Specifying Fire Resistive Coatings

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Specifying Fire Resistive Coatings

• Presented by
• Jayson L. Helsel, P.E.
• KTA-Tator, Inc.

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Learning Objectives

• Comprehension 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

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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)

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Fire Resistive Coatings

• Intumescent Coatings
• Are categorized as SFRMs
• Similar to conventional coatings
• Have unique fire resistant properties

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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

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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

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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

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Fire Resistance Classifications

• Certifications are design specific by coating
  manufacturer
• Numbering system defines an alphanumeric design
  number

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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

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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

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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

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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

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Fire Resistance Classifications

• ANSI/UL 263 Classified Coatings
• Typical use for structural steel in commercial
  structures

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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

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Fire Resistance Classifications

• ANSI/UL 1709 Classified Coatings
• Typical use for steel structures at petrochemical
  facilities, e.g.
• Chemical plant
• Refineries
• Offshore oil platforms

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Other Approvals

• Intumescent coatings may also need approval by
  city building codes
• Coating manufacturers should provide approvals as
  applicable

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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

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Generic Coating Types

• Acrylic/vinyl
• Thin-film coating
• Solvent or water-based
• Single component
• Typically rated under UL 263

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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.

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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

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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

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Generic Coating Comparison
Coating Type Required Thickness (mils) Number of Coats Recoat Time (between coats) _at_50F Time to Finish Coat _at_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

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Testing for Coating Cure
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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

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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

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Use of Primers

• Intumescent coating manufacturer may have
  approved list of primers
• Types include alkyd, acrylic, epoxy and zinc-rich
• Application thickness important

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Primers

• Function of primer
• Provides adhesion to substrate
• Provides suitable surface for intumescent
• Provides additional barrier protection
• Can also provide inhibitive or sacrificial
  protection

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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

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Finish Coats

• Function of topcoat
• Color and gloss
• Abrasion resistance
• Chemical resistance
• Washability
• Resistance to the environment

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Finish Coats

• Acrylics
• Advantages
• Single component
• Ease of application
• Color gloss retention
• Flexibility
• Low VOC content for waterbased

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Finish Coats

• Acrylics
• Limitations
• Limited alkali and solvent resistance
• Moderate abrasion resistance
• Application temperature gt50ºF for waterbased

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Finish Coats

• Urethanes
• Advantages
• Color gloss retention (aliphatic)
• Adhesion
• Acid, alkali resistant
• Chemical resistant
• Impact/abrasion resistant

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Finish Coats

• Urethanes
• Limitations
• Multi-component
• Short recoat intervals
• Limited pot life
• Moisture sensitive during cure
• Difficult to recoat

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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)

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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

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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 lt80 of specified
  design thickness

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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

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Specifying Fire Resistive Coatings

• Questions?