Galvanizing Process and its uses

1. Galvanize It! Seminar
American Galvanizing
Association

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American Galvanizers Association
The American Galvanizers Association (AGA)
is a non-profit trade association dedicated to
serving the needs of after-fabrication
galvanizers, fabricators, architects, specifiers,
and engineers
The AGA provides technical support on today's
innovative applications and state-of-the-art
technological developments in hot-dip
galvanizing for corrosion control

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American Institute of Architects
Learning Units (HSW)
Continuing Education Credit
National Council of Examiners for
Engineering & Surveying
Professional Development Hours

4. 4
Continuing Education
AIA/CES Policy on Endorsement: The following
program is registered with the AIA/CES and
does not include content that may be deemed
or construed to be an approval, sponsorship, or
endorsement of any material of construction or
any method or manner of handling, using,
distributing, or dealing in any material or
product.

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Continuing Education
The American Galvanizers Association has met
the standards and requirements of the
Registered Continuing Education Providers
Program. Credit earned upon completion of this
program will be reported to RCEPP. A certificate
of completion will be issued to each participant.
As such, it does not include content that may be
deemed or construed to be an approval or
endorsement by NCEES or RCEPP.

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Purpose of this Seminar
The purpose of this seminar is to inform
and educate architects, engineers, and
other specifiers about hot-dip galvanized
steel and how it can address the growing
corrosion problem throughout North
America.

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Learning Objectives
At the end of this presentation you will be able
to:
• Recognize the corrosion issues confronting the
United States
• Describe how zinc coatings, specifically hot-dip
galvanizing, can protect against steel corrosion
• Incorporate sound corrosion protection into the
design of steel products that can significantly
decrease maintenance costs over the life of a
structure

8. Tour of the City

9. 9
The Corrosion Problem

10. 10
The Corrosion Problem
Bridge in Denver, CO
Bridge in Denver, CO

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The Corrosion Problem
Corroded Trolley

12. 12
The Corrosion Problem
Coors Field – Denver, CO

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The Corrosion Problem
Corroded Pier

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The Corrosion Problem
Williamsburg Bridge - New York City, NY

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Corrosion Costs
NACE, CC
Technologies, &
FHWA jointly
produced a report in
2001 detailing the
costs of corrosion
• $297 billion USD
annually
• 3.1% of US GDP
(1998)
Hazardous
• Public safety, property
damage,
environmental
contamination
Natural Resources
• Waste production,
increased energy
consumption
Public Outcry
• Traffic, inconvenience

16. The Solution: Hot-Dip
Galvanizing

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Barrier Protection
Weathered Guardrail

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Cathodic Protection: Galvanic Series
ZINC - Anode
STEEL - Cathode
This arrangement of
metals determines what
metal will be the anode
and cathode when the two
are put in a electrolytic cell
(arrangement dependent
on salt water as
electrolyte).

19. 19
Cathodic Protection
With a cathodically protective coating, such as
galvanized steel, damaged areas will be
protected by the surrounding zinc
Zinc Coating
Bare Steel
Exposed Steel
is Protected

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HDG Process
Steel is dipped in a series of tanks including solutions
that remove impurities from the steel surface. The
galvanizing reaction only occurs on perfectly clean steel.
The steel is inspected after galvanizing to ensure
conformance to the appropriate specifications.

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Long-Lasting Zinc Protection
Barrier
Cathodic
Zinc Patina
Zinc Patina Cathodic
Barrier
Long-lasting
Protection

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HDG Process: Surface Prep
Zinc-iron metallurgical
bond only occurs on clean
steel
Degreasing
• Removes dirt, oils, organic
residue
Pickling
• Removes mill scale and
oxides
Fluxing
• Mild cleaning, provides
protective layer
Caustic cleaning

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HDG Process: Galvanizing
Steel articles are
immersed in a bath of
molten zinc (≈ 830 0F)
> 98% pure zinc, minor
elements added for
coating properties (Al, Bi,
Ni)
Zinc reacts with iron in
the steel to form
galvanized coating.
Zinc bath removal

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HDG Process: Inspection
Steel articles are
inspected after
galvanizing to verify
conformance to
appropriate specs.
Surface defects easily
identified through visual
inspection.
Coating thickness verified
through magnetic
thickness gauge
readings.

25. Hot-Dip Galvanized Coating
Properties

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Metallurgical Bond

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Edge Protection
Micrograph of galvanized edge
Same thickness at corner

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Additional Benefits of HDG
Complete Coverage

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Additional Benefits of HDG
Variety of
sizes and
shapes

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Additional Benefits of HDG
Availability

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Galvanizing is Green
Zinc is 100% recyclable as is
the steel
• Properties of zinc do not degrade
w/ reprocessing
• Zinc is a natural element in the
Earth’s crust
The longevity of galvanizing
means no additional energy
exerted or waste created
maintaining galvanized
structures

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Estimated Service Life of HDG

33. Other Zinc Coatings for
Corrosion Protection

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Metallizing
Shop or in-field
application
Suitable for very large
pieces
Coating Properties:
• Thick coating
• Mechanical bond
• Less dense than HDG
zinc layers
• No interior coverage Metallizing Appliation

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Zinc Rich Paint
Metallic zinc dust
• Inorganic
• Organic
Barrier protection
Cathodic protection
• Limited
• Dependent on % Zn
Use salt spray data to
make performance
claims
Zinc Rich Paint Application

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Sheet Galvanized
Produced by a
continuous in-line
hot-dip process
• Coil-to-coil process
• 400-500 FPM
• “Air knives” remove
excess zinc
• Pure zinc with little
alloy layer
• Galvannealed (Zn-Fe)
• Galvalume (55% Al)
Sheet Steel of Continuous

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Sheet Galvanized
ASTM A653 – specify total coating weights,
most common G60 and G90
• Weights represent total coating weight for both sides
of the sheet
Coating Weight
(ounces/sq. ft.)
Coating
Thickness per
Side (mils)
G60 0.60 0.54
G90 0.90 0.81

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Electroplated
Strip, sheet, or small
parts
• Smooth finish
• Slightly more
expensive than sheet
galvanized
Good formability
Paintable
Electroplating Application

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Zinc (Mechanical) Plating
Similar to
electroplating
• used for fasteners and
small parts
Parts are tumbled in
drum with zinc
powder and glass
beads
• mechanically bonded
zinc
Mechanical Plating Application

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Other Zinc Coatings
Metallizing
Hot-Dip Galvanized
Zinc-Rich Paint
Sheet Galvanized
Electroplated

41. Design & Fabrication

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Materials Suitable for
Hot-Dip Galvanizing

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Hot-Dip Galvanized Fasteners
Hot-dip galvanized
fasteners are
recommended for joining
HDG structurals

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Steel Reactivity

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Coating Appearance
Newly
Galvanized
Newly
Galvanized
Newly
Galvanized
Newly
Installed
No Spangle
Highly Spangle
Dull Coating
Shiny & Dull
Coating

47. 47
Combining Different Materials

48. 48
Weathering of Galvanized Steel
Photo taken: 12/18/02
Photo taken: 03/28/03

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Dissimilar Thicknesses
Different thickness
• Zinc bath
temperature at
different times
Similar thickness
• Maintain original
shape

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Galvanizing Oversized Pieces
Progressive Dipping

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Material Handling

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Venting & Drainage
Drain
Vent

53. Specifications & Inspection

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ASTM Standards for Galvanizing
Galvanized Products
• ASTM A 123 – general
• ASTM A 153 – small parts
• ASTM A 767 – rebar
Supporting Specifications
• ASTM A 143 – embrittlement
• ASTM A 384 – distortion
• ASTM A 385 – high-quality coatings
• ASTM A 780 – repair
• ASTM D 6386 – surface prep for painting over

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ASTM A 123
Standard Specification
for Zinc (Hot-Dip
Galvanized) Coatings on
Iron and Steel Products
• Coating Thickness – material category and steel
thickness
• Finish – continuous, smooth, uniform
• Adherence – should be tightly adherent through all
expected uses of article

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ASTM A 153
Standard Specification
for Zinc Coating (Hot-
Dip) on Iron and Steel
Hardware
• Coating Thickness – material category, steel
thickness, length
• Finish – continuous, smooth, uniform
• Adherence – should be tightly adherent through all
expected uses of article

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ASTM A 767
Standard Specification
for Zinc-Coated
(Galvanized) Steel Bars
for Concrete
Reinforcement
• Coating Thickness – smooth or deformed (no wire),
bar size
• Chromating –prevent reaction between fresh cement
and recently galvanized material
• Bend Diameters – flaking and cracking due to
fabrication are not rejectable.

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ASTM A 780
Standard Practice for Repair of Damaged
and Uncoated Areas of Hot-Dip Galvanized
Coatings
• Zinc-rich paint, zinc-based solder, or metallizing
• Zinc-rich paint - most common but must have certain
amounts of zinc dust as required by spec
• Zinc-based solder – good for small areas, closely mirrors
typical HDG coating appearance
• Metallizing – excellent corrosion protection

59. Hot-Dip Galvanizing
Costs Less &
Lasts Longer

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Quantitative Analysis
Initial cost vs. Life-
cycle cost
• Based on 2006 galvanizing
industry survey -
nationwide
• 2006 KTA-Tator paper
paint industry survey –
nationwide
• Standard mix of steel
products (structural, tubing,
plate)
• 10,000 ft2 project

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www.galvanizingcost.com
Survey data organized in a database
Based on specific project data input by the
user, (job size & location, coating type,
expected service life, etc.)
The web site automatically calculates
initial and life-cycle cost for the specified
paint systems and hot-dip galvanizing

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Initial Cost
Material
Shop cleaning labor
Shop application
Field labor
Pneumatic Bulk Trailers

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Initial Cost ($/ft2)
Coating System $/ft2
Inorganic Zinc $1.31
Inorganic Zinc/Epoxy $2.09
Hot-Dip Galvanizing $1.92
Acrylic WB Primer/Acrylic WB
Intermediate/Acrylic WB Topcoat
$2.51
Inorganic Zinc Primer/
H-B Epoxy/Acrylic Urethane
$3.07

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Life-cycle Cost
Maintenance on a ‘practical’ (vs. ideal)
cycle - unique to each paint system, as
recommended by paint manufacturers
NACE Model for NFV and NPV
calculations
• 4% inflation
• 7% interest
Maintenance repaint at 5% rust in a
moderately industrial environment
30-Year Project Performance

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Life-Cycle Cost ($/ft2)
50-Year Project Performance
Coating System $/ft2
Hot-Dip Galvanizing $1.92
Inorganic Zinc $3.21
Inorganic Zinc/Epoxy $4.83
Inorganic Zinc Primer/
H-B Epoxy/Acrylic Urethane
$6.43
Acrylic WB Primer/Acrylic WB
Intermediate/Acrylic WB Topcoat
$7.98

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What Does All of This Mean?
Coating System Cost
Hot-Dip Galvanizing $19,200
Inorganic Zinc $32,099
Inorganic Zinc/Epoxy $48,261
Inorganic Zinc Primer/
H-B Epoxy/Acrylic Urethane
$64,302
Acrylic WB Primer/Acrylic WB
Intermediate/Acrylic WB Topcoat
$79,802

67. Duplex Systems:
Painting & Powder Coating
Hot-Dip Galvanized Steel

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Why Paint a Perfectly Good
Galvanized Part?
Aesthetics
• Architects decision
Identification
Hostile Environment
to Zinc
Repair of Existing
Galvanized Articles
• Extended Life of the
Product
Light Rail Station

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Galvanized Surface
Coating Condition
Newly Galvanized
Steel
Partially Weathered
Galvanized Steel
Fully Weathered
Galvanized Steel
Painted Bridge Rail

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Passivation Cycle
1
2
3
Time
0 – 48 hrs.
48 hrs. – 6 mo.
6 mo. – 2 yrs.

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Sweep Blasting

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Duplex System Layers
Fence Pole

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Duplex System
Synergistic Effect
Paint Provides Barrier for
Galvanized Surface
Galvanized Coating
Provides Slow Corrosion
Under Paint
Paint Peeling due to
Corrosion is Minimized
Paint & Galvanizing
together have 1.5x to 2.5x
Life of Individual Lifetimes Skaneateles Community Center

74. Galvanized Steel
Project Applications

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Brooklyn Bridge
Date Galvanized
1999
Sector
Bridge &
Highway
Environment
Industrial
Location
New York, NY

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CALTRANS District 7 HQ
Date Galvanized
2004
Sector
Building &
Architecture
Environment
Urban
Location
Los Angeles, CA

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The Cloud at Fashion Show Mall
Date Galvanized
2003
Sector
Building &
Architecture
Environment
Urban
Location
Las Vegas, NV

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Harrisburg Airport
Transportation Facility
Date Galvanized
2004
Sector
Building &
Architecture
Environment
Urban
Location
Harrisburg, PA

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Cell Towers – Tree Application
Date Galvanized
2004
Sector
Electrical, Utility &
Communication
Environment
Rural
Location
California

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Leprino Foods
Date Galvanized
Unknown
Sector
Food & Agriculture
Environment
Rural
Location
Waverly, NY

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Piers 1 & 21 Replacement
Date Galvanized
2002
Sector
Water & Marine
Environment
Marine
Location
Norfolk, VA

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AGA Resources
1-800-HOT-SPEC (800.468.7732)
aga@galvanizeit.org
www.galvanizeit.org
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