Unavailability assessment of redundant safety instrumented systems subject to process demand

Sriramula’s work within the Lloyd’s Register Foundation Centre for Safety and Reliability Engineering at the University of Aberdeen is supported by Lloyd’s Register Foundation. The Foundation helps to protect life and property by supporting engineering-related education, public engagement and the application of re-search.Peer reviewedPostprin

Emergency shutdown valve reliability function test by automated Partial Stroke Testing System

Partial stroke testing (PST) is a technique that is regularly practiced in oil and gas industries to test the emergency shutdown (ESD) valve by closing a certain percentage of the valve position and stop any flow through the pipeline. Generally, it only functions when there is an emergency occurring in the production system. When the ESD valve remains in one position for a long period, there is a risk and potential of fail on demand which is, the ESD valve fail to operate during the emergency shutdown. This testing can reveal approximately 75 of unrevealed failures in valves. It can also provide predictive maintenance data that can contribute to the extension of the preventive maintenance for the ESD valve. The objectives of this paper are to design, simulate, build and test the performance of the automated PST system based on PLC. Four guidelines and methodology are used in this work. First, understanding the operation of the PST system. Then, the utilization of the capability of MATLAB-Simulink software as the simulation tool for the PST design system. Next, designing the PST automated system based on PLC design and lastly, testing the performance of the PST design system using lab scale PST system prototype that has been built. Results of the project shows that the PST system is successfully designed and simulated via MATLAB-Simulink and the PLC programming is working in the correct order as performed on the prototype

Modelling of Diagnostics Influence on Control System Safety

If the control system besides the standard control functions also realizes the functions (known as safety functions), failures of which can influence safety of the controlled process, then the control system may be a source of risk for assets, that are within the scope of the controlled process. Early detection of these failures and subsequent negation of their effects can have a significant influence on the safety integrity level of the safety function and thus also on the elimination of risks related to the controlled process. Therefore, the diagnostics is the means which, if appropriately applied, can increase not only the availability, but also the safety of the control system. The paper deals with using the homogeneous Markov chains to influence the evaluation of on-line diagnostics on the hardware safety integrity of the safety function, depending on the application method of several simultaneously operating diagnostics mechanisms and their basic parameters - the failures diagnostic coverage coefficient and the failure diagnostics time

Safety lifecycle management in the process industries : the development of a qualitative safety related information analysis technique

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Partial stroke testing for emergency shutdown valve using integrated PLC control design and human-machine interface

Partial stroke testing (PST) is a technique that is regularly practiced in oil and gas industries to test the emergency shutdown valve (ESD) by closing a certain percentage of the valve position and stop any flow through the pipeline. Generally, it only functions when there is an emergency occurs in the production system. When the ESD valve remains in one position for a long period, there is a risk and potential of fail on demand which is, the ESD valve fail to operate during the emergency shutdown. The partial stroke testing system still requires manual ignition by human. The distance between the control box with the plant area is limited which might increase the risk in safety issue to the workers. The objectives of this project are to design the PST automated system based on PLC design and to test the performance of the PST design system using lab scale PST system design. The capability of Mitsubishi GT-Designer 3 and Mitsubishi GX-Developer / GX Works 2 as the Human-Machine Interface (HMI) simulation platform for the PST design is applied. The system control and monitoring of PST will be developed by using Mitsubishi GT-Designer 3 interfacing it with Mitsubishi GX-Developer. This interfacing does not only control the mode of the system, it allows data monitor from the HMI which is the PC such as the state of the valve, alarm when PST failed, the alarm history records and pressure flow data. Then, the PST is simulated and tested in real time using PLC design system connected with a PC

Reliability modeling and analysis for a novel design of modular converter system of wind turbines

Converters play a vital role in wind turbines. The concept of modularity is gaining in popularity in converter design for modern wind turbines in order to achieve high reliability as well as cost-effectiveness. In this study, we are concerned with a novel topology of modular converter invented by Hjort, Modular converter system with interchangeable converter modules. World Intellectual Property Organization, Pub. No. WO29027520 A2; 5 March 2009, in this architecture, the converter comprises a number of identical and interchangeable basic modules. Each module can operate in either AC/DC or DC/AC mode, depending on whether it functions on the generator or the grid side. Moreover, each module can be reconfigured from one side to the other, depending on the system\u27s operational requirements. This is a shining example of full-modular design. This paper aims to model and analyze the reliability of such a modular converter. A Markov modeling approach is applied to the system reliability analysis. In particular, six feasible converter system models based on Hjort\u27s architecture are investigated. Through numerical analyses and comparison, we provide insights and guidance for converter designers in their decision-making

Математична модель надійності для аналізу непрацездатних станів електротехнічної системи із загальним навантажувальним резервуванням

Математична модель надійності для аналізу непрацездатних станів електротехнічної системи із загальним навантажувальним резервуванням

The 1981 current research on aviation weather (bibliography)

Current and ongoing research programs related to various areas of aviation meteorology are presented. Literature searches of major abstract publications, were conducted. Research project managers of various government agencies involved in aviation meteorology research provided a list of current research project titles and managers, supporting organizations, performing organizations, the principal investigators, and the objectives. These are tabulated under the headings of advanced meteorological instruments, forecasting, icing, lightning and atmospheric electricity; fog, visibility, and ceilings; low level wind shear, storm hazards/severe storms, turbulence, winds, and ozone and other meteorological parameters. This information was reviewed and assembled into a bibliography providing a current readily useable source of information in the area of aviation meteorology