H2S Corrosion in an Upstream Separator Vessel Permanently Stopped


Deep pitting corrosion in the bottom third (liquid zone) of separator vessel shell, circumferential welds, drain nozzles and manholes caused by an acidic process feed combined with high operating temperatures


IGS HVTS technology chosen to upgrade the internal metallurgy of the vessel surface, avoiding costly and time-consuming replacement.


Inspection in January 2023 confirmed HVTS cladding to be in perfect condition with no new corrosion or metal loss.

Separator Vessel

Leading exploration and production upstream company with around 209 producing oil&gas wells (onshore and offshore), was experiencing deep pitting (up to 8mm) in the bottom shell area between 4 to 8 O’clock position, the bottom third of the circumferential welds, bottom drain nozzles and manholes. The corrosion is caused by an acidic process feed (hydrocarbon gas/liquid & water) and the high operating temperatures.

Without addressing the corrosion mechanism, the vessel containment would be lost and replacement required.

High Velocity Thermal Spray Technology

IGS High Velocity Thermal Spray technology was selected to upgrade the carbon steel internal surface metallurgy of the vessel in-situ, with a high nobility alloy, arresting further metal degradation from the corrosive environment and substantially extending the asset service life, thereby avoiding costly and time-consuming replacement of the vessel.

HVTS Application

Surface grinding was conducted to remove sharp edges and open up deeply pitted areas to comply with the surface acceptance criteria for HVTS application.

IGS applied HVTS to clad of a total of 157 M² of the Flow Splitter Vessel internal surface + 17 Nozzles:

  • HVTS applied to Bottom Half of Vessel 180° from 3 O’clock to 9 O’clock.
  • HVTS applied to 17 selected Nozzles, complete internal bore surfaces (access from both sides).


IGS provide a turnkey solution, installing in-situ a metallurgical upgrade to vessel/column internal shell areas and nozzles. IGS operational capabilities were proven by executing the project during the height of the COVID-19 pandemic in September 2020, delivering IGS high performance HVTS cladding ahead of schedule. IGS quality control standards were in full compliance with the Client’s specification for High Velocity Thermal Spray Coating.

Key Dates inspecting HVTS cladding in a flow stripper separator vessel after H2S HT corrosion



  • 6th of September 2020 – Mobilization of IGS crews to the site
  • 9th of September 2020 – HVTS application start
  • 20th of September 2020 – HVTS application completion
  • 14th of January 2023 – HVTS inspection after 3 years in service


The asset owner’s maintenance team and IGS inspected the V6701 Flow Splitter in January 2023. They found that the H2S corrosion mechanism had been permanently mitigated with the application of IGS proprietary HVTS technology.

For the asset owner, this inspection was a crucial milestone in the validation process of the HVTS technology, and, as a result, they will now adopt IGS HVTS to permanently stop metal degradation in high-temperature acidic environments throughout the company’s field equipment.



IGS HVTS cladding technology is installed in-situ to protect the internal surfaces (shell and nozzles) of mission critical equipment against aggressive corrosion or erosion, thereby substantially reducing the total life cycle costs of equipment operation at upstream and downstreamoil and gas facilities in the Middle East and throughout the world.


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JanAlbert Schutte

IGS Subject Matter Expert


Thermal spray

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