Widely used engineering symbols and drawings Standard ISA-5.1 updated by ISA
The International Society of Automation (ISA) — the leading professional society for automation — has published a new update of its most widely used standard, the internationally recognized ANSI/ISA-5.1, “Instrumentation and Control Symbols and Identification.” ISA-5.1 establishes a uniform means of depicting and identifying instrumentation and control functions used for measurement, monitoring and control in the process industries.
The 2024 revision of this standard changed the title from “Instrumentation Symbols and Identification” to “Instrumentation and Control Symbols and Identification” to emphasize that symbols for control are included. The ISA5 standards committee — the body that updated the standard — also improved the readability of ISA-5.1 by clarifying and simplifying the organization of the document, providing definition consistency and clarification and eliminating redundant text. In addition, the group updated the document to add new symbols and recognize new automation technology, add new reference sections and add the loop instrument diagrams symbol table.
“The ISA5 standards committee worked diligently for two years to update this renowned standard,” said Jim Federline, P.E., who led the revision. “ISA-5.1 is ISA’s oldest standard, celebrating 75 years of publication in 2024. We were proud to add new content and improve the readability of ISA-5.1, which continues to find wide use across the global process industries today.”
The latest revision to ISA-5.1 also reorganized annexes from the previous 2022 version into separate technical reports. The new technical reports (TRs) are ISA-TR5.1.02, “Instrumentation and Control Identification System Guidelines” and ISA-TR5.1.03, “Instrumentation and Control Graphic Symbols Guidelines.” These TRs offer examples and information on how to apply requirements in the standard. Examples in these TRs were updated with additions, revisions and deletions, with changes listed in Annex A of the respective document. Users are encouraged to read and use these TRs together with the standard.
The ISA5 Committee now is working on a new technical report on instrumentation and control content of process flow diagrams (PFDs) and piping and instrument diagrams (P&IDs). While ISA-5.1 deals with instrumentation and control content on various engineering drawings, including PFDs and P&IDs, this new TR will provide guidance and examples specific to PFDs and P&IDs. This will include guidance to help users decide on the level of detail of instrumentation and control they want to show on their PFDs and P&IDs and what information should be provided at a minimum.
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