ISO 7458 Glass Containers - Internal Pressure Resistance - Test Methods

The ISO 7458 Glassware - Internal pressure resistance - Test methods standard, published by the International Organization for Standardization (ISO), describes two test methods used to determine the internal pressure resistance of glassware:

• Method A is performed by applying uniform internal pressure for a predetermined period of time.
• Method B is performed by applying increasing internal pressure at a predetermined constant rate.

The test is performed on a predetermined number of vessels. The vessels used in the test must not have been subjected to any other mechanical or thermal tests that could affect their internal pressure resistance.

When applying Method A, a consistent internal pressure is applied for a specific period of time. The device must comply with the following principles:

• The container to be tested should be held so that it hangs from its opening.
• A flexible seal must be present between the sealing surface and the pressure head to retain the pressurized medium during testing.
• A method must be found for applying a specific level of fluid pressure and maintaining that pressure constant throughout the test.

The containers are first filled with water. Ideally, the temperature difference between the container and the water should be within plus or minus 5 degrees Celsius to avoid applying extra stress to the container before testing.

Depending on the purpose of the test, one of the following test procedures is used:

• Pass-through test: The internal test pressure is applied to a predetermined level and held constant for 60 seconds plus/minus 2 seconds, or for a different duration provided the device has the capability to correct the pressure readings to those obtained for a 60-second test.
• Progressive testing: The test described above is continued by increasing the pressure in specified increments until 50% or 100% of the containers break.

When applying Method B, internal pressure is increased at a predetermined constant rate. The test device must conform to the following principles:

• The container to be tested should be held so that it hangs from its opening.
• A flexible seal must be present between the sealing surface and the pressure head to retain the pressurized medium during testing.
• A method must be found to apply increasing fluid pressure until the vessel fails or a predetermined level is reached.
• The device must include a method for indicating the pressure level at which the vessel failed or the maximum pressure reached during the test.
• The device should include a mechanism that shows the relationship between constant speed testing and constant duration testing.

First, the containers are filled with water. Ideally, the temperature difference between the container and the water should be within plus or minus 5 degrees Celsius to avoid applying extra stress to the container before testing.

Depending on the purpose of the test, one of the following test procedures is used:

• Pass-through test: The internal test pressure is increased by a specified rate until a predetermined pressure level is reached.
• Breakage test: The internal test pressure is increased at a specified rate until each vessel breaks.

In short, the ISO 7458 standard outlines procedures for determining the ability of glass containers to withstand internal pressure. This standard is widely used in the packaging industry, particularly for bottles and containers designed for carbonated beverages, sparkling wines, beer, and other pressurized products. It helps manufacturers ensure that glass containers are safe, reliable, and able to withstand the pressures encountered during filling, storage, transport, and consumer use.

The ISO 7458 standard, which defines methods for evaluating the internal pressure resistance of glass containers, is applicable to various glass packaging products and provides consistent procedures for quality control and product development.

The main objectives of the ISO 7458 standard are:

• To verify the durability of glass containers under pressure.
• To reduce the risk of bottle breakage during serving.
• To increase consumer safety.
• To support quality assurance programs in glass production.
• To provide a standardized testing method for international trade and product comparison.

Test method A simulates real-world conditions where containers are subjected to continuous pressure. It determines whether a container can withstand a specific pressure level without failure. This method is commonly used for routine quality control. Typical applications include:

• Carbonated beverage bottles.
• Beer bottles.
• Carbonated beverage containers.

Test method B measures the maximum pressure resistance of the container. It provides information about the safety margin of the design. It is useful during product development and container optimization. Typical applications include:

• Design validation.
• Comparative evaluation of glass container performance.
• Research and development projects.

Testing according to the ISO 7458 standard typically requires the following equipment:

• A calibrated pressure generation system.
• Pressure measuring devices.
• Safety shields to protect operators.
• Fixtures for securely positioning glass containers.

The equipment must be able to apply pressure accurately and consistently throughout the test.

The ISO 7458 standard is commonly used in the following areas:

• Glass container manufacturing.
• Beverage packaging.
• Food packaging.
• Beer industry.
• Production of carbonated beverages.
• Quality assurance laboratories.

Organizations that implement the ISO 7458 standard gain several advantages:

• Enhanced safety: Helps prevent hazardous glass failures during testing, filling, handling, and consumer use.
• Improved product quality: Manufacturers can identify defective containers before they reach the market.
• International recognition: ISO standards are globally recognized and facilitate international trade and supplier competence.
• Cost reduction: Early detection of manufacturing defects minimizes product recalls, waste, and customer complaints.
• Improved process control: Routine pressure testing provides valuable feedback for optimizing the production process.

Internal pressure resistance is one of the most critical performance characteristics of glass beverage containers. Factors affecting performance include:

• Glass composition.
• Wall thickness distribution.
• Production quality.
• Surface defects.
• Bottle design geometry.

The ISO 7458 standard provides a consistent framework for evaluating these factors and ensuring container reliability.

In conclusion, the ISO 7458 standard is a fundamental standard for evaluating the internal pressure resistance of glass containers. By defining fracture test methods under both constant pressure and pressure, it enables manufacturers to assess the durability of containers, enhance safety, and maintain consistent product quality. This standard plays a crucial role in the beverage and packaging industries, where glass containers must reliably withstand internal pressures throughout their lifespan.

For many years, our organization, with its competent and experienced staff, has been understanding the needs of its clients, providing the advanced testing services they require, and assisting them in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services compliant with the ISO 7458 standard.