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Priming and Painting Slip Critical Steel Connections

Protective & Marine Coatings10 May 2012

Troy Fraebel Corrosion Specification Specialist

• 25 years in industrial coatings

• SSPC Protective Coatings Specialist

• SSPC C-1 and C-2 Instructor

Protective & Marine Coatings

• NACE Certified Coatings Inspector

• Former AWWA D-102 Voting Member

• 13 Years with KTA-Tator, Inc.

• 3.5 Years with Caldwell Tanks

Incorporated in 1866Henry Sherwin

Edward Williams


Edward Williams

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Over 3,325 Service Centers


With Dedicated Protective & Marine Representatives


The Protective & Marine Group is Dedicatedto Providing Coatings for the Prevention of

Corrosion, which Results in the Loss of $300+ Billion Annually

Research & Development

John Breen Tech Center Cleveland


John Breen Tech Center, Cleveland

AW Steudel IM Lab, Chicago

Warrensville Lab, Cleveland

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Agenda• Structural Joints Using High Strength Bolts and

Coatings Qualified for Class A or Class B Slip• Surface Preparation of Steel (SSPC-SP 1 to SP 15)• Steel Primers

– Zinc-rich– Epoxy

MCU


– MCU – Alkyd– Acrylic

• High Performance Steel Topcoats– Fluoropolymers– Polysiloxanes– Polyurethanes– Acrylic

Slip-Critical Joint

A joint that transmits shear l d h l d i


loads or shear loads in combination with tensile loads in which the bolts have been installed . . . to provide a pretension in the installed bolt (clamping force on the faying surfaces), and with faying surfaces that have been prepared to provide a calculable resistance against slip.


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Standards Organizations Involved


“Familiarity with the referenced AISC, ASCE, ASME, ASTM and SSPC specification requirements is necessary for the proper application of this Specification.”

From the Glossary• Faying Surface. The plane of contact between two plies

of a joint.

• Coated Faying Surface. A faying surface that has been primed, primed and painted or protected against

i t b h t di l i i


corrosion, except by hot-dip galvanizing.

• Mean Slip Coefficient. μ, the ratio of the frictional shear load at the faying surface to the total normal force when slip occurs.

3.2.2. Slip-Critical Joints

The faying surfaces of slip-critical joints as defined in Section 4.3, including those of filler plates and finger shims, shall meet the following requirements:


. . . . . .(b) Coated Faying Surfaces: Coated faying

surfaces shall first be blast cleaned and subsequently coated with a coating that is qualified in accordance with the requirements in Appendix A as a Class A or Class B coating as defined in Section 5.4.

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Why Blast Clean?

• Clean and Profile

• Paints Adhere to the Surface by


• Paints Adhere to the Surface by Mechanical and / or Chemical Bond

• Whatever interferes with mechanical or chemical bond will, in turn, interfere with adhesion.

StandardsSSPC-SP 1 Solvent CleaningSSPC-SP 2 Hand Tool CleaningSSPC-SP 3 Power Tool CleaningSSPC-SP 5 / NACE 1 White Metal Blast CleaningSSPC-SP 6 / NACE 3 Commercial Blast CleaningSSPC-SP 7 / NACE 4 Brush-Off Blast CleaningSSPC-SP 8 Pickling


SSPC-SP 10 / NACE 2 Near-White Blast CleaningSSPC-SP 11 Power Tool Cleaning to Bare MetalSSPC-SP 12 / NACE 5 Surface Preparation and Cleaning of Steel

and other Hard Materials by High and UltraHigh Water Jetting

SSPC-SP 14 / NACE 8 Industrial Blast CleaningSSPC-SP 15 Commercial Power Tool CleaningSSPC-SP 16 Brush-Off Blast Cleaning of Coated and

Uncoated Galvanized Steel, Stainless Steels, and Non-Ferrous Metals

SSPC-SP1 Solvent Cleaning

“Solvent Cleaning is a method for removing all visible oil, grease, soil, drawing and cutting compounds, and other soluble contaminants from steel surfaces.”


It is the first step by definition in every preparation method!

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SSPC-SP2 Hand Tool Cleaning“Hand Tool Cleaning removes all loose mill scale, loose rust, loose paint, and other loose detrimental foreign matter. It is not intended that adherent mill scale, rust, and paint be removed by this process. Mill scale, rust, and paint are considered adherent if they cannot be removed by lifting with a dull putty knife ”


a dull putty knife.

SSPC-SP3 Power Tool Cleaning““Power Tool Cleaning removes all loose mill scale, loose rust, loose paint, and other loose detrimental foreign matter. It is not intended that adherent mill scale, rust, and paint be removed by this process. Mill scale, rust, and paint are considered adherent if they cannot be removed by lifting with a dull putty knife.”


SSPC-SP 7 / NACE 4 Brush-Off Blast Cleaning has the same definition.

Appropriate for LARGE areas. “The entire surface shall be subjected to the abrasive blast. . . .When a coating is specified, the surface shall be roughened to a degree suitable for the specified coating system.”

SSPC-SP6 Commercial Blast“A Commercial Blast cleaned surface, when viewed without magnification, shall be free of all visible oil, grease, dust, dirt, mill scale, rust, coating, oxides, corrosion products, and other foreign matter, except for staining as noted below…

“… random staining shall be limited to no more than 33% of


each unit area of surface (9 in2), and may consist of light shadows, slight streaks, or minor discolorations caused by stains of rust, stains of mill scale, or stains of previously applied coatings …”

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SSPC-SP10 Near-White Blast“A Near-White Blast cleaned surface, when viewed without magnification, shall be free of all visible oil, grease, dust, dirt, mill scale, rust, coating, oxides, corrosion products, and other foreign matter, except for staining as noted below…

“… random staining shall be limited to no more than 5% of each unit area of surface (9 in2) and may consist of light


each unit area of surface (9 in ), and may consist of light shadows, slight streaks, or minor discolorations caused by stains of rust, stains of mill scale, or stains of previously applied coatings …”

SSPC-SP5 White Metal Blast

“A White Metal Blast cleaned surface, when viewed without magnification, shall be free of all visible oil, grease, dust, dirt, mill scale, rust, coating, oxides, corrosion products, and other foreign matter.”


AASHTO R31 for Evaluation of Protective Coating Systems for Structural Steel requires abrasive blast cleaning to achieve a White Metal Blast using 100% S280 steel shot to produce a 2‐3.5 mil surface profile for the slip coefficient test. Steel shot was selected to produce a peened surface texture (lower peak density) to create a worst‐case scenario.

Centrifugal Blast Cleaning

Shops will often combine steel shot and grit for blasting.The shot impacts the mill scale while the grit imparts profile.


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Centrifugal Blast Cleaning

• Savings of time, labor, energy, and abrasive

• Superior, more uniform cleaning


• Reduces blast waste by

recycling abrasive

• Protects of the

environment

MagnesiumZincAluminumCadmiumTinLeadSteelIron

Active/Anodic

Mill Scale


Copper410 Passive304 PassiveSilverGraphite GoldPlatinum

Passive/Cathodic

SSPC-VIS 1


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The plies of slip-critical joints with coated faying surfaces shall not be assembled before the coating


before the coating has cured for the minimum time that was used in the qualifying tests.

AASHTO R31 specification requires curing at 25 +/‐ 2°C and 65 +/‐ 5% relative humidity.

1985 Publication now modified and APPENDIX A of Specification for

Structural Joints Using High-Strength Bolts


Appendix APurpose and Scope

The purpose of this testing procedure is to determine the mean slip coefficient of a coating for use in the design of slip-critical joints. Adherence to this testing method provides that the creep


method provides that the creep deformation of the coating due to boththe clamping force of the bolt and the service-load joint shear are such that the coating will provide satisfactory performance under sustained loading.

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Definition of Essential Variables

• The time interval between application of the coating and the time of testing

• The coating thickness per SSPC PA2


The coating thickness . . . per SSPC PA2 . . is 2 mils less than the average thickness ”The specimens are to be coated to an average thickness that is 2 mils greater than the maximum thickness to be used in the structure on both of the plate surfaces(the faying and outer surfaces)”

• Coating Composition and Method of Manufacture

TestingConfigurations


Contact Surface of Bolted Parts• Class A- Slip Coefficient not less than 0.33

– Clean Mill Scale and Blast Cleaned Surfaces with a Class A Coatings

• Class B- Slip Coefficient not less than 0.50

– Blast Cleaned Surfaces and Blast Cleaned Surfaces with Class B Coating

0.30 per AISC


• Class C-Slip Coefficient not less than 0.35

– Hot Dipped Galvanized Steel and roughened surfaces

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NO Masking


Reduced Cost

How Coatings Protect Surfaces

• Barrier

• Inhibitive

• Sacrificial


• Sacrificial

Corrosion PreventionStop the deterioration of a substrate. Corrosion is a

natural process that displays the tendency of materials to

“give up” energy and return to its natural state.

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Barrier

• Most coatings serve as a protective barrier by isolating the metal from the environment. Film reinforcement further slows this action down.


• This can also be true when protecting concrete, wood or other substrates.

• Some pigments used in manufacturing primers control corrosion by forming inhibitive compounds.

Th d li htl l bl i t

Inhibitive


• These compounds are slightly soluble in water, and upon contact with water vapor, passivate the substrate.

Rust inhibitive primers should never be specified or recommended for use in immersion service.

• When a zinc coating is applied to steel, the zinc, being more “active” than the steel, sacrifices itself to protect the steel from corrosion.

SacrificialMagnesiumZincAluminumCadmiumTinLeadSteelI

Active/Anodic


• This is based on the galvanic series.IronCopper410 Passive304 PassiveSilverGraphite GoldPlatinum

Passive/Cathodic

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• Two or three-component, solvent-based, inorganic, ethyl silicate, zinc-rich coating

• Two or three-component, water-based, inorganic, zinc silicate coating

• Two or three-component catalyzed polyamide

Class B Primers


• Two or three-component catalyzed polyamide epoxy, organic zinc-rich coating

• Three-component water based organic amine• adduct zinc-rich coating• Moisture-cured urethane (MCU) zinc primer• Non-zinc Epoxy Primer

Zinc-Rich Primers

Contain High Percentage of Zinc Dust in the Dried Film So That There Is Direct Contact Between Zinc Particles and Steel


(SSPC Guide 12.00 Guide to Zinc-Rich Coating Systems:

Organic zinc-rich primers must contain 77% zinc and inorganic zinc-rich primers must contain 74% zinc in the dried film)

• Sacrificial / Galvanic Protection (like galvanizing)• Corrosion Protection Prevention of Undercutting

• IOZ = Solvent Evaporation / Moisture Curing or CO2

• OZ = Solvent Evaporation / Chemical

How Zinc-Rich Primers Cure


• OZ = Solvent Evaporation / Chemical Reaction (Epoxy)

Solvent Evaporation / Moisture Curing (MCU)

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Corrosion Rate of Zinc vs. pH

40

50

60

ros

ion

Ra

te


0

10

20

30

0 2 4 6 8 10 12 14 16

pH

Re

lati

ve

Co

rr

IOZ Zinc Rich Primers• Better Surface Preparation Required

(Requires Angular Surface Profile)

• Requires Special Application and Mixing Equipment

• Recommended pH Range of 5.0 - 9.0 (untopcoated)


• Prone to “Mud Cracking” at high DFT

• Shop Application

• Performance Similar toGalvanizing

• Heat Resistance to 750 F• Low Temperature Application

Fabrication Shop Paint Booth


Application ofZinc Rich Primer

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Organic Zinc Rich• Tolerates Less Stringent Surface Preparation

• Used to Touch-up Inorganic Zinc (IOZ)


Moisture Cured Polyurethanes

• Can be applied during high humidity• Ease of Application• Fast Recoat / Fast Cure Times• Low Temperature Application 20° F.


p pp• Single Package Zinc-Rich Available

• Special Reducers Required• Unused Portion Has Limited Shelf Life• Needs Relative Humidity to Cure

Class A Primers• Standard two-component fast cure

epoxy


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• Epoxy Resins or Emulsions of Epoxy Resins Which Cross-Link with Polyamides, Amines, or Other Hardeners.

Epoxy Primers


• They Cure by Polymerization - The chemical joining of polymer chains

Catalyzed Epoxies

Epoxy Resin Hardener Product


Epoxy ResinPart A

HardenerPart B

ProductPart C=

+

• Excellent Alkali, Solvent, and Water Resistance

• Good Abrasion Resistance

• Good Acid Resistance

Solvent Based Epoxies


• Good Acid Resistance

• Good Exterior Durability

• High Film Builds Possible in One Coat

• Low Temperature Application Available

• Dry Heat Resistance to 250° F

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• Barrier Protection Only• Two-Component, Limited Pot Life• Chalks and Fades on Exterior

Solvent Based Epoxy Limitations


• Chalks and Fades on Exterior Exposure

• Recoat Window Restrictions• Solvent Odor• Special Application Equipment

Might be Required

On the Data Page


Manufacturer Certifications

Available


Available

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• Fast dry alkyds (Solvent or water-based)

• Industrial acrylics (DTM)

Non-Slip Critical Primers


• Industrial acrylics (DTM)

Alkyds• Synthetic Resins Derived From a Reaction Between an Alcohol and an Acid. The Resins are Blended With Drying Oils and


• Cure by Solvent Evaporation & Oxidation

• Barrier and Inhibitive ProtectionProne to Yellow / Saponify

Traditional Versions were High in Volatile Organic Compounds (VOC)

How Alkyds Cure


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Short Oil Alkyd Medium Oil Alkyd Long Oil Alkyd

Fast Dry Slow Dry

Aromatic Solvent Res.

Aliphatic Solvent Res.

P P t t

Drying Oil Amount


Poor Penetration

Penetrates Rust

Fast Recoatability (2 Hrs)

Long Recoat Time

Harder Film Quickly Embrittles

Softer / Pliable Film

Quickly Chalks

Good Exterior Durability

Waterborne Acrylic Primer• Single Component Water Based

• Fast Dry

• Fast Re-Coat

• Excellent Corrosion


Excellent Corrosion

Protection

• Must Contain Inhibitors

Sensitive to Temperature and Humidity During Application AND Curing (up to 30 days for cure)

Industrial Acrylics

• Cure by SolventEvaporation AND Coalescence

• Co-Solvents (coalescing


solvents) act as plasticizers for acrylics. These co-solvents contribute VOC’s to WB coatings. Co-solvents must remain in the film until evaporation.

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“Ambient Cure” WB Acrylics

O2


Polymer after film formation before ambient cure.

Polymer chains after crosslinkingat ambient temperature in the presence of atmospheric oxygen.

Primers and

Topcoats

“Regular” Acrylics “Ambient Cure” Acrylics

High Performance Steel Topcoats


Fluoropolymer Urethane• Ambient cured

• Superior color and gloss retention

• Available in a wide range of colors

G ffiti i t t


• Graffiti resistant

Like Liquid Kynar

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• High solids epoxy siloxane combines the properties of both a high performance epoxy and a polyurethane in one coat

• Isocyanate-free• Replaces a two coat epoxy/polyurethane

t l i i h i

Polysiloxane Technology


system alone or over zinc-rich primer• High-gloss, self-priming coating• High solids, low VOC• Long term color and gloss performance• Corrosion and chemical resistant• Outstanding application properties

Polysiloxane Topcoat


• A polyurethane coating is that derived from the reaction product of an isocyanate component and a resin blend component.

• Polyol + Isocyanate = Polyurethane + CO2• Good Chemical Resistance

Polyurethanes


Good Chemical Resistance• Hard, Yet Flexible Films• Excellent Color and Gloss Retention• Low-Temp, Formula Dependent

Application• No Sweat-In Time Required

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Types of PolyurethanesAliphatic

Excellent Color Retention

Excellent Gloss Retention

Primarily Used as Finish Coats

More Expensive than Aromatics


AromaticYellows & Chalks in Sunlight

Yellows & Chalks in Bright Artificial Light

Used as Primers & Intermediate Coats

Less Expensive than Aliphatics

SSPC Paint 36

“2K UV-Stable Polyurethane topcoats”

• ASTM D4587 Level Standard of Measurement

High Performance Aliphatic


• 500h Level I “color change less then 2 delta E

• and gloss loss less then 30 units”

• 1000h Level II ASTM D2244 & ASTM D523

• 2000h Level III

Two component, limited pot life.Sensitive to moisture during application & cure.

Aliphatic Moisture Cured Urethane


Isocyanate + Humidity = Amine + CO2 Amine + Isocyanate = Polyurethane (Urea Linkage)

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Mildew Resistant Polyurethane

• Mildew Resistant aliphatic acrylic polyurethane


polyurethane

• Excellent color and gloss retention

High Performance Acrylics

• Ambient Cure

• Cross-linking / branching


branching

• Superior Color &

Gloss Retention


http://www.paintsquare.com/sspcvideoproceedings/?fuseaction=view&procID=6

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Troy FraebelSherwin-Williams Company

1703 Auburn Circle

Questions?


1703 Auburn Circle Lexington, KY 40505

859.552.7027216.830.7977 efax

[email protected]/protective

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