HAZOP_GUIDE_BRITISH_STANDARD_IEC_61882_2001

Equipment piping and system layout c for programmable

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: sheets, functional block diagrams, control diagrams, electrical circuit diagrams, engineering data sheets, arrangement drawings, utilities specifications, operating and maintenance requirements; b) for process flow systems: · p iping and instrumentation diagrams, material specifications and standards equipment, piping and system layout; c) for programmable electronic systems: · d ata flow diagrams, object-oriented design diagrams, state transition diagrams, timing diagrams, logic diagrams. In addition, the following information should be provided: · t he boundaries of the object of the study and the interfaces at the borders; · e nvironmental conditions in which the system will operate; · o perating and maintenance personnel qualifications, skills and experience; · p rocedures and/or operating instructions; · o perational and maintenance experience and known hazards with similar systems. 6.4.3 Guide words and deviations In the planning stage of a HAZOP study, the study leader should propose an initial list of guide words to be used. The study leader should test the proposed guide words against the system and confirm their adequacy. The choice of guide words should be considered carefully, as a guide word which is too specific may limit ideas and discussion, and one which is too general may not focus the HAZOP study efficiently. Some examples of different types of deviation and their associated guide words are given in Table 3. 18 81 81 © BSI 28 1002−80ISB © 1002−80 ISB August 2001 BS IEC 61882:2001 6 1882 Ó I EC:2001 – 20 – Table 3 – Examples of deviations and their associated guide words Guide word Example interpretation for process industry Example interpretation for a Programmable Electronic System, PES Negative Licensed Copy: Puan Ms. Norhayati, Petroliam Nasional Berhad 4397000, 01 October 2003, Uncontrolled Copy, (c) BSI Deviation type NO No part of the intention is achieved, e.g. no flow No data or control signal passed Quantitative modification MORE A quantitative increase, e.g. higher temperature Data is passed at a higher rate than intended LESS A quantitative decrease e.g. lower temperature Data is passed at a lower rate than intended AS WELL AS Impurities present Simultaneous execution of another operation/step Some additional or spurious signal is present PART OF Only some of the intention is achieved, i.e. only part of an intended fluid transfer takes place The data or control signals are incomplete REVERSE Covers reverse flow in pipes and reverse chemical reactions Normally not relevant OTHER THAN A result other than the original intention is achieved, i.e. transfer of wrong material The data or control signals are incorrect EARLY Something happens early relative to clock time, e.g. cooling or filtration The signals arrive too early with reference to clock time LATE Something happens late relative to clock time, e.g. cooling or filtration The signals arrive too late with reference to clock time BEFORE Something happens too early in a sequence, e.g. mixing or heating The signals arrive earlier than intended within a sequence AFTER Something happens too late in a sequence, e.g. mixing or heating The signals arrive later than intended within a sequence Qualitative modification Substitution Time Order or sequence Guide word – element/characteristic combinations may be interpreted differently in studies of different systems, at different phases of the system life cycle, and when applied to different design representations. Some of the combinations may not have meaningful interpretations for a given study and should be disregarded. The interpretation of all guide word – element/characteristic combinations should be defined and documented. If a given combination has more than one sensible interpretation in the context of the design, all interpretations should be listed. On the other hand, it may also be found that the same interpretation is derived from different combinations. When this occurs, appropriate cross references should be made. 6.5 The examination The examination sessions should be structured, with the study leader leading the discussion following the study plan. At the start of a HAZOP study meeting the study leader or a team member who is familiar with the process to be examined and its problems should · o utline the study plan, to ensure that the members are familiar with the system and objectives and scope of the study; © BSI ISB © 1002−80 August 1002−8028ISB © 2001 19 91 91 BS IEC 61882:2001 6 1882 Ó I EC:2001 – 21 – o utline the design representation and explain the proposed elements and guide words to be used; · Licensed Copy: Puan Ms. Norhayati, Petroliam Nasional Berhad 4397000, 01 October 2003, Uncontrolled Copy, (c) BSI · r eview the known hazards and operational problems and potential areas of concern. The analysis should follow the flow or sequence related to the subject of the analysis, tracing inputs to outputs in a logical sequence. Haza...
View Full Document

Ask a homework question - tutors are online