Overview
ISO 15519-2:2015 - Specifications for diagrams for process industry, Part 2: Measurement and control - is an international standard that defines rules and guidelines for representing measurement, control, and actuation in process-industry diagrams. Published in 2015, this part of ISO 15519 focuses on how measurement and control information should be shown in common diagram types such as Process Flow Diagrams (PFD), Process and Instrumentation Diagrams (PID), Process Control Diagrams (PCD), and Typical Diagrams (TYD). It complements ISO 15519-1 (general rules) and supports clear, consistent process control documentation across engineering disciplines.
Key topics and technical requirements
- Diagram types and life-cycle aspects: Guidance on which diagram types to use at different engineering and operational phases.
- Representation rules: Conventions for signal lines, graphical symbols, instrument grouping, integrated displays, and multi-function instruments.
- Process Control Information (PCI) symbols: Symbols and placement rules for exchanging measurement/control data between process and control systems.
- Letter codes (PCI letter codes): Standardized letter-code schemes for process variables and control functions to ensure unambiguous identification.
- Reference designation: Application of reference designation principles (illustrated with IEC 81346 series) to identify equipment and control elements.
- Information exchange & interoperability: Specifications supporting exchange of process control information between process and control systems, including examples and annexes with practical representations.
- Informative annexes: Annex A–E provide graphical symbol sets, representation examples, diagram samples, information-exchange details, and control-term relationships.
Practical applications
- Creating standardized PFDs, PIDs, PCDs, and TYDs for chemical, petrochemical, power, pharmaceutical, food, pulp & paper industries.
- Producing unambiguous instrumentation and control documentation used during design, construction, commissioning, operation, and maintenance.
- Enabling consistent information exchange between process engineering, instrumentation, electrical, and control system teams.
- Supporting integration with modern control systems (PLC/DCS) and helping bridge traditional diagram documentation with self-documenting control technologies.
Who should use this standard
- Process, instrumentation and control engineers
- Piping and mechanical designers, electrical engineers
- CAD and plant documentation teams
- Operations, maintenance staff, and plant safety/compliance personnel
- Technical writers and documentation managers preparing manuals and handover packages
Related standards
Keywords: ISO 15519-2:2015, measurement and control diagrams, PFD, PID, PCD, instrumentation diagrams, PCI letter codes, process control documentation, IEC 81346.
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