Careers Eliminate PWHT and Protect Your Alky Reactors in Just Three Critical Path Days
Proven HVTS® Solution for H₂SO₄ Alkylation Corrosion
In sulfuric acid alkylation units (SAAUs), severe corrosion caused by high-concentration H₂SO₄ can lead to costly repairs, extended downtime, and major safety risks. Weld Metal Overlay (WMO) is traditionally used to address this problem — but it comes with long application times, high stress on the asset, and the need for Post Weld Heat Treatment (PWHT).
IGS High Velocity Thermal Spray (HVTS®) offers a superior solution:
- No PWHT required
- Application completed in 3 shifts
- Proven long-term corrosion protection
- Millions saved in avoided downtime
The Challenge: Sulfuric Acid Corrosion in Alky Reactors
A major Gulf Coast refinery faced internal metal loss in three sulfuric acid alkylation reactors due to sustained exposure to high-strength H₂SO₄. The equipment was on the turnaround’s critical path, and the client needed a fast, proven corrosion barrier that wouldn’t introduce heat-related risks or delay the project.
The goal:
- Avoid full window replacement or WMO
- Apply a protective corrosion-resistant alloy in the shortest possible time
- Eliminate the need for PWHT and preserve structural integrity
The IGS HVTS® Solution
Following rigorous technical evaluation and testing, IGS HVTS® was approved by the refinery’s corporate engineering team for the application.
Why HVTS®?
- No Heat Affected Zone (HAZ) — avoids structural stress
- No preheat or post-weld heat treatment
- Dense, impermeable CRA barrier — stops acid permeation
- True high-velocity spray — superior adhesion, low porosity
Our 5000-series alloy system is engineered to resist H₂SO₄ acid attack and isolate the base material from further chemical interaction. HVTS® cladding effectively halts corrosion mechanisms without the downtime and risks associated with traditional overlay.
The Application: On-Time, On-Spec, On-Budget
Despite the complex geometry of the internal vessels — including fixed baffles and internal hardware — the IGS team completed the entire application within six shifts per unit.
- All work was delivered in just 3 critical path days per reactor
- Zero safety incidents
- Full specification compliance
By comparison, Weld Metal Overlay would have extended the critical path by up to 21 days, significantly impacting the turnaround schedule.
The Value: Millions Saved in Turnaround Costs
Refineries estimate that each critical path day costs approximately $1 million USD. By choosing IGS HVTS®, this client avoided 18 extra days of critical path time — resulting in a cost saving of over $18 million for this project alone.
“The client is delighted with the results. We completed the work within the allocated timeframe, and the units are now protected from further degradation.”
— Eric Duvekot, Director of North American Operations, IGS
This project success has since led to additional IGS HVTS® work across the client’s alkylation network.
Comparison: HVTS® Cladding vs Weld Metal Overlay for Sulfuric Acid Alkylation Units?
Application Time
• HVTS® Cladding: 3 days
• Weld Metal Overlay: 21+ days
PWHT Required
• HVTS® Cladding: No
• Weld Metal Overlay: Yes
HAZ (Heat Affected Zone) Created
• HVTS® Cladding: No
• Weld Metal Overlay: Yes
Thermal Stress
• HVTS® Cladding: Low
• Weld Metal Overlay: High
Critical Path Impact
• HVTS® Cladding: Minimal
• Weld Metal Overlay: Significant
Let’s Talk About Your H₂SO₄ Alkylation Corrosion Challenge
If you’re planning a turnaround or need to mitigate corrosion in your alkylation reactors, speak to IGS today. Our HVTS® solution is field-proven, fast, and built for harsh acid service.
I’m here to help
Colin Bateman
IGS Subject Matter Expert
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