Roots Systems approached us with a critical issue: a gas pumping unit was failing to meet API 619 vibration limits. Excessive levels raised concerns regarding system reliability and long-term operational safety.
Case Study: Reducing Excessive Vibration to Obtain API 619 Compliance
How specialized vibration control engineering resolved critical failures at a Roots Systems gas pumping station in Wales.
Overview: Vibration Control for API 619 Compliance
Initial Site Observations: Exceeding API Limits
Upon inspection at the Wales facility, we found improvised solutions (wooden blocks) that failed to address the root cause. Notably, the vibration worsened as differential pressure increased from 0.2 bar toward the intended 2 bar.
Identifying the Source: Resonance and Frequency
Our investigation revealed a blower pulsation frequency of 47.2Hz. By ruling out critical speeds of the motor, we identified the true culprit: Structural Resonance.
The natural frequency of the frame was too close to the blower's pulsation frequency, violating screw compressor bearing limits.
FEA Vibration Analysis & Simulation
Using Ansys software, we performed a Finite Element Analysis (FEA). This digital twin approach confirmed that the frame’s natural frequency was dangerously synchronized with the 47.2Hz operational frequency.
The Solution: Structural Stiffening
To eliminate resonance, we implemented a frame stiffening strategy. This shifted the natural frequency away from the excitation source, allowing for immediate reduction in vibration without redesigning the entire compressor assembly.
Validation: Confirmed Compliance
Post-modification, we utilized Experimental Modal Testing and Frequency Response Function (FRF) testing. Results confirmed:
- Natural frequency shifted to a non-critical range.
- Vibration levels successfully fell within API 619 thresholds.
- No resonances detected near the 47.2Hz mark.