How do I choose between different plant design engineering firms for a facility expansion with existing system tie-ins?

Choosing between plant design engineering firms for a facility expansion with existing system tie-ins is mostly about finding the firm that can manage brownfield complexity without creating risk to operations, schedule, or cost. For these projects, the cheapest proposal is often not the best one.

Here’s a practical way to evaluate firms.

1) Prioritize brownfield experience

Look for firms that have done:

• Facility expansions within operating plants
• Tie-ins to live utilities and process systems
• Shutdown/turnaround planning
• Tie-in execution with minimal production disruption
• Field verification and as-built validation

Ask for specific examples:

• “Show us 2–3 projects with live tie-ins similar to ours.”
• “What was the biggest challenge, and how did you handle it?”
• “How did you manage outage windows and cutover plans?”

A firm with strong greenfield experience but weak brownfield execution can struggle badly on an existing facility.

2) Evaluate their field investigation approach

Tie-in projects live or die on how well the existing conditions are understood.

Ask:

• Do they perform detailed field surveys and laser scans?
• How do they verify existing drawings and P&IDs?
• How do they handle unknowns in old systems?
• Do they reconcile discrepancies between drawings and reality?

Red flags:

• Heavy reliance on old drawings without field validation
• Vague scope around site data collection
• No clear process for discovering hidden conditions

3) Check their tie-in and outage planning capability

For existing system tie-ins, the firm should be able to define:

• Tie-in points and isolation boundaries
• Temporary bypasses or reroutes
• Outage duration estimates
• Commissioning and startup sequencing
• Cutover plans and contingency options

Good firms will talk about constructability and operations impact early, not just design intent.

4) Assess multidisciplinary coordination

Expansion projects usually require close coordination across:

• Process
• Civil/structural
• Mechanical
• Piping
• Electrical
• Instrumentation and controls
• Automation/SCADA/DCS
• Safety / HAZOP / PHA support

You want a firm that can manage interfaces cleanly. Ask:

• Who is the lead discipline coordinator?
• How do they manage inter-discipline reviews?
• What project controls/tools do they use?
• How do they track design changes affecting tie-ins?

5) Review their constructability and commissioning support

The best firm will think beyond drawings and into execution.

Look for support in:

• Constructability reviews
• Sequencing around active operations
• Temporary works planning
• Commissioning support
• Start-up troubleshooting
• Punchlist and closeout support

Ask whether they stay involved through startup or stop at IFC drawings. For brownfield work, design support during construction is very valuable.

6) Compare project management discipline

A facility expansion is a coordination-heavy project, so evaluate:

• Schedule management
• Change control
• Risk management
• Cost estimating quality
• Communication cadence
• Issue escalation process

Ask for examples of how they handled:

• Scope creep
• Unforeseen field conditions
• Owner-driven changes
• Permitting or code issues
• Long-lead equipment delays

7) Verify safety and operational risk mindset

You want a firm that understands:

• Process safety
• MOC (Management of Change)
• Plant operating procedures
• Hazard reviews
• Isolation/lockout requirements
• Permitting and regulatory constraints

If they treat tie-ins as just another design task, that’s a warning sign.

8) Consider how well they collaborate with your team

Some firms are excellent technically but hard to work with. For live facilities, collaboration matters a lot.

Evaluate:

• Responsiveness
• Clarity in communication
• Willingness to challenge assumptions respectfully
• Ability to work with operations and maintenance staff
• Ability to incorporate tribal knowledge from plant personnel

The best firms will actively pull knowledge from your operators, mechanics, electricians, and reliability staff.

9) Ask for a clear execution plan, not just qualifications

A strong proposal should show:

• Understanding of your facility and constraints
• Recommended site investigation approach
• Assumptions and exclusions
• Key risks and how they’ll be managed
• Staffing plan and key personnel
• Preliminary schedule with tie-in milestones
• Deliverables and review checkpoints

If a proposal reads generic, it may mean they don’t truly understand the complexity.

10) Use a weighted scorecard

A simple scorecard can help you compare firms objectively.

Example categories:

• Brownfield/tie-in experience — 25%
• Field verification approach — 15%
• Multidiscipline coordination — 15%
• Outage/commissioning planning — 15%
• Project management — 10%
• Safety/process risk management — 10%
• Team quality and communication — 10%

Then score each firm 1–5 in each category and compare totals.

11) Don’t ignore the people assigned to your project

The proposal may come from a strong firm, but the actual project team matters more.

Interview:

• Project manager
• Lead process engineer
• Lead piping/mechanical engineer
• Lead construction/field engineer
• Controls/instrumentation lead, if applicable

Ask who will actually do the work, not just who sold the project.

12) Red flags to watch for

Be cautious if a firm:

• Underestimates tie-in complexity
• Avoids discussing unknown conditions
• Gives an overly aggressive schedule without explanation
• Lacks field verification detail
• Has weak references from operating facilities
• Doesn’t ask enough questions about your existing systems
• Has poor communication during the proposal phase

A good short list criterion

If I were narrowing firms for this kind of project, I’d favor those that can demonstrate:

1. Proven brownfield expansion work
2. Strong field verification and as-built reconciliation
3. Real tie-in/outage planning experience
4. Tight multidisciplinary coordination
5. Strong construction/startup support
6. A practical, safety-conscious mindset

Best next step

Ask each firm to respond to the same scenario-based prompt, such as:

“Describe how you would approach an expansion project with tie-ins to live utilities and process systems, including field verification, outage planning, risk management, and startup support.”

Their answers will reveal far more than a generic qualifications package.

If you want, I can also give you:

• a vendor evaluation scorecard template
• a list of interview questions
• or a sample RFP scope for a brownfield facility expansion.