Transcript Preparing a Coating Inspection Plan

Specifying Fire Resistive
Coatings
Presented by:
Jayson L. Helsel, P.E.
KTA-Tator, Inc.
1
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
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
Comparison
Coating Type
Required
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
33
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 zincrich
– 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?