Trg braided seal with lavsan thread. Gland packings made of thermally expanded graphite
Gland seals are one of the most common types of seals. And despite the fact that stuffing boxes are gradually being replaced by other designs, for example, stuffing box packings will be widely used for a long time because of their simplicity and low cost.
The standard applies to fibrous and combined gland packings used to fill stuffing boxes in order to seal movable and fixed joints of various machines and devices. This standard does not apply to packings of special designs.
Table 2 shows the characteristics of packing grades according to
Table 3 shows the grades of stuffing box packings depending on the application.
Most of the packings mentioned in , are still in demand and in demand in the industry.
Today, manufacturers of sealing materials offer both traditional packings and more modern materials, with the emphasis being placed on packings based on and various polymer materials(primarily ). Today, materials produced by Russian and foreign companies are widely represented on the market.
The largest Russian manufacturers:
JSC "Barnaul Plant of Asbestos Technical Products", JSC "UralATI", JSC "VATI", CJSC "Unihimtek - Graflex", LLC "Silur", CJSC "TREM Engineering", etc.
The largest foreign manufacturers:
Companies related to this type of seals:
Gland packings from thermally expanded graphite. Thermally expanded graphite in the production of gland packings in Russia and China. Characteristics, parameters and applications of graphite packing. Expanded graphite packing types. Recommendations for the use of graphite sealing materials. Information about gland packings made of thermally expanded graphite is accompanied by photographs.
Additional Information
The section presents more than twenty types of gland packings based on thermally expanded graphite. All products are manufactured by the industrial holding IFI Technical Production Co., Ltd (China). Graphite packings are designed and manufactured by IFI Technical Production Co., Ltd in accordance with the State National Standards PRC JBT 7370-1994 and JBT6620-2008 as well as with Specifications(TU) of the manufacturer. TU 2573-001-91200348-2011 are registered on the territory of the Russian Federation in established by law RF order and entered in the state register. All products have a certificate of conformity of the State Standard of Russia, as well as a sanitary and epidemiological conclusion Federal Service on Supervision of Consumer Protection and Human Welfare on the compliance of IFI Technical Production Co., Ltd products with sanitary standards.
Graphite stuffing reinforced with cotton thread RK-240C
Gland packing RK-240C, woven from high quality expanded graphite yarn reinforced with cotton threads. Packing RK-240C is designed to seal shafts of high speed pumps with minimal leakage of working fluid for cooling, stuffing boxes of valves in power plants and boiler houses, in the petrochemical industry and many other industrial areas. The packing is self-lubricating, has increased flexibility, excellent thermal conductivity, chemical inertness. The stuffing has an extended shelf life, does not harden over time. Graphite packing RK-240C is designed for use in environments: steam, water, different kinds fuels, gases, chemical substances, mineral and synthetic oils, drains. Not intended for use in strong oxidizing environments (concentrated nitric acid, sulfuric acid, etc.). Graphite packing RK-240C has a density of 1.20 ~ 1.30g/cm³, which gives more meters of packing per unit weight, which makes the packing very economical compared to other types of stuffing box packing.
Note
Gland packing graphite reinforced with glass fiber RK-240G
Gland packing RK-240G, woven from high-quality thermoexpanded graphite yarn reinforced with fiberglass. Packing RK-240G is designed to seal shafts of high speed pumps with minimal leakage of the working fluid for cooling, stuffing box valves in power plants and boiler houses, in the petrochemical industry and many other industrial areas. The packing is self-lubricating, has increased flexibility, excellent thermal conductivity, chemical inertness. The stuffing has an extended shelf life, does not harden over time. Graphite packing RK-240G is designed for use in environments: steam, water, various fuels, gases, chemicals, mineral and synthetic oils, drains. Not intended for use in strong oxidizing environments (concentrated nitric acid, sulfuric acid, etc.). Graphite packing RK-240G has a density of 1.20 ~ 1.30g/cm³, which gives more meters of packing per unit weight, which makes the packing very economical compared to other types of stuffing box packing.
Note: Not intended for use in strong oxidant environments, including concentrated nitric and sulfuric acids, oleum, chromic and perchloric acids, molten salts and oxidizing agents.
Graphite stuffing box reinforced with wire (Inconel) RK-240I
Gland packing RK-240I, woven from high quality expanded graphite yarn reinforced with inconel wire 1 . The number of Inconel reinforcing elements in a graphite yarn is determined by the thickness of the graphite yarn itself. The thicker the graphite yarn (the higher the amount of tex 2 ), the more reinforcing elements. The same principle applies when reinforcing graphite yarn with cotton, glass fiber and other materials.
Packing RK-240I is designed for sealing valves at high pressure and at high temperatures in the oil refining and petrochemical industries, as well as in many other industrial areas. The packing is self-lubricating, has increased flexibility, excellent thermal conductivity, chemical inertness. The stuffing has an extended shelf life, does not harden over time. Graphite packing RK-240I is recommended for use in environments: steam, acid solutions, various fuels, alkalis, toxic media, solvents. Not intended for use in strong oxidizing environments (concentrated nitric acid, sulfuric acid, etc.). Graphite packing RK-240I has a density of 1.20 ~ 1.30g/cm³, which gives more meters of packing per unit weight, which makes the packing very economical compared to other types of stuffing box packing.
Note: Not intended for use in strong oxidant environments, including concentrated nitric and sulfuric acids, oleum, chromic and perchloric acids, molten salts and oxidizing agents.
Special graphite packings made of expanded graphite reinforced yarn:
RK-240Cu- omental packing for the energy complex. The stuffing is woven from high quality expanded graphite reinforced yarn. copper wire.
RK-240Ca- the packing is woven from high quality expanded graphite yarn reinforced with carbon fiber. Gland packing for pumps and control valves with media of heavy and light hot oil products, oil and gas products and solvents.
RK-240SS- graphite packing reinforced with high-temperature and heat-resistant stainless steel wire. This is an economy version of graphite packing RK-240I
RK-240A- the stuffing is woven from high-quality thermoexpanded graphite yarn reinforced with aramid (Kevlar) fiber. Omental packing RK-240A, due to the properties of aramid fiber, has increased mechanical strength.
Inconel 1 (English Inconel) registered trademark SMC's family of austenitic nickel-chromium based superalloys. Inconel is applied at high temperatures. Often the name is shortened to "Inco" (sometimes "Iconel"). The family includes: Inconel 625, Chronin 625, Altemp 625, Haynes 625, Nickelvac 625 and Nicrofer 6020. Inconel alloys are resistant to oxidation and corrosion. When heated, Inconel forms a thin, stable, passivating oxide film that protects the surface from further degradation. Inconel retains strength over a wide temperature range, making it suitable for applications where aluminum or steel would not work.
Tex 2 - unit of measurement of thread thickness in international system. Characterizes the ratio of the mass of yarn to its length and is defined as the weight of 1 kilometer of thread in grams.
Note: RK-240Cu, RK-240Ca, RK-240SS, RK-240A gland packings are not intended for use in environments with strong oxidizing agents, including concentrated nitric and sulfuric acids, oleum, chromic and perchloric acids, molten salts and oxidizing agents.
Graphite packing with low sulfur content RK-240N
Gland packing RK-240N is woven from high-quality expanded graphite yarn produced using a special technology. The method used for the production of thermally expanded graphite makes it possible to significantly reduce the content of sulfur impurities. Sulfur content of packing RK-240N
RK-240N gland packing, similar to standard expanded graphite packing, can be reinforced with all available materials, including: cotton, fiberglass, metal wire, aramid, carbon fiber, etc.
Note: Not intended for use in strong oxidant environments, including concentrated nitric and sulfuric acids, oleum, chromic and perchloric acids, molten salts and oxidizing agents.
Gland packing graphite impregnated with polytetrafluoroethylene (fluoroplastic) suspension RK-240P
Gland packing RK-240P, woven from high-quality thermoexpanded graphite yarn, reinforced with specially prepared natural fibers with sealing additives and pre-impregnated polytetrafluoroethylene (PTFE) suspension. After weaving, the packing is additionally impregnated with polytetrafluoroethylene suspension. RK-240P fibers are strong yet pressurized stuffing box covers. Unlike most traditional packings, RK-240P does not unravel at the cut.
Compared with traditional graphite packings, it has excellent sealing cross-section, structural strength and has a very low coefficient of friction. The packing has increased resistance to wear (abrasion), but, due to the unique properties of polytetrafluoroethylene impregnation, it does not damage the walls of shafts and stuffing boxes.
Packing RK-240P is designed for sealing shafts of centrifugal and plunger pumps, and is also suitable for use on fittings.
Packing friction coefficient 0.05 - 0.1.
Note: Not intended for use in strong oxidant environments, including concentrated nitric and sulfuric acids, oleum, chromic and perchloric acids, molten salts and oxidizing agents.
Gland packing made of thermally expanded graphite yarn in a glass-metal casing RK-240CAS
Packing omental RK-240CAS is woven from high quality expanded graphite yarn. The packing has a glass-metal body, made by the method of dense diagonal braiding. Graphite packing RK-240CAS is a product of the latest research and development. Unique gland packing for fittings at high pressures and temperatures. The body of the stuffing is made of fiberglass and inconel wire. There are no analogues of this stuffing in the Russian Federation.
Working pressure for graphite packing RK-240CAS, 55 MPa, which is much higher than the allowable maximum pressure for all other types of stuffing box packings made of thermally expanded graphite.
Expanded graphite yarn, from which the packing body is made, can be reinforced with mineral or synthetic fibers or metal wire, for example: glass fiber, basalt fiber, aramid fiber (Kevlar), carbon fiber, Inconel, stainless or copper wire. In the photo on the right, the packing is reinforced with carbon fiber.
Note: Not intended for use in strong oxidant environments, including concentrated nitric and sulfuric acids, oleum, chromic and perchloric acids, molten salts and oxidizing agents.
Graphite stuffing box packing with inconel wire braid RK-240IJ
Gland packing is woven from thermally expanded graphite yarn. Each strand is pre-braided with a mesh of inconel wire. The finished packing assembly is braided with a mesh of inconel wire.
Note: Not intended for use in strong oxidant environments, including concentrated nitric and sulfuric acids, oleum, chromic and perchloric acids, molten salts and oxidizing agents.
Gland packing RK-240SSJ- economy version of graphite packing RK-240IJ, for the braiding of graphite yarn and the body of the packing, not inconel is used, but a wire made of heat-resistant and stainless steel. As a standard, steel wire of the SS304 brand is used - this is an analogue of steel 08X18H10 - heat-resistant stainless steel austenitic grade, with a high content of chromium and nickel, as well as additives of titanium and manganese. On request, it is possible to use wire from a different steel grade.
Gland packing RK-240AJ- a variant of RK-240IJ graphite packing, but not inconel wire, but aramid (Kevlar) threads are used for the braiding of graphite yarn and the body of the packing. The packing has a lower weight and increased mechanical strength due to the properties of aramid fibers.
Graphite stuffing box packing with inconel wire binding RK-240CJ
Gland packing is woven from thermally expanded graphite yarn. The body of the packing assembly is tied with a mesh of fine inconel wire.
The packing has excellent cross-sectional tightness and increased structural strength, has excellent thermal conductivity, and is suitable for use at high pressures in a wide temperature range. The packing is recommended for use on fittings in power plants and boiler houses, in the petrochemical industry and many other industrial applications.
The main difference between RK-240CJ graphite packing and RK-240IJ stuffing box packing is the method of reinforcing the body of the Inconel packing with wire. In RK-240IJ stuffing box packing, the stuffing body is reinforced by braiding (braided mesh) inconel wire around the stuffing body, and in RK-240CJ stuffing box, by tying (knitted mesh).
Note: Not intended for use in strong oxidant environments, including concentrated nitric and sulfuric acids, oleum, chromic and perchloric acids, molten salts and oxidizing agents.
Graphite gland packing with carbon yarn angle braid RK-240CC
This is a diagonal weave stuffing box made of thermoexpanded graphite yarn reinforced with glass fiber. For added mechanical strength, the corners of the padding are braided with high quality, pure carbon yarn. Angular carbon interlacing can increase the stuffing box extrusion resistance and mechanical strength by 2 ~ 2.5 times compared to RK-240C or RK-240G packing.
Scope: Can be used for sealing dynamic and static units. Particularly suitable for high temperatures and operating pressures in fittings, pumps, compensators, mixers in the pulp and paper industry, power plants and the chemical industry.
stuffing box RK-240SSC- packing with carbon fiber corner braid, made of thermoexpanded graphite yarn reinforced with heat-resistant, stainless steel wire SS304.
stuffing box RK-240CUC- stuffing with carbon fiber corner braid, made of thermoexpanded graphite yarn reinforced with copper wire.
Note: Not intended for use in strong oxidant environments, including concentrated nitric and sulfuric acids, oleum, chromic and perchloric acids, molten salts and oxidizing agents.
Graphite stuffing box packing with PTFE corner braid (PTFE) RK-240PC
Universal stuffing box packing made of high-quality expanded graphite yarn with a corner braid of the packing body with PTFE yarn. The packing has all the properties of thermally expanded graphite and is complemented by the unique parameters of fluoroplastic seals. The angled braid reinforces the packing, reducing packing wear and preventing extrusion of graphite into the gland gaps.
Scope: Can be used for sealing dynamic and static units. Particularly suitable for medium temperatures and operating pressures in fittings, pumps, compensators, mixers in power plants and in the chemical industry.
stuffing box RK-240GPC- Universal stuffing box packing made of high-quality expanded graphite yarn with an angled braid of the graphite packing body filled with polytetrafluoroethylene yarn
Note: Not intended for use in strong oxidant environments, including concentrated nitric and sulfuric acids, oleum, chromic and perchloric acids, molten salts and oxidizing agents.
Graphite stuffing box packing with angled aramid (Kevlar fiber) braid RK-240AC
Multipurpose universal stuffing box packing based on thermally expanded graphite with an angled braid of aramid (Kevlar) fiber. The new kind gland packing, not represented on the Russian market.
The packing combines the advantages of aramid fiber, while the graphite body of the packing promotes efficient heat transfer (high thermal conductivity) and low coefficient of friction. The aramid fiber corner braid provides reinforcement of the packing material, preventing extrusion of graphite into the stuffing box gaps and makes it possible to seal abrasive media.
However, due to the strength of the aramid fiber, it is not recommended to use RK-240AC gland packing on shafts (bushings, etc.) with metal hardness less than 60 HR.
Depending on the wishes of customers, the packing can be made of reinforced graphite yarn. Reinforcement material - on request, it can be cotton fibers, lavsan, fiberglass, carbon, aramid, metal wire, etc.
Upon request, the packing can be treated with a PTFE suspension.
Packing RK-240AC is designed for various media, including aggressive environments: hot and cold water, steam, solvents, oils, greases, non-concentrated acids and alkalis, salt water, drains, sewage, and so on.
Like all gland packings based on thermally expanded graphite, packing RK-240AC is not suitable for strong oxidizers, concentrated nitric acid, oleum, chromic and perchloric acids, molten salts and oxidizers.
Graphite tape with adhesive layer (self-adhesive) RK-240T
Sealing tape RK-240T, for flat connectors, is made of flexible woven graphite fiber reinforced with inconel wire (stainless, nickel, copper, brass wire or synthetic fiber) and impregnated with a corrosion inhibitor. The tape is designed to seal flange connections with smooth sealing surfaces, with "protrusion-cavity" and "thorn-groove" surfaces of fittings, pipelines, vessels, apparatuses, pumps and similar equipment of the chemical, oil refining, energy and other industries. For ease of installation, an adhesive layer is applied on one side. The tape is reinforced with Inconel wire, which increases the maximum allowable gasket pressure and its reliability, including for real, not ideal operating conditions. Easy to install, suitable for sealing flanges and large diameter connectors.
On request, graphite tape can have an external metal reinforcement in the form of a woven or knitted mesh.
Note: Not intended for use in strong oxidant environments, including concentrated nitric and sulfuric acids, oleum, chromic and perchloric acids, molten salts and oxidizing agents.
Dear Sirs! Most of the typical expanded graphite packings are presented in this section. In fact, IFI Technical Production China produces a much wider range of TEG packings for special conditions operation, according to individual orders of our customers. The production uses modern synthetic reinforcing materials, specially designed multifunctional inhibitors and fillers. For all questions, including the procedure for placing orders for the production or development of stuffing box packings, you can contact the central office in China at the email address This e-mail address is being protected from spambots, you need to have JavaScript enabled to view it Javascript, and to the Moscow Representative Office of Rus-Kit.
Graphite packings or stuffing box packings based on thermally expanded graphite (TEG), today, due to the unique properties of thermally expanded graphite itself, are the most popular stuffing box seals of all types of stuffing box packings. The volume of consumption of stuffing box packings from TRG is about 70% ~ 80% of the total consumption of stuffing box packings in the Russian Federation.
This is due to the fact that graphite packings combine a number of unique properties. None of the yarns used today for the production of stuffing boxes have at the same time the same properties as TRG yarn. Gland packings made from other types of yarns have several specific properties inherent in this type of yarn, but only expanded graphite packings combine most of the properties of other types of packings, making TRG packings universal packings. Graphite packings are used in both dynamic, and in static sealing modes, in systems operating at high temperatures, pressures and in chemically aggressive environments.
The only competitor in the technological segment where stuffing boxes made of thermally expanded graphite are used is RK-270HG stuffing box made on the basis of high modulus carbon fibers. High modulus carbon fibers are high-tech products made from petroleum pitches or the mineral graphite. The pH index for RK-270GH packing, like graphite packing, is in the range of 0~14, working temperature up to +850°C in an acidic environment, the strength of the RK-270HG packing fiber allows it to be used in abrasive environments. But the production cost and final cost of high modulus carbon fiber packing is six times higher than that of TRG packing.
Fluids Recommended for Use of Thermally Expanded Graphite (TEG) Seals
| organic acids | Aqueous solutions of salts | inorganic acids |
| Acrylic | Acetates | Nitrogen 20-65% up to 20ºС |
| other | Borates | Nitrogen up to 20% |
| Hexachlorophenylacetic | Bromides | Bornaya |
| Fatty acid | Hypochlorites | Silicofluoride |
| Maleic | iodides | Sulfur 70-90% up to 100ºС |
| Monochloroacetic | Carbonates | Sulfuric up to 70% |
| Formic | Nitrates | sulphurous |
| Sulfonic acids | Nitrites | Salt |
| Trichloroacetic | Sulfates (including alum) | Coal |
| Acetic | Sulfites | Phosphoric (ortho-) up to 20% |
| Phenylacetic | thiosulfates | Hydrofluoric |
| sorrel | Phosphates | Chrome up to 10% |
| Salicylic | Fluorides | Salt melts |
| Folic | Chlorates | Potassium and sodium borates |
| Phthalic | chlorides | Potassium hydrosulfate |
| Other inorganic substances | Chromates up to 20% | calcium chloride |
| bromine water | Halogenated hydrocarbons | hydrocarbons |
| Hydrazine | Paradichlorobenzene | Acetylene |
| bleaching agents | Freons | Benzene |
| Hydrogen peroxide | Chlorobenzene | Butane |
| Sulfur | Chloroethylbenzene | Isooctane |
| Chlorine water | Chloroform | xylene |
| Thionyl chloride | carbon tetrachloride | Methane, natural gas |
| Aldehydes | alkalis | Propane |
| Acetaldehyde (acetaldehyde) | Ammonium hydroxide (aqueous ammonia) | Propylene |
| Benzaldehyde | Potassium hydroxide up to 400ºС | Styrene |
| Formaldehyde (formaldehyde) | Sodium hydroxide up to 400ºС | Ethylene |
| inorganic gases | Metal melts | Other organic matter |
| Nitrogen | Aluminum | Acrylonitrile |
| Ammonia | Gold | Dimethyl sulfoxide |
| Hydrogen bromide | Potassium up to 350ºС | Carbon disulphide (carbon disulfide) |
| Air up to 550ºС | Magnesium | Carbamide (urea) |
| nitrogen dioxide | Copper | Mercaptans |
| Sulfur dioxide (sulphurous anhydrite) | Sodium up to 350ºС | Nitrobenzene |
| Carbon dioxide up to 600ºС | Tin | pyridine |
| Nitrous oxide | Mercury | Silicones (polyorganosiloxanes) |
| Oxygen up to 350ºС | Lead | Siloxanes |
| Carbon monoxide (carbon monoxide) | Silver | Acetic anhydride |
| Steam up to 600ºС | Zinc | Alcohols |
| hydrogen sulfide | Technical liquids | Butanol (butyl alcohol) |
| Fluorine | hydraulic fluid | Glycols |
| Hydrogen fluoride | Fuel (gasoline, diesel fuel, kerosene) | Isopropanol (isopropyl alcohol) |
| Chlorine dry | Machine oils | Glycerol |
| Chlorine dioxide | Oil and oil products | Methanol (methyl alcohol) |
| hydrogen chloride | Solvents for paints | Cyclohexanol |
| Sulfur hexafluoride | Cutting fluids | Phenol |
| Ethers | transformer oils | Ethanol (ethyl alcohol) |
| Amyl acetate | Ketones | Amines |
| Dibenzyl ether | Acetone | Aniline |
| diphenyl ether | Isobutyl methyl ketone | Diethylamine |
| diethyl ether | Methyl ethyl ketone | Monoethanolamine |
| Methyl acetate | Cyclohexanone | Triethanolamine |
| Cellosolves (ethyl cellosolve, butyl cellosolve) | ||
| Ethyl acrylate | ||
| Butyl acrylate |
Comparative characteristics and parameters of asbestos seals and seals based on thermally expanded graphite
The reliability and safety of operation of the main equipment is largely determined by the reliability of the auxiliary equipment: pumps, shut-off, safety and control valves. As practice shows, emergency shutdowns and equipment failures are often associated with unsatisfactory operation of the sealing system. Until recently, asbestos-based sealing materials were used in the seals of flanged joints, valve rods, shafts of centrifugal pumps.
Long-term operation of these materials has shown that they have a number of significant drawbacks:
- - burnout of the components of the sealing material causes loosening of the tightening of the seal, and, as a result, loss of tightness of the seal assembly;
- - equipment parts in contact with the sealing material are subject to electrochemical corrosion;
- - to ensure the tightness of the sealing unit, it is required high altitude stuffing box;
- - asbestos packings have a high coefficient of friction, which requires an increase in the power of the electric drive and leads to significant wear of the protective sleeve of the pump shaft and valve rods.
At present, in the world, in particular in China, areas related to the development of new highly reliable sealing products of a new generation based on thermally expanded graphite and its composites are actively developing.
Possessing a number of unique properties (low density, large specific surface, ability to be pressed without a binder, resistance to aggressive media, high thermal conductivity, high reducibility, heat resistance, etc.), TRG is widely used as a sealing material at power plants, oil refineries, petrochemistry, chemistry and other industries. The main characteristics of the sealing material from TRG are presented in comparative table below.
| Characteristic | Sealing materials based on asbestos | Sealing materials based on TRG |
| Density, g/cm³ | 2,25 | 1...1.7 |
| Environmental friendliness | Belong to the class of carcinogens | Non-toxic, environmentally friendly |
| Guarantee period | Missing | 4 years |
| Working temperature, °С | Up to 400 | Up to 450 air, up to 550 steam |
| Chemical resistance | Reacts with strong acids and alkalis | Chemically inert |
| Plastic | non-plastic | Plastic |
| Elasticity, % | 1...3 | 9.. .15 |
| Coefficient of friction on steel | 0,3 | 0.02. ..0,12 |
Graphite. World production and reserves
Explored reserves of graphite in the world are estimated at 220 million tons and are concentrated in several dozen countries (more than 30 countries). The main volume of natural graphite in the world, which is about 140 million tons, is concentrated in China - this is 64% of the total volume of natural graphite. It should be noted here that there are still quite a lot of undeveloped graphite deposits in the world, which makes it impossible to make an accurate assessment of the distribution of natural graphite by country. But, nevertheless, this factor does not affect the leadership of the PRC in this area. In 2010, the volume of graphite production in China amounted to about 900 million tons. In second place after China is India, whose production in 2009 amounted to 140 million tons, which is six times less than in China. Further, Brazil, North Korea, Canada, Mexico with an approximate production volume of 75, 30, 25, 10 million tons, respectively. All other graphite producing countries account for less than 40 million tons.
Graphite used for the production of sealing and gasket materials
For the production of graphite seals, including stuffing box packings, thermally expanded graphite is used. Thermally expanded graphite is an intercalated (oxidized) graphite subjected to special heat treatment (at temperatures from +900°С to +1500°С). As a result of this heat treatment, intercalated graphite, in addition to retaining the properties of natural graphite, such as resistance to high temperatures and chemical inertness, acquires additional properties of plasticity (flexibility), pliability, compressive and tensile strength. These thermal expansion properties of expanded graphite distinguish it from other carbons and graphite and make it an excellent and high performance packing and sealing material.
The properties of thermally expanded graphite allow its use for the production of gaskets and sealing materials
Thermally expanded graphite has a number of properties that provide the TEG sealing material with a set of unique characteristics. These properties of TRG include: high thermal stability, high chemical inertness (does not react with most media), increased chemical resistance (resistance to aggressive environments), environmental safety, resistance to aging regardless of the time of operation or storage, high ductility and ductility, compressive and tensile strength.
Obtaining thermally expanded graphite
At the first stage, the initial crystalline graphite is oxidized (intercalated), such graphite is called intercalated graphite or IG. Coarse-flake natural graphite is used for the subsequent production of gaskets and sealing materials to obtain thermally expanded graphite. Oxidation (intercalation) is reduced to the introduction of molecules and ions of sulfuric or nitric acid in the presence of an oxidizing agent (hydrogen peroxide, potassium permanganate, etc.) between the layers of the graphite crystal lattice. The oxidized graphite is washed and dried. Then the oxidized graphite is subjected to heat treatment at a temperature of about 1000°C with a temperature increase rate of 400-600°C per second. Thanks extremely high speed heating, there is a sharp release of gaseous decomposition products of the introduced sulfuric acid from the crystal lattice of graphite. As a result, the interlayer distance increases by about 300 times, and the number of small particles of graphite and the volume of the sample increases by 60-400 times. A certain amount of sulfur or nitrogen oxides remains in the resulting material, depending on the technology used. Next, the resulting thermally expanded graphite is rolled into foil. To obtain TRG yarn, the foil is cut into tapes, which, if necessary, are reinforced with glass fiber, steel, copper or inconel wire, carbon, aramid or cotton fiber and twisted into graphite yarn (thread) on special equipment.
Production of thermally expanded graphite in the Russian Federation
As noted earlier, the volume of production of thermally expanded graphite of good and highest quality in Russia is not high, due to a number of both objective and subjective reasons. The objective reasons include the quality of the extracted natural graphite, and the high cost of developing and extracting graphite. There are a number of economic, administrative and technological reasons due to which this situation is observed. Graphite ore mined in the Russian Federation, for the most part, contains a large amount of impurities. A special criterion that determines the low quality of graphite mined in Russia is its high sulfur content. Purification of graphite ore is quite expensive, which greatly increases the cost of graphite. So, for example, the leading enterprises of the Russian Federation for the production and sale of graphite, for example, OJSC Magnezit, import graphite from abroad, in particular from China. One of the two Russian enterprises for the production of sealing and gasket materials, independently expanding graphite in its production, is forced to import graphite raw materials also from China. Graphite comes from China to the Kirovo-Chepetsk Chemical Combine, where the graphite is purified and oxidized. Further, the above enterprise takes the prepared graphite and subject it to further processing. Against this background, the introduction of protective duties on the import of graphite into the Russian Federation looks at least strange.
"The ATI plant produces graphite packings under its own trademark Grafiteks. The packings are represented by the following brands: TRG-100L - made of graphite threads, reinforced with lavsan or cotton threads; TRG-100LF - made of graphite threads, reinforced with lavsan or cotton b threads, impregnated with fluoroplastic suspension; TRG-101N - made of graphite threads, reinforced with stainless wire; TRG-102S - graphite threads reinforced with glass threads; TRG-102SF - graphite threads reinforced with glass threads, impregnated with fluoroplastic suspension; NU-103UNF - combined graphite and carbon threads NU-104f - carbon, made of carbonized PAN fiber impregnated with graphite suspension Application: (1-2) Control and shut-off valves, centrifugal pumps, mixers, autoclaves; (3) Control and shut-off valves; (4 -5) Control and shut-off valves, plunger and centrifugal pumps with low speeds; (6) Control and shut-off valves, plunger valves rotary pumps, agitators, autoclaves; (7) Closing rings for control and shut-off valves. seals for working environments with a low content of abrasive particles with c / w pumps."
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Graphite packing PGN 3100, 3300, 3500
The packing is made by interlacing threads of thermally expanded graphite and reinforced with glass or cotton thread, with corrosion inhibitors (retarders), if necessary, it is additionally impregnated with PBraided graphite packing PGN 6200
PGN 6200 - PTFE packing (impregnated with PTFE suspension). The packing is made from pure PTFE fibers and impregnated with a PTFE slurry. Area of application: in fittings where contamination is not allowedBraided graphite packing PGN 6400
The packing is made by interlacing PTFE and graphite threads. Scope: pumps, autoclaves, centrifuges. Working environment: water, steam, solvents, hydrogen sulfide. Graphite is not washed out in the processBraided graphite packing PGN 4100 and PGN 4100-1 based on carbon fiber
PGN 4100 - carbon fiber packing impregnated with PTFE suspension. The packing is made of high quality carbon fiber impregnated with PTFE suspension and woven in a special way. RegionThe stuffing box is a simple and effective device for sealing fixed and moving joints. Glands are widely used in pipelines, in transport, in the installation of cable penetrations, in hydraulic presses, pumps, and chemical apparatuses. In the simplest case, oiled hemp can be used, but modern industry produces special gland packings.
The stuffing box filled with packing is tightened with bolts and nuts, and the connection is reliably sealed, leakage of the working medium or penetration of corrosive substances is excluded. From right choice gland packing depends on the performance of many critical units.
Types of gland packings
- Asbestos and non-asbestos (containing cotton or other fibers).
- Dry (graphitized and clean) and impregnated - fat, graphite-adhesive compounds, fluoroplastic suspension are used for impregnation.
- Section shape: square, rectangular, round.
- According to the method of manufacture: wicker, twisted, rolled.
- According to the structure of weaving (braided): with a single-layer, multi-layer and through core, reinforced (brass wire).
Classification of gland packings
Fibrous and combined packings are standardized in Russia according to GOST 5152-84. They differ primarily in the presence of asbestos in the composition. Its presence is indicated by the letter "A" in the product abbreviation. In asbestos-containing gland packings, there is a core made of glass roving or rubber, brass wire. For impregnation, an oil extract, a fatty anti-friction composition, a suspension of fluoroplastic with graphite, talc or mica are used. The packing can be graphitized, rubberized. A separate category is PAFS polypropylene packing with an asbestos core impregnated with fluoroplastic and mica.Asbestos-free gland packings are woven from bast fibers, fluoroplast, fluorolon, cotton materials, carbon threads. Graphitization, impregnation with a suspension of fluoroplast, a fatty antifriction composition are used. Rolled up rubberized cotton packings are available, optionally with a rubber core.
Such an abundance of brands of stuffing box packings allows you to choose the most suitable option for these operating conditions. GOST determines for each brand the permissible temperature limits, pressure, sliding speed, pH of the medium. It is indicated in which units and assemblies packing can be used - fittings, fixed connections, centrifugal and piston pumps, plunger pumps, hydraulic presses, stern tube sealing devices.
The working medium for various brands of gland packing can be air, water vapor, nitrogen, inert gases, drinking and process water, sea water, organic substances, petroleum products, ammonia (gaseous and liquid), alkalis and acids, ammonium carbon salts.
Gland packings made of thermally expanded graphite
TRG packings have advantages over traditional ones. Braided graphite fiber in the stuffing box under pressure forms a homogeneous mass, there is no leakage of the working medium between the fibers. Less force is required when tightening the stuffing box, which prolongs its life. Graphite conducts heat well and dissipates it efficiently. The coefficient of friction of graphite is very low, which reduces heat generation and consumption of electrical energy in pumps.TRG packings are self-lubricating. The worn layer of material is replaced by the same. This reduces wear on bushings and shafts. Expanded graphite packings do not require additional lubrication. Over time, TRG-packings almost do not lose weight and volume at temperatures up to +650ºС, do not harden. A small loss of mass during the burnout of the polymer binder is compensated by the elastic deformation of the material. There is no need to regularly tighten the gland. TRG packings are chemically resistant in almost all environments, except for strong oxidizing agents.
Packings are made from thermoexpanded TRG graphite, expanded fluoroplastic (PTFE yarn), high and low temperature carbon fiber and aramid (Kevlar) yarn. Packings are made both from the above materials and from various combinations of these fibers with various additives and impregnations.
Advantages of TRG packings over traditional packings.
In conventional braided packings (based on asbestos, linen, synthetic and other threads), there are possible leakage paths between the fibers. However, the woven graphite fiber packing under pressure of the stuffing box cover forms a homogeneous mass and no leakage occurs. In this way, leaks are controlled with significantly lower tightening forces, which contributes to a longer packing life. Graphite has a significantly higher thermal conductivity (40....100 W/m*K) than traditional packing materials (for example, asbestos has 0.1...0.3 W/m*K), due to which In the pump chambers, heat is efficiently dissipated - the amount of leakage required to carry heat away is kept to a minimum.
Graphite has an extremely low coefficient of friction, around 0.05. This indicator significantly lower than many fibers used for packing. For comparison, the coefficient of friction of asbestos is 0.5. Thanks to the use of graphite packing in stuffing box seals, heat generation is drastically reduced and it is possible to reduce the energy consumption of pumps.
Gland packings made of woven thermally expanded graphite - TRG are self-lubricating. To replace a worn layer of material, a layer of exactly the same material is exposed, and not a layer of, for example, dry abrasive asbestos. This drastically increases packing life and also reduces shaft/bushing wear.
Advantages:
Thermally expanded graphite - TRG has a very low coefficient of friction on steel compared to asbestos:
Packings from TRG at temperatures up to 650°C almost do not lose volume and mass with time, especially in the closed volume of the stuffing box, and a small (less than 6%) mass loss due to the burning out of the polymer binder is compensated by high elastic deformations of the material, while asbestos-containing seals lose mass as a result of the change chemical composition even in a vacuum. In addition, TRG packings do not lose their sealing properties in the temperature range from -200 to +200°C during the entire service life. Asbestos packings inevitably harden and their sealing characteristics deteriorate. Thus, when using TRG packings, there is no need for regular tightening of the stuffing box.
Unlike the material of asbestos and fibrous packings, TRG is practically impervious to liquids and gases. The excellent compressibility of the material ensures the tightest possible contact with the surface of the shaft or stem and between the threads in the weave. This allows not only to ensure the tightness of the assembly, but also to reduce the amount of packing used to 4 - 6 rings, instead of 8 - 10 asbestos-containing rings.
TRG packings are universal, as they have high chemical resistance to almost all media, with the exception of strong oxidizing agents.
TRG packings, due to the elastic properties of the material, transfer well the pressure from the bottom box to the surface of the shaft or rod. The lateral pressure value is 60 . 70% of the axial, while for asbestos-containing packings this value does not exceed 30%. That is, to ensure the same contact pressure on the sealing surfaces, at least half the tightening force is required.
The thermal conductivity of TRG 100 ... 150 W/m K is significantly higher than the thermal conductivity of asbestos and fluoroplastic, which does not exceed 0.3 W/m K and 2.4 W/m K, respectively, which ensures efficient heat removal from the friction zone and allows operate pumps without overheating even in the absence of leaks necessary for cooling when using asbestos-containing and fluoroplastic packings.
non-abrasive media, as well as other similar equipment in the chemical, petrochemical, oil refining and oil industry, energy, as well as in pipelines public utilities, in the practice of cold and hot domestic and drinking water supply, melioration and food industry.
Medium: Steam and superheated steam, water, oil and oil products, chemical media.
Omental packing "Carboflex -101" (MS-101)
Manufactured from flexible woven graphite fiber with corrosion inhibitor.
Designed to seal the shafts of high-speed pumps with minimal leakage of the working fluid for cooling.
Omental packing "Carboflex -105" (MS-105)
Made of flexible woven graphite fiber with glass fiber and corrosion inhibitor.Impregnated with a suspension of polytetrafluoroethylene (fluoroplastic).Designed to seal the shafts of centrifugal and plunger pumps with minimal leakage of the working fluid for cooling.
Omental packing "Carboflex-131" (MS-131)
Manufactured from filaments of flexible thermally expanded graphite, reinforced with inconel wire with a corrosion inhibitor. It has high hydraulic resistance and allows reliable sealing of liquids with high fluidity and gases.
Omental packing "Carboflex-161" (MS-161)
Manufactured from flexible woven graphite fiber reinforced with high quality carbon fiber with corrosion inhibitor. Designed for sealing shafts of centrifugal pumps with minimal leakage of the working fluid for cooling, as well as stuffing box fittings.
Omental packing "Carboflex-250" (MS-250)
Stuffing box packing is made of high-strength low-temperature carbon fiber impregnated with fluoroplastic suspension. The packing is designed for sealing shafts of centrifugal and plunger pumps.
Omental packing "Carboflex-500" (MS-500)
Braided packing made of expanded fluoroplast fibers (PTFE). Square packing designed for use in fittings. Woven from 100% polytetrafluoroethylene (PTFE) fibers.
Omental packing "Carboflex-510" (MS-510)
Braided packing made of fibers of expanded graphite-filled fluoroplast (PTFE). It is designed for sealing stuffing box chambers of pumps pumping solutions of acids and alkalis and other aggressive media.
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