This category covers establishments primarily engaged in manufacturing gaskets, gasketing materials, compression packings, mold packings, oil seals, and mechanical seals. It includes gaskets, packing, and sealing devices made of rubber leather, metal, asbestos, and plastics.
339991 (Gaskets, Packing, and Sealing Devices)
By definition, a seal is a "device for eliminating or controlling the leakage of liquids and/or gases while preventing the entrance of external contaminants such as dust and dirt," according to John J. Carr in the Vanderbilt Rubber Handbook.
Seals are divided into two classifications: static or dynamic. Static seals are used on surfaces where there is no relative motion between the surfaces. An example of a static seal would be an engine cylinder-head gasket. Dynamic seals are used wherever relative motion exists between two surfaces, either intermittently or continuously. Examples are engine crank-shaft seals and hydraulic cylinder-rod seals.
There are several basic types of seals. Cup-packings are mainly used as piston-head seals. Previously made from leather, elastomers are now used for low-pressure, smaller cups, while an elastomer/fabric blend is used for high-pressure applications. Cup-packings are particularly effective where clearance between surfaces to be sealed is excessive—for example, when sealing rough metal surfaces.
Gaskets typify the compression-sealing method. They are made from a wide variety of materials, often times used in combination with one another. For example, cork and elastomers are a popular combination in automotive usage because cork's compressibility and rubber's resiliency combine to give excellent results in such uses as engine gaskets. Gaskets can be molded or cut from a sheet. They are installed between two surfaces, and pressure from bolting or clamping provides the sealing force.
Elastomeric gaskets are the most common type of nonmetallic gasket. They can be made of synthetic rubber or thermoplastic elastomers TPEs)—materials that have properties similar to rubber but are processed like plastics. Elastomeric gaskets are produced in a variety of sizes, colors, and finishes. They also can be produced to be especially resistant to such things as temperature, oil, chemicals, weathering, aging, and abrasion. With all these variations, as well as the variety of elastomers available, the applications vary tremendously. Simple applications would include such things as plumbing gaskets, while other, more sophisticated gaskets find advanced applications in aerospace products.
The simplest and most common sealing device, O-rings are used in numerous systems. They can be used in static and dynamic applications, depending on the proper design. Among their primary uses are as components in automotive steering and brake systems, off-road heavy equipment, aircraft, and other industrial and household items.
Mechanical face seals are a multicomponent sealing device used to create a leakage-free seal between a rotating shaft and a member through which the shaft passes. They are used in automotive water pumps and in the chemical process industries.
Molded packings and seals are mainly used in such things as fluid handling pumps, valves, cylinders, piston-type accumulators, and other equipment. They can be used as seals on the rod, ram, piston, plunger stem, or spool to develop and maintain hydraulic working power. They find their main applications in static sealing uses. Molded seals include squeeze-type ring seals and lip types. Squeeze seals are used in low-pressure applications, with lip seals finding more usage in high-pressure needs.
Radial lip seals are used in dynamic, low-pressure applications. Many are available in standard sizes but the trend is to customize production.
U-packings are pressure-activated sealing devices commonly used in low to moderate dynamic sealing applications. They can be found in such things as pneumatically or hydraulically activated door openers.
Three or more seals are often used together in the low-speed, high-pressure dynamic applications common to V-packings. In one of this type of seal's many end-product uses, V-packings are found in heavy-duty hydraulic cylinders of off-road earth-moving equipment.
Gaskets and seals are vital to the operation of many types of equipment. Three markets—transportation equipment, industrial equipment and machinery, and electrical equipment—account for more than 90 percent of total demand. Of this, sales to original equipment manufacturers (OEMs) account for about 40 percent of revenue, and aftermarket sales an additional 60 percent.
Transportation equipment, including automobiles, is the largest OEM customer, accounting for 40 percent of total sales. The cyclical nature of the market resulting from such dependency on automobile sales has been offset by the relative stability of aftermarket demand for industry products.
By 2000, U.S. shipments in the seal and gasket industry totaled nearly $6.1 billion, according to government figures, nearly triple that of the mid-1980s. Compressed, nonmetallic gaskets and gasketing held the greatest share, followed by molded gaskets and gasketing, metallic gaskets and machined seals, and other nonmetallic gaskets and gasketing.
This industry supports varied manufacturing and other industries, gaining its existence from the end use of its products rather than from the products themselves. Because of the industry's dependency on the health of the economy in general, the demand for gaskets, seals, and packings mirrors the cycles experienced by the makers of the durable goods that utilize such supplies.
Makers of gaskets and seals are also influenced by their customers in areas such as product development, production processes, marketing, and pricing. With the large number of suppliers available, end users can bargain not only for better pricing, but for better service as well.
Other variables outside the control of U.S. gasket and seal manufacturers combine to affect the market. For example, since the early 1980s the industry saw a rise not only in the amount of gaskets and seals imported into the United States, but also in the variety of types of machinery in which such products were used. Varying levels of industrial production have also impacted the market.
Transportation equipment has traditionally been the leading market for gaskets and seals. Other markets include industrial equipment and machinery, electrical equipment, and photographic equipment, among others.
There are two professional organizations associated with the gasket and seal market: the Gasket Fabricators Association and the Fluid Sealing Association. Founded in 1979, the Gasket Fabricators Association had approximately 100 members in 2000. The association consists of gasket cutters and industry suppliers who come together to discuss problems within the industry and to develop possible solutions to those problems. The organization also develops industry standards. The Gasket Fabricators Association meets twice per year and publishes a technical handbook as well as a quarterly newsletter. The Fluid Sealing Association is an international trade association founded in 1933. Its membership is heavily concentrated in North America but includes companies from other continents as well. According to its Web site, the objective of the Fluid Sealing Association is to "serve as the point for worldwide efforts to improve the manufacturer's understanding and application of fluid sealing devices and to promote a safe, clean environment."
Historically, a number of different types of seals have been used in general applications. They are: gaskets, U-packings, V-packings, cup-packings, and O-rings. In time, the uses for seals have multiplied and improvements in materials and technology have allowed seal manufacturers to offer a product with extended life and better performance.
The sealing industry encountered many challenges during the 1980s and 1990s as applications for sealing products became more complex. Aeronautical and oilfield consumers were among the first to push for more demanding requirements. Elastomeric seal chemists and engineers were forced to advance technology from a "socalled art," to an "engineering science," according to Kerry C. Smith in Rubber & Plastics News.
Traditional materials such as cork, rubber, paper, and felt soon began to give way to specialty materials. For example rubber gaskets used to be found in low-pressure and temperature uses. However, rubber is not always the material of choice for gaskets, because contact with oil and grease negatively impacts its performance in such uses as the automobile aftermarket. The success of rubber in such usage is dependent on proper installation. Higher engine temperatures also negatively impact the selection of rubber for automobile gaskets. Specialty rubbers and TPEs more easily met the newer, more demanding standards and allowed the number of possible gasket applications to grow.
The synthetic rubber category can be broken into three subcategories: commodity rubbers, medium performance rubbers, and specialty rubbers. The commodity types generally cost the least, but offer less in the area of performance. In the past, these types generally took the largest percentage of elastomeric gasket usage. More recently the trend has been toward the medium performance and advanced rubbers. Among medium performance types, ethylene-propylene rubber, commonly known as EPDM, has found greater acceptance because it offers better weatherability and abrasion resistance.
Specialty rubbers are usually available in low volume and give the best performance, but at a markedly higher cost. These advanced materials have seen wider applications in head gaskets, manifold gaskets, and oven-door and other appliance gaskets. A number of these elastomers offer higher heat resistance, along with high fuel and oil resistance. Silicone rubber, especially, is being used more and more in aerospace applications.
Various TPEs find gasketing applications because they are resistant to oil and other engine fluids, are lightweight and offer superior durability. But TPEs haven't achieved greater market share because their heat resistance has not been comparable to some of the specialty rubbers. TPEs are expected to continue to gain in noncritical uses and will grow into more critical areas after their heat resistance is improved.
About 80 percent of the elastomeric gaskets manufactured have been made of various synthetic rubbers, with TPEs accounting for the remainder. Since the early 1980s, however, TPEs have increased their share. By the early 2000s, seals and gaskets made from carbon and aramid fibers were projected to show the most growth in demand.
Examples of increasingly demanding design-requirements and life-requirements in automotive applications have included the ability to seal the nonchlorinated refrigerants that began replacing the chlorofluorinated refrigerants (CFCs) that were historically used. Automakers looked for near-zero permeation but also expected seals to last up to 150,000 miles in engines operating at increasingly higher temperatures.
The early 1990s saw a substantial increase in the demand for gaskets and seals, and that demand continued to increase into the early 2000s. After declining slightly from $5.41 billion to $5.37 billion between 1998 and 1999, shipments of gaskets and seals grew to a record $6.09 billion in 2000.
The Freedonia Group, a leading provider of industry studies, predicts that growth will slow among original equipment manufacturer products through 2006, due to a slow-down in motor vehicle production and capital spending. The Freedonia Group also predicts that growth in the demand for seals and gaskets made from carbon and aramid fibers will continue to surpass growth in demand for more traditional products such as compression packings and gaskets made from less reliable materials like cork, paper, or commodity rubber.
In 1999, the three leading companies in this industry in sales were the Parker Seal Group of Irvine, California, with $210 million in sales; Garlock Sealing Technologies of Palmyra, New York, with $208 million in sales; and John Crane Inc. of Morton Grove, Illinois, with $200 million in sales. Since these firms derive revenue from sales of other products besides seals, packing, and gaskets, it is difficult to pinpoint how much of their sales figures can be attributed directly to these products. Other firms with a significant presence in this industry include Freundenberg-NOK of Plymouth, Michigan, and Niantic Seal Inc. of Lincoln, Rhode Island.
As with many other industries in the late 1990s, mergers were common among gasket and seal industry leaders. Both Freundenberg-NOK and Niantic Seal closed big deals. Niantic and Sealing Devices Inc. of Lancaster, New York created a joint venture for sealing distribution and elastomeric parts fabrication. Mergers of this kind were expected to continue in the next decade.
Total industry employment in 2000 was about 44,451 according to the latest figures available from the U.S. government, compared to 41,980 in 1997. Of the 44,451 workers employed in 2000, 32,298 were production workers earning an average of $14.07 per hour. The range of employment varied extensively, from factory workers producing the products, to chemists and engineers who develop the compounds and designs, to the sales force that deals with OEM and aftermarket accounts. The average number of workers per establishment was approximately 65.
In response to increasing imports, many makers of gaskets and seals took a proactive stance: cutting manufacturing costs, going to advanced production concepts such as computer-aided design, and after-uses that had the opportunity to provide greater than average growth. Examples of such applications are nonasbestos gasketing, or seals designed to reduce emissions in process industries. Industry participants also spent to improve product design. These actions helped the industry maintain steady growth since the early 1980s.
Despite their uses in highly complex applications, gasket and seal technology itself is more defined. Developments have come in the form of the new materials being used and demands from customers for longer lasting materials. Capital costs aren't immense, but investment has been needed to keep up with these continuing shifts.
One new type of material is an oil-resistant liquid-silicone-rubber (LSR) introduced by Dow Corning STI in Plymouth, Michigan. Typical applications of this product are gaskets, O-rings, grommets, rollers and electrical components. These new silicones should extend "hot-oil performance and high speed processing to manufacturers of automotive, off-highway, and industrial equipment"; according to Mechanical Engineering. The automobile industry demanded a new type of silicone due to rising temperatures in engine compartments, and the need for longer service-life in the automobile industry.
Technology is also sometimes governed by regulation. For health and safety reasons, the Department of Environment, Transport and the Regions banned the use and supply of white chrysotile asbestos as of November 24, 1999. Use of the material as a sealing material was allowed until January 2001 for saturated steam, superheated steam, and particularly hazardous substances. Seal manufacturers that once used this material will have to develop alternatives.
Carr, John J. The Vanderbilt Rubber Handbook. Norwalk, CT: R. T. Vanderbilt Co. Inc, 1990.
"Chlorine Producers Refuse to Adopt Non-Asbestos Seals." Engineer. 24 September 1999.
D&B Million Dollar Directory. Dun and Bradstreet, 1999.
Darnay, Arsen J., ed. Manufacturing USA. 5th ed. Detroit: GaleResearch, 1996.
Fluid Sealing Association Home Page. Available from: http://www.fluidsealing.com
Fredonia Group, Inc. Study #959 Abstract Gaskets and Seals to 2001. 1998. Available from: http://ecnext.imrmall.com/freescripts/ip_catalog_all.pl?0001&9&959
Gasket Fabricators Association Home Page. Available from http://www.gasketfab.com
GBR Document. 5053, General Statistics. Farmington Hills, MI: Gale Group, 1999.
GBR Document. 5053, Product Share Details. Farmington Hills, MI: Gale Group, 1999.
"Sealing Devices and Niantic Seal from Sealing Devices for Elastomer Parts Fabrication and Seal Distribution." Rubber and Plastics News, 8 November 1999.
Smith, Kerry C. "Seal Industry Rediscovers Stress Relaxation." Rubber and Plastics News, 31 January 1994.
"Technology Focus: Oil Resistant Silicone." Mechanical Engineering, September 1996.
United States Census Bureau. 1992 Annual Survey of Manufactures. Washington: GPO, Updated 1996. Available from http://www.census.gov/epcd/ec92/mc92ht30.html .
United States Census Bureau. "Statistics for Industries and Industry Groups: 2000." Annual Survey of Manufacturers. February 2002. Available from http://www.census.gov .