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(a) Explain the principles of HAZOP.

Hazard and operability (HAZOP) studies are undertaken by the application of a formal,

systematic, and critical approach to examine the process and engineering intentions of a process design. The potential for hazard is thus assessed, and the chances of malfunction

of an individual equipment and its consequences for a whole system, are identified. The

examination of the design is structured around a specific set of guidewords, and then

ensure complete coverage of all possible problems while allowing sufficient flexibility for 

an imaginative approach.

The overall aims to which any HAZOP should be addressed are:

1. To identify all deviations from the way the design is intended to work, their causes, and 

all the hazards and operability problems associated with these deviations.

2. To decide whether action is required to control the hazard or the operability problem,

and if so, to identify the ways in which the problems can be solved.

3. To identify cases where a decision cannot be taken immediately and to decide on what 

information or action is required.

4. To ensure actions decided are followed through. 

HAZOP can be used on new plant, part of the plant or existing facilities, but is always

 best done at the design stage. Any change or modification to such plant, temporary or 

 permanent must also undergo a HAZOP to ensure plant safety is not jeopardised by the

change.

(b) Explain the principles of FTA (Fault Tree Analysis)

Fault tree analysis is one of many symbolic "analytical logic techniques" found in

operations research and in system reliability. In many cases there are multiple causes for 

an accident or other loss-making event. Fault tree analysis is one analytical technique for 

tracing the events which could contribute. It can be used in accident investigation and in a

detailed hazard assessment.

It uses a top-down block diagram approach by working backwards from a top event or 

undesired occurrence. The fault tree diagram is constructed by using this reverse logic to

establish relationship between cause and event.

(c) Explain the principles of ETA (Event Tree Analysis)

Event tree analysis (ETA) is an analysis technique for identifying and evaluating the

sequence of events in a potential accident scenario following the occurrence of an

initiating event. ETA utilizes a visual logic tree structure known as an event tree (ET).

The objective of ETA is to determine whether the initiating event will develop into a

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serious incident/accident/failure/damage or if the event is sufficiently controlled by the

safety systems and procedures implemented in the system design.

An ETA can result in many different possible outcomes from a single initiating event, and 

it provides the capability to obtain a probability for each outcome. The purpose of ETA is

to evaluate all of the possible outcomes that can result from an initiating event. Generally,there are many different outcomes possible from an initiating event, depending upon

whether design safety systems work properly or malfunction when needed. ETA provides

a probabilistic risk assessment (PRA) of the risk associated with each potential outcome.

(d) Explain the principles of FMEA (Failure Mode and Effects Analysis)

Failure Mode and Effects Analysis (FMEA) is an analytic tool with methodologies

designed to identify potential failure modes for a product or process, to assess the risk 

associated with those failure modes, to rank the issues in terms of importance and toidentify and carry out corrective actions to address the most serious concerns.

In general, Failure Modes, Effects Analysis (FMEA) requires the identification of the

following basic information:

  Item(s)

  Function(s)

  Failure(s)

  Effect(s) of Failure

  Cause(s) of Failure

  Current Control(s)

  Recommended Action(s)

  Plus other relevant details

Most analyses of this type also include some method to assess the risk associated with the

issues identified during the analysis and to prioritize corrective actions.