The Critical Role of Rupture Discs in Extrusion 

A rupture disc, also called a burst plug, pressure plug or other similar names, is a safety device designed to prevent overpressure conditions in pressure-containing systems such as vessels and pipes, extruders and injection molding machines.  

Made from thin metallic material, the disc is engineered to burst at a predetermined pressure level, allowing the excess pressure to escape and protect the equipment from damage. Unlike pressure relief valves, rupture discs are single-use, low-cost, and require no maintenance, making them ideal for protecting high-value equipment and employees. 

Every Graham extruder has a rupture disc at the barrel discharge to ensure that pressure does not exceed safe levels. If the discharge pressure exceeds allowable limits, the rupture disc bursts, preventing pressure buildup that could damage the system. Additionally, rupture discs are used in the melt stream, including at melt pumps and screen changers, to manage pressure changes effectively. 

Our Product: Thread-in Rupture Discs 

Graham Engineering primarily offers thread-in rupture discs for extrusion processes. This design is robust, convenient, and standardized. We provide a range of options with various pressure ratings, materials (including Inconel for high temperatures and corrosive processes), lengths, and thread sizes to meet diverse customer needs.  

Our expertise in process analysis and our rupture disc monitoring system, which can alert operators or shut down the system in the event of a burst, set us apart from other rupture disc suppliers. 

As your partner, Graham will work with you to ensure proper use of rupture discs to avoid common issues and protect your equipment. 

Common Issues You May Face 

Single-use Limitation: Rupture discs must be replaced after they burst. While this is intentional and the discs are inexpensive, it requires maintaining an inventory of spares to avoid downtime.

Material Leakage: A burst rupture disc will cause material leakage, which can be disruptive if not addressed promptly.

Handling Sensitivity: Rupture discs are manufactured with tight tolerances and can be damaged if handled improperly, affecting their performance. 

Causes of Issues 

Improper Sizing: Incorrectly sized rupture discs can burst too frequently or fail to burst when needed. Accurate pressure assessment and proper sizing are essential. In-depth knowledge of the various components of a particular extrusion system is crucial for proper sizing to protect the components and people. 

Improper Installation: Installation must ensure the rupture disc is flush with the inner wall of the melt stream. Incorrect depth can impede flow or cause material buildup, reducing effectiveness. 

Impact on Production and Product Quality 

Loss of Product: Leakage can lead to product loss. Undetected bursting may also lead to hours’ worth of scrapped product in multi-layer systems. 

Safety Hazards: Material spillage can create hazards directly by extruding hot polymer on employees’ skin or indirectly by melting polymer over electrical cables and other sensitive machinery. Correct design and placement of the rupture discs can minimize these issues. 

Downtime: Delays in replacing burst discs can halt production. 

Solutions to Minimize Issues and Increase Rupture Disc Effectiveness 

Rupture Disc Monitoring System: Our monitoring system will help you detect bursts and manage shutdowns, decreasing the potential for product loss and injuries.  

Consult Processing Professionals: As your trusted OEM, we will help you evaluate and ensure correct sizing and installation, increasing effectiveness. 

Maintain Spare Parts: Keep an inventory of spare rupture discs to minimize downtime. 

Common Misconceptions 

Rupture Discs vs. Pressure Relief Valves: Rupture discs and pressure relief valves each serve a different purpose, and neither is inferior to the other. They can be complementary in certain systems as well. 

One-Size-Fits-All: Not all rupture discs are suitable for all applications. Specific pressure ratings and materials must be chosen based on the process conditions. 

Troubleshooting Tips 

Pressure Issues: If you cannot build pressure, check if the rupture disc has burst. 

Installation Checks: Ensure that the rupture disc is installed correctly, flush with the melt stream’s inner wall. 

Life Expectancy 

Shelf Life: Rupture discs have an indefinite shelf life as spare parts if stored properly. 

Operational Life: Discs should be replaced yearly, even without bursting, due to pressure fluctuations causing fatigue. After a burst, immediate replacement is necessary as the disc is no longer functional. 

Reach out to our parts team with any questions.  

Parts Discount 

Email our parts team with the subject line  SPOTLIGHT ON Rupture Discs to receive a discount on the rupture discs you need to run your extruder.  

The discount is valid for September.