Clamshell grabs are commonly used equipment in wastewater treatment plants (WWTPs) for the extraction of sludge, sand, and solids in units such as primary clarifiers, pumping stations, or inlet channels. Although their operation may appear simple from the outside, they actually rely on an oleohydraulic system subjected to repeated opening and closing cycles under highly variable load conditions and with limited direct instrumentation.
In practice, this makes the grab a relatively “opaque” system from a diagnostic standpoint. Operators or maintenance teams typically verify that the equipment opens and closes correctly and completes its cycle, but there is usually no detailed information about the internal condition of the hydraulic system during operation. This makes progressive degradation difficult to detect in its early stages.
Oleohydraulic Failures in Clamshell Grabs: Progressive Degradation
Most failures in these systems do not occur suddenly but evolve gradually. The first symptom is often a slight increase in closing time or a less responsive cylinder, without yet causing equipment downtime. Over time, small efficiency losses may appear, along with the need for higher pressure to complete movements or slight inconsistencies in cycle repeatability.
The root cause of these issues is typically found in the oleohydraulic system, especially in the actuation cylinders. Progressive loss of sealing integrity, non-visible internal leaks, or degradation of components subjected to cyclic loads are common failure modes in this type of application. The main challenge is not the occurrence of the failure itself, but the difficulty in detecting it before it impacts equipment performance.
Hydraulic Cylinder Diagnostics in WWTPs: Limitations of Conventional Maintenance
Conventional diagnostics in WWTPs present clear limitations. The lack of specific sensors in the hydraulic system means that analysis is primarily based on observing equipment behavior or identifying anomalies only after they have already affected operations. This places maintenance in a largely reactive position—or at best, preventive based on experience rather than continuous real-condition data.
In this context, minor deviations in hydraulic behavior may go unnoticed until the system crosses a functional threshold, at which point the failure becomes evident through performance loss or equipment shutdown.
IoT Monitoring in Industrial Oleohydraulics Applied to WWTPs
The integration of monitoring and remote diagnostic systems is beginning to change this scenario. Instead of focusing solely on the visible state of the equipment, these systems analyze hydraulic behavior through indirect variables, identifying deviations from normal operating conditions.
In this field, solutions such as those developed by Stemm provide an additional analytical layer for oleohydraulic systems in equipment like clamshell grabs, enabling the detection of early-stage anomalies in cylinders and hydraulic circuits before they result in operational failure.
The value of this approach lies not in replacing traditional maintenance, but in enhancing its diagnostic capabilities through more continuous and contextual information about hydraulic system behavior.
Predictive Maintenance in WWTPs: Early Fault Detection in Clamshell Grabs
The ability to identify progressive changes in hydraulic behavior makes it possible to anticipate interventions, reduce uncertainty in decision-making, and prevent minor deviations from evolving into unplanned downtime. In this sense, maintenance no longer depends solely on visible symptoms but also on the interpretation of behavioral patterns.
In a WWTP, this has a direct impact on equipment availability. A clamshell grab may continue to operate seemingly normally while its hydraulic system is progressively degrading. Detecting this change at an early stage allows maintenance to be planned rather than reactive, reducing operational impact and improving overall maintenance management.
