Loop Checking and Field Instrument Testing Procedure ______________________________________________ Everybody knows that loop checking and field instrument testing is the last piece of the puzzle in each project before commencing the commissioning of any system. It is time-consuming and depends upon the completion of other systems like piping, electrical equipment, control valves etc. Each contractor or company has its own procedure and common practices for instrument loop checking and functional testing. I found this forum is good place to discuss this topic in more detail, for eample! ". #an we have a common or guide line procedure for loop checking$ %.
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'his is a very good topic for discussion. (e do the following in our organisation ".) detailed loop check format is prepared for each project %.)bove is based on latest I*+ list , I and process narrative. &./or each I*+ point, all connected details*elements like 0#*#1 I*+ module,anel 'erminal 2lock, 3arshalling panel 'erminal 'erminal 2lock, 4unction 2o 'erminal 'erminal 2lock,Instrument*/inal #ontrol element tag, 1ervice description,calibration range,cable tag.... 5.(e do this testing by involving owner6s as well as prime E# bidder6s Engineer as witnesses. )fter successful completion, the document gets signed by them. (e follow the same procedure for commissioning the logic as well as to demonstrate the same to end user7 'his is time consuming and we do it religiously to eliminate last minute surprises. ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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I fully agree with all & points. ) guide is really needed. I takes much time to get agreed such procedure in every new project and a unified approach would be very effective here. 'o the second point I may add that a list of such documents would be very useful as well to avoid creating of a huge dossier and got all needed papers in place. 'emplates for certificates would be fine. )s to the third point I6d a recommended list of personal of performing and witnessing parties. 3ikhail )ravin, 1enoir Instrument #ommissioning Engineer. -------------------------------------------------------------------------------------------------------------------------------------
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'he loop testing procedure can vary depending on the instrumentation and I*+ in frastructure. ) foundation fieldbus or rofibus ) based system would be different from a system using conventional or 8)9' instrumentation on a system with 8)9' I*+ cards. (hile one can perform a loop test with a handheld communicator when 8)9' I*+ is not present on the automation system that process would require multiple people similar to performing loop tests with conventional instruments. +ne benefit 8)9' instrumentation has over conventional is the non intrusive nature of the testing. +ne does not need to break the loop to insert a m) simulator. 8)9' instruments have a 0oop 'est method that allows the tester to drive the m) output of the instrument from a hand held communicator or an )sset 3anagement 1oftware application, (hen using )sset 3anagement software, testing can be done more efficiently because a single person can be commanding devices from one window and observing results on another. )n additional benefit when using )sset 3anagement software is that multiple instruments can be put into loop test simutaneously which allows one to incorporate interlock logic checks along with the loop tests which further streamlines the comissioning process. 1ince loop tests are often the final step before start-up, and projects schedules often slip, there is always pressure on the loop testing team to gain efficiencies to pull in the plant startup milestone.
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:nfortunately, even today6s large manufacturers have lost qualified process control specialists and engineers, leaving sometimes, unqualified personnel to decide how a ;system; should be validated. ) systematic approach is necessary and a legitimate step towards ensuring the ;completeness; of even the smallest of project, upgrade or cha nge to or within a 2#1 or 1I1 on the plant floor. +f course regulations apply to safeties, but many times the even the fundamentals of instrumentation go unchecked and now become a liability. 1tandardization is needed - especially within chemical and petro-chemical applications. '.otts, #ontract EI# 'echnician * roject manager. -------------------------------------------------------------------------------------------------------------------------------------
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I would like to share some perspectives ! 0oop testing and plant commissioning done in-house is one aspect.
'hings change slightly when this work is been done under contract by a &rd party. +nce again the policies and procedures are required. /)' and 1)' procedures should be issued to the supplier*contractor within &? days of contract signature. )s a #onsultant, I have witnessed so many poor /)' and 1)' company procedures in many different countries = #ultures if you like>. 'his has compounded poor /)' testing into total 1)' failures as the fault could not be isolated to anel or /ield . 3any hours could have been saved if the bookwork had been done up front. -------------------------------------------------------------------------------------------------------------------------------------
