Feb. 05, 2024
HISTORY OF MACHANICAL SEALS
Mechanical Seal Industry is over 100 years old. The first known company was established in USA in 1905.The mechanical seal was invented by George Cook and was originally called a "Cook Seal". He also founded the Cook Seal Company. Cook's seal (which actually did not have a means of drive) was first used in refrigeration compressors. The Cook Seal company was a sideline product for Cook and he sold the company to Muskegon Piston Ring Company where it was renamed as The Rotary Seal Division of Muskegon Piston Ring Co. Muskegon Piston Ring sold the Rotary Seal Division to EG&G Sealol who in turn was largely acquired by John Crane in 1998.
Crane Packing Company started manufacturing of Auto motive mechanical seal in 1939 in USA; they had operations in USA, Canada & England. Crane Packing Company – renamed as John Crane in England. Crane Packing Company USA & Canada merged under John Crane in 1987.
Pacific & Dura metallic first manufactured mechanical face seals in 1930 in USA. BorgWarner started manufacturing mechanical face seals from 1955 in USA. These companies along with PAC Seals merged under Flowserve corporation- Flow solution.
Burgmann-Germany developed mechanical seal in 1962. Nippon – Sealol Co.Ltd. A joint venture between Sealol USA & Nok Japan started manufacturing mechanical face seal in 1964. This company changed its name to Eagle Industries Co.Ltd. in 1978. Burgmann & Eagle merged in 2004, to be known as Eagle – Burgmann.
The Rope Packing Companies like Chesterton, Johncrane and Garlock introduced Face mechanical seals in their Product Range.
An end face mechanical seal, also referred to as a mechanical face seal but usually simply as a mechanical seal, is a type of seal utilised in rotating equipment, such as pumps and compressors. When a pump operates, the liquid could leak out of the pump between the rotating shaft and the stationary pump casing. Since the shaft rotates, preventing this leakage can be difficult. Earlier pump models used mechanical packing to seal the shaft. Since World War II, mechanical seals have replaced packing in many applications.
An end face mechanical seal uses both rigid and flexible elements that maintain contact at a sealing interface and slide on each other, allowing a rotating element to pass through a sealed case. The elements are both hydraulically and mechanically loaded with a spring or other device to maintain contact. For similar designs using flexible elements, see Radial shaft seal (a.k.a "lip seal") and o-rings.
The initial requirements of sealing water in Automotive, Agriculture, Domestic sea water pumps for ships lead to the development of simple rubber end face seals.
Mechanical Rotary shaft seal is an assembly of two faces. One is stationary, fixed in the housing and the other is fixed on a rotary shaft. These two lapped faces are kept in contact with each other through a nominal positive pressure provided by the use of one or more springs.
A mechanical seal must contain four functional components:
1) Primary sealing surfaces,
2) Secondary sealing surfaces,
3) A means of actuation and
4) A means of drive.
1) The primary sealing surfaces are the heart of the device. A common combination consists of a hard material, such as silicon carbide or tungsten carbide, embedded in the pump casing and a softer material, such as carbon in the rotating seal assembly. Many other materials can be used depending on the liquid's chemical properties, pressure, and temperature. These two rings are in intimate contact, one ring rotates with the shaft, and the other ring is stationary. These two rings are machined using a machining process called lapping in order to obtain the necessary degree of flatness.
2) The secondary sealing surfaces (there may be a number of them) are those other points in the seal that require a fluid barrier but are not rotating relative to one another.
3) In order to keep the two primary sealing surfaces in intimate contact, a means of actuation must be provided. This is commonly provided by a spring. In conjunction with the spring, it may also be provided by the pressure of the sealed fluid.
4) The primary sealing surfaces must be the only parts of the seal that are permitted to rotate relative to one another; they must not rotate relative to the parts of the seal that hold them in place. To maintain this non-rotation a method of drive must be provided.
With the growth of process industry the appropriate measured and the SEALING TECHNOLOGY adopted itself to meet the requirements.
Rubber end face seals
1945-1960
Face Seals – Unbalanced &Balanced pusher seals.
1960s &1970s
Some of the leading companies like Johncrane, Flixibox, Burgman, Borg Warner, Pilar, Pacific, Dura metallic and Sealol spread their operations by setting up Joint Ventures in other Asian/Australia/South America/European and African Countries. Chesterton appointed Distributors across the Globe.
1970- 1980
Invention of Metal Bellow Seals & Silicon Cartridge for high temperature & cryogenic application a superior face material.
1980s
European Countries tried to standardise seal sizes and stuffing box cavity by introducing DIN Standards. This allowed interchangeability between Seal Manufacturers. Both U.K. and American companies still persist with Inch standards.
Late 1980s
Non Contacting Dry Gas Seals by Johncrane for High Speed centrifugal compressors.
1995
Seal Companies face severe competition among them and try to acquire to survive. The result was formation of three groups.
2000
Some Distributors of Chesterton breakaway to form their own manufacturing companies like AESSEALS.
2000s
New Concepts of Hydraulics introduced in Sealing Technology like:-
For the inventor of mechanical seals, George Cook, the company «Cook Seal» was not the only source of income, and he sold it to the company «Muskegon Piston Ring», where it was renamed into a division engaged in rotary connections «Muskegon Piston Ring Co». Later «Muskegon Piston Ring» sold its unit «Rotary Seal EG & G Sealol», which in turn was purchased by «John Crane» in 1998.
Сompany «Crane Packing Company» began production of mechanical seals for cars in 1949 in the United States, their units also worked in Canada and England. Later «Crane Packing Company» in England was renamed the company «John Crane». Сompany «Crane Packing Company USA» and «Crane Packing Company Canada» also united under a common brand «John Crane» in 1987.
Сompany «Pacific & Durametallic» for the first time manufactured mechanical seals in the USA in 1930. «Borgwarner» began the production of mechanical seals since 1955 in the United States. Later, these companies merged with «PAC Seals», within the holding «Flowserve corporation-Flow».
The German company «Burgmann» developed the mechanical seal in 1962. Сompany «Nippon - Sealol Co.Ltd.» was a joint venture «Sealol» - USA and «Nok» - Japan, which began the production of mechanical seals in 1964. And already in 1978, the company changed its name to. In 2004 there was a merger of companies «Burgmann» and «Eagle», their products are now produced under the brand name «Eagle Burgmann».
The mechanical seal, also called mechanical seal, is a type of seal used in rotating equipment, such as pumps and compressors.
When the pump is running, liquid can flow out of the pump between the rotating shaft and the stationary pump housing. As the shaft rotates, preventing this leakage can be difficult. Early models of pumps used stuffing box packing to seal the shaft. After the Second World War, the mechanical seals replaced the stuffing box packing in many fields of application.
In the mechanical seal, both rigid and flexible elements are used which are in direct contact and are rubbed against each other, allowing the rotating element to remain hermetic.
The initial requirements for sealing water in cars, agriculture and sea water pumps for ships led to the development of simple rubber mechanical seals.
The seal for the rotating shaft is a pair of friction between the two rings. One is fixed, fixed in the body, and the other is fixed on the rotating shaft. These friction pairs are in contact with each other due to the nominal positive pressure generated by one or more springs.
1. Primary seals, they are also called a pair of friction. The overall combination consists of a solid material such as silicon carbide or tungsten carbide embedded in the pump casing and a softer material such as carbon in a rotating sealing assembly. Many other materials can be used depending on the operating conditions, chemical properties, pressure and temperature of the liquid. These two rings are in close contact, one ring rotates together with the shaft, the other ring is motionless. In the production of friction pairs, these rings are processed in a process called lapping to obtain the required degree of flatness.
2. Secondary seals, ensure the sealing of other points of contact in the seal, they prevent the leakage of liquid and do not rotate relative to each other.
3. Springs, are used to create pressure and maintain a close contact between the primary seals. In combination with the spring, a reliable contact of the friction pairs is also provided by the pressure of the pumped liquid.
Primary sealing surfaces should be the only parts of the seal that can rotate with respect to each other, they should not rotate with respect to the seal parts that hold them in place. As the processing industry developed, it was necessary to evaluate the efficiency of mechanical seals to adapt them to modern requirements.
In 1929, JM Ryan of the «Crane Packing Company» developed a mechanical seal called the «Ryan Seal». The «Ryan Seal» used steel and bronze surfaces, one coil spring and a stuffing box seal as the second sealing element. At that time, the fixed sealing ring had not yet been invented. Later, the stationary rings of the mechanical seal were started to be made of steel and mounted with interference on the pump shaft. Sealing surfaces were machined, not by grinding.
In the early mechanical seals, a combination of hardened steel and lead bronze was often used. This combination of materials for mechanical seals was suitable for lubricants. The best way to provide lubrication, a double mechanical seal, was developed by Durametallic in 1937. In addition, double seals have also been used in aggressive and dirty environments, as well as in high-pressure environments. In a sense, the double mechanical seals resembled a stuffing box that was separated by a ring to feed the sealing fluid into the stuffing box. Even though the first mechanical seals are now considered not completely reliable sealing seals, the losses due to leakage in them were an order of magnitude smaller than leaks from the stuffing box packing. In fact, the leakage through the stuffing box and the consumption of the cooling oil were measurable, in some cases up to 10% of the capacity of the refinery.
In the mechanical seals of the 1930s, soft materials were used as secondary sealing elements. Secondary seals were made of natural fibers, rubber, neoprene (synthetic rubber) or asbestos. The stationary sealing ring was developed in the 1930s, but was not used in mechanical seals before the Second World War. Neil Christensen found the optimal size for the O-ring and its groove in 1933. He applied for a patent in 1937, and received it in 1939. Prior to World War II, natural rubber was still used, although much work had already been done to develop synthetic materials. During the war, natural rubber was difficult to obtain, and the production of synthetic rubber became the priority of wartime. The first synthetics were: neoprene, butadiene-acrylonitrile, butadiene-styrene and butyl rubbers. The use of synthetic rubbers was usually limited to temperatures of not more than 121°C.
1920-1945. Development of rubber sealing rings.
1945-1960. Development of mechanical seals, unbalanced type and balanced pusher.
1960-1970. Some of the leading companies, such as «John Crane», «Flexibox», «Burgman», «Borg Warner», «Pilar», «Pacific», «Durametallic» and «Sealol», expanded their activities by creating joint ventures in other countries in Asia, Australia, South America, Europe and Africa. Then the company «Chesterton» began to actively develop a distribution network around the world.
1970 - 1980. The invention of metallic bellows seal and silicon cartridge for high-temperature and cryogenic application.
1980. Standardization by the European countries of the sizes of seals and cavities of stuffing box packing, introduction of DIN standards. This allowed the interchange of seals from other manufacturers. English and American companies still adhere to these standards.
1981. Company development «John Crane» non-contact seals for dry gases used in high-speed centrifugal compressors.
1995-2005. Companies that manufacture mechanical seals face serious competition among themselves and try to absorb each other in order to stay on the market.
As a result, the market remains four major manufacturers:
- Сompany «John Crane», which bought «Sealol», «Safematic» and «Flexibox».
- Сompany «Flowserve», which united «Durametalic», «Borg Worner», «Pacific».
- Сompany «AESSEAL», formed by the distributors of «Chesterton», which separated and formed their own enterprise.
- Сompany «Eagle Burgmann», merged «Burgmann» and «Eagle of Japan».
At the moment, the mechanical seal market is estimated at more than 14 billion US dollars.
John Crane
John Crane Mechanical Seals, part of the Smiths Group of the United Kingdom, is headquartered in Chicago, Illinois. John Crane is the largest and one of the oldest seal companies being incorporated as Crane Packing Company on March 9, 1917 in Chicago, Illinois.
Frank E. Payne, founder of Crane Packing Company, was a salesman for the Warren Steam Pump Company when he first heard about a local mechanic, John Crane, who made his own variation of metallic packing for pumps. Legend is that Crane discovered the improvement by wrapping his metal foil cigar wrapper around conventional packing. For a while, Payne sold metallic packing for John Crane on a commission basis but he left Warren Pump in 1916 to go into partnership with Crane. Although John Crane soon sold his shares and left the company, Payne kept the name Crane Packing Company for the business.
The first products of Crane Packing Company were flexible gland packings – particularly metallic packings. This packing was used extensively on tubes in steam condensers and heat exchangers as well as rotating and reciprocating pumps. In the 1920’s the product line was expanded to include braided packing as well as gasket materials.
In 1919, Crane Packing moved from the original location, 31 South Clinton Street, to 1800 Cuyler where it remained until 1956. The current location, 6400 West Oakton, in Morton Grove, was acquired in 1950 and by 1956 all Crane Packing operations had been moved to Morton Grove.
In 1923, Frank Payne toured Europe and established Crane Packing Ltd. in Slough, England.
In 1936, Crane Packing Company sold its interest in the English company, Crane Packing Ltd., to the local management; however, Crane Packing Company in the USA and Crane Packing Ltd in England continued to work together technically and commercially.
In the mid 1930’s Crane Packing Company licensed a mechanical seal design from Chicago Rotary Seal. Through several Crane patents, this design evolved into the full convolution rubber bellows seal. By 1938, Crane Packing Ltd in England was making their own mechanical seals for pumps in oil refineries.
In the late 1930’s, probably about 1937, mechanical seals began to replace packing on automobile water pumps. At first only the more expensive automobiles used mechanical seals in the water pump. The famous Jeep of WWII used a Crane rubber bellows seal in the water pump. After WWII, all automobile water pumps used mechanical seals.
During the mid 1940s, mechanical seals began to replace gland packing. Crane Packing Company developed its Type 1 and Type 2 rubber bellows mechanical seals in 1946. Because special lapping machines are required to manufacture mechanical seals, Crane Packing Company founded the Lapmaster Division.
In 1944, an amazing new material called Teflon (TM) was developed by Dupont. This material was relatively inert to many chemicals and held great promise for the sealing industry. To take advantage of the unique properties of Teflon, Crane developed the Type 9 (USA) and Type 109 (Europe) seals. In 1956, an all-PTFE acid-resistant seal, the Type 20, was launched.
In 1947, Crane Packing Ltd. (England) was acquired by Tube Investments of London, England. Tube Investments, later to become TI Group, plc in 1982, was founded in 1919. In 1963, Crane Packing Company (USA) regained a 49% interest in Crane Packing Ltd (England).
During the late 1940’s and early 1950’s a number of the core product lines of Crane Packing Company were developed. In addition to the Type 1 and Type 2 rubber bellows seals and the Type 9 and 109 Teflon wedge seals, the well-known Type 8 family of seals was developed in this time frame. The Type 8 seal is an unbalanced seal for low pressures, the Type 8-B a high pressure seal for pipeline services and the Type 8B-1 is a very adaptable version of the Type 8-B for typical refinery and chemical plant services. Decades later, these seals (with modern materials and improvements, of course) are still among the most popular seals in the world.
In 1951, Crane Packing Company moved from Chicago to Morton Grove, Illinois where today’s industrial complex is located on 26 acres of land.
In 1979, Crane Packing Company developed the Type 28 non-contacting, dry running gas seal to replace conventional oil lubricated seals then used on compressors. A patent was awarded for this unique mechanical seal which used spiral grooves to provide hydrodynamic lift and separate the sealing faces.
In 1981, Crane Packing Company was purchased by Kohlberg, Kravis and Roberts in a leveraged buyout as part of Houdaille Industries. The corporate name was changed from Crane Packing Company to John Crane in 1983.
In 1987, TI Group plc purchased Houdaille Industries thus unifying the American and British Crane companies as John Crane International.
In 1998, John Crane acquired Sealol, Safematic and Flexibox.
In 2000, TI Group merged with Smiths Industries to become Smiths Group plc, a global technology company based in London.
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China SBT Oil Seal is an international company integrating design, research and development, production and processing.
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