A Methodology For The Achievement Of Target SIL - ABB

1y ago
26 Views
2 Downloads
716.16 KB
24 Pages
Last View : 16d ago
Last Download : 2m ago
Upload by : Averie Goad
Transcription

A methodologyFor the achievement of Target SIL

Contents1.0 Methodology . 31.1 SIL Achievement - A Definition . 41.2 Responsibilities . 61.3 Identification of Hazards and SIL Determination . 81.4 Safety Requirements .151.5 Design and Engineering .151.6 Demonstrating SIL Achievement .151.7 Summary .15References .152 Oil & Gas and Petrochemical SIL Methodology

1.0 MethodologyThe purpose of this document is to describe a methodology bywhich an organisation can demonstrate that the Target SafetyIntegrity Level (SIL) of a safety instrumented function has beenachieved. Throughout this document this methodology is referredto as SIL Achievement.Successful demonstration that the Target SIL for a safetyinstrumented function has been achieved is reliant on manyaspects of the overall safety lifecycle, such as Hazard andRisk Assessment, SIL Determination, Safety RequirementsAllocation, and Realisation - phases 1 to 10 of the IEC 61508safety lifecycle.These phases are described in detail elsewhere in thismanual. The evidence required in order to demonstrate that asafety instrumented system function meets its Target SIL (i.e.the SIL Achievement exercise) is far more than a quantitativeexercise, based solely on target failure measure. Architecturalconstraints and Systematic capability must also be takeninto account. How all of this data is identified, interpretedand used for SIL achievement is described in the followingsections.SIL Methodology Oil & Gas and Petrochemical 3

1.1 SIL achievement - a definitionSIL Achievement is a demonstration that for each SafetyInstrumented Function, the Target SIL, as derived fromSIL Determination, has been met in accordance with therequirements of IEC61508. Achievement of SIL, for asafety instrumented function, is dependent on the followingparameters; Architectural Constraint, in terms of - Safe Failure Fraction(SFF) and - Hardware Fault Tolerance (HFT) Target Failure Measure, expressed as either:- Pfd, or- Dangerous Failure Rate (hour) Systematic Capability, in terms of- Each element* that carries out the safety function- The method by which the safety instrumented functionwas designed and implemented* An element relates to a piece of equipment, such as a limitswitch or a barrier. Multiple elements are connected to form thesubsystems (Sensor, Logic Solver and Output) of a safetyinstrumented function. Refer to section 1.5 for further information.Only when a safety instrumented function meets the criteria set byIEC 61508 in terms of architectural constraint, target failure4 Oil & Gas and Petrochemical SIL Methodologymeasure and systematic capability, can the Target SIL be said tobe achieved.The following sections provide guidance on; Responsibilities – the responsibilities of End User/Operators and Engineering/Equipment suppliers inproviding, compiling and demonstrating that the target SILhas been achieved Identification of Hazards and SIL Determination – identifyingthe safety instrumented functions, and assigning a TargetSIL Safety Requirements – The importance of SafetyRequirements in specifying the safety instrumentedfunction Design and Engineering – the importance of correctlyspecifying and integrating the equipment to be used toperform the safety instrumented function SIL Achievement – how to demonstrate that SIL has beenachieved for a specified safety instrumented function inrespect of a Safety Instrumented System.

1.2 ResponsibilitiesIn implementing any phase of the safety lifecycle, itis important to understand, and clearly define, theresponsibilities assigned to each organisation involved indelivering the safety instrumented system. When performingSIL Achievement, this is particularly important, becausewithout the correct activities, processes and data (outputs)specified during the front end activities of the Overall SafetyLifecycle, SIL Achievement not only becomes very difficult toperform, but the accuracy of the results and how they relateto each safety instrumented function could be brought intoquestion, challenging the initial design assumptions. Failureto achieve the Target SIL, as well as questioning whether theSafety Instrumented System is deemed fit for purpose, maywell have other far-reaching effects, such as affecting thefundamental architecture of the Safety Instrumented Systemand the resulting impact on schedule and cost.The safety lifecycle can be broken down into three key stages,Pre-Design, Design and Installation and Operation. For eachof these stages, responsibility can be assigned as follows;Responsibilities may be delegated to third parties, forexample: An Engineering/Procurement/Construction (EPC) companyoperating in the generic role of Engineering/EquipmentSupplier (see diagram) may be appointed by the End Userto perform pre-design; the EPC is responsible for deliveringthe required information to the next organisation in thesupply chain. A System Integrator may be appointed by the Engineering/Equipment supplier to perform the design of the logicsolver subsystem. The system integrator is responsible forengineering the logic solver in accordance with the safetyrequirements, and following good practice as defined inIEC 61508 and IEC 61511 during the design engineeringprocess. It is the responsibility of the Engineering/Equipment supplier to provide all the necessary informationto the System Integrator in order that the latter can buildthe Safety Instrumented System to meet the specifiedfunctional safety requirements.ResponsibilityEnd User/OperatorEngineering/EquipmentSupplierEnd User/OperatorActivitiesPre-Design(Phases 1-5 & 9)Correctly identify hazards, specifyrequirements, set the target SILDesign andInstallation(Phases 6-8 & 10-13)Configure to requirements,achieve the target SILOperation(Phases 14-16)Correctly operate, maintain,modify and maintain SILperformanceIt can be seen from the diagram above, that each organisationhas a responsibility to implement processes and to deliverpackages of work to the next organisation in the supply chain.For example, the End User or Operator has a responsibility toprovide sufficient information to the Engineering/EquipmentSupplier to allow them to complete the design stage of thesafety lifecycle.In terms of SIL Achievement, it is normally the responsibilityof the Engineering/Equipment supplier to demonstrate thatthe Target SIL has been achieved for each safety function, butthis is based on the premise that hazards have been correctlyidentified and safety requirements correctly specified by theEnd User/plant operator.SIL Methodology Oil & Gas and Petrochemical 5

1.3 Identification of hazards andSIL determinationWith reference to IEC61508-5 (clause A.2), the concept of riskreduction, ‘is of fundamental importance in the developmentof the safety requirements specification for the E/E/PE safetyrelated systems (in particular, the safety integrity requirementspart of the safety requirements specification). The purpose ofdetermining the tolerable risk for a specific hazardous eventis to state what is deemed reasonable with respect to boththe frequency (or probability) of the hazardous event and itsspecific consequences. Safety-related systems are designedto reduce the frequency (or probability) of the hazardousevent and/or the consequences of the hazardous event.’ Itis necessary that a hazard and risk analysis be undertakenon the Equipment Under Control (EUC) and the EUC controlsystem in order to identify the process hazards; the riskresulting from the hazardous event(s) associated with theidentified hazard and, if necessary, identify what has to bedone (prevention and/or mitigation) and to what performancecriteria, to ensure that the tolerable risk is achieved. Furtherinformation relating to the concept of tolerable risk can befound in IEC61511-3 (Annex A). To achieve functional safety itis necessary to determine: What has to be done to prevent the hazardous event (thesafety function); The required performance of each safety function (theSafety Integrity Level). Therefore, for each identified hazard,which requires a risk reduction measure, a safety functionis identified, which is required to meet a specified (Target)SIL. Typically Hazard and Operability Studies (HAZOP)are used to identify where protection is required and thesafety function required, whilst SIL determination methodsare employed (such as LOPA or Risk Graph) to determinethe required (target) SIL. These concepts are described indetail elsewhere in this document.For example, after performing a HAZOP study on theEquipment Under Control (EUC) and the EUC control system,the functionality of the safety function shall be specified. Forexample: ‘In order to prevent the rupture of pressure tankVS-01, Valve V-01-01 must be opened within 2 seconds,when the pressure in vessel VS-01 rises to 2.6 bar’ This is thefunctionality of the safety function.After performing the risk assessment, the safety integrity ofthe safety function shall be specified. For example:‘The safety integrity of the safety function must be SIL 1’ Thisis the Target SIL of the safety function.6 Oil & Gas and Petrochemical SIL MethodologyIn conclusion:‘In order to prevent the rupture of pressure tank VS-01,Valve V-01-01 must be opened within 2 seconds, when thepressure in vessel VS-01 rises to 2.6 bar’. The safety integrityof the safety function shall be SIL 1’An important concept here is that safety integrity is applied toa safety function, not to the safety-related system so; It is correct to say that ‘Safety Function x requires a TargetSIL of y’ It would be incorrect to say that the ‘safety related systemrequires a target SIL of y’, without also providing therequired safety integrity of each of the safety functionsexecuted by the safety-related system.The safety function descriptions and their associated targetSIL’s need to be provided to the Engineering/EquipmentSupplier, to enable them to complete Phase 10 of the OverallSafety Lifecycle, and ultimately demonstrate SIL Achievement.The mechanism by which this information (functionality of thesafety function and safety integrity of the safety function) isprovided is through the Safety Requirements Specification.

1.4 Safety requirementsFor every Safety Instrumented System, it is the responsibility of theend user/operator to provide a Safety Requirements Specificationto the engineering/equipment supplier. This is identified as Phase4, Overall Requirements, in the IEC 61508 safety lifecycle model.RefGuidance is provided in IEC 61508 Part 1 clause 7.10 regardingthe content of the Safety Requirements Specification, this isstrengthened, for the process industry, in IEC 61511 part 1 clause10.3.1. For completeness this guidance is given below:Requirement to be considered/addressed1A description of all the safety instrumented functions necessary to achieve the required functional safety2Requirements to identify and take account of common cause failures3A definition of the safe state of the process for each identified safety instrumented function4A definition of any individually safe process states which, when occurring concurrently, create a separate hazard (forexample, overload of emergency storage, multiple relief to flare system)5The assumed sources of demand and demand rate on the safety instrumented function6Requirement for proof-test intervals7Response time requirements for the SIS to bring the process to a safe state8The safety integrity level and mode of operation (demand/continuous) for each safety instrumented function9A description of SIS process measurements and their trip points10A description of SIS process output actions and the criteria for successful operation, for example, requirements for tightshut-off valves11The functional relationship between process inputs and outputs, including logic, mathematical functions and any requiredpermissives12Requirements for manual shutdown13Requirements relating to energize or de-energize to trip14Requirements for resetting the SIS after a shutdown15Maximum allowable spurious trip rate16Failure modes and desired response of the SIS (for example, alarms, automatic shutdown)17Any specific requirements related to the procedures for starting up and restarting the SIS18All interfaces between the SIS and any other system (including the BPCS and operators)SIL Methodology Oil & Gas and Petrochemical 7

1.4 Safety requirements continued19A description of the modes of operation of the plant and identification of the safety instrumented functions required tooperate within each mode20The application software safety requirements as listed in section 12.2.2 of IEC 61511-1(2003-01)21Requirements for overrides/inhibits/bypasses including how they will be cleared; the specification of any action necessary toachieve or maintain a safe state in the event of fault(s) being detected in the SIS. Any such action shall be determined takingaccount of all relevant human factors22The mean time to repair which is feasible for the SIS, taking into account the travel time, location, spares holding, servicecontracts, environmental constraints23Identification of the dangerous combinations of output states of the SIS that need to be avoided242526The extremes of all environmental conditions that are likely to be encountered by the SIS shall be identified. This may requireconsideration of the following: temperature, humidity, contaminants, grounding, electromagnetic interference/radiofrequency interference (EMI/RFI), shock/vibration, electrostatic discharge, electrical area classification, flooding, lightning,and other related factorsIdentification to normal and abnormal modes for both the plant as a whole (for example, plant start-up) and individual plantoperational procedures (for example, equipment maintenance, sensor calibration and/or repair). Additional safetyinstrumented functions may be required to support these modes of operationDefinition of the requirements for any safety instrumented function necessary to survive a major accident event, for example,time required for a valve to remain operational in the event of a fireThere is also an additional requirement to add to the tableabove regarding the consideration of the potential of cybersecurity threats to the system which should be identifiedduring the earlier hazard and risk assessment phases.A number of these requirements are a pre-requisite toperforming an accurate and complete SIL Achievement.For the purpose of this section, only those pre-requisiterequirements will be discussed.1.4.1 Safety Functions and Target SILFrom section 1.2, it can be seen that a key feature of thesafety requirements specification is to clearly identify eachsafety function in terms of its functionality and its Target SIL.Specifically: IEC61511-1 (Clause 10.3.1) requires:‘A description of all the safety instrumented functionsnecessary to achieve the required functional safety’8 Oil & Gas and Petrochemical SIL Methodology‘The safety integrity level and mode of operation (demand/continuous) for each safety instrumented function’Frequent use is made of Cause and Effect charts, often as asubstitute for Safety Requirements Specifications. However,whilst the chart does provide the logic requirements forthe safety system, it does not traditionally identify safetyinstrumented functions and the Target SIL’s. The cause andeffect charts may be supported by a ‘generic specification’which addresses such items as demand response times,maintenance override schemes, and the required SIL for the‘system’.

PID - 01 - 14V - 01 - 09DescriptionP&IDTag1High Pressure in Vessel 01PID - 01 - 14PT - 01 - 01X2High Temp in Vessel 01PID - 01 - 14TT - 01 - 01X3Vessel 01 HI Out PressPID - 01 - 14PT - 01 - 021. How can individual Safety Instrumented Functions (SIF) beidentified? Does cause 1 and 2 or only cause 1 constitute thesafety instrumented function? Consider the following extractfrom a generic specification: ‘The ESD system shall be a PLCClose Inlet ValvePID - 01 - 14V - 01 - 07NumberTwo important questions can be asked:Open Cooling ValvePID - 01 - 14V - 01 - 01Open Vent ValvePID - 01 - 14M - 01 - 01Stop Discharge PumpP&IDCause and Effect Emergency ShutdownLogic Pressure Vessel VS-01TagDescriptionConsider the following extract from a generic specification: ‘TheESD system shall be a PLC based system and shall be certified byTUV for safety related interlocks for SIL 3 as a minimum’XXXbased system and shall be certified by TUV for safety relatedinterlocks for SIL 3 as a minimum’2. What is the Target SIL of the safety instrumented function?The basic specification stated that the PLC system wasrequired to be certified to SIL3.SIL Methodology Oil & Gas and Petrochemical 9

P&IDPID - 01 - 14PID - 01 - 14PID - 01 - 14PID - 01 - 14M - 01 - 01V - 01 - 01V - 01 - 07V - 01 - 09NumberDescriptionP&IDTag1High Pressure in Vessel 01PID - 01 - 14PT - 01 - 01X2High Temp in Vessel 01PID - 01 - 14TT - 01 - 01X3Vessel 01 HI Out PressPID - 01 - 14PT - 01 - 02NumberDescriptionP&IDTag1High Pressure in Vessel 01PID - 01 - 14PT - 01 - 01X2High Temp in Vessel 01PID - 01 - 14TT - 01 - 01X3Vessel 01 HI Out PressPID - 01 - 14PT - 01 - 02If a comprehensive safety requirements specification is produced,we would know that:‘In order to prevent the rupture of pressure tank VS-01, ValveV-01-01 must be opened within 2 seconds, when the pressure invessel VS-01 rises to 2.6 bar’ and ‘The safety integrity of the10 Oil & Gas and Petrochemical SIL MethodologyPID - 01 - 14PID - 01 - 14PID - 01 - 14PID - 01 - 14V - 01 - 01V - 01 - 07V - 01 - 09XM - 01 - 01SIL?SF?XP&IDSIL?XTagSF?Tag1.4 Safety requirements continuedXXXsafety instrumented function must be SIL 1’This provides a clear description of the requiredfunctionality of the safety instrumented function and theTarget SIL for the safety function.

1.4.2 Mode of OperationThe required mode of operation of the safety instrumentedfunction is important when assessing the target failuremeasure. IEC61511 Part 1 Clause 10.3.1 requires: ‘The safetyintegrity level and mode of operation (demand/continuous) foreach safety instrumented function to be defined. The mode ofoperation of each safety function impacts the calculation ofachieved SIL for the target failure measure; refer to IEC61508Part 1 Clause 7.6.2.9:b) Does this refer to a safety function operating in a highdemand or continuous mode of operation and 2.25 x 10-5represents the probability of dangerous failures per hour(Pfh)?Table 1: Target failure Measures for a Safety Function Operating inLow Demand Mode of Operation1.4.3 Proof Test IntervalIt is a requirement in both IEC 61508 and IEC 61511 that for aspecified safety instrumented function, being carried out by aSafety Instrumented System, the Pfdavg of the dangerousrandom hardware failures be evaluated. It is possible to dothis by estimating the Pfdavg for each subsystem and thensummating them to find the total for the Safety InstrumentedSystem (see IEC 61508-6 (Annex B).Low Demand Mode of OperationSafetyIntegrityLevelAverage probability of the failure to perform its designfunction on demand (Pfdavg)4321 10-510-410-310-2totototo 10-410-310-210-1Table 2: Target failure Measures for a Safety Function Operating inHigh Demand Mode of OperationHigh Demand or Continuous Mode of OperationSafetyIntegrityLevelProbability of a dangerous failure per hour4321 10-910-810-710-6totototo 10-810-710-610-5It can be seen from Tables 1 and 2, that the target failure measureis: For low demand mode of operation, the average probability ofthe failure to perform its design function on demand (Pfdavg) Forhigh demand or continuous mode of operation, the probability ofdangerous failures per hour (Pfh) These different target failuremeasures for the different modes of operation have a have asignificant impact on how the required SIL is determined.For example:A safety controller is selected by the Engineering/EquipmentSupplier. The element is certified by a third party, and the supportingcertification documentation states that 2.25 x 10-5 has beenachieved for the element.This raises two questions:a) Does this refer to a safety function operating in a low demandmode of operation and 2.25 x 10-5 represents the averageprobability of failure on demand of the element for dangerousrandom hardware failures (Pfdavg)?; orIf the answer is (a), then the Pfdavg achieved is in the SIL4 band. Whereas if the answer is (b), then the Pfh is onlyin the SIL 1 band.An important parameter when undertaking such anevaluation is the proof-test interval. IEC61511-1 (Clause10.3.1) requires a specification of the: ‘Requirement forproof-test intervals’The calculated Pfdavg for a subsystem is based on thefollowing calculation (Note that this is a very simplisticcalculation; refer to IEC61508-6 (Annex B) for a fulleraccount of this issue): For a 1oo1 architecture, PFD λDUx T/2Where:Pfdavg Average probability of failure on demand for thegroup of voted channels in respect of the dangerousrandom hardware failuresλDU Undetected dangerous failure rate for randomhardware failuresT Proof Test Interval in hoursIt can be seen from the calculation that, without knowingthe required proof test interval, the Pfdavg cannot bedetermined. An example of how the change of the prooftest interval can affect the Pfdavg is as follows:A safety controller is selected by the Engineering/Equipment Supplier. The safety controller has beencertified by a third party, and the supporting certificationdocumentation states that a Pfd of 2.25 x 10-5 has beenachieved based on a proof test interval of 8 years. It canbe seen that if the proof test interval was to be changedto, say 6 months, then assuming all the other reliabilityparameters where to remain the same then the Pfdavg forthe safety controller would be reduced by a factor of 16.SIL Methodology Oil & Gas and Petrochemical 11

1.5 Design and engineeringThe following section provides an example SIF architecturearranged to emphasise the importance of architecturalhierarchies as required of IEC 61508. The key issue is todetermine the maximum allowable SIL for a safety functionand this is dependent on whether the element is a type A ortype B device and is also reliant on both the SFF and the HFTof the element.Element - part of a subsystem comprising a singlecomponent or any group of components thatperforms one or more element safety functionsThe requirements for determining the maximum SIL withrespect to the parameters previously mentioned, arespecified in clause 7.4.4.2 of 61508 Ed 2, Part 2 if Route1H is to be used for compliance. Also with respect to Ed2 of the standard, an uplift can be made for SIL level usebased on systematic claims providing independence can bedemonstrated between the sub-system elements.System - implements the required safety functionsnecessary to achieve or maintain a safe state for the EUCElementsSystemLogic solverSensorsFinal elementsSubsystemsSub-system - entity of the top-level architectural design ofa safety-related system where a dangerous failure of thesubsystem results in dangerous failure of a safety functionWith reference to the simple example above, it is importantto stress that the designer needs to define the architecture,elements, subsystems, and overall system and fully understandhow failures will impact on the ability of the individual SIF‘s toperform on demand. These requirements should be undertakenbefore commencing the SIL Achievement exercise. Also itis an essential stepping stone for providing the necessaryassessment information for future SIF SIL Achievementdemonstration. See IEC 61508 Ed 2 Part 2, 7.4.2.Phase 10 of IEC 61508, realisation of the safety lifecycle, relies oninformation produced by the end user/operator during phases 4, 5& 9 of the safety lifecycle, Overall Safety Requirements and SafetyRequirements Allocation. Based on the safety requirementsspecification the engineering/ equipment supplier can begin toallocate safety functions and design the safety system.As part of the design and engineering process, each safetyfunction defined in the safety requirements specification, isdeconstructed into the sub-systems and elements required inorder to execute that function:12 Oil & Gas and Petrochemical SIL MethodologyWhere: The Safety Instrumented System, to carry out the safetyinstrumented function, comprises of an Input Sub-System,Logic Solver and Output Subsystem Sub-Systems comprise of single or multiple elements. Elements are identifiable pieces of equipment, consisting ofindividual components, for example a pressure transmitter,safety controller.Consider the design of the high pressure safety function describedin section 1.2;‘In order to prevent the rupture of pressure tank VS-01, ValveV-01-01 must be opened within 2 seconds, when the pressure invessel VS-01 rises to 2.6 bar’‘The safety integrity of the safety function must be SIL 1’The architecture for this high pressure safety function can beinterpreted as opposite.

Safety FunctionSensor (input sub-system)ElementLogic solverElementFinal Element (output afety instrumented functionSafety FunctionSensorPressureXmitterLogic solverIS BarrierAnalogueInputModuleFinal ElementSafetyControllerIn the example above, it can be seen that the Safety InstrumentedSystem comprises of three subsystems and seven elements: Sensor Sub-System- Pressure Transmitter Element- IS Barrier Element Logic Solver Sub-System- Analogue Input Module Element- Safety Controller Element- Digital Output Module Element Output Sub-System- IS Barrier Element- Solenoid ElementIn addition to the above subsystems, the Safety InstrumentedSystem will also comprise of additional ancillary elements such ascables and power supplies and power voters that may not have adirect impact on the achievement of SIL. How to deal with thisequipment is described in section 1.5.1 and 1.5.2.When considering what equipment to select for each definedelement of the Safety Instrumented System, the Engineering/Equipment Supplier must consider the following: The technical suitability of the element [Does the elementprovide the technical functionality required for the loop] The safety suitability of the element [Is the element certifiedor assessed for the application it is intended for]DigitalOutputModuleIS BarrierSolenoidTechnical suitability will be addressed as part of the standarddesign process. As will be seen in the following sub-sections,wherever possible elements should be selected based on theircompliance and certification or assessment to IEC 61508.1.5.1 Adoption of Good Practice Design and Installation StandardsFor any Safety Instrumented System, there are elements where theadoption of good installation practice is deemed reasonable toachieve the degree of safety integrity required to preventsystematic failures from arising.An example where the adoption of good practice may be sufficientwould be failures arising from incorrect cable or module installationor termination. Failures from such causes may not be consideredto be materially significant because of the adoption of appropriateinstallation guidelines and procedures including verificationactivities and appropriate proof test intervals.(Note that this example is provided for guidance, and should notbe interpreted as the rule. Clearly, the higher the SIL of the safetyinstrumented function, the more rigorous need to be the measuresto protect against systematic failures).SIL Methodology Oil & Gas and Petrochemical 13

1.5 Design and engineering continued1.5.2 Power suppliesIn the context of Power Supplies and Power Voting devices forde-energise to trip safety instrumented functions, no specialmeasures for functional safety need be taken providing that it canbe established that the power supplies and power voting deviceshave no dangerous undetected failure modes. For energise to tripsafety functions, power supplies and voting devices may havedangerous undetected failure modes, and therefore will requireconsideration during SIL Achievement.Whether an element of asafety instrumented function is considered during SILAchievement or not is of course dependant upon the safetyinstrumented function itself and each must be assessedindividually. Wherever an element is excluded from SILAchievement, the rationale for this exclusion must be clearlystated.1.5.3 Suitability of Safety ElementsBefore selecting elements for a safety system, it is first importantto understand what safety related data is required. In order todemonstrate compliance to IEC 61508 in terms of SIL Capability,each element should have the following information available: Safe Failure Fraction (SFF) Hardware Fault Tolerance (HFT) Type Classification A or B Target Failure Measure, expressed as either:- Pfdavg, or- Dangerous Failure Rate [hour-] Systematic Capability (SC)The objective of gathering the data above for each element of thelogic solver is to enable SIL Achievement for the end to end safetyfunction to be performed. Consideration must be given to theavailability and supportive evidence of these parameters for eachelement when selecting those elements on the basis of theirfunctional safety suitability. In the case of elements being suppliedfrom a third party, a validated claim that the elements suppliedhave the claimed parameters. In the absence of a validated(validated by either an accredited certification body, orindependent assessor) claim of any of these

Equipment supplier to perform the design of the logic solver subsystem. The system integrator is responsible for engineering the logic solver in accordance with the safety requirements, and following good practice as defined in IEC 61508 and IEC 61511 during the design engineering process. It is the responsibility of the Engineering/

Related Documents:

May 02, 2018 · D. Program Evaluation ͟The organization has provided a description of the framework for how each program will be evaluated. The framework should include all the elements below: ͟The evaluation methods are cost-effective for the organization ͟Quantitative and qualitative data is being collected (at Basics tier, data collection must have begun)

Silat is a combative art of self-defense and survival rooted from Matay archipelago. It was traced at thé early of Langkasuka Kingdom (2nd century CE) till thé reign of Melaka (Malaysia) Sultanate era (13th century). Silat has now evolved to become part of social culture and tradition with thé appearance of a fine physical and spiritual .

On an exceptional basis, Member States may request UNESCO to provide thé candidates with access to thé platform so they can complète thé form by themselves. Thèse requests must be addressed to esd rize unesco. or by 15 A ril 2021 UNESCO will provide thé nomineewith accessto thé platform via their émail address.

̶The leading indicator of employee engagement is based on the quality of the relationship between employee and supervisor Empower your managers! ̶Help them understand the impact on the organization ̶Share important changes, plan options, tasks, and deadlines ̶Provide key messages and talking points ̶Prepare them to answer employee questions

Dr. Sunita Bharatwal** Dr. Pawan Garga*** Abstract Customer satisfaction is derived from thè functionalities and values, a product or Service can provide. The current study aims to segregate thè dimensions of ordine Service quality and gather insights on its impact on web shopping. The trends of purchases have

Bruksanvisning för bilstereo . Bruksanvisning for bilstereo . Instrukcja obsługi samochodowego odtwarzacza stereo . Operating Instructions for Car Stereo . 610-104 . SV . Bruksanvisning i original

Chính Văn.- Còn đức Thế tôn thì tuệ giác cực kỳ trong sạch 8: hiện hành bất nhị 9, đạt đến vô tướng 10, đứng vào chỗ đứng của các đức Thế tôn 11, thể hiện tính bình đẳng của các Ngài, đến chỗ không còn chướng ngại 12, giáo pháp không thể khuynh đảo, tâm thức không bị cản trở, cái được

10 tips och tricks för att lyckas med ert sap-projekt 20 SAPSANYTT 2/2015 De flesta projektledare känner säkert till Cobb’s paradox. Martin Cobb verkade som CIO för sekretariatet för Treasury Board of Canada 1995 då han ställde frågan