RECENT PROJECTS

Asintech has successfully executed and concluded (amongst others) the following projects since incorporation in 2019:

Following elevated vibration levels in the operating range of a decanter installation in the Northern Cape, South Africa, Asintech was contracted to perform a dynamic analysis and assessment of proposed structural modifications to improve the structure and manage vibration levels. In order to establish a reasonable degree of confidence in the proposed upgrades prior to execution of proposed remedial measures, the existing and upgraded structural design was subjected to a finite element investigation, supported by comprehensive vibration measurements on site in order to calibrate the model and confirm the root cause of the elevated vibration levels. Analysis of the proposed structural modifications predicted satisfactory dynamic response of the structure within the desired operating range, which was subsequently attained.

Asintech was approached assist with a vibration investigation and fitness for service assessment on a dew point correction refrigeration train at the client’s processing facilities. Two units were critically investigated and analysed by means of extensive strain and vibration measurements, from where the units’ structural dynamic behaviour could be quantified and translated into a fatigue related fitness for service assessment as per API 579. A high-level structural integrity management program, in conjunction with structural modifications was proposed in order to mitigate the risk of failure in the context of the limited remaining life of the assets.

Asintech was contracted to perform a design audit on the lifting pins that are utilized in conjunction with certified shackles and a 4-point hoisting system to handle a dragline bucket.  The pins were assessed analytically and numerically according to the provisions of ASME BTH-1-2014 “design of below the hook lifting devices” in conjunction with the regulations of the Occupational Health and Safety Act as well as the Mine Health and Safety Act. Analysis of the system and load distribution was complicated and required linear static FEA, from where the contact response of the pins and bucket was analyzed by means of non-linear FEA.

Asintech was subcontracted by an engineering consultancy to assist with the data analysis and vibration assessment on a suite of heat exchangers that form part of a large polypropylene plant.

The investigation reviewed technical observations and information as received from the client, as well as comprehensive data analysis and literature survey, which indicated that the high vibration levels stemmed from the off-gas compressors and were are pulsation driven.

Asintech was requested to assist with the root cause analysis of premature bearing failures during startup on a Francis turbine assembly at a hydro electric power station. Two turbine assemblies (one denoted as healthy, the other being the problematic one that experienced failures) were comprehensively instrumented with telemetry, runout sensors, strain gauges and a suite of accelerometers. The emphasis of the measurement campaign and associated data processing was to capture and understand the torsional and linear dynamics of both units, detect differences, and develop robust condition monitoring parameters that were subsequently employed to monitor the startup of the turbine in real time and avoid failures due to unforeseen transient conditions. The developed algorithms assisted with a successful startup of the problematic unit.

Asintech formed part of a collaboration process between the winder OEM, the mine and an additional electronic equipment consultancy in order to develop an algorithm that monitors crack growth in the winder structure, based on ordinary strain measurements away from the cracks. The basis of the algorithm was the consolidation of large amounts of operational strain data and the translation thereof into robust parameters that can detect marginal stiffness changes that indicate crack propagation. The system was successfully implemented by the OEM in conjunction with an online dashboard for continuous monitoring.

Following premature fatigue cracking around the welds on a primary aggregate crusher base and subframe, Asintech was contracted by the end user to perform strain and vibration measurements in order to identify the root cause of the failures. Strain data was processed to yield stress response in the crusher subframe and base for fatigue assessment, while acceleration data was processed in order to determine the crusher’s vibration mode and possible elastic deformation, for correlation with the stress response to establish remedial measures.

Following concerns regarding bearing and shaft design, input loading and fan casing dynamics of a recently commissioned ventilation fan installation, Asintech was approached to assist with a strain and vibration measurement campaign in order to quantify the input loading on the shaft w.r.t bending moment, torsion and thrust, capture the torsional and linear dynamics of the drive train and bearings and capture the dynamic strain and acceleration response, impulse transfer functions and operational deflection shapes of the impeller housing. Measurements were successfully performed while data processing yielded quantified shaft response i.t.o. bending moment, thrust and torque as well as valuable insights into the impeller housing response from a steady state and transient perspective.

Asintech was contracted to assist with the root cause analysis of premature shaft coupling failures in a baghouse fan installation by means of torsional strain and vibration measurements The emphasis of the measurement campaign and associated data processing was to capture and understand the torsional dynamics of the shaft in order to (a) establish whether the problem was related to torsional dynamics and (b) identify suitable mitigation measures in the event that (a) was positive. Measurements were successfully completed while data processing identified  the main driver for excessive torsional vibration, being a first torsional natural frequency within the operating range of the VSD, which was successfully eliminated by replacement of the rigid coupling with a resilient coupling.

Asintech was contracted to assist with a failure investigation and risk mitigation campaign on a Koepe winder assembly at one of the group’s shafts, following fatigue failure on the traction sheave of the winder. The traction sheave and shaft assembly were subjected to a strain measurement campaign, backed by a comprehensive finite element analysis (supported by first principle calculations) to determine the fatigue relevant stress response on the traction sheave drum, cheeks, and associated welds as well as the shaft and bolting arrangement. Numerically obtained results correlated well with measured stress response. Assessment of the stress response against IIW guidelines and material S-N curves pointed to inadequate fatigue resistance of the cheek plates and shaft, explaining the prevalence of premature failures. Asintech assisted the client with an upgraded design of adequate fatigue resistance.