Pressure & Stability in Metal Expansion Joints
In any industrial piping system, pressure containment and mechanical stability are two of the most critical factors in the design and performance of metal expansion joints (MEJs). These components must not only absorb movement but also withstand internal pressure without deformation, failure, or instability.
| Unreinforced Bellows / Expansion Joints | Reinforced Bellows / Expansion Joints |
| Suitable for lower-pressure applications where flexibility is the priority. | Designed with additional structural support such as root rings or equalizing rings to handle higher pressures and provide enhanced stability. |
The Inspection & Testing
Every LSI Make expansion joint undergoes rigorous In-house pressure testing to ensure safety and structural integrity.
Our testing capabilities include
• Hydro static Pressure Testing
• Pneumatic Testing
• Prototype Testing for new or custom designs
We also specialize in the design and testing of externally pressurized bellows, which are ideal for high axial movement under high-pressure conditions without risk of instability.
Designed for Pressure. Built for Reliability
At LSI-MECH, all metal expansion joints and bellows are engineered to perform under demanding conditions and are rated for various pressure classes, including PN ratings and ANSI #150, #300, and higher.We offer two main types of MEJs based on pressure and reinforcement.
Bellows Instability
Bellows are thin-walled, flexible components, and their stability under pressure must
be carefully evaluated.The two main types of instability are:
(a) Column Instability
Column squirm Occurs when the bellows deforms laterally under internal pressure, resulting in a gross shift or bowing of its center line.This reduces the joint’s effectiveness and can lead to failure.
(b) In-plane Instability
In-plane squirm Happens when individual convolutions rotate or shift from their original alignment, causing the plane of the convolutions to tilt. This misalignment can compromise pressure capacity and flexibility.
Did You Know?
At LSI, every bellows design is checked for pressure stability using advanced simulation tools and validated through physical testing ensuring reliable performance under expected operating Pressure.
Why Pressure & Stability Matter in Metal Expansion Joints?
• Prevent catastrophic failure in pressurized systems.
• Ensure long-term operational safety and performance.
• Enable higher movement capacity without compromising structure.
• Minimize risk of squirm and deformation under load.
• Comply with international pressure vessel and piping codes.