22 févr. 2014 (il y a 7 années et 4 mois)

324 vue(s)

Surface Engineered
Coatings in Pressure

Dale M. Homeniuk, C.E.T.

Plant Manager / Materials Engineering

Inotec Coatings and Hydraulics Inc.


Coatings/Overlays in Pressure Vessels
take many forms

Organic Coatings

Metallic Coatings

Corrosion Resistant Cladding

Corrosion Resistant / Hardsurface Welding

Newer Technologies

High Velocity Oxygen Fuel and Twin
Wire Arc Thermal Spray Coatings

Mechanically bonded!

Plasma Transferred Arc (PTA) Welded

Metallurgically Bonded

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!

Aluminum Application
Utilizing Flame Combustion!

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

Manual and Automated applications

HVOF on Exchanger Tubesheets

HVOF in Amine Contactor

TWA on Exchanger Tubesheets

Past 10+ Years… Pulp &

High Velocity Oxygen Fuel coatings
have been utilized in Black Liquor
Recovery Boilers on firewall tubes to
stop corrosion/washing issues

Alloy of choice…Inconel 625!

Power Boiler I.D. Fans and Tungsten

Manual and Automated Applications!

HVOF in Recovery Boiler!

Power Boiler HVOF Application

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 Environments…stop the corrosion attack at the
coating before it gets to the substrate!

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.

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.

Welding in Pressure

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)

Arc On!

PTA Process Description

Valve Spools with T.C.

Cavitation Resistance

Pulp and Paper Industry utilized Eccentric
Reducers in almost every facet of piping

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

Best of all, smooth overlay surfaces!

Overlay Roughness

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.

Ground Surfaces on any Component

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!

Valve Tube Overlaid with
Tungsten Carbide


Thermal Spray coatings and PTA welded overlays
can be utilized in pressure vessel applications as
long as they are chosen correctly and applied

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!