Different Types of Pressures in Aerospace Engineering

Burst Pressure / Rupture Pressure

Burst or rupture pressure is the maximum pressure a component can withstand before catastrophic failure. In aerospace applications, rupture disks and pressure vessels are designed with precise burst pressure ratings to provide fail-safe overpressure protection. Ensuring that burst / rupture pressure is well above normal operating conditions while considering factors like temperature fluctuations and material fatigue is crucial in system design.

Engineering Insight:
The rupture disk burst pressure is independent of the housing burst pressure but affects the design factor of safety (FOS) as all of the variables eventually lead back to the material properties of the raw material. Typical operating ratios of rupture disks range from 75% to 90% of marked burst pressure.

Operating Pressure / Maximum Expected Operating Pressure (MEOP)

Operating pressure, or MEOP, refers to the highest pressure a system is expected to experience during normal operation. In aerospace, this parameter is critical in designing propulsion systems, life support systems, and fuel tanks. MEOP is typically a fraction of burst pressure to allow for safety margins and accommodate pressure variations during flight or launch sequences.

Engineering Insight:
In atypical applications, the operating pressure of fluid media can be higher than the rupture disk burst pressure due to an intentional activation (or burst) of the rupture disk. The housing assembly of the rupture disk is therefore designed by the highest design pressure instead.

System Pressure / Design Pressure / Maximum Design Pressure (MDP) / Maximum Allowable Working Pressure (MAWP)

These terms relate to the maximum pressure a system or vessel is designed to handle safely:

• System Pressure / Design Pressure: The baseline pressure used in engineering calculations and component selection.
• Maximum Design Pressure (MDP): The highest pressure a system is expected to experience, considering normal operation and transient events.
• Maximum Allowable Working Pressure (MAWP): The highest pressure a component or vessel can sustain under ASME and aerospace design standards. MAWP is determined through material strength, wall thickness, and safety factor analysis.

Understanding these parameters helps engineers select rupture disks and pressure relief solutions that align with aerospace safety requirements.

Proof Pressure / Hydrostatic Shell Test Pressure

Proof or Hydrostatic pressure is the pressure in which a system or component is tested to without permanent deformation or failure. Typically, proof or hydro pressure tests involve subjecting aerospace pressure vessels, fittings, and rupture disks to pressures several times beyond their operating pressures. This ensures that components can withstand transient pressure spikes, launch stresses, and emergency scenarios without compromising integrity.

Engineering Insight:
Under standard applications, these tests subject production units to 1.5 or 2 times their operating pressures.

Housing Burst Pressure / Tensile Burst Pressure

Housing burst pressure (or tensile burst pressure) is the pressure at which the structural housing of a component, such as a rupture disk holder or pressure vessel, fails due to material rupture. This value is critical in aerospace applications where pressure containment is vital to mission success. Engineering teams analyze housing burst pressure to ensure containment structures remain intact under extreme conditions.

Engineering Insight:
In a typical application, a minimum of 3.5 or 4 times FOS from the highest design pressure is used understanding that qualification units undergo destructive testing or equivalent to prove the design.

Pressure Tolerance

Pressure tolerance defines the acceptable variation in pressure ratings for aerospace components. For example, rupture disks are often specified with a ±5% or ±10% tolerance on their burst pressure. Precise pressure tolerances are essential in space and aviation applications where slight deviations can impact system performance and safety.

Engineering Insight:
Certain variables can affect the design of the housing assembly and the disk models used for different applications. There are often highly advised design practices for tolerance requirements, however there can be compromises in design in pressure systems as long as the risks and factors of safety are considered.

Conclusion

Understanding these different pressure ratings allows aerospace engineers to design safer, more reliable pressure management systems. Whether specifying rupture disks for spacecraft, fuel tanks, or hydraulic systems, precise pressure control ensures compliance with aerospace safety standards while optimizing performance in extreme conditions.

For expert guidance on aerospace pressure relief and activation systems, contact ZOOK Aerospace Technologies today.