We discuss about ON/OFF Valves Loop Checks Procedure. This involves valve loop checks, shutdown valve loop checks, ESD valves loop checks.
ON/OFF Valves Loop Checks Procedure
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Valve response time shall be recorded in loop record sheet.
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Check and verify the DCS / ESD configuration for applicable points.
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If any ESD logic / interlocking are involved in applicable loop to energized solenoid valve, should be prepared ESD points on functional logic and same procedure to be carried out for DCS logic.
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If instrument air supply is not available then connect nitrogen cylinder. In big size of valve cases, big volume of nitrogen will be required then in that case on/off valves function test will be executed upon air supply availability.
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Apply the command from DCS / field for open and close as applicable.
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Verifying the corresponding valves position in DCS and field.
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Verify the partial stroke function test of âZVâ.
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Verify the valve action on air supply failure.
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Check the hand wheel / hand jack manual operation / function as applicable.
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Normally On/Off 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 air.
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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.
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Loop will be initiated only and signed after the clearance of the punch list.