything needed to perform burst strength tests, although they can be prohibitively expensive for small companies, and require a certain level of expertise to achieve accurate results. Burst strength testers typically consist of the following components:

1. Sample Holder: This is where the material sample is placed. It usually has clamps to hold the sample in place.
2. Plunger: The plunger is used to apply force to the sample. Some models of testers use a diaphragm.
3. Pressure Indicator: This shows the pressure exerted on the sample. This may be analog or digital and may be shown on a computer screen in the form of a graph.
4. Controls: These are the buttons and knobs used to control the process. Some testers are fully automated, requiring minimal controls.
5. Hydraulic or Pneumatic System: These systems provide the pressure used to apply force to the material during the burst strength test.

Do All Manufacturing Companies Perform Burst Strength Testing?

Burst strength testing is not done in all manufacturing companies. However, burst strength testing provides a crucial metric for manufacturers that they can use to assess the pressure resistance of their packaging or other materials.

How Is Mullen Burst Strength Testing Different?

Mullen burst strength testing is another term for burst testing. It refers to the specific testing methodology of measuring the amount of hydraulic pressure required to burst a material sample. 

What Is the Difference Between Bursting Strength and Bursting Factor?

The bursting strength and bursting factor are two key measures in determining the strength and durability of packaging materials. While they seem similar, the difference between the two provides two distinct measures that manufacturers can use to evaluate their material.

The bursting strength of a material is the maximum amount of pressure that a material can handle before tearing or bursting. It is a measure of how resistant the material is to tearing. Bursting strength is typically measured in pounds per square inch.

The bursting factor is the bursting strength of a material divided by the weight of the tested sample. It gives a measure of how strong the material is relative to its weight. It is used to give a deeper understanding of the strength of the material beyond the pure strength of the tested sample.

Summary

This article presented burst strength, explained it, and discussed how it's tested and its various types. To learn more about burst strength, contact a Xometry representative.

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