HAZOP_GUIDE_BRITISH_STANDARD_IEC_61882_2001

32 design intent designers desired or specified range

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Unformatted text preview: quantitative property of an element NOTE Examples of characteristics are pressure, temperature, voltage. 3.2 design intent designer’s desired, or specified range of behaviour for elements and characteristics 6 6 © BSI 28 1002−80ISB © 1002−80 ISB August 2001 BS IEC 61882:2001 6 1882 Ó I EC:2001 –8– 3.3 deviation departure from the design intent Licensed Copy: Puan Ms. Norhayati, Petroliam Nasional Berhad 4397000, 01 October 2003, Uncontrolled Copy, (c) BSI 3.4 element constituent of a part which serves to identify the part’s essential features NOTE The choice of elements may depend upon the particular application, but elements can include features such as the material involved, the activity being carried out, the equipment employed, etc. Material should be considered in a general sense and includes data, software, etc. 3.5 guide word word or phrase which expresses and defines a specific type of deviation from an element’s design intent 3.6 harm physical injury or damage to the health of people or damage to property or the environment 3.7 hazard potential source of harm 3.8 part section of the system which is the subject of immediate study NOTE A part may be physical (e.g. hardware) or logical (e.g. step in an operational sequence). 3.9 risk combination of the probability of occurrence of harm and the severity of that harm 4 4.1 Principles of HAZOP Overview A HAZOP study is a detailed hazard and operability problem identification process, carried out by a team. HAZOP deals with the identification of potential deviations from the design intent, examination of their possible causes and assessment of their consequences. Key features of HAZOP examination include the following. · T he examination is a creative process. The examination proceeds by systematically using a series of guide words to identify potential deviations from the design intent and employing these deviations as “triggering devices” to stimulate team members to envisage how the deviation might occur and what might be the consequences. · T he examination is carried leader, who has to ensure logical, analytical thinking. records identified hazards resolution. © BSI ISB © 1002−80 August 1002−8028ISB © 2001 out under the guidance of a trained and experienced study comprehensive coverage of the system under study, using The study leader is preferably assisted by a recorder who and/or operational disturbances for further evaluation and 7 BS IEC 61882:2001 6 1882 Ó I EC:2001 –9– T he examination relies on spets from various disciplines with appropriate skills and experience who display intuition and good judgement. · T he examination should be carried out in a climate of positive thinking and frank discussion. When a problem is identified, it is recorded for subsequent assessment and resolution. · Licensed Copy: Puan Ms. Norhayati, Petroliam Nasional Berhad 4397000, 01 October 2003, Uncontrolled Copy, (c) BSI · S olutions to identified problems are not a primary objective of the HAZOP examination, but if made they are recorded for consideration by those responsible for the design. HAZOP studies consist of four basic sequential steps, shown in Figure 1. 8 8 © BSI 28 1002−80ISB © 1002−80 ISB August 2001 BS IEC 61882:2001 6 1882 Ó I EC:2001 – 10 – Definition (6.1-3) Licensed Copy: Puan Ms. Norhayati, Petroliam Nasional Berhad 4397000, 01 October 2003, Uncontrolled Copy, (c) BSI · Define scope and objectives · Define responsibility · Select team Preparation (6.4) · · · · · Plan the study Collect data Agree style of recording (6.6.2) Estimate the time Arrange a schedule Examination (6.5) · · · · · · · · · Divide system into parts Select a part and define design intent Identify deviation by using guide words on each element Identify consequences and causes Identify whether a significant problem exists Identify protection, detection, and indicating mechanisms Identify possible remedial/mitigating measures (optional) Agree actions Repeat for each element and then each part of the system Documentation and follow-up (6.6-7) · · · · · · Record the examination Sign off the documentation Produce the report of the study Follow up that actions are implemented Re-study any parts of system if necessary Produce final output report IEC 450/01 Figure 1 – The HAZOP study procedure © BSI ISB © 1002−80 August 1002−8028ISB © 2001 9 BS IEC 61882:2001 6 1882 Ó I EC:2001 Licensed Copy: Puan Ms. Norhayati, Petroliam Nasional Berhad 4397000, 01 October 2003, Uncontrolled Copy, (c) BSI 4.2 – 11 – Principles of examination The basis of HAZOP is a “guide word examination” which is a deliberate search for deviations from the design intent. To facilitate the examination, a system is divided into parts in such a way that the design intent for each part can be adequately defined. The size of the part chosen is likely to depend on the complexity of the system and the severity of the hazard. In complex systems or those which present a high hazard the parts are likely to be small. In simple systems or those which present low hazards, the use of larger par...
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