Transcript Installing Quality Internal Linings: A Perspective

Installing Quality Internal Tank
Linings: A Perspective
David Cushman
West Virginia Paint LLC
General Manager
NACE Certified Coating Inspector #1591
Copyright 2013
External Paint or Internal Paint
• What is the difference?
• Immersion service calls for better surface
preparation
• Confined space issues
• Surface access
• Uninspectable for many years
• And of course….
Dust
• Abrasive blasting is a
dusty process!
If you don’t manage your dust….
• You can wind up with a
coating like this.
How do you measure clean?
• Cleanliness is very
important
• Surface preparation needs
to be a minimum SP-10 near
white metal or better yet
SP-5 white metal blasting
• Test for contaminants in the
air stream
• Test for contaminants in the
abrasive
Test for chloride contamination
• Can test using various
methods
• What are the sources of the
contaminant?
• Hydro test water
• Product sludge
• Tracking on feet
Surface preparation is a visual
standard that needs to be met with
tough working conditions
SP-10 near white vs. SP-5 white metal
Recycled media
Advantages
• Less disposal
• Less dust
• “Cleaner” working
conditions
Disadvantages
• Does not access to all
surfaces to be prepared
• May be challenging to get
equipment into the tank
• Difficult to ensure “sharp,
angular profile”
• Recycle process does not
remove any contaminants,
just classifies by particle size
Dehumidification
Two cardinal rules
Rule 1: What goes in, must come out!
=
Rule 2: What goes up, must come down!
Cleaning the residual dust and grit
• Where to look?
Blowing and vacuuming
• Blowing is often used to
remove dust from the
surface
• OR Combination of
Methods
• OSHA regulations
regarding blowing with
compressed air
• Vacuuming is used to
cleaning the surface
• Vacuuming has hazards
from static
Dancing?
Once the surface is clean …
• Applying the proper
coating at the proper
thickness
• Applying the proper
coating to the proper
surfaces
Selecting the Coating
•
•
•
•
MIL –PRF-4556(F)
Types of Coating- Generic
Film Build
Where to apply?
Epoxies- Generic
•
•
•
•
Amine
Phenolic
Novolac
Other high performance products
Which surfaces get coated?
How high do you coat?
• Do you coat the lower three feet?
• Do you coat the entire wetted surface?
• Do you coat the roof underside and structure?
• Internal piping and equipment?
• Where is corrosion occurring?
Inaccessible areas
• A tank built to API 650 with a lap welded roof
and a rafter structure has plenty of areas that
cannot be coated
• Only a best effort can be made
Film Thicknesses
• Specifications define
film thickness
• It is possible that there
is excessive pitting and
there is not enough
coating film
So what substrate condition are you
starting with?
If you apply a thin film too thick…
If you apply a thick film too thin
This coating is just right!
Holiday testing and cure
• Holiday testing is done to ensure that the film
has no voids
• This is the subject of an entire presention,
beyond the scope of this discussion
Curing
• Proper curing is essential to a good job.
• If you rush the cure, you might be throwing
away the whole job.
Importance of floating suction
Coating may be performing
multiple functions
• Protecting the steel substrate from corrosion
• Preserving product quality
ULSD and MIC- A connection?
• Recent developments showing accelerated
corrosion for ULSD service
• Uncoated tank bottoms needing replacement
after only 10 years
• New phenomenon- never had issues with
conventional distillate products (high sulfur)
• MIC- “microbially induced corrosion”
Good operations procedures are
essential to keep the product clean!
• IN ADDITION TO INTERNAL COATING:
• Floating suction
• Filtration and filter maintenance
• Removal of residual dust and grit following
coating
• Regular dewatering and sludge removal
Any questions?