Customer Challenge

A common maintenance strategy has been to retighten the hub studs during routine servicing. Unfortunately, this approach often fails to address the underlying root cause. When fasteners are bent, pinched, or already compromised, torque-based retightening produces preloads that may be a fraction of the required level, leaving the turbine vulnerable to recurring failures.

EchoBolt Solution: BoltWave Ultrasonic Measurement

To help operators resolve this fleet-wide issue, EchoBolt deployed its BoltWave ultrasonic fastener measurement system across multiple SWT-3.6 assets. BoltWave allows technicians to measure actual bolt elongation, providing a direct indication of true fastener preload—something torque alone cannot reliably produce.

Key Findings

Using BoltWave, EchoBolt was able to:

• Identify high variability in fastener tension on several hub connections.

• Detect turbines exhibiting early signs of misalignment-driven preload loss before visible loosening occurred.

• Pinpoint individual fasteners that had been previously damaged—bent, stretched, or pinched—producing false torque readings and dangerously low clamp force.

Outcome for the Customer

With data-driven insight into each fastener’s true condition, the operator was able to:

• Prioritise the highest-risk turbines for corrective maintenance.

• Replace compromised fasteners where elongation data indicated permanent deformation.

• Retighten all remaining studs using elongation measurement, ensuring the correct preload was achieved consistently across all positions.

• Substantially improve joint reliability and minimize the likelihood of future hub-shaft misalignment.

Results

• Early detection of problematic turbines

• Reduction in unscheduled downtime

• Improved long-term joint integrity

• Elimination of ineffective torque-only retightening practices

EchoBolt’s BoltWave solution has proven to be an effective and repeatable way to maintain the hub-to-main shaft connection on the SWT-3.6, giving operators the confidence that every fastener is set to the correct preload and ready for long-term service.