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Polyurethane, Polyurea and Hybrid Lining Technology. Presented by: Dudley Primeaux, PCS VersaFlex Incorporated. Introduction.
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Polyurethane, Polyurea and Hybrid Lining Technology Presented by: Dudley Primeaux, PCS VersaFlex Incorporated
Introduction This webinar reviews application of polyurea, polyurethane, or polyurea/polyurethane hybrid thick film coatings to steel or concrete surfaces using plural-component spray application
SSPC Standards • SSPC-Paint 45, Two-Component, Thick-Film Polyurea and Polyurea/Polyurethane Hybrid Coatings, Performance-Based • Expected to be released by December 2013 • SSPC-PA 14, Application of Thick Film Polyurea and Polyurethane Coatings to Concrete and Steel Using Plural-Component Equipment
SSPC-Paint 45 A coating standard that contains minimum performance requirements for polyurea and polyurea/polyurethane hybrid coatings
SSPC-Paint 45 Coating Types • 2 types defined • Type 1 • Polyurea • 1a, Fast Cure • Dry in less than 2 minutes • 1b, Moderate Cure • Dry time is 2 minutes – 30 minutes • Type 2 • Polyurea/Polyurethane Hybrid • 2a, Fast Cure • Dry in less than 2 minutes • 2b, Moderate Cure • Dry time is 2 minutes-30 minutes
Polyurea A coating material which is the reaction product of an isocyanate and a polyamine.
Polyureas • Isocyanate Component can be aromatic or aliphatic • Resin / Polyamine Component can be aromatic or aliphatic • Aromatic based systems will yellow or fade but not crack • Aliphatic based systems have excellent weatherability
Polyurea Properties Good elongation and flexibility Excellent chemical/solvent resistance Can be applied in low temperatures Good thermal shock resistance Turn Around Time 100% Solids
Polyurea Standard • SSPC Paint No. 39, Two-Component Aliphatic Polyurea Topcoat Fast or Moderate Drying, Performance Based • Type 1: Fast Drying • Less than 30 minutes • Type 2: Moderate Drying • 30 minutes to 2 hours
SSPC Paint 39 From Table 1: Summary of Performance Testing Results to be Reported
Polyurethane A coating binder material formed by the reaction of an isocyanate with hydroxyl-containing substances (polyols) to produce an organic polymer compound known as a urethane
Types of Polyurethanes Conventional 2-part (thin film) Moisture cure polyurethane single component 100% solids/elastomeric (thick film)
Conventional 2-Part Polyurethane • Waterborne formulations • Use water dispersible polyisocyanate • Slower cure • Longer potlife • Typically aliphatic • SSPC Paint Specification No. 36 • Two Component Weatherable Aliphatic Polyurethane Topcoat, Performance-Based
SSPC Paint No. 36 Accelerated UV-A Testing From Table 1: Time Corresponding to Each Performance Level
SSPC Paint No. 36 From Table 2: Summary of Performance Testing Results to be Reported
Conventional 2-Part Polyurethane Excellent color and gloss retention Good chemical/solvent resistance Good hardness/abrasion resistance
Characteristics of Moisture-Cured Urethane Coatings • Moisture-Cured Urethane (MCU) Coatings • Advantages • Limitations
Polyurethane Advantages • Turn Around Time • 100% Solid • Can Have Some Limited Ability to Apply During Winter Months • Unique “Self-Inspecting” Property
Hybrid A blend of polyurea and polyurethane
100% Solids/Elastomeric Typically aromatic Fast cure High build, up to 100+ mils (2.5+ mm) Good elongation and flexibility Excellent chemical and solvent resistance Can be applied in low temperatures Low VOC
Thick Film • Shown here is a wet film gage used in some Moderate Cure systems • Fast Cure systems would require the use of either a Type 1 magnetic or Type 2 electronic gage, or an ultrasonic gage Greater than 20 mils (500 µm) dry film thickness
Service Environments • SSPC-Paint 45 coatings are suitable for application in the following SSPC environmental zones: • 1A (Interior, normally dry) • 1B (Exterior, normally dry) • 2A (Frequently wet by fresh water, excluding immersion) • 2B (Frequently wet by salt water, excluding immersion) • 2C (Fresh water immersion) • 2D (Salt water immersion)
Surface Preparation of Steel • Removal of Visible Contaminants • SSPC-SP 1, Solvent Cleaning • Removal of Non-Visible Contaminants • SSPC Guide 15, Field Methods for Retrieval and Analysis of Soluble Salts on Steel and Other Nonporous Substrates • Minimum Surface Profile of 3 mils (76 µm) • ASTM D4417, Standard Test Methods for Field Measurement of Surface Profile of Blast Cleaned Steel • Method B • SSPC-PA 17, Procedure for Determining Conformance to Steel Profile/Surface Roughness/Peak Count Requirements
Surface Preparation of Concrete • Verify that the concrete substrate is sound and solid • ASTM C805, Standard Test Method for Rebound Number of Hardened Concrete • Repair surface defects such as: bugholes, voids and cracks • Clean the surface so it is free of dust, dirt, grease and oils, contaminants, laitance, and loosely adhering concrete (SSPC-SP 13) • Create a surface roughness within ICRI 310.2, CSP range of 2-6
Rebound Hammer and ICRI 310.2 CSP replicate plaques • ASTM D7682, Standard Test Method for Replication and Measurement of Concrete Surface Profiles Using Replica Putty
Coating Material Receipt • Check that coatings delivered: • Are in original, unopened containers with labels intact • That containers are not damaged • Have readily accessible PDS’s and SDS’s • Each container is marked, showing: coating identification, date of manufacturer, batch number, and basic chemical composition • Coatings are stored in accordance with applicable federal, state and local safety regulations • Coatings are stored in accordance with manufacturer’s recommendations • Are within applicable shelf life
Mixing Mix each individual component of the coating system in accordance with manufacturer’s instructions Verify proper mix ratio of coating components prior to placement into plural component equipment
Pre- Application Checks • Prior to application of the coating check: • Ambient conditions • Coating is not to be applied in wind, snow, fog, mist or rain. • Coating is not to be applied to wet or damp substrates • Temperature • The surface temperature, temperature of the coating and ambient air temperature must be within coating manufacturers requirements
Pre-Application Checks (Cont’d) • Humidity • Coating shall not be applied when the surface temperature is less than 5 degrees Fahrenheit (3 degrees Centigrade) above the dew point • Concrete Substrate Moisture • The moisture level of the concrete shall comply with the coating manufacturer’s requirements as determined by the measurement method specified on the PDS • Steel Substrate Moisture • Apply coating to dry substrates that are free of any water in seams, fasteners or joints
Application Equipment • Coating are applied by high-pressure or low-pressure plural component spray equipment • Equipment is capable proportioning and heating the fluid • The spray gun is capable of mix and dispense of the thick film coating to the desired DFT and pattern specified on PDS • DFT can be achieved in 1-3 overlapping passes
Mixing at the Gun Air purge gun Mechanical purge gun
Test Area • Prior to spraying project area, create a test area • ~11 square feet (1 square meter) in size • Test adhesion • For steel test in accordance of ASTM D4541, Method D or E • Average of 3 pulls • For concrete test in accordance of ASTM D7234 • Average of 3 pulls
Application • Primer • Applied in accordance with PDS • Applied in a visually continuous film with overlapping at the edges of the spray pattern • Topcoat • Applied in accordance with PDS • Not applied until primer has cured • Applied within recoat window of primer
Coating Thickness • The coating thickness is verified by: • Steel: SSPC-PA 2, Procedure for Determining Conformance to Dry Coating Thickness Requirements - Type 1 (magnetic) or Type 2 (electronic) • Concrete: SSPC-PA 9, Measurement of Dry Coating Thickness on Cementitious Substrates Using Ultrasonic Gages
Coating Continuity • Inspect coating for a cured film that is continuous and pinhole free • NACE SP0188, Discontinuity (Holiday) Testing of New Protective Coatings on Conductive Substrates • ASTM D4787, Standard Practice for Continuity Verification of Liquid or Sheet Linings Applied to Concrete Substrates
Summary By following appropriate test methods and good practices, polyurea, polyurethane and hybrid coatings can provide excellent corrosion protection for concrete and steel substrates This protection includes a variety of interior and exterior coating work, as well as immersion lining application areas