Asbestos Detection in Vermiculite Spray-on Fireproofing ...
Transcript of Asbestos Detection in Vermiculite Spray-on Fireproofing ...
Asbestos Detection in Vermiculite Spray-on Fireproofing (SOF-V)
Item No. 198.8
Presenter: Craig Huntington
January 28, 2015
Part 1: History of Vermiculite with Asbestos
Part 2: RJ Lee Group LAB.055.1 • Determination of Asbestos in Spray-on Fireproofing containing
Vermiculite (SOF-V)
• Matrix reduction achieved through ashing, mild acid treatment, water washing and aggressive acid / base dissolution.
• PLM is used to identify and quantify chrysotile asbestos.
• PLM/SEM/EDS is used to identify and quantify both regulated and non-regulated amphibole asbestos.
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Item No. 198.8 Polarized-Light Microscopy method for identifying and quantitating asbestos in SOF-V bulk samples.
• Matrix reduction achieved through ashing, mild acid treatment, water flotation and heavy liquid mineral separation.
• PLM analysis identifies and quantifies chrysotile asbestos.
• PLM quantifies all amphibole asbestos together, but does not differentiate between regulated and non-regulated amphibole asbestos minerals.
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The “New Approved Methods” include RJLG LAB.055.1 and Item No. 198.8
Introduction
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Microscopic exam to check for vermiculite
Subsampling and crushing
Ashing to remove organics / cellulose
PLM analysis for amphibole asbestos
Heavy liquid centrifugation for amphibole asbestos
PLM analysis for chrysotile
Acid / Water treatment to dissolve carbonate and gypsum
If chrysotile % is >1%, then process complete
“Item No. 198.8 incorporates a two-step approach for the identification and quantitation of chrysotile and amphibole asbestos, including Libby amphiboles, in SOF-V.”
Organic material, hydrated calcium sulfates and carbonates are eliminated
from the sample through low temperature ashing, mild acid treatment
and water flotation.
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Vermiculite Identification
• Vermiculite is a clay mineral produced by the low temperature
hydrothermal alteration and weathering of mica.
(Mg,Ca)0.7(Mg,Fe+3,Al)6.0[(Al,Si)8O20](OH)4.8H2O
• Vermiculite exfoliates when heated suddenly due to steam generation which forces the structural layers apart.
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• Prior to the introduction of asbestos regulations in the 1970s, chrysotile was added to the fireproofing to provide mechanical strength and spalling resistance. Chrysotile does not occur naturally in vermiculite deposits.
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Fiberglass bundle
• After the asbestos regulations were introduced, fiberglass was substituted for chrysotile.
Chrysotile: an asbestiform serpentine mineral mined and used extensively in North America.
Mg3[Si2O5](OH)4
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35x Binocular photo
Occurs as a rolled sheet, which forms hollow fibers
Preliminary Examination of Spray-on Fireproofing as Received
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The sample is ground, then ashed in a muffle furnace at 485 ± 5°C for a minimum of 10 hours.
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Sample ground in mortar and pestle Sample ashed in muffle furnace
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250ml conical flask with sample in 150 ml solution of hydrochloric acid and filtered water and stirred for 15 minutes.
Additional filtered water is added to bring the water surface to the top of the flask.
Float is removed from surface
The ashed sample is acid treated to remove carbonate and gypsum.
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Dried float material Filtered sink material
Microscopic Analysis of Chrysotile
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Filtered sink fraction
Ground sink fraction ready for PLM analysis
In Polarized Light Microscopy, chrysotile is Colorless
Occurs in fiber bundles
Exhibits asbestiform morphology
Refractive indices are typically nα=1.548 nγ=1.556
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Plane Polarized Light 1.550 RI oil Cross Polarized Light 1.550 RI oil
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Plane Polarized Light Cross Polarized Light
PLM photomicrographs of a vermiculite flake and chrysotile bundle (arrows) in 1.630 refractive index oil from ground sink fraction.
Heavy Liquid Centrifugation is used
to separate less dense minerals from amphibole for asbestos
determination.
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The sink residue which remains following chrysotile examination is dispersed into two centrifuge tubes containing density-adjusted heavy liquid 2.75 g/cc and placed in centrifuge.
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PLM Analysis for Amphibole Asbestos
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• Amphibole minerals
May be asbestiform, non-asbestiform, or both.
Asbestiform amphiboles found in SOF-V typically occur as individual bundles or naturally intergrown into the vermiculite sheets; they are not added as a separate constituent to the fireproofing.
The amphibole asbestos minerals typically associated with vermiculite deposits:
• anthophyllite asbestos - regulated
• tremolite-actinolite asbestos - regulated
• richterite-winchite asbestos - non-regulated
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35x binocular image of filtered sink fraction
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Filtered sink fraction from heavy liquid separation showing abundant sheet structures in sink fraction
Item No. 198.8 utilizes PLM for analysis of amphibole asbestos. PLM is unable to determine the species of amphibole asbestos due to overlapping optical characteristics. Therefore:
Results are quantified as “amphibole asbestos,” but are not distinguished between regulated and non-regulated minerals.
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PLM photos of amphibole asbestos between the sheets from heavy liquid sink fraction in 1.630 RI oil.
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Plane Polarized Light Cross Polarized Light
Summary of Results
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The total asbestos content is calculated as:
Total percent asbestos = %Chrysotile + %Amphibole Asbestos *The percentage of asbestos will be rounded to two significant digits.
The SOF-V sample is classified as ACM (asbestos-containing material) if the total percent asbestos is
greater than 1%.
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• “No asbestos detected” – samples contained no asbestos points or trace asbestos by PLM.
• “Trace chrysotile / amphibole asbestos detected” –samples contained no asbestos points out of the 400 (or more) non-empty points, but did contain asbestos positively identified by PLM.
• “Chrysotile / amphibole asbestos detected at ___%” – percentage given for each type of asbestos if asbestos was identified at the point(s) being counted.
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A Comparative Summary
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RJLG LAB.055.1 vs. Item No. 198.8
RJLG LAB.055.1 Item No. 198.8 Both methods utilize two step matrix reduction processes prior to determining chrysotile and
amphibole asbestos content in SOF-V.
Utilizes ashing and mild acid dissolution prior to PLM analysis for chrysotile.
Utilizes ashing, mild acid dissolution and water flotation prior to PLM analysis for chrysotile.
Utilizes PLM to identify and quantify chrysotile using a 400 point count method.
Utilizes a 400 point count process to quantify chrysotile only if its presence is confirmed during the initial PLM scan of 8 slides.
Dissolves vermiculite matrix prior to PLM and SEM analysis for amphibole asbestos; liberates amphiboles trapped between the vermiculite sheets.
Utilizes heavy liquid (2.75 g/cc) and centrifuge to separate low from high density minerals prior to PLM analysis for amphibole asbestos.
Utilizes both PLM and SEM to quantify amphibole asbestos and EDS to speciate the amphibole mineral(s). Distinguishes between regulated and non-regulated amphibole species.
Utilizes PLM to quantify amphibole asbestos, but is unable to speciate the amphibole or determine whether it is regulated or non-regulated amphibole species.
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VermicuLine: 724.387.1972
or
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The 19th Annual PACNY Environmental Conference
February 25, 26, 27, 2015 Turning Stone Resort and Casino, Verona, NY
Annual Joint NYC AIHA/ASSE/SENY Meeting
February 24, 2015 (9:30AM – 12:00AM) Lennox Hill Hospital - Training Center
100 East 77th Street, New York, NY
RJ Lee Group
VermicuLine: 724.387.1972
or
All webinars are available for download at http://hubs.ly/y0tdxM0.
Be sure to watch for our future webinars!
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