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Specifying Fire Resistive Coatings
Presented by:Jayson L. Helsel, P.E.
KTA-Tator, Inc.
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Learning ObjectivesComprehension of the webinar will enable the participant to:
•Describe how intumescent coatings protect underlying steel from heat
exposure
•List two fire rating classification tests that are used to qualify
intumescent coatings for use in building construction
•Identify two primary resin types that are used to formulate intumescent
coatings
•Explain how steel size and structure design affect specified thickness
and number of coats
Fire Resistive Coatings
• Sprayed Fire Resistive Materials (SFRM) are broad group of materials including:– Cementitious and gypsum based
materials– Intumescent coatings
(Note: There is a separate category for “Fire Retardent” coatings, which are not reviewed here)
Fire Resistive Coatings
• Intumescent Coatings:– Are categorized as SFRMs– Similar to conventional coatings – Have unique fire resistant properties
Intumescent Coatings
• How they function: – Intumescent coatings char and swell
when exposed to fire/heat– The charred layer acts to insulate the
steel from fire
Intumescent Coatings
• Performance ratings– Coatings rated by how long steel is
protected at specified thickness– Ratings from 1 to 3 hours (at 30
minute intervals– Specific to shape/size of steel,
e.g. W10 x 49 column
Fire Resistance Classifications
• Underwriters Laboratories (UL) is recognized authority that evaluates and approves intumescent coatings for a certain classification and fire rating
• Certifications can be verified online at www.ul.com
Fire Resistance Classifications
• Certifications are “design” specific by coating manufacturer
• Numbering system defines an alphanumeric design number
Fire Resistance Classifications
• Beams– W, M or S shaped steel sections (AISC)– Minimum beam size for fire resistance is
expressed as W/D ratio• W = weight of beam per lineal foot• D = perimeter of protection material
– Beams of same configuration with greater W/D ratio may be used in design
Fire Resistance Classifications
• Columns– Minimum column size and configuration
specified in X and Y series designs– Same hourly rating applies when section
with equal or greater W/D ratio is substituted for same configuration
Fire Resistance Classifications
• Beams and Columns– Required coating thickness increases as
weight of steel decreases• Lighter steel heats up more rapidly and
requires more protection
Fire Resistance Classifications
• ANSI/UL 263– Used for resistance to cellulosic fire (e.g.
combustion of wood or building materials)
– Slower rise in temperature• 1000 F at 5 min.; 1550 F at 30 min.; 1700 F
at 60 min.; 1925 F at 180 min.; 2000 F at 240 min.
– Interior and exterior exposures
Fire Resistance Classifications
• ANSI/UL 263 Classified Coatings– Typical use for structural steel in
commercial structures
Fire Resistance Classifications
• ANSI/UL 1709– Used for resistance to a hydrocarbon fire– Rapid rise in temperature
• 2000 F at 5 minutes
– Interior and exterior exposures• Environmental tests include, accelerated
aging, high humidity, salt spray, thermal cycling for exterior exposure
Fire Resistance Classifications
• ANSI/UL 1709 Classified Coatings– Typical use for steel structures at
petrochemical facilities, e.g.• Chemical plant• Refineries• Offshore oil platforms
Other Approvals
• Intumescent coatings may also need approval by city building codes
• Coating manufacturers should provide approvals as applicable
Generic Coating Types
• Intumescent coatings are generally the following generic resin types:– Acrylic/vinyl– Epoxy
• Intumescents are also generally categorized as “thin-film” or “thick-film” coatings
Generic Coating Types
• Acrylic/vinyl• Thin-film coating• Solvent or water-based• Single component • Typically rated under UL 263
Generic Coating Types
• Acrylic/vinyl• Applied in several coats• Time-frame for a complete application may
span several days• Additional time may be needed before
application of any required exterior finish coat.
Generic Coating Types
• Epoxy• Thick-film coating• Applied by plural component spray
equipment in one or two coats• Rapid cure• Typically rated under UL 1709
Generic Coating Types
• Epoxy• May require mesh reinforcement (e.g. metal,
fiberglass, carbon)• Typically requires the use of applicators
licensed or approved by the coating manufacturer
Generic Coating ComparisonCoating
TypeRequired Thickness
(mils)
Number of Coats
Recoat Time (between
coats) @50F
Time to Finish Coat
@50F
Solvent based acrylic
130 5 24 hours 25 days
Solvent based vinyl
375 4 4 hours 20+ days
Water based acrylic
180 6 8 hours 10+ days
Epoxy 180 1 n/a 24 hours
Epoxy w/mesh
340 1-2 n/a 48 hours
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Testing for Coating Cure
• Intumescents may require testing for proper cure
• Typical test is Durometer Hardness (Shore D)– Resistance of coating film to indentation
by Durometer instrument– ASTM D2240, “Standard Test Method for
Rubber Property-Durometer Hardness”
Testing for Coating Cure
Coating Appearance
• Intumescents generally have a rough or orange peel appearance
• Methods to improve include:• Back rolling following spray application• Sanding (not recommended)• Finish coat application (may be required)
• Test sections recommended
Coating Systems
• Intumescent design approvals typically include a primer and/or finish coat– When included in design primer/finish
must be applied to meet fire rating
• Primer/finish must be endorsed by intumescent coating manufacturer– Preference always for same
manufacturer
Use of Primers
• Intumescent coating manufacturer may have approved list of primers– Types include alkyd, acrylic, epoxy and
zinc-rich– Application thickness important
Primers
• Function of primer– Provides adhesion to substrate – Provides suitable surface for
intumescent– Provides additional barrier protection
• Can also provide inhibitive or sacrificial protection
Use of Finish Coat
• May be required in design approval for exterior exposure
• Intumescent coating manufacturer must endorse finish material– Types include 100% acrylic and aliphatic
urethane coatings
• May affect/improve appearance
Finish Coats
• Function of topcoat– Color and gloss– Abrasion resistance– Chemical resistance– Washability– Resistance to the environment
Finish Coats
• Acrylics– Advantages
• Single component• Ease of application• Color & gloss retention• Flexibility• Low VOC content for waterbased
Finish Coats
• Acrylics– Limitations
• Limited alkali and solvent resistance• Moderate abrasion resistance• Application temperature >50ºF for
waterbased
Finish Coats
• Urethanes– Advantages
• Color & gloss retention (aliphatic)• Adhesion• Acid, alkali resistant• Chemical resistant• Impact/abrasion resistant
Finish Coats
• Urethanes– Limitations
• Multi-component• Short recoat intervals• Limited pot life• Moisture sensitive during cure• Difficult to recoat
Fire Resistive Coating Inspection
• Technical Manual 12-B– Published by Association of the Wall and
Ceiling Industries (AWCI International)– Individual measurement = average of 3
gauge readings (similar to SSPC-PA 2)– Testing frequency one bay per floor or
one test per 10,000 square feet (further defines required shapes)
Fire Resistive Coating Inspection• Technical Manual 12-B
– Scope– General Information– Substrate Conditions– Site Conditions– Inspection Procedures– Method of Tests– Conditions of Finished Application– Patching
Fire Resistive Coating Inspection
• Intumescent (and Mastic) Coatings– Coating thickness specification in a
design is minimum average thickness measured in accordance with Technical Manual 12-B• Average thickness should not exceed
maximum thickness published (if listed) in individual designs
• No individual measurement <80% of specified design thickness
Summary of Key Points
• When specifying intumescents consider:– Required UL approval– City building code approval– Include required primer and finish coats– Applicator certification if needed (e.g.
plural component materials)– Include test sections to evaluate
appearance
Specifying Fire Resistive Coatings
• Questions?