Control Valves Loop Checks Procedure

DCS
1

We discuss about Control Valves Loop Checks Procedure. This involves valves loop checks, control valves loop checks, FF loop checks, DCS loop checks, ESD loop checks.

Control Valves Loop Checks Procedure

  1. For FF device commission FF segment prior to loop testing by measuring resistance and DC voltage of segment conductor if all devices are connected otherwise only resistance will be recorded and voltage will be measured after all devices are connected and compare the results with FF segment checkout form.

  2. Check and verify the DCS configuration for applicable points. Reference drawings are to be P&ID and ISS.

  3. If any logic / interlocking are involved in applicable loop. Energize the solenoid valve by forcing the applicable ESD points on functional logic and same procedure to be carried out for DCS logic.

  4. If instrument air supply is not available then, dry and clean air or nitrogen shall be used.

  5. Apply the command from DCS for 0%, 25%, 50%, 75%, 100% and monitor the response of the valve from the field.

  6. Verify the corresponding valve position.

  7. Verify the controller action.

  8. Verify the control valve action on increase signal.

  9. Verify the control valve action on air supply failure.

  10. Verify the control valve max / min travel stopper setting if applicable.

  11. Check the hand wheel manual operation / function if applicable. Auto/ manual calibration is applicable.

  12. Normally control valve loop test should be performed after completion of the external air supply piping works. In some cases when required, loop test can be executed without the internal air supply piping.

  13. In case of air piping is not installed and tested then this exception item to be mentioned in the loop test exception log sheet prior to signing the loop folder.

  14. Loop will be installed only and signed after the clearance of the punch list.

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