Document RavYNnKDNQDXz8ZRbJOjva9qk
INDUSTRIAL HYGIENE FOUNDATl6N OF AMERICA.INC.
Mellon Institute. aaoO Fifth Avenue
Pittsburgh 13. Pa.
September 30, 1963
Mr. C. C. Ruddick Pittsburgh Plate Glass Company 1 Gateway Center Pittsburgh, Pennsylvania 15222 Dear Mr. Ruddick:
Enclosed are seven copies of our report on "Evaluation of The Asbestos Dust Hazard in Tyler, Texas Plant". If you have any questions or comments regarding this work, do not hesitate to call on us. Also, we have several extra copies if you have need of them.
A statement of charges covering these investigations will be submitted at a later date.
Sincerely yours,
, c 7. P7c /, TV-
Robert T. P. deTreville, M.D. Managing Director
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'V-/' INDUSTRIAL' HYGIENE FOUNDATION OF AM ERICA, I NC.
' ' M'CtLON fNSTITUI ;r..'4.4 00 FlFTH-AVENUE
Report on
Pittsburgh 13. Pa.
-n
EVALUATION OF THE ASBESTOS DUST HAZARD IN TYLER, TEXAS PLANT
of the
.... PITTSBURGH CORNING CORPORATION
-'-July 8, August 6, 7 , .1963
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-Field Inve stigation By:
Jacob Cholak Lawrence J. Schafer William J. Schreibeis
Samples Analyzed By:
The Kettering Laboratory Cincinnati, Ohio
William J. Schreibeis, P.E Industrial Hygiene Engineer
Robert T. P. deTreville, M.D. Managing Director
/
AN ASSOCIATION Of INOUS1 R>C3 FOR THE ADVANCEMENT or h ALT iiTUL wORKinO CONOlTlONO
1.
INTRODUCTION
On July 8, the plant of the Pittsburgh Corning Corporation, Tyler, Texas was visited by Messrs. Jacob Chiolali and William J. Schrcibeis in order to review the .potential health hazard-S of handling asbestos during manufacture of asbestos pipe insulation. ;KpnTAugust 6._and 7, 1963, sampling wjs conducted at the plant by Mr. Lawrence J. Schafer and an evaluation made of the airborne dust concentrations.
DISCUSSION OF RESULTS
In Table 1, the concentrations of particulate matter, when pos siblc, are expressed both on a weight basis and as the number of particles present in one cubic foot of air. Samples collected with the high volume sampler and the electrostatic precipitator were suitable for gravimetric and other analysis while samples collected on membrane filters were suitable for dust counting only. The number of particles present in the air as total particulate matter and as asbestos fibers were determined. Any rodlike particle with length definitely greater than width was considered as asbestos fiber. It may be seen that the per cent of fibers in the dust varied from a low of 29% to a high of 56%. The dust in the sawing area contained a slightly higher content of asbestos fibers than did the airborne dust in the production area. It will also be noted that more parti cles of dust and fibers of asbestos were present in the air near the scrap crushers
^7
2.
than, surprisingly, was the case for air in the sawing area. The values in
Table 1 followed by an asterisk are estimated counts taken from the straight lines
Cn Julv
the -'an: of tne rittsburch Cerr.ina Corporation, Tvler,
in Figure 1, fitted to the data by the method of Least squares.' It may 'be/seen,
that the dust counts'and the mass concentrations arc closely related. Figure 1
offers the plant a rather simple method for estimating the numbers of total
particles and of the fibers of asbestos present per cubic foot of air from the mass
weight data and volumes of air sampled.
Highest dust counts, at the threshold limit, were obtained in the case
of samples collected at the scrap crusher. The highest concentration of dust oc
curred for the five-minute period that the three-unit dust collector in the saw
area was being cleaned. The an1 at the take-off areas of the building machines
was the least contaminated with dust.
It should be noted that the threshold limit for asbestos, (5 mppcf) is
assumed to apply only to asbestos fibers while dust in the air of the plant will
contain other particulates, including filler materials used in the process. Since
there is some evidence that the most active particles are those fibers between 20
and 50 microns in length, the numbers of fibers present in various size categories
were also determined. These data are given in Table 2. Data in Table 2 and the
asbestos fiber counts in Table I were used to derive the data in Table 3. As may
be seen from Table 2, the fibers in the air of the sawing area were generally
shorter than were those in the process area.
In Table 4 are tabulated the per cent of the numbers of the fibers of
asbestos or, more properly, bundles of fibers varying from 5 microns to less
3.
than 1 micron in diameter. The fibers, in. the air of. the sawing .area appear to
have slightly smaller diameters than was the case for fibers in the air of the pro-
Tabie i ioiiowcvi by an asteriSK are estimate?; counts i..: :
-:r: : .
cess area. , .. . ^
The results of other analytical work performed on these samples are
that "hr oust counts a no tnemass tone a:-1 ration:-.
.. . ;. -.: .7. i
given in Table 5. As may be seen dusts or fiber s-removed from the air in the
production and sawing areas did not contain any free crystalline silica. Two dif
ferent samples of Dacolite contained variable small amounts of quartz and cristoba-
lite. In view of the warning printed on each bag, the low concentrations of free
silica in this material were rather surprising.
It would appear from the analysis of the samples that were collected
intentionally only at those processes that appeared to be the principal producers
of dust, that the number of asbestos fibers present in the air, with few exceptions,
were well below the threshold limit of 5 mppef. One significant exception was
the brief period of time during which a collector system was being cleaned. Dur
ing this period, excessive quantities of dust and fiber were being dispersed into
the air for a period of about 5 minutes. It would appear, from an examination of
the total numbers of particles and of fibers, as well as observation of the operations,
that the crusher and the sawing operation may at.times produce large quantities
i`
of dust. However, the dust, because of its physical characteristics, appears to
settle out of the air rapidly. Particles of particulates in samples collected at
breathing level heights, were well below threshold limits, even though some cp-
erat'ons were observed to produce what appeared visually to be large clouds of
dust.
4.
The type of asbestos used in the plant is "amosite" an iron-magnesium
have slinhtl y smaller d:;;nc!i.::s rhar. \v-s me ear-;
1V-~ v r<\ r.hn air o:. tra
silicate. The specific gravity of this material is 3.45 as compared to 2.55 for
CC5 :i ci. '*tl 'X.
chrysotile, the material more widely used in this country.
The fibers of chrysotile are also much smaller in diameter than are
m i :
a. A s may be seen ousts or .mens i c-mc veu mom the- am
those of amosite, the minimum diameters being 0.5 micron and 0.03 micron
respectively for amosite and chrysotile. Another factor in favor of the rapid
settling, of the fibers from the air of the plant is that the asbestos bundles are not
given the drastic shredding as in the textile industry.
RECOMMENDATIONS
At no time during the survey was the air of the plant contaminated
with dust to the point to affect visibility, and one could always see down the entire
length of the rather long building in which the operations were being conducted.
Nevertheless, our observation of the operations leads us to make the following
recommendations:
T n e i. w-Lsa.i ~ ur.~i l* c r s 31 o 2r 11c; s 2 *i c r.- 1 ; oi' .- v.
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1. There was an obvious need to institute a better housekeeping pro
gram, especially in the sawing area. Floors, equipment and other structures
1 should be cleaned regularly and frequently according to a definite supervised
schedule. Dry sweeping should be avoided and only vacuum cleaning equipment
provided with suitable collectors should be used.
2. Hoods and ducts should be maintained in good working order and
all breaks and leaks in connecting ducts, etc. should be repaired promptly.
/
5,
3L.ll'Tlie hoods' and'thel'c>rft'u'usr`system- at the wheel cutter7 in the.: saw-
i'rig'fob'm should be imp roved. l'" "n*s
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: * ~c ~~ area
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' sc`**~ 4V' More'spac'd'should be pro^d'ccfbetvv'ecn the sawing equipment to
reduc e cros s-c"ohtarrirnati6ri'oi"th'e" air' with; dusf; '
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' It is'suggested'thkf the-crusher be fedrby: means of a short con
veyor "system- in order1 to 'keep"`the "bjjfe'ratorblear of the cloud of dust produced
when the machine is in operation. "" S'. Operators should be'educated in respect to working habits which
will reduce the dispersion of dusts. For example (a) carts of crushed material
should be moved from the crusher 'Only after the crusher has been turned off and
a brief period has elapsed to permit dust to settle, (b) Work should be removed
from the large slitter only after the exhaust'system has cleared the dust from the
interior of the piece being cut. A wait of only a few seconds would accomplish
this, (c) Bag collectors should be opened only when the discharge end of the col
lector is closed.
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- ;r Tabhe 3
The Numbers of Asbestos Fibers (mppcf)
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Present in '-the Air According lo the Range
of the Lengths of tile Fibers
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Sample No.
'
y ~y
; Millions.of Fibers Per Cubic Foot of Air
..j 5 - 5,0 M'-i crons
10 - 50 Microns
y. in Longtli
in Length
2
<L 68'
0. 39
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4
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9. .
11
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12
13
14 7
15
16
17 .
19
20
0.4 3 1.50
1.90 0.90
.? 1 09.. 0.43
2.40
0.78 20.70
1:
3.06
o.25;
0. 14
0.20 0.60
0;,87-
0.25 1 . 10 1.07 0.40 0. 36 0.27 0. 67 0.26 6.80 1.64 0. 15 0.07
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0.07 0.40 0.46
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w T^able S
Free Silica Content of.a Number-of Samples Collected in the Plant
;D-escription of Sample
Per Cent Free Crystalline Silica
(Quarts
^ Cristobalitc ^ TTridymite _
A sample of Dacolite collected
~ on 7-10-63
r~r
-
.-3.0
2.5 .
Absent
A sample of Dacolite collected on 8-5-63 .
2 / 2.0
Absent
General air sample collected in the sawing;area. between the large-slitting saw and the large-edging saw. ~
; <"2.0
Absent -
Absent
General air sample collected 5 feet from the scrap crusher.
<2.0
Absent
Absent
General air sample collected in the feed area.
<2.0
Absent
Absent