An investigation of how good specifications prevent coating failures Abstract:  This webinar presents a scientific approach to the analysis and prevention of common paint and coating failures on industrial structures. It begins with a close look at the structure, composition and properties of polymers used in the formulation of modern paints and coatings, followed by a systematic consideration of failures induced by weather, corrosion, mechanical and chemical influence, light, heat, and other agents. 

Prevent Coating Failures Corrosion Protection Good Design Good Paint Good Specifications Good Contractors Good Inspection Good Maintenance

NATURAL CYCLE OF CORROSION Iron ore Corrosion / Rust Exposure Blast Furnace Steel (Iron) Plate

FOUR CONDITIONS NECESSARY FOR CORROSION An ANODE (Oxygen reacts with Iron) A CATHODE (Oxygen + water react) An ELECTROLYTE (Source of Ions) A CIRCUIT connecting the Anode and Cathode (Moisture) Section 1 - Understanding the Science of Corrosion

COATING INTERRUPTS CORROSION Paint is a BARRIER that can stop the flow of electrical currents. Section 1 - Understanding the Science of Corrosion

Prevent Coating Failures Corrosion Protection Good Design Good Paint Good Specifications Good Contractors Good Inspection Good Maintenance

Examples of Design Problems Back to Back Angles Channels Turned Up Too Close to Headwalls (Deck) Skip Welds Poor Bolt (Rivet) Spacing Limited Access

BACK – TO – BACK ANGLES

CHANNELS TURNED UP

TOO CLOSE TO HEADWALLS

SKIP WELDS

POOR BOLT (RIVET) SPACING

LIMITED ACCESS

Prevent Coating Failures Corrosion Protection Good Design Good Paint Good Specifications Good Contractors Good Inspection Good Maintenance

DEFINITIONS Coatings LININGS A layer of a substance spread over a surface for protection or decoration. LININGS A covering or coating for an inside surface. Something that is used to line another thing; a layer of material on the inner side or surface of something.

DEFINITION Coating System The application of a number of coats, separately applied, in a pre-determined order and thickness, with suitable intervals to allow for drying or curing. Finish – uv/esthetics Intermediate – barrier coat Primer – corrosion inhibitor steel

COATING THICKNESS Measured in Thin Film (< 20 mils or 500 microns) mils (thousandths of an inch) Microns (24.6 microns per mil) Thin Film (< 20 mils or 500 microns) Thick Film (>20 mils) Example – Copy paper is typically 4-5 mils thick

GOOD PAINT Two Specifying Methods Formula / Design (decreasing in popularity) Performance Reputation Laboratory Testing Weighting Factors

GOOD PAINT FORMULA / DESIGN SPECIFICATION A Formula/Design specification provides in-depth detail about the coating formulation. It provides the user with all of the information and references necessary so they can achieve the intended outcome. The design specification result should be consistently reproducible providing the same standard outcome Provides specific instructions

GOOD PAINT PERFORMANCE SPECIFICATION Reputation Case histories of coating systems on similar structures

GOOD PAINT PERFORMANCE SPECIFICATION Laboratory Testing NTPEP data available online Exposures: Salt Fog Cyclic Weathering (cycles = 1 week prohesion / 1 week QUV) Tensile (Pull-off) Adhesion Freeze Thaw Stability

GOOD PAINT PERFORMANCE SPECIFICATION Weighting Factors: Coating System must be matched to the service environment Guidance available: SSPC “Selecting Materials for Industrial and Marine Structures” NORSOK M-501

COATING SYSTEM A coat is a single application (one layer) applied to form an evenly distributed film when dry.

COATING SYSTEM Common system terminology Primer Stripe Coat Intermediate Finish

PRIMER First coat applied Contains ingredients which provide for adhesion to the substrate. Provides for subsequent coats Dictates the degree of cleanliness required of the substrate. May provide anti-corrosion properties

STRIPE COAT Not always required Provide additional coating in sensitive areas Cervices Welds Sharp edges Fasteners Commonly brush applied

INTERMEDIATE Not always required May improve chemical resistance. May be a “Tie Coat” between the primer and finish coat when not compatible. Increase the film thickness.

TOP COAT / FINISH Last coat applied May improve chemical resistance. May provide for: Color Gloss Mildew resistance Wear resistance (hardness) Critical that each coat in a multi-coat system be different colors/tinted for easy identification during the inspection process.

CORROSION PROTECTION Provided by Protective Coating Systems through BARRIER PROTECTION INHIBITIVE GALVANIC May incorporate combinations of the above.

BARRIER PROTECTION The partial blocking of any or all elements by a semi-impermeable film. Examples: Tank Linings, Ballast Tanks

INHIBITIVE - INHIBITION Slowing down of the corrosion reaction by passivation of the substrate Primers Red Lead, Chromates

GALVANIC - SACRIFICIAL Pigment is anodic to the substrate and corrodes in preference to the steel Cathodic Protection Most common: Zinc rich primers

COATINGS Are classified by their methods of film formation or cure. The curing mechanism for a generic category of coating is the method or reaction causing the liquid coating to convert into a solid membrane which is resistant to that particular environment.

COATINGS The method of cure may effect and/or require a specific mixing requirement, timing or “Sweat-in Time”, or have specific environmental/ambient condition requirements during the application process.

CURING MECHANISMS Oxidation Evaporation Chemical Reaction Hydrolysis or Hydration Coalescence

OXIDATION Reacts with the oxygen and allowed to polymerize or harden. One component material Typically an oil modified, solvent-based coating. Used in mild environments Poor chemical resistance Poor solvent resistance

OXIDATION Good penetration into and around irregular surfaces and/or poorly prepared surfaces. Drying oils Alkyds Silicone alkyds Epoxy esters

EVAPORATION Allows the liquid coating to stay in-place long enough for the liquid carrier or solvent to evaporate and the solids to become hard. The resins are dissolved within the solvent during the manufacturing process. Typically used as intermediate and finish coats.

EVAPORATION Good chemical resistance Limited solvent resistance Dries at low temperatures Dries very quickly Chlorinated rubbers Vinyls

CHEMICAL REACTION Is curing that results from a chemical reaction between the resin and the curing agent (activator) to form a hard film. Small molecules form into large molecules. May require an “Induction” or “Sweat” time prior to application. Limited pot-life

CHEMICAL REACTION Temperature sensitive Humidity sensitive to low: incomplete cure to high: reduced pot-life Humidity sensitive Good chemical and solvent resistance Epoxies (will chalk when exposed to UV) Urethanes

HYDROLYSIS or HYDRATION Hydrolysis is the taking of moisture from the air to produce a hard film. Solvent-based inorganic zinc-rich primers and certain urethanes. Inorganic zinc-rich primers involve a two-step process. First evaporation takes place with the solvent and a reaction takes place between the zinc and binder. The film is dry, although until the film reacts with moisture in the air, it is not cured.

COALESCENCE A combination of evaporation of water and coalescence of particles of polymers. Higher concentrations of solids Latex, Acrylics

RECENT TECHNOLOGIES Fluoropolymer Coatings Exceptional resistance to solvents, acids, and bases. Longer life in terms of color retention and gloss over traditional urethanes. Typical costs per gallon of >$400.00

Premature Coating Failures Common Failure Mechanisms UV degradation (color, gloss reduction, chalking) Osmotic blistering Cathodic delamination Corrosion Poor adhesion Chemical attack Abrasion

UV degradation (color, gloss reduction, chalking) Cause: Exposure to sunlight Resistance to UV degredation: Polymers with more stable bonds such as siloxanes and fluoro carbons Need polymers which do not have unsaturation, i.e. no carbon-carbon double bonds, aromatic groups, etc. UV resistance can be enhanced by adding hindered amine light stabilizers (HALS) and UV absorbers Need to use light stable pigments. Example Rutile TiO2 is light stable (especially with silica and alumina coating) while Anatase TiO2 is not stable. Susceptible to UV degredation: Examples: epoxies, aromatic isocyanates and alkyds (have unsaturation in their polymers) Consider laboratory QUV exposure data

Osmotic blistering Causes: water soluble ionic compounds or water soluble covalent compounds remaining on substrate Coating moisture permeability Make sure the surface is clean from water soluble ionic compounds or water soluble covalent compounds. Specify desired surface cleanliness

Corrosion 4 sources of common corrosion: Erosion induced corrosion The coating wears away due to weathering effects until the substrate becomes exposed to the elements. Rates of erosion and relative costs of common coatings: Alkyd > Epoxy > Polyurethane > Polysiloxane > Fluoropolymer Damage induced corrosion Scratching/Cutting of films to the substrate Impact and breakage of the film Cracking of films due to excessive thickness and temperature variations Conductive pathway induced corrosion Microscopic pathways in the coatings film which may allow ions to transport to the steel substrate. Contamination induced corrosion Corrosion resulting from contaminants (ions and water solubles) residing on a substrate that has been overcoated with a coating.

Poor adhesion Adhesion to steel Adhesion to previous coats of paint Proper surface preparation Quality primer Use polymers with strong and concentrated Lewis basicity. Tightly adhering rust on steel surface enhances adhesion To metallic iron, use covalently reacted polymers such as silanes and siloxanes Adhesion to previous coats of paint Properly matched coating system Match Lewis acidity/basicity of the coatings Beware of low molecular species in the coating that will migrate to the surface Proper Recoat times

Chemical attack Proper coating selection for the exposure environment

Prevent Coating Failures Corrosion Protection Good Design Good Paint Good Specifications Good Contractors Good Inspection Good Maintenance

GOOD SPECIFICATIONS Must Be Understandable Must Be Enforceable If not, Inspectors then rely on “Painting Common Sense” Requires Education Must Be Enforceable At all levels By the Courts

SPECIFICATION TYPE - DESIGN A Formula/Design specification provides in-depth detail about the functional and non-functional design requirements. It provides the user with all of the information and references necessary so they can achieve the intended outcome. The design specification result should be consistently reproducible providing the same standard outcome. Provides specific instructions.

SPECIFICATION TYPE - PERFORMANCE Permits greater contractor flexibility to develop innovative solutions and build in quality through process control and continuous process improvement Enhances competition and much needed force modernization Means & methods are up to the Contractor

SPECIFICATION LANGUAGE SHALL: A requirement SHOULD: A preference or strong recommendation MAY: Acceptable alternatives

SPECIFICATION FORMATS CSI (Construction Specifications Institute) Part 1 – General Part 2 – Products Part 3 - Execution

PART 1 – GENERAL (SPECIFICATIONS) 1.7 Project/Site Conditions 1.8 Sequencing and Scheduling 1.9 Safety and Environmental Compliance 1.10 Warranty 1.11 Maintenance (optional) 1.1 Scope 1.2 References 1.3 Definitions 1.4 Submittals 1.5 Quality Assurance 1.6 Delivery, Storage, and Handling

STANDARDS & REFERENCES A standard is a general document that does not change from job-to-job. Typically included within specifications, thus becoming a binding part of the contract. Inspectors must be familiar with all reference standards.

STANDARDS & REFERENCES ACI – American Concrete Institute AISI – American Iron & Steel Institute ANSI – American National Standards Institute, Inc. API – American Petroleum Institute ICRI – International Concrete Repair Institute. ASTM – American Society for Testing and Materials AWWA – American Water Works Association NACE – National Association of Corrosion Engineers SSPC – Society of Protective Coatings

PART 2 - PRODUCTS 2.1 Manufacturers 2.2 Materials 2.3 Equipment 2.4 Source Quality Control

PART 3 - EXECUTION 3.1 Examination 3.2 General Preparation 3.3 Surface Preparation 3.4 Application 3.5 Quality Control 3.6 Site Clean-up

3.3 SURFACE PREPARATION The majority of premature coating failures can be tied to surface preparation Reference appropriate surface preparation standards

PREPARATION STANDARDS SSPC-SP1 SSPC-SP2 SSPC-SP3 SSPC-SP5/NACE 1 SSPC-SP6/NACE 3 SSPC-SP7/NACE 4 SSPC-SP10/NACE 2 SSPC-SP11 SSPC-SP12/NACE 5 SSPC-SP13/NACE 6 SSPC-SP14/NACE 8 SSPC-SP15/NACE 6

3.5 QUALITY CONTROL (Hold-Point) Defines the minimum testing required by the contractor and/or the inspector. Determines who provides inspection equipment. Provides for dispute resolution between multiple parties Describes documentation requirements.

Prevent Coating Failures Corrosion Protection Good Design Good Paint Good Specifications Good Contractors Good Inspection Good Maintenance

OR GOOD APPLICATORS (TRAINED) GOOD CONTRACTORS OR GOOD APPLICATORS (TRAINED) Past experience Currently Can they get bonded? Changes (pre-qualified) New improved specifications Pre-bid meeting Disbarment investigations Probably higher prices

QUALIFICATIONS Pre-Qualified by Owner Pre-Qualified by Others (SSPC – PCCP) SSPC QP 1 SSPC QP 2 SSPC QP 3

SSPC QP 1 The program’s objective is to determine if an industrial/marine coatings Contractor has the personnel, organization, qualifications, procedures, knowledge, and capability to produce quality surface preparation and coating application of complex industrial and marine structures.

SSPC QP 2 Assess the primary capabilities of contractors to protect worker health and safety and the environment, while successfully completing industrial/marine hazardous paint removal projects.

SSPC QP 3 Verify the capabilities of shop facilities to perform quality surface preparation and coating application. SSPC achieves this by independently auditing shops to determine whether they have the personnel, organization, quality procedures, knowledge, and capability to produce quality surface preparation and protective coating application in a shop environment.

Prevent Coating Failures Corrosion Protection Good Design Good Paint Good Specifications Good Contractors Good Inspection Good Maintenance

INSPECTION CONSISTS OF Witness Verify Measure Document

THE QC INSPECTOR The role of the Inspector is to assure that all the requirements of the Specification are accomplished and documented, to report any deviation, and assure that they are corrected.

THE QC INSPECTOR Must have the authority to make decisions. Must have the freedom to identify problems. Should report directly to management.

HOLD-POINT INSPECTIONS During surface preparation During mixing and thinning operations During coating application

DURING SURFACE PREPARATION See that surface is cleaned as specified.

DURING MIXING & THINNING Coating is mixed thoroughly and in the proper proportions. Correct amount of thinner is used. Correct type of thinner is used. Temperatures and pot-life observed.

DURING COATING APPLICATION Correct coating thickness is attained. Specified recoat window is observed. Specified surface temperature is observed. Specified coating is applied.

COMMUNICATION Avoids Confusion Delays Misunderstandings Conflicts

DOCUMENTATION Daily Inspection Reports (DIR’s) Meetings Communication Hold-Point inspections

DAILY INSPECTION REPORTS (DIR’S) Site & Environmental Conditions Surface Preparation Coatings (Materials) Application Dry Film Thickness Crew & Equipment Non-Compliance “Hold-Points”

Prevent Coating Failures Corrosion Protection Good Design Good Paint Good Specifications Good Contractors Good Inspection Good Maintenance

MAINTENANCE PAINTING Typical Rehabilitative Options Do Nothing Spot Repair Zone Repair Spot/Zone + Overcoat Full Removal & Replacement In most company’s budgets, maintenance is typically one of the first items that is reduced if not eliminated completely when monies become tight. Whether the initial painting costs were only a few thousand dollars or as much as a few millions, getting the most out of those dollars is critical since future budgets to maintain the assets are often unknown; too slow to react in a timely manner; and or just eliminated. The technology being built into coating technology is generating systems that can last up and extending beyond 20 years with little to minimal attention/repair.

REVIEW A successful coating project requires a complete and thorough understanding of: Corrosion Coatings (chemistry) Industry Standards Surface Preparation Application Inspection (Hold-Points, Equipment & Communication) Maintenance

QUESTIONS Thank you