Case Study

Azule Onshore Gas Treatment Plant — DCS Integration & Commissioning

ICSS • FGS • ESD • ABB 800xA • Modbus • Structured Text Logic

ClientAzule Energy (Angola)
LocationOnshore, Angola (fed by 2 offshore platforms)
My RoleCommissioning recovery: hardware redesign, ST voting logic, metering, HMI, Modbus & network

Overview

The Azule onshore gas treatment plant integrates gas from two offshore platforms into an onshore processing facility. The project uses ABB 800xA as the supervisory DCS and requires tight integration with vendor-supplied ICSS, Fire & Gas (FGS) and ESD systems. I joined during commissioning and led a focused engineering recovery to bring key systems to operational readiness for Early Gas.

Technical highlights

  • Redesigned control panels to resolve voltage incompatibilities between field and panels
  • Implemented structured-text voting logic (1oo2, 2oo3 & custom votes) inside 800xA
  • Installed DTMs for PST on SDV valves and enabled valve diagnostics
  • Rebuilt operator graphics to match validated P&IDs
  • Created Modbus database & mapping for motors, VSDs, and vendor skids
  • Configured LV/MV switchgear network switches and assisted vendors with Modbus alignment

My Scope (detailed)

Panel Redesign & Power Segregation

Addressed mismatched voltages observed at site by redesigning marshalling, power distribution and termination strategies to protect field devices and ensure signal integrity.

DTM & Valve Integration

Installed and validated DTMs for PST on SDVs to allow on-line valve health checks and enable predictive maintenance workflows.

Modbus Database & Motor Control

Built the Modbus register database in 800xA, implemented mapping for motor telemetry and control, and developed control logic for motor & VSD sequences.

Structured Text Voting Logic

Authored robust voting functions in ST for ESD/FGS logic — central to safe plant behaviour under multiple-fault scenarios. Implemented reusable vote blocks with diagnostics.

HMI Graphics Rebuild

Recreated operator graphics directly from validated P&IDs, improving operator clarity and reducing alarm overload during plant bring-up.

Network & Vendor Support

Configured LV/MV switchgear switches (VLANs, redundancy, port security) and assisted vendors in correcting Modbus maps to ensure consistent communications.

Challenges & Solutions

Impartial / Incomplete FATs
+
Many subsystems arrived with incomplete factory testing. I performed on-site verification, corrected mappings, and enforced loop-by-loop checks to meet commissioning standards.
Late client changes
+
P&ID and sequence changes were managed with modular ST blocks and an organised tag database, enabling safe and quick updates during live commissioning.
Vendor Modbus misalignment
+
I assisted vendors to correct register maps and implemented translation layers where required so the DCS could consume consistent data.

Outcome & Status

Early Gas operations were achieved in 2025 following targeted hardware fixes, voting logic implementation and Modbus alignment. The project remains in commissioning and final completion is planned for early 2026. The work has stabilised DCS behaviour, improved safety logic determinism and ensured robust communications across vendor systems.

Want more practical insights like this? Let’s continue the conversation.

Click Get in touch below to ask a question, discuss real-world challenges, or request guidance.

Get in Touch Back To Projects