ASTM C147 Standard Test Methods for Internal Pressure Strength of Glass Containers

Get Certified ASTM C147 Testing for Reliable Glass Container Pressure Safety 

Glass containers used for carbonated drinks, medicines, and other products that are processed at high pressures and then expand in pressure must not split. ASTM C147 testing verifies that a glass container design has the internal container pressure necessary to safely package products. Accredited laboratory testing helps to verify packaging design, qualify suppliers, and implement quality control programs for glass container manufacturers. Testing to the ASTM C147 certification provides manufacturers with an extra layer of security that their container won’t break during filling, storage, or use by consumers to ensure a safe and intact product. 

• Material type: Products that undergo a reaction that creates pressure within the material, in glass containers, such as bottles or jars. 
• Purpose: Selection of breaking strength of glass containers, generation of application data, and quality control.
• Properties evaluated: Breaking strength when subjected to internal pressure, in kPa (psi). 
• Testing Method: Test Method A, constant internal pressure applied for a specific period of time, or Test Method B, increase of internal pressure at a specified constant rate.
• Result: the pressure at which containers break or the percentage of containers that pass a specified pressure. 
• Test Limitations: These test methods apply to containers that are expected to withstand a sustained pressure of 138kPa (20psi) or higher after processing.
• Environmental conditions: The measured strength of the internal pressure is influenced by environmental conditions, such as the pressurizing medium, rate of pressure increase, and container fill condition. 
• Applications: Qualification for carbonated beverage bottles, design of pharmaceutical containers, cosmetics packaging, and quality control for glass containers. 

What are the Uses of ASTM C147 Testing?

Manufacturers and quality control laboratories use ASTM C147 testing to test the ability of a glass container to endure a sustained internal pressure. Makers of packaging machinery apply the results to the choice of suitable packaging container designs and to guarantee packaging production quality. This standard- 

• Establishes the strength of glass containers against internal pressure.
• Supports passing tests for routine quality control of production line samples.
• Allows progressive testing to a specified percentage of breakage to compare designs.
• Complies with total progressive testing to obtain the final failure pressure of the container.
• Helps the selection of containers for products that are likely to generate their own pressure.
• Generates design information for the development of new glass containers. 

What Materials Can Be Tested Under ASTM C147? 

ASTM C147 is applicable to glass containers such as bottles and jars that are produced for use to hold a product that is reasonably anticipated to exert a sustained pressure of 138 kPa (20 psi) or higher after processing. The test method is appropriate for containers for carbonated beverage, pharmaceutical, and cosmetic packaging applications. An analyst first verifies the service pressure of a container and the type of test (A or B) for the test program before starting a test program.

Why is ASTM C147 Important? 

ASTM C147 is a standard practice that measures the capacity of a glass container design to withstand continuous or increasing internal pressure. Pressure testing prevents expensive breakage during filling, storage, transport, and consumer use—the way consumption containers such as carbonated beverages, pressurized pharmaceuticals, and other products are routinely used in service. This test method is useful in the selection of containers, the development of container design data, and quality control for the development of safe containers. Manufacturers use this standard to compare container design, qualify their suppliers, and ensure their packages perform reliably in response to the internal pressures generated by their product. 

ASTM C147 Testing Process and Data Collection

The testing process starts by filling each glass container with a low-density liquid, e.g., water, as a medium to apply the internal pressure. In Test Method A, either a standard pressure is applied for a set amount of time in a pass test, or a standard pressure is applied incrementally until a specified percentage of containers fail, or the container is incrementally tested until all containers fail – this is called a total progressive test. For Test Method B, the internal pressure is applied at a desired rate of increase until the container explodes. Each container is monitored for failure, and the pressure at which failure takes place is documented. This data is gathered throughout the aforementioned test procedure to aid in the selection of a container, generation of design data, and quality control.

Common Challenges and Troubleshooting

Common issues associated with ASTM C147 testing are inconsistent pressure application rate, incomplete filling of the container, and pressure gauge calibration drift. Such problems may result in misleading breaking strength data and yield incompatible pass or fail results for multiple test runs. Any variation in the rate of increase of pressure during Test Method B moves the failure pressure from the desired test condition. If the container is not filled with the pressurizing liquid, it traps air, which interferes with pressure transmission and measured results. If the pressure gauge or transducer is not calibrated, it results in systematic error. These problems can be minimized by using the correct filling method, proper application of pressure, and by using calibrated pressure-measuring equipment. By using routine processes and keeping instrumentation calibrated, experienced technicians obtain reliable results. 

• The laboratory reports the pressure at which each container ruptures, or the percentage of containers that do not burst under the pressure being tested.
• The analyst writes down the experiment type (A or B) and pass test, progressive test, or total progressive test.
• The laboratory records information about the pressurizing medium and the rate at which pressure is applied to the material during testing. Results show if the container is suitable for products that are likely to generate the tested internal pressure.
• The laboratory reports the results as failure pressure or percentage breakage; it does not report an overall performance number.
• Laboratories achieve consistent and repeatable results from different container designs through consistent filling and applying pressure. A comparison of container design and qualification of suppliers is supported by results of internal pressure strength. 

Link to ASTM C147