P&ID engineering

  P&IDs serve as the primary source of design information for utility systems and process equipment. They are used to depict the process flow, equipment configuration, process parameters, instrumentation, and materials of construction. They also are used to perform overall material and energy balances along with pressure balances.

  The following guidelines are recommended to obtain the maximum benefit from these drawings:

  • Ensure that the CADD software is compatible with existing plant drawing management system.
  • Use CADD system capability to identify system components and generate component schedules. Component schedules facilitate the commissioning and qualification process and future assignment of tag numbers.
  • Indicate entering/leaving support services and process streams; include reference to appropriate drawing and/or sheet number.
  • Identify system boundaries, with respect to support services and entering/leaving process streams.
  • Identify the battery limits of skid-mounted (or packaged) equipment.
  • Identify all components with appropriate tag numbers, using nomenclature consistent with existing plant practices. This eliminates the need for re-numbering or cross-reference listings.
  • Indicate line number, service, line size, and direction of flow for all piping and tubing
  • Indicate material type and insulation type/thickness (if applicable) for all pipe lines
  • Indicate use (purpose), size, capacity, material type, and insulation type/thickness (if applicable) for all equipment (e.g., tanks, pumps, heat exchangers).
  • Indicate size, type, and material type of all valves.
  • Provide material and energy balance information for each line number.

  Good Engineering Practice suggests that these documents be kept up to date throughout the project and the life of the facility or system.

  Specifications

  Detailed specifications should explicitly define the system requirements, codes, and standards to be followed during fabrication and construction, test requirements, acceptance criteria, and the associated deliverables.

  To prevent unnecessary costs and delays, the following items should be considered:

  • Who is responsible and for what.
  • Service or equipment to be provided.
  • Timing of service or equipment provision.
  • System performance requirements.
  • Factory test requirements (including written test plan review, revision, and approval).
  • Installation requirements.
  • Construction inspections and test requirements (including test methods, acceptance criteria, planned witnessing, and means of documentation).
  • Start-up, commissioning, and qualification requirements.
  • Training requirements (including scope, number of participants, duration, timing).
  • Documentation requirements (including manuals, operation, maintenance, cleaning, and calibration procedures, cut sheets, drawings).
  • Language of drawings, specifications, and other documentation.

  Appropriate representatives from Engineering, Operations, Validation, Maintenance, Safety, and for systems which QA has agreed are “Direct Impact” systems, Quality Assurance should review and approve the specifications.