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Unformatted text preview: lications of this DJ 12 Tachometer Output signal AS WELL AS Confused output signal Other signals mixed in May indicate wrong speed Investigate whether this is a credible failure BA – 97 – Guide word 6 8812 E BS IEC 61882:2001 I2:C100 40 04 Table B.3 ( continued) © BSI 28 August 2001 1002−80 ISB © 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 B.4 – 42 – Example involving emergency planning Organizations make plans to deal with a variety of anticipated emergencies. These emergencies can vary from reaction to a bomb threat, the provision of emergency power supplies or the escape of personnel in the event of a fire. The validity and integrity of these plans can be tested in a variety of ways – typically by some form of rehearsal. Such rehearsals are valuable, but can be expensive and, by their very nature, disrupt normal working. Fortunately, real emergencies which test the system are rare and in any case, even rehearsals may not cover all possibilities. HAZOP studies offer a relatively inexpensive way of identifying many of the deficiencies which may exist in an emergency plan, in order to supplement the experience obtained by the relatively infrequent rehearsal or the even rarer actual emergency itself. On an offshore oil and gas platform there needs to be in place effective arrangements for Escape, Evacuation and Rescue (EER) in the event of potentially life-threatening incidents. These arrangements would aim to ensure that personnel are quickly alerted to the existence of a dangerous situation, are able to make their way rapidly to a safe muster point, then evacuate the platform preferably in a controlled manner by helicopter or lifeboat and then be rescued and taken to a place of safety. Effective EER arrangements are an essential part of an overall offshore installation system. Within typical EER arrangements there are usually a number of different stages (elements) such as: a) raising the General Purpose Alarm (GPA) by automatic instruments or manually by any operator; b) communicating the situation both to the local stand-by vessel and to onshore emergency services; c) personnel making their way along designated access routes to the muster point; d) mustering involving registration of personnel present; e) donning of survival equipment, etc.; f) await “Prepare to Abandon Platform Alarm” (PAPA) which has to be initiated by the Offshore Installation Manager (OIM) or his deputy; g) egress in which personnel make their way from the muster point to the chosen method of evacuation; h) evacuation normally by helicopter or by special forms of lifeboat; i) escape directly into the sea if the preferred means of evacuation is not available; j) rescue, where either personnel in a lifeboat or those who had escaped directly into the sea would be recovered and taken to a place of safety. © BSI ISB © 1002−80 August 1002−8028ISB © 2001 41 14 14 Licensed Copy: Puan Ms. Norhayati, Petroliam Nasional Berhad 4397000, 01 October 2003, Uncontrolled Copy, (c) BSI 6 8812 E BS IEC 61882:2001 I2:C100 42 24 Table B.4 – E xample HAZOP worksheet for emergency planning PART CONSIDERED: ALARM SYSTEM DESIGN INTENT: TO SOUND A GENERAL PURPOSE ALARM (GPA) ELEMENTS: INPUTS: INITIATION SIGNAL ELECTRICAL ENERGY PERSONNEL: SOURCES: DESTINATIONS: No. ALL ALARM GENERATORS ALL PERSONNEL ON PLATFORM Deviation Possible causes Consequences Safeguards Comments Actions required GPA Initiation signal and electrical energy NO No inputs 1) Instruments or personnel do not initiate GPA Failure to alert personnel None Unlikely but possible None As above Duplicated connections and fail safe logic, i.e. "Current to open, spring to close" Unlikely 3) No electrical energy As above Uninterruptible power supply As above 1) False alarm Personnel stressed unnecessarily None Possible Should initiation require two buttons? 2) Mischief alarm As above Discipline and code of practice Unlikely None Unlikely None 2 © BSI 28 August 2001 1002−80 ISB © 3 4 MORE Inputs More inputs MORE More inputs More electrical energy Damage to alarm system Dedicated protected power supply LESS Less initiation Initiation signal only reaches some alarms Some personnel not alerted Routine alarm checks Action by – 38 – Guide word 2) Personnel try to initiate GPA, but signal fails to reach alarm 1 Element None Licensed Copy: Puan Ms. Norhayati, Petroliam Nasional Berhad 4397000, 01 October 2003, Uncontrolled Copy, (c) BSI No. Element Guide word AS WELL AS 7 Consequences Safeguards Comments Actions required Some loss of power Alarms may not sound Dedicated power supply Unlikely None As well as initiation Initiation triggers other activities As well as electrical energy 6 Possible causes Less electrical energy 5 Deviation Some energy in wrong form, e.g. spikes Possible damage Personnel not alerted PART OF Part of inputs Signal but no energy or energy but no signal 9 REVERSE Reverse inputs Multiple None No constructive meaning Other than inputs Screened supply circuit Reverse of alarm initiation Reverse electrical energy None 10 Inputs OTHER THAN Already considered above System as described does not include the sounding of an "all clear" Depends on inputs Unlikely with dedicated shielded circuits Develop an "all clear" system May need "battle proof" system Consider Pyrotenax wiring – 58 – 8 Not possible...
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