Systems dynamic model of wear evolution for sheaves used in oil and gas hoisting operations

The global offshore drilling contracted fleet consisted of 378 jack-ups, 68 semisubmersibles and 73 drillships, according to Westwood Global Energy Group, as of September 2023. In most regions of the world, rig activity has picked up from increased operator demand and pushed the marketed utilization for jack-ups from 76% to 85%, semis from 60% to 80% and drillships from 82% to 90%. The utilization of a drilling rig depends on various factors, mainly drilling demand, rig capability and specifications, and rig efficiency and reliability. Worn sheave grooves can pull down the efficiency of a drive by 8% accelerate the wearing of ropes reduce rope life, increase maintenance costs, and the need for more frequent rope replacements. Wear depth for sheaves is typically measured as the depth of wear in the groove of the sheave, which indicates the extent to which the sheave has worn down over time. Research on surface wear of wire rope caused by the contact between the wire rope and the sheave has rarely been carried out. Upgrading Archard's Wear model is needed to provide a better estimation of wear depth for sheaves. Moreover, the wear coefficient shall be determined. Therefore, the purpose of this paper is to model the wear evolution caused by the sliding contact between the wire rope and the sheave. To achieve this purpose, case sheaves were purposefully selected, studied and modelled using both the analytical and simulation modelling approaches.publishedVersio

Assessing the Technical Specifications of Predictive Maintenance: A Case Study of Centrifugal Compressor

Dependability analyses in the design phase are common in IEC 60300 standards to assess the reliability, risk, maintainability, and maintenance supportability of specific physical assets. Reliability and risk assessment uses well-known methods such as failure modes, effects, and criticality analysis (FMECA), fault tree analysis (FTA), and event tree analysis (ETA)to identify critical components and failure modes based on failure rate, severity, and detectability. Monitoring technology has evolved over time, and a new method of failure mode and symptom analysis (FMSA) was introduced in ISO 13379-1 to identify the critical symptoms and descriptors of failure mechanisms. FMSA is used to estimate monitoring priority, and this helps to determine the critical monitoring specifications. However, FMSA cannot determine the effectiveness of technical specifications that are essential for predictive maintenance, such as detection techniques (capability and coverage), diagnosis (fault type, location, and severity), or prognosis (precision and predictive horizon). The paper proposes a novel predictive maintenance (PdM) assessment matrix to overcome these problems, which is tested using a case study of a centrifugal compressor and validated using empirical data provided by the case study company. The paper also demonstrates the possible enhancements introduced by Industry 4.0 technologies.publishedVersio

Internal clearance behaviour in healthy and faulty bearings

Internal clearance is a critical parameter in bearing design and operation because it affects the bearing's performance. It can be considered as a special type of the looseness fault. Several studies indicate that rolling bearings with large internal clearances showed a short predicted fatigue life. However, the time waveform and spectral features of bearing with internal clearances are partially studied and require further studies. To address this gap, the purpose of this paper is to study the effect of internal clearance on the dynamic response of healthy and faculty rolling bearings in both time waveform and spectral representations. Four experiments are designed and performed: (1) rigid bearing with no defect, (2) rigid bearing with bearing defect, (3) bearing with high internal clearance, (4) bearing with high internal clearance and bearing defect. The results indicate an increase in the overall vibration level with high internal clearance is introduced, however, there is an increase in the overall vibration level when high internal clearance and bearing defect are both presented. The internal clearance negatively affects the impact amplitude of the bearing defect, which also affects the spectral pattern at the natural frequency zone.publishedVersio

The Impact of Patient Infection Rate on Emergency Department Patient Flow: Hybrid Simulation Study in a Norwegian Case

The COVID-19 pandemic put emergency departments all over the world under severe and unprecedented distress. Previous methods of evaluating patient flow impact, such as in-situ simulation, tabletop studies, etc., in a rapidly evolving pandemic are prohibitively impractical, time-consuming, costly, and inflexible. For instance, it is challenging to study the patient flow in the emergency department under different infection rates and get insights using in-situ simulation and tabletop studies. Despite circumventing many of these challenges, the simulation modeling approach and hybrid agent-based modeling stand underutilized. This study investigates the impact of increased patient infection rate on the emergency department patient flow by using a developed hybrid agent-based simulation model. This study reports findings on the patient infection rate in different emergency department patient flow configurations. This study’s results quantify and demonstrate that an increase in patient infection rate will lead to an incremental deterioration of the patient flow metrics average length of stay and crowding within the emergency department, especially if the waiting functions are introduced. Along with other findings, it is concluded that waiting functions, including the waiting zone, make the single average length of stay an ineffective measure as it creates a multinomial distribution of several tendencies.publishedVersio

Service and inventory model for maintenance workshop in the short cycle operation region: Agent-based simulation approach

Tools used in the North Sea region has a high cycle and come very often to maintenance workshop to be checked, repaired if needed and prepared for the next operations. The availability of spare parts at the workshop plays a significant role to keep the flow time as short as possible and meet such high-cycle operations. Supplying spare parts from the best-cost countries to the North Sea region with about one-year lead time makes the situation more critical and the economic order quantity and reorder point need to be found. However, having inventory at the workshop and ordering a batch of spare parts increases operational expenditures. Moreover, frequent supplies increase the environmental impacts of shipping CO2 and spare scrap rates, whereas repairing the used spare parts and reusing them again can offer a more sustainable solution. Therefore, the purpose of this paper is to develop a simulation model that can quantify the cost and benefits of reusing repaired spares compared to supplying newly built spares from the best-cost countries. To achieve this purpose, a case study has been implemented on a specific maintenance workshop within the North Sea region and the entire tool repair and spare part supply operations are conceptualized and modelled with the help of the simulation modelling approach. Two scenarios have been simulated: (1) the maintenance workshop fully depends on supplying newly built spares from the best-cost countries with no inventory stock or spare reuse, and (2) the Maintenance workshop is primarily dependent on repaired spares with an optimal level of spares stock. The simulation results, from the studied case, support the second scenario where a repair path cycle is introduced to the maintenance workshop, as a 78% reduction in lead times, a 116% improvement in worker utilization, a 73% reduction in crowding levels, a 52% reduction in scrap rate, and a potential profit increase of roughly three million NOK (20%). Therefore, it can be concluded that a local repair service is required to keep maintenance workshops in high-cycle regions at high-performance levels.publishedVersio

A summary of adapting Industry 4.0 vision into engineering education in Azerbaijan

Industry 4.0 vision and associated technologies are rapidly adopted in several industrial sectors to gain the benefits of creating smart cyber-physical systems and operations. Some sectors, e.g. manufacturing, oil and gas, offshore wind energy, have progressed in developing digitization strategies, executing pilot projects and progressing toward mature implementation of industry 4.0 vision. Offshore Oil and Gas industry highly believes in the potential industrial and societal impacts of digital transformation, due to the need for stochastic and remote operations. Azerbaijan as one of the countries that heavily depend on the Oil and Gas industry is developing more projects in the Caspian Sea. There are several worldwide challenges, mainly, lack of standards, business models, ready products/services and competent and skilled employees. Fortunately, specific developed countries are working hard to standardize industry 4.0 architecture. Moreover, large-scale companies are creating alliances to create a trustful and long-term business model. Furthermore, large-scale companies of information and operational technology are creating robust products and services to be commercially available off the shelf. In terms of education and training, many worldwide universities are upgrading their programs, curriculums, teaching approaches with the goal to support the industry with competent future employees and entrepreneurs. Therefore, the purpose of this paper is, to present the status of engineering education programs in adapting the industry 4.0 vision in Azerbaijan and address the skills that are required for future employment. In order to present the targeted status, the curriculums of all engineering education programs at the master level were collected and analyzed. However, five of them were directly adapting industry 4.0 vision and relevant for industry 4.0. Moreover, a semi-structured interview with industrial managers was applied to extract the future required skills. This study can be considered as a first step in developing a roadmap for engineering education, particularly industrial engineering, to adopt industry 4.0 vision at the national level.acceptedVersio

Characterization of acoustic emission signals under 3-point bending test

This paper summarizes a master’s thesis project which explored whether the characteristics of Acoustic Emission Testing (AET) signals can be used to detect yielding in steel samples undergoing a three-point bending test. A subset of existing data from a three-point bending test was exported and used as input. Data was processed by utilizing and developing tools to visualize and analyse the signal characteristics, primarily through a parameter-based approach. Signals were visualized, and parameters were optimized to identify and classify signal types. According to the obtained results, some limitations on classification were experienced due to the length of the hit data recorded. Though the work reported in this article lead to a reliable method for detecting yielding, the developed algorithms were not successful in identifying characteristics that could be used to detect yielding.publishedVersio

Problems with using Fast Fourier Transform for rotating equipment: Is it time for an update?

Condition-Based Maintenance (CBM) is widely used to manage the condition of rotating machinery. They require a number of CBM tools to detect acous-tic and vibration signals. One such method is the Fast Fourier Transform (FFT). FFT converts a vibration signal from time domain to its equivalent fre-quency domain representation. Unfortunately, there are dramatic assumptions made related to the proper use of FFT. The paper will provide evidence that this approach may not be the perfect tool for fault detection and diagnosis. The paper celebrates with the limitations of FFT and does not muffle the culpa-bilities of our developed diagnosis culture. The aim is to challenge researchers to come up with something more developed to eventually take use of the processing power we have today

Sliding wear analysis of cobalt based alloys in nuclear reactor conditions

The study of the wear behaviour of cobalt based alloys in nuclear reactor environmental conditions is the focus of this work. The alloys are used in components within reactors due to their excellent wear and corrosion resistance and their high hardness in the high pressure and temperature water facing environment. In the nuclear reactor core, cobalt is irradiated producing a highly penetrative gamma emitting isotope, cobalt 60 from stable cobalt 59. Wear of the cobalt alloys, producing wear debris, exacerbates this problem as it may be transported and deposited at various locations throughout the primary loop increasing the potential of radiation exposure. Removing this problem will require the removal of cobalt from the system. In order for suitable replacement materials to be identified, a better understanding of the behaviour of these alloys in the prototypical working conditions must be obtained. This work focuses on two cobalt based alloys used in the ball and race components of rolling element bearings in the reactor core, Stellite 20 and Haynes 25, respectively. The sliding wear behaviour of the alloys in an environment designed to replicate reactor conditions is examined using a bespoke pin on disc tribometer. Wear measurement and microstructural and compositional analysis of the samples tested over a range of conditions are presented and discussed. Concurrent to the experimental work is the development of a wear prediction model using a semi analytical method. The model employs Archard’s wear law as the method of predicting wear using data obtained through experimentation. The accuracy of the semi analytical model is limited however it does give a good estimation for maximum wear depth of the test specimens