Brownfield upgrades without the blowout
How to modernise control systems in ageing plants while keeping your people, production, and budget intact
Walking the tightrope
If you’re leading operations in a mineral processing plant, chances are you’re juggling production targets, safety metrics, and the push to modernise. Control system upgrades in brownfield environments are often treated as a technical exercise, but for those responsible for plant performance, they’re a high-stakes operational challenge.
The risk of unplanned downtime, commissioning delays, safety breaches and budget overruns hangs over every decision. Worse still, many upgrades miss the mark because they underestimate the time, access and complexity required to validate what’s physically possible in an ageing plant. These projects rarely fail because the logic was wrong; they fail because the shutdown didn’t go to plan, or the field cabling didn’t match the drawings.
This guide unpacks the real-world challenges and practical strategies that matter most to operations leaders responsible for delivering upgrades without disruption.
The core challenges - and why they're so hard to solve
1. Unknowns everywhere
Legacy systems often come with incomplete documentation. Over years of patchwork changes and stop-gap fixes, much of the system knowledge disappears, either undocumented or retired with past employees. That makes risk assessment tricky and planning even harder.
2. Old systems that can’t talk to new tech
Upgrading typically means integrating with outdated hardware, proprietary platforms or unsupported protocols. That brings compatibility risks, and often requires deep reverse engineering just to avoid breaking what’s already working.
3. The illusion of “minimal downtime”
The phrase “minimal disruption” gets tossed around early in every project, but short shutdown windows compress risk into tight timeframes. Even small oversights can delay commissioning, push past your restart window and start chewing into production hours.
4. Misaligned stakeholders
Operations, maintenance, engineering and IT all come with valid but competing priorities. One wants uptime, one wants new capability, and the other wants stability. If these priorities aren’t reconciled early, projects can stall in a cycle of redesign, rework and finger-pointing.
5. Compliance and cybersecurity pressure
Legacy systems weren’t built for today’s regulatory, environmental or cyber expectations. As part of any modernisation, controls need to be hardened, documented and often revalidated against new standards, adding scope and risk to already-complex projects.
Smart moves that change the game
1. Treat assessment like an engineering task, not an admin step
Start with a forensic site audit. Document everything: hardware, I/O allocation, software versions, network topology, comms protocols, instrumentation, and alarming strategy. But don’t stop at the control room. Talk to the frontline operators. They’ll flag the workarounds and idiosyncrasies that don’t show up on a P&ID.
Projects that skip this step typically walk straight into commissioning issues later.
2. Don’t overlook the physical infrastructure
A frequent pitfall in control system upgrades is assuming the field layer will support the new system. In practice, many brownfield projects hinge on verifying the capacity and condition of the existing electrical and instrumentation infrastructure; power systems, cable trays, conduit space, spare terminal availability, I/O cards, and instrument health.
These checks can’t be done from drawings alone. They require site access, and often a substantial effort to confirm what’s actually in place. If this isn’t scoped and planned early, it becomes the single biggest source of cost and schedule blowouts, especially during commissioning.
3. Break it down: don’t upgrade everything at once
Phased implementation helps manage risk. Prioritise the most critical or failure-prone areas first and use pilot installations or proof-of-concept runs to iron out technical issues.
Dual-running systems, where the new system is tested in parallel with the old, can provide added assurance before final cutover. Just be sure your operators are across both systems during this period.
4. Plan for change fatigue
Change management in brownfield environments is as much about people as it is technology. Resistance is common, especially from teams who’ve built deep muscle memory around old systems.
The fix isn’t posters and slogans – it’s involvement. Get site teams engaged in testing, validation and FAT/SAT processes. Show them how their workflow improves and equip them to operate the new system before go-live, not after.
5. Design for downtime – before the clock starts
Shutdowns attract every project on the plant’s wish list. And when multiple trades pile into the same work window, access gets limited, sequencing becomes confused, and commissioning suffers.
Control system commissioning needs to be prioritised, protected and logically staged. That means getting alignment across stakeholders in advance, who needs access when, what’s mission-critical, and where dependencies lie.
A poor start-up sequence can burn hard-won credibility, even if the upgrade itself was technically flawless.
Technical levers worth pulling
1. Design for interoperability
Avoid lock-in. Use open protocols and modular systems wherever possible. The ability to mix, match and extend components from different vendors reduces long-term complexity and cost.
2. Add visibility without adding complexity
Modern instrumentation, edge devices and IoT gateways provide high-granularity data that improves decision-making. When layered carefully, without overwhelming operators, they improve response time, reduce troubleshooting and feed predictive maintenance strategies.
3. Futureproof for cybersecurity
As systems become more networked, exposure increases. Build cybersecurity in from the start. Align to IEC 62443 or similar frameworks, enforce user access controls, and keep patching and backup strategies up to date.
Making it stick: adoption, support, and continuity
1. Train early – not just after go-live
Operators and maintainers need more than just a manual; they need hands-on experience. Include them in testing environments, simulate normal and abnormal conditions, and walk them through recovery scenarios.
Training before commissioning gives your team a stake in success and shortens the post-startup learning curve.
2. Assign ownership
After the handover, who owns system health? Make sure that’s clear. Set up a plan for ongoing support, backups, updates and tuning. Don’t let the system drift into neglect just because the upgrade was “done”.
3. Document the system you wish you’d been left
You don’t want the next team starting from scratch. Produce up-to-date control philosophies, I/O lists, alarm settings, and network diagrams. Capture the logic behind key decisions. Future upgrades, and troubleshooting, will be far easier
A better way forward: what the best projects share
Here’s what we’ve seen in successful brownfield projects:
- They start with a full picture of the field layer—not just the control room.
- They build buy-in across operations, maintenance and engineering.
- They run phased rollouts with clear milestones and fallback options.
- They protect commissioning time and plan for people, not just systems.
Kansanshi Smelter PCS7 upgrade
At First Quantum’s Kansanshi smelter in Zambia, Mipac helped upgrade the Siemens PCS7 control system under a tight eight-week schedule.
Thanks to rigorous upfront planning and onsite commissioning support, the project was delivered on time, without disrupting the smelter’s aggressive production schedule.
Kazzinc plantwide control system upgrade
At the Ust-Kamenogorsk complex in Kazakhstan, Mipac upgraded the plantwide Emerson DeltaV DCS and installed a CellView® wireless system.
The work improved production consistency, enhanced worker safety and gave operators better visibility of critical process areas.
Kiunga control & instrumentation upgrade
At Ok Tedi’s Kiunga Port, Mipac replaced ageing GE Fanuc PLCs and Citect SCADA with an ABB 800xA DCS. Despite the remote location, the upgrade was fully engineered and commissioned from Brisbane, including a full simulator and online training modules.
By aligning the new system with the mill’s DCS and using existing shutdown windows, the team delivered a seamless cutover without disrupting port operations.
Final thought:
Modernisation without mayhem
Brownfield control system upgrades aren’t just about legacy technology: they’re about enabling better decisions, reducing operational risk, and building a system your people can trust. But success depends on more than just logic and hardware. It requires operational leadership, rigorous planning, and a clear understanding of what’s physically, and humanly, possible on site.
If you’re considering a control system upgrade, start by asking: what’s really there? What needs to change? And how do we give our team the best chance of a smooth transition?
Planning a control system upgrade? Don’t start without this.
Upgrading control systems in a brownfield plant is high-stakes work. From unknown legacy wiring to tight shutdown windows, the risk of delays is real and expensive.
Our Pre-Upgrade Checklist gives you a clear, practical framework to get your team aligned, your site ready, and your project off on the right foot.
Download the checklist now to make sure nothing critical gets missed before the work begins.
Looking to modernise your control system without disrupting production?
Contact us to speak with one of the control system experts in our Brownfield Specialist Group. We’re here to help you plan with confidence, execute with clarity, and deliver upgrades that stick.
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