I/O Checking

Personally, I'd check all instrument's I/O. I don't know what's your reason for asking this question so a little more info might get you more answers.

regards,

Vulcan

Hi there,

As Vulcan stated all IO should be checked. This is not dependant on whether you are comissioning for the first time or whether you have had a shutdown.

You should always check as anything could have happened while the plant was down.

Regards,

Craig

My Friend,

Firstly, I would like to ask whether you have experience in I&C system? Secondly, What activity, you should used checking or verifying the Input/Output (I/O)?

To give you a guide and please bear in mind that ALL instruments SHALL be checked its I/O, whether it is transmitter, transducer, thermocouple, RTD.... etc.

First Stage of I/O Checking: Bench Calibration

All new and retrofitted (repaired and refurbished) instruments shall undergo bench calibration to check and record its functionality. This mean, you are checking its I/O.

Once, the bench calibration and functional test or check has been completed you might proceed to install it, whether in the field (field instruments) or DCS/PLCmodules.

Second Stage of I/O checking: Loop Check and Verification.

This mean that, you will be checking the entire system of one (1) loop from primary (field instruments) to final instruments (valves, digital controllers, switches... etc).

Primarily: you will substitute any available injector or simulator as field instrument output (mA, mV, ohms (decade box)) to feed as the output signal down to DCS/PLC, to final instruments. You may require some adjustments to the DCS/PLC/final instrument (*but, not to primary instrument) and this shall be recorded to get, record and calculate the loop instrument accuracy.

The above activities are commonly applied to all instruments, whether it is for bench calibration to loop check and verification.

Finally, just remember this, "There is NO excuse for losses" as I&C motto. Once you have practice this with all your heart you may consider to work in any I&C system from nuclear and fossil fired power plants, oil & gas, petrochem or any industrial plants.

Eren

Er, yes. All of them. What is the point of not <...checking...> them?

The purpose of commissioning is to have the equipment in a known state with a high level of confidence that the thing will work for real. Without <...checking...>, the condition of the equipment is not known and the level of confidence will be less than it could be.