Negative temperature in bearing due to Joule Thompson effect
Read the full story about how Shape Lighthouse avoided a potentially catastrophic failure in an offshore compressor.
Plant:
Floating Production Storage and Offloading (FPSO)​
Equipment:
Multi Stage Centrifugal Compressor
Description:
The client has 114 large centrifugal compressors monitored by Shape Lighthouse in multiple plants, supporting its centralized condition-based monitoring strategy. On 16th August, 07:04h, Lighthouse called user attention to an anomaly behavior in one compressor, where it was possible to identify negative temperatures (-12,7ºC) in its radial bearings just after it was turned off. The engineer responsible had directly contacted the offshore production supervisor, who sent an operator to the field to evaluate the issue. One valve closure was detected, and an internal leakage was mitigated to close the drain system. If no action were taken, a brittle, fragile rupture of the closed drain lines could occur with further gas leakage and possible explosion.
Event summary:
How does Shape Lighthouse detect the issue?
On 16th August, 07:04h, an anomaly detection event was raised by the Shape Lighthouse alarm pointing to the compressor set of sensors anomaly without relation with other sets of sensors from the machine.
​
The anomaly detection AI approach from Shape Lighthouse is focused on detecting failure modes and causes that are not yet known by the system. It is an algorithm trained in equipment historical data but also considers similar compressor behavior in the calculations to reduce false alarms.
​
​​A consequence of no Shape Lighthouse detection:
As there is no control room alarm for this situation, there was a high chance that this situation would go unnoticed until one field operator visually identified the issue.
​
If the bundle’s casing drain valve were kept open, the process gas had a preferential path to depressurization. Thus, due to the Joule-Thomson effect, the internal temperature of the compressor is reduced drastically, which could cause a Process safety event related to loss of containment due to brittle fracture of the closed drain pipeline.
​
Action after Shape Lighthouse identification:
Just 6 hours after the initiation of the anomaly, the engineer identified the alarm in the Shape Lighthouse and immediately contacted the offshore production supervisor to investigate the issue locally.
​
The closed drain system line was found with ice, and the closed drain valve was closed to interrupt the joule Thompson effect and prevent further damage. A maintenance notification was raised to investigate and correct the downstream check valve and shut-down valve for internal leakage.
Savings:
How savings were calculated:
Savings financial values were calculated based on the client's past similar events related to this failure mode and possible consequences, supported by the Lighthouse savings calculation feature.
​
Consequence (unavailability):
Process safety event due to loss of containment fracture of the pipeline.
​
Maintenance scope:
Overhaul the compressor and repair the pipeline.
Avoided losses: