Golden Dome's Hidden Pressure Challenge

Rupture disks are one of the engineered safeguards that allows higher-profile propulsion and defense systems to function as a layered defense shield.

Golden Dome for America is a rapidly developing, multilayered homeland defense initiative being developed to protect the United States from ballistic, advanced hypersonic and cruise missiles, as well as next-generation aerial threats. Much of this discussion has focused on space-based sensors and interceptors, integrated command-and-control systems and artificial intelligence, and the significant technical challenges involved in connecting these technologies into a functioning defense system that seamlessly connects ground, air and space technology.

However, beneath those high-profile technologies is a less visible engineering requirement likely to be repeated across much of the architecture: the ability to safely contain, control and relieve pressure in propulsion systems, launch infrastructure, ground support equipment and pressurized spacecraft subsystems.

This is where pressure-relief technology comes into play. Although largely hidden from view, these devices provide a critical safeguard within many of the propulsion and support systems that make the larger system possible.

In that environment, rupture disks may not attract public attention, but they already play an important role in protecting pressurized systems that support civil aviation, space operations and military platforms. The Golden Dome initiative presents new application challenges for pressurized systems that must work correctly for long periods of ‘ready for action’ status as well as in the instant of active deployment.

“For all the attention now being placed on Golden Dome as a next-generation defense shield, the challenge may be less glamorous and far more difficult: the United States may ultimately have to build, launch, fuel, test and sustain a much larger network of systems that depend on pressure containment working exactly as intended,” explains Geof Brazier, Managing Director of BS&B Safety Systems’ Custom Engineered Products Division, which specializes in rupture disk technology for aerospace, defense and other demanding OEM applications.

“Before any of those systems can perform their intended mission, they have to survive a long chain of very practical engineering validation to confirm suitability for the intended use involving propellants, pressurants, cryogenic fluids, compressed gases, feed systems, ground support equipment and test infrastructure,” adds Brazier.

In propulsion and support systems, the issue is not simply whether pressure can be contained under normal operating conditions. The more important question is what happens when pressure moves outside the expected range, when temperature changes create rapid expansion, when cryogenic systems begin to warm, when a control valve fails to respond, or when a test stand, launch system or spacecraft subsystem has no margin left for error.

In those cases, pressure relief is not an accessory. It is part of the safety architecture, along with pressure containment and pressure isolation.

That makes rupture disks a quiet but critical enabling component, particularly when the consequences of uncontrolled pressure can range from damaged equipment and interrupted testing to the loss of a mission-critical system.

Where Rupture Disks Fit

Rupture disks serve as a passive safety mechanism to protect against overpressure or as a seal that can be actuated to give a controlled opening to release a pressurized fluid on demand. The disk, which is a one-time-use membrane made of various metals including exotic alloys, is designed to activate within milliseconds when a predetermined differential pressure is achieved.

The concept itself is straightforward. The system contains pressure during normal operation. If pressure exceeds predetermined limits, the rupture disk opens to provide a relief path before the pressure can damage or destroy the equipment it is designed to protect, or when intentionally actuated to release a normally constrained pressurized fluid.

One of the most direct roles is in the space-based systems potentially required for Golden Dome and the launch-related infrastructure needed to place them into orbit. Both can require pressure systems to store, move and control propellants, gases and other fluids.

These systems can include tanks, cylinders, piping and other equipment designed to contain gases or liquids under pressure. These ‘stored energy’ applications are required to release a pressurized fluid with accuracy. In these applications, a rupture disk device frequently uses manufactured precision lines of weakness to contribute to the accuracy of opening pressure or to achieve a desired pattern of opening that contributes to the fluid flow conditions.

For launch vehicles and launch-support infrastructure specifically, potential applications can include propellant tanks, pressurant tanks, transfer lines, fill-and-drain systems, vent stacks, test stands and ground storage systems.

The applications could also extend to the satellites and other space-based assets envisioned as part of Golden Dome. Depending on their design and mission requirements, satellites can require compact propulsion systems for functions such as reaching or adjusting orbit, maintaining position, avoiding collisions or eventual deorbiting.

Some utilize chemical propulsion. Others rely on electric propulsion systems using xenon, krypton or iodine. In either case, the propellant still has to be stored, controlled and delivered through the system under very specific operating conditions.

Once a top-level architecture has been selected, detailed system designs, acquisition decisions and implementation requirements continue to evolve. Rupture disks can be used to protect high-pressure gas storage and propellant tanks, isolate sensitive downstream components, or provide pressure relief during ground handling, qualification testing and operation.

Selecting the Right Rupture Disk

Identifying a potential application is only part of the engineering challenge. The disk itself may be small, but the engineering behind its selection and acceptance is not.

This becomes particularly important for the types of advanced aerospace and defense systems potentially associated with Golden Dome, where pressure relief or pressure actuation may have to account for cryogenic temperatures, thermal gradients, vacuum, launch vibration, stored-energy hazards, propellant compatibility, contamination control, vent routing, backpressure, equipment inspection, maintenance access, and qualification testing.

These requirements can vary considerably from one system to another. A low-pressure system, for example, may require a very different rupture disk design than a compact propulsion system operating at thousands of pounds per square inch. Other applications may require resistance to repeated pressure cycling, full vacuum, extremely high pressures, or a device small enough to fit within tightly constrained aerospace hardware that is ‘light enough to fly.’

As a result, there is no single rupture disk technology that fits every potential application.

BS&B offers several rupture disk technologies that address these different operating conditions. The LPS, for example, is a low-pressure reverse buckling rupture disk for applications with burst pressures as low as 5 psig, while the compact FRB provides highly accurate reverse buckling performance in sizes down to 1/8 inch and pressures from 100 to 1000psi.

Other technologies address increasingly demanding operating requirements. The QRB is designed for smaller, higher-pressure systems where pressure-cycle resistance is important, while the MRB extends into extremely high-pressure applications reaching as high as 70,000 psig.

The XTI uses a forward-acting, tension-loaded design, providing the unique option of an integral assembly whereby the rupture disk is formed into the machined body requiring no weld or other assembly technique to combine the rupture disk to its holder arrangement. CT and XTI technologies address additional compact and high-pressure applications where dimensional constraints, leak integrity or assembly requirements must also be considered.

Given the number and variety of propulsion, satellite, launch, test and support systems potentially involved in Golden Dome, OEMs could face widely different requirements involving pressure, size, weight, materials, temperature, vacuum, vibration and available installation space.

In most cases, the rupture disk and holder can be supplied as an engineered assembly, using welded, bolted, adhesive-bonded or crimped construction where requirements such as low mass, leak tightness, cleanliness, burst test certification as a ready to use device, temperature exposure or installation geometry require a higher level of design and performance.

Fast Tracking Custom Rupture Disk Prototypes for Golden Dome Applications

The development of the United States’ Golden Dome missile defense system will require the rapid development and integration of advanced defense and aerospace technologies. For defense contractors and OEMs participating in such a large-scale initiative, the challenge of time remains significant, particularly when a custom solution must be developed within an acceptable timeframe.

Equipment reliability is essential, and this demands high integrity from the pressure relief technology used to protect low- and high-pressure OEM systems. As a result, OEMs are increasingly turning to integrated rupture disk assemblies with all components combined by the manufacturer, as opposed to loose rupture disk and holder devices that leave much to chance.

These assemblies are tailored to the application, miniaturized, and utilize a wide range of standard and exotic materials, as required. This approach ensures the rupture disk device performs as expected, enhancing equipment safety and reliability while simplifying installation and replacement.

For flight hardware of the types that may support programs such as Golden Dome, tailoring integrated rupture disk applications for use with lightweight, compact materials like titanium and aluminum may also be important, since it takes more energy to get heavier vehicles off the ground.

The final requirements will depend on government and contractor specifications. However, product developers are certain to face time constraints, particularly when developing advanced defense technologies on accelerated schedules.

For Golden Dome and other advanced defense programs, where development schedules are compressed and equipment reliability is essential, the ability to rapidly develop, test and refine custom pressure relief technology could become increasingly important.

OEMs often require a unique rupture disk in terms of its dimensions, material combinations or operating conditions. In many cases, the rupture disk is a late stage project consideration once other design parameters are defined, so a custom prototype must be delivered within relatively tight timelines as part of product development.

Recognizing the need, BS&B Safety Systems developed a comprehensive support program called the Prototype Introduction Team (PIT) for OEMs that require expedited development of custom rupture disk devices. The fast-tracked development process involves the coordination of specialized internal teams with unique skillsets to deliver prototypes prepared for evaluation, additional adjustments or full-scale production.

“Achieving such rapid turnarounds requires meticulous planning, rigorous training and teamwork,” explains Brazier. “At BS&B, the PIT team involves experts assembled from sales, engineering, purchasing, manufacturing and quality control. The PIT team incorporates design engineering throughout and manages scheduling and development requirements through completion and delivery.”

The custom engineered products team has decades of machining experience along with fast-track techniques for prototype manufacturing and testing fixtures based upon 3-D printing capabilities to reduce the time required for prototype manufacture. Validation capabilities further support the testing and refinement required to meet project requirements.

Ultimately, Golden Dome will depend on far more than the high-profile technologies most closely associated with aerospace and defense systems. Existing and newly developed sensors, interceptors, launch assets and support systems will need to be integrated, tested and operated reliably.

Many of the components that make this possible will remain largely unseen. Rupture disks that protect critical equipment against overpressure are one example. For an initiative as technically ambitious as Golden Dome, successfully addressing those less visible engineering challenges will be just as necessary as developing the technologies.

For more information or assistance in selecting a solution for your application, call BS&B Safety Systems at (918) 622-5950; e-mail: sales@bsbsystems.com; or visit bsbsystems.com.