installing quality internal tank linings: a perspective david cushman west virginia paint llc...

Installing Quality Internal Tank Linings: A Perspective

David CushmanWest Virginia Paint LLC

General ManagerNACE 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?