Surface Engineered Coatings in Pressure Vessels

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Surface Engineered Coatings in Pressure Vessels

• Dale M. Homeniuk, C.E.T.
• Plant Manager / Materials Engineering
  Technologist
• Inotec Coatings and Hydraulics Inc.

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Introduction

• Coatings/Overlays in Pressure Vessels take many
  forms
• Organic Coatings
• Metallic Coatings
• Corrosion Resistant Cladding
• Corrosion Resistant / Hardsurface Welding

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Newer Technologies

• High Velocity Oxygen Fuel and Twin Wire Arc
  Thermal Spray Coatings
• Mechanically bonded!
• Plasma Transferred Arc (PTA) Welded Overlays
• Metallurgically Bonded

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History of Thermal Spray in Pressure Vessels

• Thermal Spray Coatings have been utilized in
  pressure vessels for 25 years in Western Canada
• Traditionally, a band aid system, due to the
  oxy-acetylene applications and poor mechanical
  characteristics
• Typical alloys applied, aluminum and stainless
  steel!

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Aluminum Application Utilizing Flame Combustion!
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Past Seven - Ten Years Oil Gas

• Twin Wire Arc and High Velocity Oxygen Fuel
  coatings have been utilized in amine contactors,
  waste heat boilers, exchanger tubesheets.
• Alloy of choice. Hastelloy C-276!
• Manual and Automated applications

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HVOF on Exchanger Tubesheets
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HVOF in Amine Contactor
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TWA on Exchanger Tubesheets
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Past 10 Years Pulp Paper

• High Velocity Oxygen Fuel coatings have been
  utilized in Black Liquor Recovery Boilers on
  firewall tubes to stop corrosion/washing issues
• Alloy of choiceInconel 625!
• Power Boiler I.D. Fans and Tungsten Carbide!
• Manual and Automated Applications!

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HVOF in Recovery Boiler!
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Power Boiler HVOF Application
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Life of Coatings?

• History has shown that TWA and HVOF applications
  have a very low failure rate if chosen properly.
  Not a Band Aid system anymore.
• Why has there been no failure.?
• Mechanical properties of coatings and application
  methods. These choices encourage the proper
  coating system for the applicable environment.
• For example.. Stopping Hydrogen Blistering in Oil
  Gas Environmentsstop the corrosion attack at
  the coating before it gets to the substrate!

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Life of Coatings?

• Inconel 625 in the Recovery Boiler has proven
  highly corrosion and wear resistant in both TWA
  and HVOF forms.
• 1997, 1998, 1999 2000. Applications occurred
  at pulp mills in Western Canada. To date there
  has been no failure of these coating systems.
• Coating thickness does not change during life of
  coating.

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Future of Thermal Spray?

• Depending on the application
• All thermal spray coating applications must be
  chosen carefully to ensure that the mechanical
  characteristics of the coating meet the physical
  characteristics of the vessel!
• If this is not done, the perception that thermal
  spray coatings are a Band Aid system, becomes
  apparent.

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Welding in Pressure Vessels?

• Who thought that a pressure containing piece of
  equipment could be welded in after final
  hydrotesting?
• New Technologies and ASME Section IX allow
  hardsurfacing technologies to occur especially
  utilizing the new technology of PTA (Plasma
  Transferred Arc Welding)

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Arc On!
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PTA Process Description
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Valve Spools with T.C.
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Cavitation Resistance

• Pulp and Paper Industry utilized Eccentric
  Reducers in almost every facet of piping
  requirements.
• Applications of Stellite 6 in eccentric reducers
  have improved the life of the piping by a factor
  of 4 6 times.
• In some cases, Inconel 625 has been utilized to
  reduce cavitation and improve corrosion
  resistance.
• Best of all, smooth overlay surfaces!

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Overlay Roughness
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Finishing of PTA Overlays!

• In some cases, the piping has been ground (32
  64 Ra) in the first 6 to reduce any further
  turbulent flow.
• Faces of flanges have been ground clean to ensure
  wear/corrosion resistant alloys are present right
  to the seal face.

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Ground Surfaces on any Component
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Down Stream Piping

• Sand at high velocities provides an amazing wear
  pattern on down stream piping elbows and pups.
• Wear resistant Tungsten Carbide overlays have
  been applied to dramatically extend the life of
  these components.
• Customer in Dawson Creek, BC, losing a section of
  pipe in a particular application once every 30
  days. The system has been in place for 135 days
  to date. Non Destructive testing indicates no
  loss of wall thickness of pipe to date!

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Valve Tube Overlaid with Tungsten Carbide
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Conclusion

• Thermal Spray coatings and PTA welded overlays
  can be utilized in pressure vessel applications
  as long as they are chosen correctly and applied
  correctly!
• Approved procedures and experienced personnel are
  critical to each application in each situation!
• Amine Contactors, Recovery Boilers, Exchanger
  Tubesheets, Pressure Piping, the applications are
  endless and the technology is at your fingertips!