Skip to content
Detailed Engineering Solutions

Process Flow Diagrams (PFDs) and P&IDs

We design and review process and instrumentation diagrams to the ANSI and ISA 5.1 standard

Start your projectBack to Detailed Engineering
Technical overview

Process Flow Diagrams
(PFDs) and P&IDs

Process flow diagrams and piping and instrumentation diagrams are the primary engineering documents that define your process flows, equipment, control systems and safety instrumentation. They form the basis for HAZOP studies, for safety instrumented system design, for procurement, for construction and for operations, which makes their accuracy and completeness critical to the safety and reliability of your plant. A poorly drawn P and ID introduces errors that propagate from the HAZOP through the safety system design and into the field installation. Our team designs your P and IDs from first principles, checks them against every discipline input and maintains them as living documents through the plant lifecycle.

Process Flow Diagrams (PFDs) and P&IDs Overview
Engineering process

Process Flow Diagrams (PFDs) and P&IDs workflow

Data Gathering & Basis

Review existing PFDs, equipment lists, line lists, HAZOP scope, and relevant process licensor documentation.

Symbology & Convention Alignment

Agree ISA 5.1 / ISO 10628 symbol library, tag numbering format, line designation, and revision control protocol.

PFD Development

Develop process flow diagrams with stream tables, heat/material balances, and major control loops per system.

P&ID Development

Detail all pipework, instrumentation, interlocks, relief devices, and utility connections per ISA 5.1 convention.

Review & Reconciliation

Cross check P&IDs against HAZOP requirements, equipment datasheets, and line schedules, resolve all discrepancies.

Controlled Issue & As Built

Issue for construction with revision register, conduct as built field survey and update documents to reflect installation.

Process Flow Diagrams (PFDs) and P&IDs Scope
Scope of work

Every deliverable from basis to handover

Complete Process Flow Diagrams (PFDs) and P&IDs scope covering every calculation, drawing, specification, and construction support activity.

We develop the process flow diagrams with stream tables, heat and material balances, major equipment and control loops
We design the P and IDs to cover all pipework, equipment, instrumentation, interlocks and relief devices
We designate instrumentation and control loops under ISA 5.1 and ISA 5.3
We represent the safety critical interlocks, the emergency shutdown trips and the safety system boundary
We represent the relief devices, vents, drains and utility connections
We generate the line list, instrument index and equipment list from the P and ID
We review the P and ID systematically against the process flow diagram, the datasheets, the HAZOP requirements and the equipment schedule
We survey the as built condition, mark it up and issue a controlled document update
Engineering outcomes

Outcomes of Process Flow Diagrams (PFDs) and P&IDs

P and ID and PFD Engineering Quality
  • We make sure accurate P and IDs form the foundation of your HAZOP and process safety studies
  • We represent safeguards correctly so they support protection layer credit in LOPA
  • We document safety system interlocks correctly for IEC 61511 compliance
  • We represent the relief devices so they support your pressure protection review
ISA 5.1, API and ASME P and ID Defence
  • We give you a sound HAZOP baseline document, since errors in P and IDs propagate straight into HAZOP findings
  • We provide the OSHA PSM process safety information, since P and IDs are required at the operating level
  • We represent equipment correctly for ASME and API code compliance
  • We represent the logic correctly so the P and ID supports the safety system design basis
Operability and Commissioning Clarity
  • We make sure your operators and maintenance technicians can rely on accurate P and IDs every day
  • We issue correct P and IDs so commissioning and startup proceed cleanly
  • We provide the MOC basis so that every change is reflected in updated P and IDs
  • We give your new operators a training resource for understanding the process
P and ID Revision and Construction Cost Efficiency
  • We catch P and ID errors at FEED where they are far cheaper to fix than during construction
  • We reduce commissioning rework and delays through accurate P and IDs
  • We prevent the costly field changes that misunderstood design intent causes
  • We provide as built P and IDs that prevent unsafe field workarounds over the plant life
Standards & references

Codes & standards we work to

ANSI/ISA 5.1ISO 10628IEC 61511ASME Y14.5BS 5070API RP 14CNORSOK P 002IBR 1950 (Indian Boiler Regulations)IS 2825 / 803 / 4503 (BIS Pressure Vessel, Tank and HX)TEMA (Tubular Exchanger)CEA Regulations 2010 (India)NEC India (National Electrical Code)ANSI Y32.11API 650 / 620 (Tanks)API 2000 (Tank Venting)ANSI/ISA 84.91.01 2020 (Process Safety Critical Instrumentation)
When to engage

Triggers that signal the need

You are at the conceptual or FEED stage for a new plantYou need P and ID development during the detail engineering phaseA process modification requires a P and ID updateYou need an as built reconciliation surveyYou need a P and ID check for a HAZOP revalidationYou need a P and ID accuracy audit on an acquisition
Industries served

Where Process Flow Diagrams (PFDs) and P&IDs applies

Oil & Gas, Upstream

Wellheads, separators, gas compression, FPSO topsides, produced water systems.

UpstreamOffshoreFPSO
Refineries & Petrochemicals

Distillation columns, reactors, heat exchangers, storage spheres, LPG handling.

RefiningPetrochemical
LNG & Gas Processing

Cryogenic exchangers, liquefaction trains, BOG compressors, storage and sendout.

LNGCryogenic
Specialty Chemicals

Reactive systems, batch reactors, solvent handling, runaway reaction scenarios.

ReactiveBatch
Power Generation

Boilers, HRSGs, steam headers, hydrogen systems, ammonia SCR units.

PowerHydrogen
Pharma & Food

Sterile vessels, CIP/SIP, pressure fermenters, solvent recovery, spray dryers.

PharmaFood & Bev
What we deliver

Tangible deliverables

  • Process flow diagram set with stream tables and heat and material balances
  • P and ID set covering the full process and utility systems
  • Instrument index and tag register
  • Line list and pipe class schedule
  • P and ID review redline mark up
  • HAZOP ready P and ID issue
  • As built P and ID update package
  • P and ID revision register and change log
Get Started

Ready to start your project?

Speak with our team to scope an engagement tailored to your facility, regulatory context, and lifecycle stage.

Start your projectView all services