Loop Folder
A loop folder is the physical or electronic dossier of every document associated with a single control loop. The relevant P&ID page, the loop diagram, the instrument datasheets, the loop-tuning record, the calibration certificate, the commissioning sign-off, and the proof-test records, for SIS loops. Commissioning teams build them, operating companies maintain them, and audits pull them.
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A loop folder is the complete dossier for a single control loop, the place where every document that proves that loop was specified, installed, calibrated, tuned, and, for safety loops proof-tested is gathered under one tag. It typically holds the relevant P&ID extract, the loop diagram that traces the field-to-system signal path, the transmitter and final-element datasheets, the calibration certificate, the commissioning sign-off, the tuning record, and, for an SIS loop, the proof-test procedure and the accumulating proof-test reports. It is built by the commissioning team as the as-commissioned record, maintained by the operating company for the life of the loop, updated through management of change, and pulled by auditors, which is why an SIS loop folder grows over time into a stack of proof-test reports while a regulatory-control folder stays close to its commissioning state. The shift from paper folders to electronic ones held in asset-management systems is now standard on greenfield projects, though operating plants commonly run a hybrid with legacy loops still on paper. The spine of the whole structure is the I/O list. Every loop on the list should have a folder, and every folder should answer to a loop on the list, so a clean, loop-numbered reading of the set is the precondition for a folder index that has no gaps and no orphans. Reconstructing that index on an inherited plant whose records have drifted is one of the recurring brownfield jobs.
What goes into a loop folder.
Front sheet. Tag, service, P&ID reference, loop number, signal class, SIL allocation if applicable. Loop diagram showing the field-to-system signal path. Datasheets for transmitter and final element. Calibration certificates. Commissioning checklist signed off by the I&C engineer. Loop-tuning record, P, I, D values, tuning method, performance test. Pre-startup verification record. For SIS loops. Proof-test procedure and the most recent proof-test record. For HART devices. Device descriptor and DD file reference.
Electronic loop folders.
Modern asset-management systems, Emerson AMS, Honeywell Field Device Manager, Yokogawa Plant Resource Manager, GE APM, Rockwell FactoryTalk Asset Centre store the loop-folder content as structured records keyed to the tag. The shift from paper to electronic loop folders started in the late 2000s and is now standard on greenfield projects. Operating plants often maintain hybrid. Electronic for new content, paper-archive for legacy loops that haven't been digitized.
Frequently asked.
Who builds the loop folder.
The commissioning team builds the as-commissioned loop folder. The operating company maintains it through its operational life. Modifications during MOC trigger updates to the relevant pages of the folder. Proof-test records, for SIS loops accumulate over time and form the bulk of the folder content for older loops.
How does the I/O list relate to the loop folder.
The I/O list is the spine of the loop folder index. Every loop in the I/O list should have a folder. Every folder corresponds to a loop in the I/O list. A clean I/O list extraction is the precondition to a clean loop-folder build. Tagsight produces the I/O list with the loop number per tag, suitable as direct input to the loop-folder structure.
How does a SIS loop folder differ from a BPCS loop folder.
A SIS loop folder accumulates proof-test records over the life of the plant, one record per proof-test interval. After five years at a 12-month interval, the folder contains five proof-test reports plus the original commissioning checklist. For a BPCS loop, the folder typically holds the commissioning sign-off and calibration certificates without the recurring proof-test stack. Auditors reviewing SIL compliance pull the SIS loop folders to verify the proof-test schedule was actually executed.