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Asbestos gaskets, ropes, packings, automotive engines, valves, and similar products:
This article describes the properties, manufacture, history, & visual identification of asbestos packings, ropes and gaskets. We describe how asbestos rope, gaskets, & paper gasket material were manufactured and give the uses & properties of these products.
This articles series about the manufacture & use of asbestos-containing products includes detailed information on the production methods, asbestos content, and the identity and use of asbestos-containing materials.
Asbestos packing and gasket seals have provided the best
means of positively sealing hydraulic or pneumatic equipment.
No subject is of more pertinent interest to the
mechanical engineer and plant executive than the proper
operation of hydraulic or pneumatic equipment. Presses,
valves, hoists, autoclaves, pumps and similarly controlled
machinery can be a source of great expense when improperly
[Click to enlarge any image]
Packing is a compressible and resilient material used as a
seal on moving parts. Gaskets are used wherever two stationary
pieces of metal are brought together in equipment
handling liquids or gases. Gaskets are also termed stationary
or static seals.
The most common use of gaskets is in the
joining of flanges on pipe lines or valves.
Seals and gaskets are identified basically by the method
of application or type of construction; i.e., asbestos-"Teflon"
seals, asbestos-fiber sheeting, floating seals, mechanical seals,
asbestos packings, rubber-sheet packings, V-U- and 0-rings,
plastic seals, tadpole, silicone-rubber sheeting, asbestos rope,
compression packings, asbestos felt seals, asbestos braiding
packing, flexible metallic packings, and oil-retainer seals.
While the use of packings and gaskets is not new, there
are always manufacturing and engineering problems associated
with the development of new seals for new equipment.
These types of problems involve the application of different
types of asbestos-base seals.
The continually growing field
of hydraulics and pneumatics has created a need for specialty
packings and gaskets of varying characteristics and
design to meet the many variations in speeds and temperatures.
Experience has shown that no one style or type of
packing can be recommended as suitable for all different
types of applications. The principal reason for this is due to
the variations to which the parts are subjected—pressure, medium
of operation, temperature, availability of lubrication,
metal clearances, speeds of operation, motion of operation
(rotary or reciprocating) and allowable space of operation.
Chrysotile asbestos fibers, as well as crocidolite, are used in gaskets
and packings along with such binders as natural rubbers,
synthetic rubbers, asphalt, "Teflon," "Kel-F," phenolic
resin, plasticizers, and other materials. Crocidolite is used
principally in packing that requires acid resistance.
Asbestos can be made to have the ability to expand and
contract with heat and cold in exactly the same manner as
the metal it contacts. Chrysotile fibers are desirable in the
seals because of their softness, durability, resistance to
charring, silkiness, and slipperiness.
What is needed in the packing is low friction, resistance
to high pressure, resistance to heat, and resistance to chemical
gases. Having a combination of these requirements,
asbestos surpasses all other materials in these properties.
Types of Asbestos Packing, Gasket, & Rope Products
Asbestos packings and gaskets are made by different
techniques. Yarn can be twisted or braided into different
shapes conforming to packing. or gasket requirements. The
braided forms or asbestos fabrics can be coated, or impregnated
with different compounds. Cloth is one of the bases
for sheet packing, folded, and wound packing. These packings
in turn are formed into various shapes and sizes.
Sheet asbestos packing is considered one of the first applications
of asbestos in the form of packing. This type of packing is
available with such different combinations as wire reinforced
asbestos fabric, graphite impregnated asbestos fabrics and
others. Metallic products can be made from woven cloth
which contains asbestos yarn—metal core. This type of
construction, impregnated with the various binders, has been
very popular and useful in the manufacture of gaskets and
Numerous government specifications are available which
pertain to asbestos gaskets and packings. The asbestos packing or
sheet requirements generally specify type and amount of
fiber in proportion to binders and other additives. Parts can
be used at temperatures up to about 700°F. For example,
for the higher temperature resistant rubber packings,
the composition generally specified includes 70 to 75 per
cent, by weight asbestos fiber, 9 to 16 per cent rubber, 1 1/2
to 1 per cent sulfur, and 10 to 14 per cent mineral fillers.
Braided asbestos packing, which is rubberized and graphited, is
suitable for high pressure and high temperature applications.
See Figure 10.1. Approximately 10 per cent rubber together
with such suitable fillers as talcum and graphite is added in
this type of product in order to thicken and build up the
body of packings. Graphite is a very popular additive since
it principally provides low frictional and binding properties.
Packing for high temperature must be firm and hard. The
packing which is vulcanized in large coils is generally difficult
to force into engineered cavities of equipment such as
stuffing boxes. A common procedure is to wind these coils in
spirals during the vulcanizing process so that they can be
Figure 10.1. Asbestos braided and woven packings_froni top to
bottom—interlocked braided, square-plaited braid, braid over braid,
Although graphite is a popular ingredient in packings, it
is not suitable in packings which will be in contact with
stainless steel shafts, rods, and valve stems. In these applications pitting of the metal will occur when packings are
lubricated with graphite.
Fabricated packing get its name from being made by
molding asbestos cloth with rubber. Different types of synthetic
rubber as well as natural rubber are used in order to
withstand operating temperatures up to 700°F.
Special packings made to withstand high steam pressures,
which in turn are subjected to both high pressures and temperatures,
are similar to millboard and paper products.
Figure 10.2 below. The special packings are made in different
shapes and sizes including ring-type gaskets, V-grooves,
and others. Medium length asbestos is generally used.
mixture can be 66 per cent fiber; the remaining constituents
are magnesia, iron oxide, clay, barite, cellulose and/or
Below we show Figure 10.2. the Fourdrinier paper machine adapted for manufacture of
asbestos paper sheet gasketing material. - Courtesy Armstrong Cork Co.
Resins, gums, or rubber are sometimes added to
provide for more bonding action. These type of binders are
generally dissolved in a volatile solvent such as naphtha
and toluene. The mixtures are pressed into any desired shape
depending on specific applications. They can be reinforced
with copper or lead foil. These mixtures can be directed
through heated calenders and pressed into sheets. See
Figure 10.3 below.
Automatic mechanisms are available with asbestos sheeters
to control the opening between the front and back rolls as
the machine forms a sheet of asbestos from which packings
and gaskets are made.
In actual operation the stock is built
up on a steam-heated roll to the required thickness, layer
by layer, as the volatile liquids are evaporated.
must be maintained by the smaller front roll which
requires that the opening between the rolls be widened as
the sheet becomes thicker. This adjustment of the opening
between the rolls is automatically accomplished by means
of a ratchet controlled worm adjustment driven by controls
directed from the front roll.
Asbestos-rubber compound sheets are sometimes not completely
vulcanized until after the material is installed and
heat is applied in the packing or gasket area. This allows
the packing to become a well fitted part in the machine,
making it almost impossible for a leak or blowout to occur.
Asbestos fabric packings are also available constructed
of an outer cover of asbestos cloth wrapped around an
intercore of resilient material. These products are also
referred to as "tadpole" gasketing tape.
The outer cloth can
be made with or without metallic inserts. Synthetic rubber,
silicone, or "Teflon" can be used as the binder in the cloth.
The cores can be made with asbestos alone, synthetic rubber,
and a metal such as stainless steel. The shape of the tadpole
tape can vary from round to flat gaskets.
Asbestos wick packing is a soft twisted packing made
from asbestos roving and is principally used in dry heat
where there is relatively no steam pressure involved. The
asbestos wick is also available in plied form to make the
asbestos rope which can also be used as a packing. When it
is made in the form of rope, it is usually supplied on reels so
that any length can be cut. In the manufacture of rope
packing, the rope is covered with one or two braids of asbestos
yarns in order to prevent the rope from untwisting
Asbestos in Automotive Engine Gaskets
Reader Question: can we identify engines whose gaskets contain asbestos
15 August 2015 Stewart Willis said:
I work in a Detroit Diesel engine re-manufacturing facility and occasionally come across engines from the 70's and 80's when asbestos gaskets were frequently used. It is hard to get management to acknowledge the possibility of asbestos being present in some gaskets.
Is there a data base that has serial numbers of engines containing asbestos, split lines in those numbers to indicate when gaskets changed content, etc. It would be nice to have pictures to compare actual engines containing asbestos with ones I work on.
Any assistance would be appreciated. My uncle died of mesothelioma so I know first hand how serious this is.
Good question, Stewart. I've not been able to find such a database of engine serial numbers vs. gasket types used, though there has been research particularly pointing to diesel engines.
Even if you know the engine year you may not know if there was prior work on the engine that changed out its original head gasket or other gasket to a later one that didn't use asbestos.
For engine gaskets that are sandwiched between metal plates and that can be removed intact, the hazard of asbestos particle release is probably pretty low - a view supported by some research on worker exposure to asbestos from automotive gaskets::
Blake (2006) found that
... automobile mechanics who worked with asbestos-containing gaskets may have been exposed to concentrations of airborne asbestos concentrations approximately 100 times lower than the current Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) of 0.1 f/cc.
And the next year Madl (2007) confirmed that
The weight of evidence indicates that the use of hand tools and hand-operated power tools to remove or install gaskets or packing as performed by pipefitters or other tradesmen in nearly all plausible situations would not have produced airborne concentrations in excess of contemporaneous regulatory levels.
For engine work in which an un-laminated gasket is adhered to the head (certainly that's what I did in the 1960's) and that has to be soaked and scraped off, it would make sense and probably be least costly and safest to use a procedure that did not create airborne dust at all. Could you specify such a procedure?
If so we could publish it here for wider comment.
Watch out: asbestos may be found in modern automotive gaskets as well. See Boardman (1992) cited below.
Research on Asbestos in Automotive Engine Gaskets & Auto Repair Worker Asbestos Exposure
Some patent research gives us an idea of when asbestos-containing engine gaskets were and later were not in common use, and there has been some research on asbestos exposure from engine gasket use that I will cite below:
Ascencio, Roman J., Brockhaus Eugene A., Furstenburg Alvin J, ""Head gasket assembly having parts therein." U.S. Patent 3,565,449, issued February 23, 1971.
Blake, Charles L., G. Scott Dotson, and Raymond D. Harbison. "Assessment of airborne asbestos exposure during the servicing and handling of automobile asbestos-containing gaskets." Regulatory toxicology and Pharmacology 45, no. 2 (2006): 214-222.
Abstract: Five test sessions were conducted to assess asbestos exposure during the removal or installation of asbestos-containing gaskets on vehicles. All testing took place within an operative automotive repair facility involving passenger cars and a pickup truck ranging in vintage from late 1960s through 1970s. A professional mechanic performed all shop work including engine disassembly and reassembly, gasket manipulation and parts cleaning. Bulk sample analysis of removed gaskets through polarized light microscopy (PLM) revealed asbestos fiber concentrations ranging between 0 and 75%. Personal and area air samples were collected and analyzed using National Institute of Occupational Safety Health (NIOSH) methods 7400 [phase contrast microscopy (PCM)] and 7402 [transmission electron microscopy (TEM)]. Among all air samples collected, approximately 21% (n = 11) contained chrysotile fibers. The mean PCM and phase contrast microscopy equivalent (PCME) 8-h time weighted average (TWA) concentrations for these samples were 0.0031 fibers/cubic centimeters (f/cc) and 0.0017 f/cc, respectively. Based on these findings, automobile mechanics who worked with asbestos-containing gaskets may have been exposed to concentrations of airborne asbestos concentrations approximately 100 times lower than the current Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) of 0.1 f/cc.
Boardman, Thomas A. "Gasket assembly." U.S. Patent 5,145,190, issued September 8, 1992.
Excerpt: In U.S. Pat. No. 3,565,449 to Ascencio et al., a main gasket body is a metal sheet with impregnated asbestos on each side.
Liukonen, Larry R., and Francis W. Weir. "Asbestos exposure from gaskets during disassembly of a medium duty diesel engine." Regulatory toxicology and pharmacology 41, no. 2 (2005): 113-121.
Abstract: Diesel engines have historically used asbestos-containing gaskets leading to concerns of fiber release and mechanic exposure. Other published studies regarding asbestos fiber release during gasket removal have reported on short-duration events; were conducted under simulated work conditions; or had other limitations. There are no comprehensive studies relating to diesel engine gaskets under conditions similar to those reported herein, evaluating asbestos fiber release from gaskets during all facets of a complete disassembly and cleaning of a medium duty diesel engine in a busy repair and service shop by a journeyman mechanic. Asbestos content of all gaskets was identified; all disassembly tasks were described and timed; and personal and area air monitoring was conducted for each task. Twenty seven of thirty three gaskets contained chrysotile asbestos in concentrations that ranged from 5 to 70%. All but one air monitoring sample reported results below the limit of reliable detection even though plumes of visible dust were evident during various removal, cleaning, and buffing procedures. The detection limit for airborne asbestos fibers in this investigation was influenced by the presence of other shop dust in the air. Our investigation demonstrates that using shop-standard procedures in an established repair facility, a journeyman mechanic has very little potential for exposure to airborne asbestos fibers during disassembly of an engine, approximately 10% or less than that currently considered to be acceptable by OSHA.
Madl, Amy K., Katherine Clark, and Dennis J. Paustenbach. "Exposure to airborne asbestos during removal and installation of gaskets and packings: a review of published and unpublished studies." Journal of Toxicology and Environmental Health, Part B 10, no. 4 (2007): 259-286.
Abstract: In recent years, questions have been raised about the health risks to persons who have been occupationally exposed to asbestos-containing gaskets and packing materials used in pipes, valves, and machinery (pumps, autos, etc.). Up until the late 1970s, these materials were widely used throughout industrial and maritime operations, refineries, chemical plants, naval ships, and energy plants. Seven simulation studies and four work-site industrial hygiene studies of industrial and maritime settings involving the collection of more than 300 air samples were evaluated to determine the likely airborne fiber concentrations to which a worker may have been exposed while working with encapsulated asbestos-containing gaskets and packing materials. Each study was evaluated for the representativeness of work practices, analytical methods, sample size, and potential for asbestos contamination (e.g., insulation on valves or pipes used in the study). Specific activities evaluated included the removal and installation of gaskets and packings, flange cleaning, and gasket formation. In all but one of the studies relating to the replacement of gaskets and packing using hand-held tools, the short-term average exposures were less than the current 30-min OSHA excursion limit of 1 fiber per cubic centimeter (f/cc) and all of the long-term average exposures were less than the current 8-h permissible exposure limit time-weighted average (PEL-TWA) of 0.1 f/cc. The weight of evidence indicates that the use of hand tools and hand-operated power tools to remove or install gaskets or packing as performed by pipefitters or other tradesmen in nearly all plausible situations would not have produced airborne concentrations in excess of contemporaneous regulatory levels.
Paustenbach, Dennis J., Amy K. Madl, Ellen Donovan, Katherine Clark, Kurt Fehling, and Terry C. Lee. "Chrysotile asbestos exposure associated with removal of automobile exhaust systems (ca. 1945–1975) by mechanics: Results of a simulation study." Journal of Exposure Science and Environmental Epidemiology 16, no. 2 (2006): 156-171.
Stecher, Friedhelm, Josef Fazekas, Paul Johren, and Martin Morsbach. "Cylinder head gasket for internal-combustion engine." U.S. Patent 3,970,322, issued July 20, 1976.
Victor, John H., Joseph B., "Laminated metal and asbestos gasket." U.S. Patent 2,130,110, issued September 13, 1938.
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Question:disposal of asbestos in isolation valve gland packings
Apr 2, 2015) Anonymous said:
When disposing of an isolation valve that has asbestos containing gland packing, can it be disposed of with other scrap metal or does it need to go with asbestos contaminated waste.
I don't know what your state or provincial department of environment would advise. Construction debris regulations vary widely among jurisdictions. If the asbestos material is not in significant quantity (you cite a single valve making the quantity most likely trivial) and considering that most of the material if not all is inside the valve, my opinion is that the hazard is most likely below the limits of detection.
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 Asbestos, its Industrial Applications, D.V. Roasato, engineering consultant, Newton MA, Reinhold Publishing Co., NY, 1959, Library of Congress Catalog No. 59-12535. We are in process of re-publishing this interesting text. Excerpts & adaptations are found in InspectApedia.com articles on asbestos history, production & visual identification in and on buildings.
 "Asbestos in Plastic Compositions", A.B. Cummins, Modern Plastics [un-dated, pre 1952]
 "Asbestos in Your Home," Spokane County Air Pollution Control Authority, Spokane WA 509-477-4727 www.scapa.org provides a one-page image, a .pdf file drawing of a house warning of some possible sources of asbestos in the home. The sources are not ranked according to actual risk of releasing hazardous levels of airborne asbestos fibers and the list is useful but incomplete.
 The US EPA provides a sample list of asbestos containing products epa.gov/earth1r6/6pd/asbestos/asbmatl.htm
 "Characterization of asbestos exposure among
automotive mechanics servicing and handling
asbestos-containing materials", Gary Scott Dotson, University of South Florida, 1 June 2006, web search 3/9/2012 original source: scholarcommons.usf.edu/cgi/viewcontent.cgi?article=3505&context=etd [copy on file as /hazmat/Automotive_Asbestos_Exposuret.pdf ].
 Asbestos Identification and Testing References
Asbestos Identification, Walter C.McCrone, McCrone Research Institute, Chicago, IL.1987 ISBN 0-904962-11-3. Dr. McCrone literally "wrote the book" on asbestos identification procedures which formed
the basis for current work by asbestos identification laboratories.
Stanton, .F., et al., National Bureau of Standards Special Publication 506: 143-151
Pott, F., Staub-Reinhalf Luft 38, 486-490 (1978) cited by McCrone
 Asbestos in Your Home U.S. EPA, Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
 Asbestos products and their history and use in various building materials such as asphalt and vinyl flooring includes discussion which draws on Asbestos, Its Industrial Applications, D.V. Rosato, engineering consultant, Newton, MA, Reinhold Publishing, 1959 Library of Congress Catalog Card No.: 59-12535 (out of print, text and images available at InspectAPedia.com).
 "Handling Asbestos-Containing roofing material - an update", Carl Good, NRCA Associate Executive Director, Professional Roofing, February 1992, p. 38-43
 EPA Guidance for Controlling Asbestos-Containing Materials in buildings, NIAST, National Institute on Abatement Sciences & Technology, [republishing EPA public documents] 1985 ed., Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460 Copy on file as - /hazmat/Asbestos_in_Your_Home_US_EPA.pdf - Asbestos in Your Home - U.S. EPA, Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
Basic Information about Asbestos, US EPA, web search 08/17/2010, original source: http://www.epa.gov/asbestos/pubs/help.html
"Handling Asbestos-Containing roofing material - an update", Carl Good, NRCA Associate Executive Director, Professional Roofing, February 1992, p. 38-43
EPA Guidance for Controlling Asbestos-Containing Materials in buildings, NIAST, National Institute on Abatement Sciences & Technology, [republishing EPA public documents] 1985 ed., Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
Copy on file as - /hazmat/Asbestos_in_Your_Home_US_EPA.pdf - Asbestos in Your Home - U.S. EPA, Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
[copy on file as /hazmat/Vermiculite_US_EPA.pdf/ Current Best Practices for Vermiculite Attic Insulation - May 2003, U.S. EPA
[copy on file as] /hazmat/Vermiculite_Health_Canada.pdf] Vermiculite Insulation Containing Amphibole Asbestos - September 2009, Health Canada
Managing Asbestos in Place, How to Develop and Maintain a Building Asbestos Operations and Maintenance (O&M) Program, U.S. EPA, web search 01/20/2011, original source: http://www.epa.gov/asbestos/pubs/management_in_place.html
Asbestos Strategies, Lessons Learned about Management and Use of Asbestos: Report of Findings and Recommendations on the Use and Management of Asbestos, 16 May 2003, US EPA, web search 01/20/2011, original source: http://www.epa.gov/asbestos/pubs/asbstrategiesrptgetf.pdf
prepared by the: Global Environment & Technology Foundation, 7010 Little River Turnpike, Suite. 460, Annandale VA 20003
Other US EPA Publications on asbestos: web search 01/20/2011, see http://www.epa.gov/asbestos/pubs/pubs.html
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