This page is under development and will during the spring and summer of 2014 be subject to many changes.
TPK 5170 RAMS Assessment and Optimization
...adds new methods and skills to your RAMS toolbox of useful tools, methods, and models.
Brief background of course
This course is the specialization course in reliability, availability, maintenance and safety (RAMS) in the last fall semester of the (2 year) international RAMS program and the (5 year) program in Mechanical Engineering (in Norwegian: Produktdesign og Produksjon - PUP).
The course is a continuation of RAMS methods with special emphasise on the application of methods, for example for the optimization of system design, operation, and maintenance. The course is part of the big envelope of courses given from the department of Production and Quality Engineering at NTNU, and it is lectured with personnel that belong to the RAMS group at this department. It is expected that the students already have taken (or have relevant background corresponding to):
- TPK 4120: Safety and Reliability
- TPK 4140: Maintenance Management
- TPK 5160: Risk Analysis
This course replaces the earlier arrangement with two specialization modules, one in risk and reliability and one in maintenance optimization (each with 3.75 credit points). The new (merged) course TPK 5170 therefore includes both subject areas: risik and reliability and maintenance optimization, and gives 7.5 credits (i.e., as a regular course normally does at NTNU).
It may be remarked that this course may, from the fall of 2015, change the name to "Asset management methods". A new course in "Reliability of safety-critical systems" may also be introduced. The course content may therefore change as a result of these changes. The changes will be available http://www.ntnu.edu/studies/courses, once implemented. The course responsible person in the fall of 2014 is Professor Mary Ann Lundteigen. I will also give about 50% of the lectures. This this is a specialization course, need the support of some "specialists" on certain topics. Some special topics will thererfore be lectured by Associate Professor Yiliu Liu and our new (at NTNU) Professor Anne Barros. As the course responsible, I will always be present in the lectures (with one or two exceptions) , also those not given by me.
Course objective and motivation
The main objective of this course is to increase the depth of understanding about RAMS methods.
Think about a system. A system will typically constitute many different parts and together they will perform many different functions. The system may be production critical, safety-critical, or even both. Safety systems may be mainly there to protect personnel from injury and death, or to protect the environment from severe damages. Railway signaling systems are one example of the first, and high pressure protection systems onboard an offshore facilitiy may be an example of the latter. Production-critical systems may, if they fail, cost "a whole lot", and have a severe effect on a manufacturer reputation, the quality of products developed, and the costs associated with correcting the system after failure. Critical infrastructures may be consideres as both production and safety-critical. Stable and safe public transportation, clean and stable water supply, power supply, and net supply are important for serving the society and business, and a failure of these could affect safety at a local level as well as at a national level.
Some key questions to ask in relation to such systems are shown in the figure below, and in many cases, they need to be solved using RAMS assessment and optimization methods.
This means that methods already introduced in other courses are studied in more detail, with assistance of new application examples and new perspectives. Some new methods are also introduced so that the students, after having taken the course, will have a heavy weighted toolbox of methods to use in their future work tasks.
Learning outcome
More specifically, the learning outcome should be:
Knowledge:
Basic insight into the theoretical foundation and practical applications of RAMS assessment and optimization.
Skills:
Being able to identify and use framework and methods available to solve RAMS assessment and optimization tasks, and to select suitable methods for also more complicated situations. Solve optimization problems in practice. Assess RAMS performance for systems.
General competence:
Understand RAMS as an important cornerstone of industrial and commercial systems and in the public administration.
Topics lectured
Topics to be covered are as part of the course are (organized according to whether the application is mainly for safety-critical systems or production-critical systms, or both) presented below. Note that more than one lecture may be used to cover one particular topic. See the lecture plan for more details.
Reliability analyses of safety-critical systems
- Development of reliability requirements
"Safety integrity level (SIL) is a key reliability performance measure used for safety-critical systems. Reliability requirements are therefore often given as SIL requirements are identified in an extension of the risk analysis, using methods often refered to as SIL allocation, SIL targeting and SIL classification. Key methods like Layers of protection analysis (LOPA), risk graph, and minimum SIL are presented and discussed." - Reliability analyses: Extending with new analytical & dynamic modeling approaches.
"In TPK 4120, some analytical formulas were introduced to calculate the average probability of failure on demand (PFD). It was also shown how the average PFD may be calculated using Markov methods and fault tree analysis. This reliability measure is of high importance in relation to SIL, as a relationship is established between a SIL requirement and the maximum PFD tolerated for a safety function. In this course, we go a step further and introduce the foundations for analytical formulas presented in IEC 61508 (a key standard for reliability of safety-critical systems), the PDS method (a method along with a set of analytical formulas widely adapted in the Norwegian oil and gas industry, but which has a wider application area), and dynamic modeling, using Petri Nets." - Special analysis challenges (possible candidates for under this heading):
- Partial and imperfect testing
- Follow-up of SIL requirements in the operational phase
- Hardware fault tolerance - Hardware design constraints of safety-critical functions
Relevance:
- Some examples showing the relevance of this topic may be found with consultancy companies, such as with Safetec, Lloyd's Register Consulting, and DNV-GL (link to the GL-part of the services), and Lilleaker Consulting. Manufacturers like ABB, Siemens, AkerSolutions, FMC, Kongsberg Maritime and many more need to design systems in light of SIL requirements, and also demonstrate (sometimes with assistance of the consultancy companies) that the SIL requirements are met. End users, like railway service providers like Jernbaneverket, oil companies like Statoil, Det Norske, GDF-Suez, Shell and Conoco-Phillips among some, and owners of smelting plants, owners of water power stations must demonstrate that the SIL requirements continue to be met throughout the life of the systems.
Maintenance optimization (production critical systems):
Lecture material supporting this topic are:
- Age, block and minimal repair strategies.
The intervals of maintenance for safety-critical systems are normally determined from the reliability analyses. For other systems, we may use decide upon intervals of testing using different maintenance strategies. These models include parameters like costs, failure rates, and aging. The models come of with the answer to the following two questions: When should we do maintenance and what tasks and equipment should be included. The application of these methods are many. Two examples are maintenance planning of railway tracks and another is planning of intervention (for maintenance purposes) of subsea equipment.
- Modeling of effective failure rate:
Maintenance interval and and intervention level (extensiveness of maintenance) is obviously influencing the failure rate of the components. This topic concerns the modeling of the relationship between these two parameters and what we can refer to as the effective (or resulting) failure rate.
- Weibull renewal
How to define requirements for safety systems and barriers, and how to assess the reliability of safety instrumented systems with background in IEC 61508 and related standards. This includes SIL allocation, risk acceptance criteria, requirements for design of technical and operational barriers, alternative strategies for treatment of common cause failures, various methods for determining proof test intervals, and trade off between safety and regularity. Within maintenance optimization the following topics are covered: Age, block, and minimal repair policies. Optimisation of intervals and intervention level in condition monitoring models. Optimum grouping of maintenance activities. Spare part optimisation. Reliability Centred maintenance. Data collection and analysis. In relation to technical safety we study how the result from the risk analysis may be utilized to assess the effect of various safety system configurations, and combination of these under various constraints.
Tutorials
Reliability analyses:
Tutorials will focus on the application of lectured methods, and in particular comparing results of using different approaches. Two or three case studies will be introduced and used as basis for the problem solving. Matlab, Maple and Grif (the latter is a rather recent software for reliability assessment in use here at the NTNU) will be preferred to assist the reliability analyses.
Maintenance optimization: