SIS safety validation

1 The objective of the requirements of this clause is to validate, through inspection and testing, that the installed and commissioned safety instrumented system and its associated safety instrumented functions achieve the requirements as stated in the safety requirement 

NOTE This is sometimes referred to as a site acceptance test (SAT). 

1 Validation planning of the SIS shall define all activities required for validation. The following items shall be included. 

No reproduction or networking permitted without license from IHS 

NOTE Examples of validation activities include loop testing, calibration procedures, simulation of application software. 

1 The objective of the SiS safety vaiidation is to vaiidate that the SIS achieves the requirements stated in the safety requirements specification. Validation activities should be completed prior to the placing of the SIS into operation. 

4 If the SIS has already been through a Factory Acceptance Test (FAT), this may be taken into consideration during the validation. The validation team should review the results of the FAT to ensure that all of the application software was successfully tested and all problems found during the FAT have been corrected. 

It may be unnecessary to repeat application software testing at the final validation. This is applicable when 

However, it will be very important to ensure that there has been no shipping/storage/handling damage, that all sensors and final elements are correctly connected to the logic solver, that the safety instrumented functions perform properly and that the operator interface provides the necessary information. The equivalent of a proof test is strongly recommended in order to claim SIS validation, because a separate test of the logic solver and the field elements does not equal a complete end-to-end proof test. 

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Clause 15 SIS safety validation Validation through inspection and testing of installed and commissioned SIS, and associated SIF achieved the safety requirements specified. 

SIS safety validation Validation of SIS including application software meet the safety requirements. 12.3... 

SIS SAFETY VALIDATION (lEC 61511 CLAUSE 15) Requirements for SIS safety validation... 

Application software safety validation planning To develop a plan for validating the application software 12.3.2 SIS application software safety requirements specification SIS application software safety validation plan Verification information... 

SIS installation commissioning validation To integrate and test the SIS. To validate that the SIS meets, in all respects, the requirements for safety in terms of the required Safety Instrumented Functions and the required safety integrity. 12.3, 14, 15 ISA-TR84.00.03... 

With initial assessment, all risks are listed and suitable IPLs are deployed. After this the entire system is reassessed. Because we are interested in SIS, in the final assessment only SIS is shown. After each assessment the IPLs and SIS are validated. After final assessment of overall safety requirements it is ensured that the risk level is at an acceptable level, as shown in the figure. This shall be a level equal to or below the ALARP level. In principle, what has been discussed here is more or less the same as discussed earlier, the only difference is that here the basic implementation process is shown. Similarly, SIS in the design phase is shown in Fig. XII/1.0-3. The reason for showing the figure is to recapitulate further details about SIS design. 

Overall safety validation planning To develop a safety validation plan for the SIS As for stage 6 Safety requirements Spec A plan to facilitate the validation of the SiS... 

Overall safety validation To validate that the E/E/PE safety-related systems meet the specification for the overall safety requirements E/E/PES safety-related systems Plan from stage 9 Confirmation that the SIS meet the safety requirements spec... 

Where the application software in a SIS is to implement safety instrumented functions of different SILs, they should be clearly separated and labelled. This allows the software of each safety instrumented function to be traceable to the proper sensor and final element redundancy. It also allows the functional and validation testing of the functions to be commensurate with the SIL. The labelling should identify the SIF and the SIL. 

The objective of the realisation phase is then to create the SIS conforming to the specification, especially in terms of safety functions and allocating SIL. This paper focuses on system requirements (Part 2), and does not develop software aspects (Part 3). The realisation phase consists of design requirement specification (for subsystems and elements), design and development, integration (software integration refers to Part 3), operation and maintenance, validation, modification, and verification. 

Validate that the SIS, including the safety application software, meets the safety requirements... 

The software validation shall show that all of the specified software safety requirements (see 12.2) are correctly performed, and the software does not jeopardize the safety requirements under SIS fault conditions and in degraded modes of operation or by executing software functionality not defined in the specification. The information of the validation activities shall be available. 

In ANSI/ISA-84.00.01-2004-1, verification, validation and functional safety assessment are three very distinct activities that are carried out during the lifecycle of an SIS, and it is important to understand the importance and requirements of each of these activities. 

Communications between the BPCS and SIS can enhance the overall safety of the application. Comparing the SIS and BPCS process variables can provide enhanced diagnostics for the sensors, improving the integrity of the SIS and BPCS sensors. However, communications, particuiarly writes to the SIS, can compromise the safety integrity of the SIS. Provision shouid be made to ensure ail writes are valid and do not negatively impact the system safety or operation. 

The purpose of this annex is to provide guidance for establishing instrument setpoints for safety instrumented functions in the process industries. The scope of ANSI/ISA-84.00.01 is requirements for... a safety instrumented system, so that it can be confidently entrusted to place and/or maintain the process in a safe state." This annex provides guidance on instrument uncertainty calculations and setpoint determination for instruments used in an SIS to ensure that each SIF responds to achieve or maintain the safe state of the process within one-half of the process safety time with respect to a specific hazardous event. If measurement uncertainty is not considered in the determination of an SIS setpoint, the SIF may not detect the presence of a valid process demand. 

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