Testing and maintenance of SIS setpoints

Periodic SIF tests should ensure that the SIF setpoints remain within their estabiished iimits during operation. Formal documentation of the test results is necessary to support the investigation and resolution of any occurrence where a limit is exceeded. Exceeding a limit in either a high or iow direction may indicate degraded performance and inability of the instrument segment to meet its intended function. 

This verification shouid be achieved by recording as-found data to determine the setpoint in terms of the measured or derived process variabies, prior to any adjustment. As-found data shouid be the data taken during the first traverse in the direction of concern during the test. 

No reproduction or n working permitted without license from IHS 

When the as-found condition is within the Performance Acceptance Test Limit, but outside the as-left tolerance, the setpoint should be returned within the range assumed in the setpoint analysis. 

If as-found data indicates that an acceptance criterion was exceeded, appropriate corrective action should be taken. This action should include, as required, investigation to determine the cause of the finding, evaluation of operability, interim compensating measures, trending, and appropriate corrective action to prevent a re-occurrence. Possible actions for consideration are  

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