73499 - Safety and Loss Prevention M

Course Unit Page


This teaching activity contributes to the achievement of the Sustainable Development Goals of the UN 2030 Agenda.

Good health and well-being Industry, innovation and infrastructure Sustainable cities Responsible consumption and production

Academic Year 2018/2019

Learning outcomes

The aim of the course is to give students the basic theoretical notions and the technical tools for:
- the identification of hazards;
- the evaluation of the consequences of accidents (through the consequence analysis and the damage models);
- the evaluation of their occurrence frequency (through reliability engineering);
- the assessment of risk measures as a combination of frequencies and consequences.
The knowledge of these issues is necessary to manage safety problems during the whole lifetime of a plant and also to assure compliance with the safety regulations of the process industries.

Course contents


The course is offered during the last year of the master degree. This implies that it is in some way "recapitulatory" with respect to the whole study plan. In fact, the analysis of the safety aspects of the process industries and of their risk quantification requires an overall view of the features of these installations, and this view is usually gained only at the end of the studies.

To fruitfully attend the classes and to fully understand the course contents, it's necessary to have a robuts knowledge of the fundamentals of termodynamics (specifically of the mass and energy balances - even in presence of phase transitions and chemical reactions - and of the vapour-liquid equilibria), of fluidodinamics (specifically of the Bernoulli equation and of the outflow of gas in critical conditions), of the transport phenomena (specifically of the local balances of mass, energy, momentum), of Boolean algebra and of calculus of probabilities.

Classes are in Italian: to fruitfully attend classes, a good comprehension of Italian is necessary (B2 level). For students not understanding Italian, it's possible to study the course contents on readings and bibliography fully in English.

COURSE CONTENS for a.y. 2018-2019


The concept of risk. Classification of risks. Industrial risk. Risk of major accidents. The concept of safety and its context. Individual / local risk. Societal Risk. The steps of a quantified risk analysis study. Risk acceptability criteria. Risk reduction. Residual risk. The norms concerning the risk of major accidents in Europe and in Italy.


Introduction. Hazardous properties of substances. A specific focus on flammability. A specific focus on toxicity. Classification of substances (introduction to the GHS system and the CLP regulation). The [Material] Safety Data Sheet. Labeling of substances. The REACH regulation.


Introduction. Analysis of case histories. Checklists. Safety reviews. HAZOP analysis. What-if analysis. FMEA and FMECA. Criteria for selecting the suitable HazID tecnique.


Introduction. Damage of fires, explosions, toxic clouds. Probit equations. Models based on threshold values. Threshold values proposed by the Italian law.


Source models. Storage conditions in the process industries. Outflow of liquid: through a hole; through a hole in a tank; through a pipe. Basic notions about the outflow of vapour through a hole in a tank. Flashing liquids. Outflow of pressure liquefied gases. Pools.
Fires. Introduction. Poolfire. Jet-fire. Fireball. Flash-fire.
Dispersion. Classification of models. The dispersion of neutral gases (from a steady-state source; for an instantaneous source; form a punctual source; form a source with finite dimensions; the evaluation of the dispersion coefficients; concentration profiles; concentration contours; mass in the flammable range; plume rise models; puff passage time). Basic notion about the dispersion of heavy gases. Basic notions about transformation and removal phenomena.
Explosions. Introduction and classification. Unconfined vapour cloud explosions (UVCE). Physical explosions and BLEVEs.
Post-release event trees: for flammable liquids; for flammable pressure liquefied gases.
Software for consequence analysis.


Introduction. Basic notions about probabilities. Non repairable components: probabilistic parameters of the repair-to-failure process (R, F, lambda, f, MTTF) and their relationships. Repairable components: probabilistic parameters of the whole repair-failure-repair process (A, Q, lambdar, mur, w, v, W, V, MTBF, MTBR) and their relationships. Systems reliability: the analysis of complex systems by means of fault trees.


Example of calculation of individual and societal risk of a distillation column.


An introduction to inherent safety. An introduction to runaway reactions.




Reference books:

  • Lees' Loss Prevention in the Process Industries, S. Mannan editor, IV ed., Butterworth-Heineman, Oxford, UK, 2012
  • R.Rota, G. Nano, Introduzione alla affidabilità e sicurezza nell'industria di processo, Pitagora Ed., Bologna, I, 2007
  • D.A.Crowl, J.F.Louvar, Chemical process safety: fundamentals with applications, III ed., Prentice Hall, New Jersey, USA, 2011
  • Centre for Chemical Process Safety of AIChE, Guidelines for chemical process quantitative risk analysis (II ed.), New York, USA, 1999
  • Center for Chemical Process Safety of AIChE, Guidelines for hazard evaluation procedures (III ed.), AIChE, New York, USA, 2008
  • TNO, Methods for the calculation of physical effects (Yellow book). Report CPR 14E (III ed.), The Hague, NL, 2005
  • H. Kumamoto, E. Henley, Probabilistic Risk Assessment and Management for Engineers and Scientists, 2nd edition, IEEE Press, New York, 2000

You can find all these books (in some cases in one of the previous editions) at the Library F.P.Foraboschi in via Terracini 28; for information about the availability of the books, please contact the librarian (Annalisa Neri, annalisa.neri@unibo.it)

Teaching methods

- Notes personally taken during the classes

- Material available on the e-learning platform of University of Bologna till the end of July 2019 (the access is limited to the students of the mailing list of the course, a.y. 2018/2019):

    copy of the dias used during the lessons

    supplementary readings

    audio / video files on specific topics

    specic software tools

    transcripts (txt format, only in Italian) of the classes held during a.y. 2014/15

Assessment methods

The exam has the aim to verify that the student has achieved the following goals:

- knowledge of the risk indexes adopted for the quantification of the risk of major accidents and of the methodological approach for their estimate;

- knowledge of the most important techniques for hazard identification;

- knowledge of the different kinds of accidental scenarios arising form a loss of containment of flammable and/or toxic fluids;

- knowledge of the consequence analysis models for the evaluation of the consequences of accidental scenarios and of the reliability engineering models for the estimate of their occurrence frequency.

The exam consists in an oral proof, generally of about 45 – 60 minutes. During the oral proof the student can be required to sketch out simple numerical exercises related to the course contents. "Simple" means that the use of a PC is not necessary, nor it is necessary to retrieve data about the chemical, physical and hazardous properties of the substances, or to perform difficult conversion of unit measures. Students should refer, as an example, to the exercises explained by the teacher during the lessons. At the exam students can (but are not forced to) present a free choice topic. The topic can be selected among those explained by the teacher or it can be a different one (but related to safety and risk aspects). In the latter case the student can prepare a brief computer presentation to support the oral exposition, which should be limited to 10 minuets. The same topic can be selected by more than one student, each one preparing his own exposition or, alternatively, a single topic can be presented by a group of 2 – 3 students presenting themselves for the exam on the same day. The topic can be a theoretical one or a numerical simulation.

To obtain a passing grade, students are required to at least demonstrate a knowledge of the key concepts of hazardous substances, of the indexes to express the risk of major accidents, of the successive steps of the risk analysis methodology and of their connections, of the main mathematical models of each step and of the meaning and unit measures of the most important parameters of these models, also being able to sketch out simple exercises. Higher grades will be awarded to students who demonstrate an organic understanding of the subject and a high ability for critical application, a clear presentation of all the course contents and the ability to face more complex problems related to safety aspects and risk quantification, applying in an appropriate manner  the expertise aquired in the whole duration of the studies. A failing grade will be awarded if the student shows knowledge gaps or superficial knowledge of several topics, confusion in distinguishig the accidental scenarios one from the other, poor knowledge of the key-concepts of relialibility engineering.

No dates are fixed for the exam for the students who make the exam for the firs time. Student have to ask the teacher for an appointment (by phone or e-mail), at least 2 days before the day they would like to make the exam. The teacher will try to satisfy the request, with a variability of 1 or 2 working days. Students who repeat the exam will be examined on fixed dates established by the teacher ( 6 days per year, on the end of January, February, June, July, September, October). The teacher will communicate long absences form work, as well as the fiexd dates for the students who must/want repeat the exam, on her webpage, in the section of the notices (avvisi): Sarah Bonvicini - Notices.

The exam will be performed in the office of the teacher, at DICAM - Dipartimento di Ingegneria Civile, Chimica, Ambientale e dei Materiali in via Terracini 28 (II floor, after the stairs door on the left).

Students retiring during the exam or not obtaining a positive mark can present themselves for a new exam after at least 21 days (=3 weeks) in the first useful date fixed by the teacher; the teacher will fix 6 dates per year for repeating the exam. Students can reject a positive mark only once and have to accept in any case a positive mark if obtained the second time; a positive mark can be refused only once and only if obtained the first time the student makes the exam. The teacher registers the exams at the end of each moth, inserting the date in which the student has been examined. The teacher usually registers negative marks too.

Teaching tools

  • Lessons performed with the aid of power point presentations
  • Viewing of videos 
  • Highlights about specific software tools
  • Numerical exercises

Office hours

See the website of Sarah Bonvicini