Hydraulic systems depend on precise pressure control, so choosing fittings with the right pressure ratings is non-negotiable. These components must endure constant stress, and sometimes extreme pressure spikes without failing. That’s why understanding the difference between working pressure and burst pressure is so important.
Mixing them up can lead to dangerous equipment failures, costly downtime, and serious safety risks. A fitting might survive a quick pressure surge, but if it can’t handle your system’s everyday operating pressure, it’s only a matter of time before something goes wrong.
In this article, we’ll break down both pressure ratings, why they matter, how they’re tested, and how to choose fittings that keep your hydraulic system safe and reliable.
What Is Working Pressure?
Working pressure, more formally known as Maximum Allowable Working Pressure (MAWP). It is the highest pressure a hydraulic fitting can safely withstand during normal, continuous operation. This value is set by manufacturers and validated through rigorous testing.
MAWP is derived from material strength, fitting geometry, thread design, and sealing method. It represents the pressure at which the fitting can function day after day without risk of fatigue or performance degradation.
Typical Safety Factors Used in Hydraulic Design
Hydraulic systems usually incorporate safety factors ranging from 2:1 to 4:1, depending on the industry and standards applied. This ensures that the fitting’s burst pressure remains well above its working pressure, providing a margin of safety for spikes and unexpected loads.
Why Working Pressure Matters
Ensuring Reliable System Performance
A fitting that can consistently withstand system pressure is vital for operational reliability. When fittings operate below their working pressure limit, they maintain structural integrity and proper sealing.
Preventing Fatigue, Leaks, and Premature Failure
Operating above the MAWP even by a small margin can cause micro-cracking, seal distortion, and material fatigue. Over time, this leads to leaks, performance loss, or sudden failure.
Relationship Between Working Pressure and Operating Conditions
Working pressure is influenced by:
➡️ Temperature changes: High temperatures weaken material strength.
➡️ Vibration: Constant vibration accelerates fatigue.
➡️ Fluid type: Certain fluids may corrode or degrade fitting materials.
These factors are considered when manufacturers establish working pressure ratings.
Examples of Working Pressure Ratings
How Working Pressure is Assigned
Manufacturers determine working pressure by analyzing:
1. Material yield strength
2. Wall thickness and geometry
3. Thread type (NPT, BSP, JIC, ORFS, etc.)
4. Manufacturing methods (forged, machined, cold-formed)
After testing, the MAWP is published and included in product specifications.
Common Working Pressure Ranges
Typical hydraulic fitting working pressures include:
1. 1,000–3,000 psi for brass fittings
2. 3,000–10,000 psi for stainless steel fittings
3. 3,000–6,000 psi for carbon steel fittings
These values vary by standard and manufacturer but offer a general guideline.
What Is Burst Pressure?
Burst pressure is the maximum pressure a fitting can endure before catastrophic failure, a sudden rupture that often results in fluid release and system shutdown.
Burst Pressure in Testing and Certification
Manufacturers determine burst pressure through:
➡️ Pressure cycling
➡️ Destructive stress testing
➡️ Rapid-pressure ramp tests
These tests validate how fittings behave under extreme pressure conditions.
Certifications typically follow industry standards such as SAE, ISO, JIC, and DIN.
Typical Burst Pressure Ratios
A general industry rule states that the burst pressure of a hydraulic fitting is 3–4 times higher than its working pressure. This ratio ensures a substantial margin of safety and accommodates:
➡️ Pressure spikes
➡️ Temperature fluctuations
➡️ Aging and wear
Working Pressure vs. Burst Pressure: Key Differences
Operational vs. Limit State
1. Working pressure = the safe, continuous operating limit.
2. Burst pressure = the absolute pressure at which failure occurs.
Fittings should never be operated near their burst pressure.
Safety Factor Comparison
Engineering safety factors ensure burst pressure remains significantly higher than working pressure. This protects the system during unexpected events such as pressure surges or equipment faults.
Misconceptions to Avoid
1. You cannot size a hydraulic system using burst pressure. Burst pressure is not a design value; it is a failure point.
2. A higher burst pressure does not guarantee better long-term performance. Durability is more influenced by working pressure, material compatibility, and proper installation.
How Manufacturers Determine These Pressures
Material and Construction Factors
Different materials provide different strengths:
➡️ Steel: High strength, commonly used in heavy-duty systems
➡️ Stainless steel: Corrosion-resistant, suitable for harsh environments
➡️ Brass: Lower pressure ratings, often used in lighter-duty or pneumatic applications
Wall thickness, plating, and sealing methods also influence pressure ratings.
Environmental Influences
Manufacturers consider:
➡️ Corrosion exposure
➡️ Temperature extremes
➡️ Shock loads
➡️ Chemical compatibility with hydraulic fluids
These factors impact both working and burst pressures.
Testing Protocols
Before publishing pressure ratings, manufacturers conduct:
➡️ Lab testing
➡️ Pressure cycling
➡️ Fatigue analysis
➡️ Burst tests
The final values are verified through strict quality control procedures.
How to Choose the Right Fitting for Your System
Steps to Selecting Proper Pressure Ratings
1. Identify the system’s operating pressure.
2. Account for expected pressure spikes and surges.
3. Choose fittings with a working pressure rating higher than system requirements.
4. Consider environmental and fluid conditions when selecting materials.
Avoiding Underrated Fittings
Selecting fittings with lower working pressures than required may lead to:
➡️ Leaks
➡️ Premature wear
➡️ Complete system failure
Considering Burst Pressure During Selection
Burst pressure is useful for:
➡️ System safety audits
➡️ Engineering validation
➡️ Risk assessments
However, it should never replace working pressure as a design criterion.
Common Real-World Scenarios
Pressure Spikes and Surges
Sudden loads, such as when a cylinder bottoms out can exceed a fitting’s working pressure. Spikes can be managed using:
1. Accumulators
2. Flow restrictors
3. Pressure relief valves
Fatigue Failure vs. Burst Failure
1. Fatigue failure: develops slowly due to repeated stress cycles.
2. Burst failure: sudden catastrophic rupture, often caused by extreme overpressure.
Improper installation, such as over-tightening can accelerate both failure types.
Case Example
A maintenance team installs a brass fitting rated for 1,500 psi into a hydraulic lift system operating at 2,000 psi. During normal use, the fitting holds temporarily, but over time, micro-cracks form. During a routine lift cycle, the system encounters a pressure spike, causing the fitting to burst. The result: a sudden fluid spray, unplanned downtime, and a costly repair.
The cause? Misunderstanding working pressure vs. burst pressure.
Best Practices for Safe Hydraulic System Design
➡️ Always follow manufacturer pressure charts and specifications.
➡️ Schedule regular inspections and maintenance.
➡️ Use compatible hoses, fittings, and adapters from trusted sources.
➡️ Avoid mixing unknown or unbranded fittings with certified components.
These practices maximize safety and system longevity.
Conclusion
Working pressure and burst pressure play distinct roles in hydraulic system design. Working pressure defines what a fitting can safely handle during everyday operation, while burst pressure represents the extreme limit at which failure occurs. Selecting hydraulic fittings based on working pressure, not burst pressure is essential for safety, performance, and long-term reliability.
By understanding these ratings and applying appropriate safety factors, you can ensure your hydraulic system operates confidently and consistently under all expected conditions.
Post time: Nov-26-2025