Calculating Coating Lifetime Costs

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Calculating Coating Lifetime Costs

• Presented by
• Jayson L. Helsel, P.E.
• KTA-Tator, Inc.

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Learning Outcomes

• Completion of this webinar will enable the
  participant to
• Define various service environments
• Identify suitable coating systems for intended
  service
• Describe a typical maintenance painting sequence
• Calculate installed cost for coating systems
• Perform economic analysis
• Calculate coating lifetime cost

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History

• Based on Expected Service Life and Cost
  Considerations for Maintenance and New
  Construction Protective Coating Work, presented
  at NACE Corrosion 2008
• Data from survey of contractors and coating
  manufacturers
• Data presented in SSPC Painting Manual Volume 1,
  Good Painting Practice, Chapter 10.2,
  Comparative Painting Costs

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Coating System Data

• Commonly used coating systems
• For typical service environments
• Service life estimates
• Time until 5-10 coating breakdown
• For practical maintenance sequence
• Current material costs
• Current shop painting costs
• Current field painting costs

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Coating Systems - Atmospheric

• Most common systems for atmospheric exposure
• Surface preparation requirement
• Blast cleaning or hand/power tool cleaning
• Minimum dry film thickness
• Service environments

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Coating Systems - Atmospheric

• Service environments per ISO 12944-2,
  Classification of Environments
• C2 Low
• C3 Medium
• C5-I Very High, Industry
• C5-M Very High, Marine

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Coating Systems - Atmospheric

• Service environment definition
• C2 LowAtmospheres with low levels of
  pollution mostly rural areas

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Coating Systems - Atmospheric

• Service environment definition
• C3 MediumUrban and industrial atmospheres,
  moderate sulfur dioxide pollution coastal areas
  with low salinity
• Production rooms with high humidity and some
  air pollution (e.g., food processing plants,
  laundries, breweries, dairies)

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Coating Systems - Atmospheric

• Service environment definition
• C5-I Very High, IndustryIndustrial areas with
  high humidity and aggressive atmosphere

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Coating Systems - Atmospheric

• Service environment definition
• C5-M Very High, MarineCoastal and offshore
  areas with high salinity

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Coating Systems - Immersion

• Most common systems for immersion service
• Surface preparation requirement
• Abrasive blast cleaning
• Minimum dry film thickness
• Service environments

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Coating Systems - Immersion

• Service environments
• Potable water
• Fresh water
• Salt water

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Hot Dip Galvanizing

• Service life for 4 mils minimum (American
  Galvanizers Association)
• Mild (rural) 68 Years
• Moderate (industrial) 33 Years
• Severe (heavy industrial) 21 Years

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Practical Service Life

• Time until 5 to 10 coating breakdown occurs
  (SSPC-Vis 2 Rust Grade 4)
• Active rusting of the substrate is evident

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Rust Grade 4 5 General Rusting
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Rust Grade 4 5 Spot Rusting
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Rust Grade 4 5 Pinpoint Rusting
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Typical Maintenance Painting Sequence

• Original Painting
• Spot Touch-Up and Repair
• Maintenance Repaint
• Spot prime and full overcoat
• Full Repaint
• Total coating removal and replacement

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Typical Maintenance Painting Sequence

• Spot Touch-Up and Repair
• The first time coating repairs are made
• Intended to be completed at the Practical Life
  (from Tables 1A or 1B)

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Typical Maintenance Painting Sequence

• Maintenance Repaint
• Estimated to be the Practical Life plus 33
• e.g. P x 1.33

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Typical Maintenance Painting Sequence

• Full Repaint
• Expected to occur at the year of Maintenance
  Repaint plus 50 of the Practical Life
• e.g. Maintenance Repaint year P x 0.5

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Maintenance Painting Example

• Service Environment C3
• Surface Preparation Abrasive Blast Cleaning
• Coating system 2 coat epoxy
• P life 12 years
• Spot touch up _at_ 12 years
• Maintenance repaint _at_ 16 years
• Full repaint _at_ 22 years

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Cost Data

• Current material costs
• Current shop painting costs
• Current field painting costs

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Cost Data

• Current material costs
• DFT
• Theoretical cost per sq ft
• Practical spray
• Practical brush/roller

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Cost Data

• Current shop painting costs
• Surface prep cost per sq ft
• Paint application cost per sq ft
• Hot dip galvanizing cost
• Cost multipliers
• Size of job
• Member size for galvanizing

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Cost Data

• Current field painting costs
• Surface prep cost per sq ft
• Paint application cost per sq ft
• Cost multipliers
• Size of job
• Complexity of structure
• Existing conditions

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Cost Comparisons

• Shop vs. Field
• Shop abrasive blast cleaning and priming
  approximately half of field cost (minimum of 250
  tons of steel)

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Cost Comparisons
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Cost Comparisons
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Cost Comparisons

• Shop applied inorganic zinc vs. hot dipped
  galvanizing
• 75,000 to 125,000 sq ft steel
• Moderate service environment (C3)
• 35 year structure life
• 4 inflation 7 interest
• Initial cost of galvanizing 43 greater
• Life cycle cost for galvanizing 15 less

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Economic Analysis

• Net Future Value (NFV)
• How much will it cost, in inflated dollars in the
  year scheduled?
• NFV Current Cost (1 i)n
• i inflation, n years

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Economic Analysis

• Net Present Value (NPV)
• The present worth of the inflated cost (in monies
  today invested at current interest rates)
• NPV NFV (1/ (1 i)n )
• i interest, n years

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Economic Analysis

• For each coating system
• Timing and number of painting operations
• Cost of each painting operations
• Carry out for projected life of structure

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Economic Analysis

• Present value analysis
• For each painting operation calculate
• Current cost
• Net future value
• Net present value

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Present Value Analysis
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Economic Analysis

• Average Equivalent Annual Cost (AEAC)
• Converts entire stream of present and future
  costs to a present worth (NPV)
• Distributes that sum in equal annual amounts over
  the structures life
• Represents coating lifetime or life cycle cost

i interest, n structure life
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Life Cycle Cost
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Life Cycle Cost
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Summary

• Coating system selection
• Surface preparation and service environment
• Determines Practical life
• Material costs
• Shop or field preparation and application
• Economic analysis
• Life cycle cost