When connecting pipeline parts with pipeline fittings, it is required to ensure the tightness of these connections in order to avoid leakage of the medium.
Leakage is especially dangerous when transporting aggressive and explosive media, as well as those under pressure and having a high temperature.
The main type of detachable pipeline connections are flange connections, and its integral element is a gasket.
The gasket material must have the following properties:
ü elasticity, in order to fill the smallest irregularities of the flange surface when creating pressure, ensuring the tightness of the connection;
ü strength, in order to withstand the force of pressure of the environment;
ü resistance to aggressive environments.
Depending on the purpose and operating conditions of pipeline fittings, cardboard, paronite, sheet asbestos, rubber, fluoroplastic, polyethylene, aluminum, lead, copper, soft annealed steel are used as gaskets.
The choice of gasket materials for sealing flange connections depends on the conveyed medium and its operating parameters.
Some gasket materials, depending on the parameters of the medium and the types of sealing surfaces, are presented in table 9.
Table 9 - Materials of gaskets depending on the parameters of the medium and types of sealing surfaces
Continuation of table 9
| Gasket material | Working environment | Limiting temperature, 0 С | Working pressure limit, MPa | ||
| smooth surface | protrusion-depression | thorn-groove | |||
| 3. Oil-and-petrol-resistant paronite (PMB) 4. Technical rubber, acid-alkali-resistant (KShch) 5. Technical rubber, oil-and-petrol resistant (MB) 6. Technical rubber, heat-resistant (T) 7. Asbestos cardboard 8. Fluoroplastic 4 9. Annealed aluminum (AMTs) 10. Sheet copper (M 2) 11. Lead grade C2 12. Corrugated asbo-aluminum 13. Spiral made of steel 12X18H10T (filler - asbestos) | Light oil products Heavy oil products Oxygen, gaseous nitrogen Oxygen, liquid nitrogen Coke oven gas Water, air, neutral solutions, neutral gases and vapors, sulfuric acid (up to 65%), hydrochloric acid (up to 30%) Heavy oil products, kerosene, oils, butyl alcohol Water vapor, dry neutral and inert gases Liquid and gaseous hydrocarbons, fuel oil, oils, resins Acids, alkalis, solvents and organic liquids Liquid and gaseous hydrocarbons, fuel oil, oils, resins Superheated water, steam, liquid and gaseous oil products Sulfuric solutions and acetic acid (up to 60%), liquefied chlorine Heavy and light oil products, hydrocarbon gases, flue gases, carbon dioxide Water vapor, dry gases, oil products | - 182 from minus 30 to 50 from minus 30 to 50 from minus 196 to 250 from minus 196 to 250 from minus 70 to 250 | 2,5 2,0 2,5 0,25 2,5 1,0 1,0 1,0 0,15 – 1,6 2,5 0,6 2,5 2,5 | – – 5,0 – 6,4 – – – – – 4,0 10,0 – 6,4 10,0 | vacuum - 5.0 - - - - - - 2.5 vacuum vacuum - - - |
Continuation of table 9
To seal the glands of pipeline fittings and stuffing box expansion joints, packings are used in the form of cords, woven from asbestos or hemp threads, impregnated with various compounds that make them resistant to aggressive media.
The material for stuffing box packing is chosen depending on the working conditions. Fatty asbestos packing can be used at temperatures not exceeding 200 0 С, since at higher temperatures fatty substances leak out and the packing density decreases.
At temperatures above 200 0 C, asbestos printed packing or special asbestos-metal packing impregnated with a special composition resistant to destruction under the influence of transported media and high temperatures is used.
Fluoroplastic stuffing is used in the form of rings or a cord, which provides high resistance to acidic and alkaline media at temperatures up to 250 0 C.
The stuffing box packing shall be made of a braided square cord with a width equal to the width of the stuffing box. From such a cord, separate rings are cut with ends beveled at an angle of 45 0. The rings should be placed in the stuffing box in a staggered manner with the cut lines, with each ring sealed separately. When assembling, the packing follower should enter the chamber by at least 5 mm, but not more than 1/7 of its height.
The oil seals should be tightened evenly, without misalignment of the packing follower.
QUESTIONS FOR SELF-CONTROL
1. What are the main criteria for classifying pipeline fittings?
2. What is the nominal diameter? What is conditional pressure?
3. What is a gate valve? What valves are there, where and how are they installed?
4. List the main advantages and disadvantages of gate valves in comparison with other types of pipeline fittings.
5. What is a valve? What are the main elements of it?
6. List the main advantages and disadvantages of the valve in comparison with other types of pipeline fittings.
7. What types of valve sealing surfaces are there?
8. What is a crane? What types of cranes do you know?
9. List the main advantages and disadvantages of valves in comparison with other types of pipeline valves.
11. What is related to safety and protective pipeline fittings?
12. How are pipe fittings marked?
13. Decipher the marking of the following types of pipeline fittings: 15kp3p; 11ch3bq; 30s64br.
14. What are the reasons for the disruption of the normal operation of pipeline fittings?
15. What is an audit of pipeline fittings, what is it?
16. How is the repair of pipeline fittings (valve, gate valve, crane) carried out? What devices are used for this?
17. How is pipeline fittings tested? What are the types of tests?
18. Formulate the basic principles of selection of pipeline fittings.
19. What properties should the gasket have?
20. List the main materials of cushioning materials and their areas of application.
21. To what maximum temperature can fluoroplastic be used as a cushioning material?
23. How to properly stuff the stuffing box?
3.1 Gasket and sealing materials
Gasket and sealing materials are used to seal flange, socket and other connections of sanitary devices.
Asbestos threads and cords are used to seal flange joints in air ducts. An asbestos cord is used to connect boiler sections on threadless nipples, as well as to fill the gaps between the section ribs. An asbestos cord impregnated with an antifriction compound is used as a stuffing box. Asbestos threads and cords impregnated with graphite mixed with natural drying oil are used to seal threaded joints at a coolant temperature of more than 105 ° C. Threads are produced with a diameter of 0.5-2.5 mm, and a cord with a thickness of 3-25 mm according to GOST 1779-72 ...
Asbestos cardboard (GOST 2850-75) is used as a cushioning material in the joints of devices, devices and communications, as well as a fire retardant, thermal insulation and electrical insulating material. Cardboard is produced in the form of sheets with a thickness of 2; 2.5; 3; 3.5; 4; 4.5; 5, 6.8 and 100 mm, dimensions 900x900, 800x100, 900 x 1000, 1000 x 1000 and 980 x 740 mm. Cardboard 2-6 mm thick is used for sealing flange connections in air ducts. Sheets of cardboard should be flat, not have cracks, dents, as well as foreign mechanical impurities.
Cushioning cardboard and gaskets made of it (GOST 9347-74) are made in sheets and rolls of grades A and B with thickness: grade A (impregnated) - 0.3; 0.5; 0.8; 1; 1.5 mm; grade B (untreated) - 0.3; 0.5; 0.8; 1; 1.25; 1.5; 1.75; 2; 2.25; 2.5 mm. The bulk density of the cardboard is 0.7 - 0.75 g / cm 3.
The surface of the cardboard should be flat, without warping, folds, wrinkles, bubbles, non-fibrous inclusions and crushed spots. In the process of making the gaskets, the cardboard should not delaminate.
Cushioning cardboard is used for gaskets used to seal flange joints of pipelines with a water temperature of up to 100 ° C. Before installation, cardboard gaskets should be moistened in water and boiled in natural drying oil.
Technical sheet rubber used for the manufacture of gaskets, valves, shock absorber seals and other parts is produced in five types: acid-alkali-resistant, heat-resistant, frost-resistant, oil-and-petrol resistant and food grade 0.25-10 m long, 200-1750 mm wide and 0.5-60 thick mm. Heat-resistant technical rubber remains operational when operated in air with temperatures up to + 90 ° C and in a water vapor environment with temperatures up to + 140 ° C. Frost-resistant technical rubber remains efficient under operating conditions at temperatures up to -45 ° C. Technical rubber of all types remains heat-resistant during operation within the temperature range from - 30 o C to + 50 o C.
Sheet technical rubber with a thickness of 3-4 mm is used as sealing gaskets for flange joints of pipelines transporting cold water. Rubber with a fabric lining is also used when transporting hot water with a temperature of up to 100 o C.
As a seal of flange connections of ventilation systems, sheet and profiled rubber, as well as elastic bands PMZH-1 and PMZH-2, are widely used.
Profiled rubber gaskets are produced in the form of a tape of any length, 19 mm and 27 mm wide, 2 mm thick with thickening along the edges, respectively, up to 3 mm and 4 mm.
Harness PMZH-1 is a polymeric elastic tourniquet with a circular cross-section with a diameter of 8-10 mm, for the manufacture of which polyisobutylene, petroleum bitumen, paraffin, asbestos and neutral oil are used.
The PMZh-2 tourniquet is similar in chemical composition to the PMZh-1 tourniquet and is produced in the form of a tape 20 mm wide and 2 mm thick with thickening at the edges up to 4 mm.
Due to their elasticity, the cords adhere well to the flange plane. Bundles are transported and stored wound on spools and sprinkled with talcum powder. The total weight of the reel must not exceed 20 kg.
Paronite (GOST 481-71) is a cushioning material made of asbestos, rubber and fillers. It is produced in the form of sheets with a thickness of 0.4; 0.5; 0.8; 1.5; 3; 4; 5 and 6 mm, dimensions 300 x 400; 400 x 500; 500 x 500; 750 x 1000; 1000 x 1500; 1500 x 1500; 3000 x 1500 mm.
Paronite sheets should have an even, slightly glossy surface on the front side; the surface of the second side can be matt.
Paronite should be stored indoors at a temperature of no more than 30 ° C at a distance of at least 1 m from devices that emit heat. It must be protected from direct sunlight, oils, gasoline and other substances that destroy it.
Paronite or paronite rings are used as gaskets for flange connections of hot water and steam pipelines with a coolant temperature above 100 ° C. Before use, a paronite gasket must be moistened in hot water and lubricated with graphite mixed with natural drying oil.
Sheet fiber (GOST 14613-69) is available in several brands. Fiber of the FPC brand (oxygen-resistant cushioning), manufactured with a thickness of 0.6 to 5 mm, is used as gaskets for neutral gaseous media (oxygen, carbon dioxide) at high pressures and normal temperatures. Fiber must be thoroughly defatted before use. Fiber of the FT brand (technical) is used as a seal in valves and taps of hot water supply systems.
Technical leather is used for the manufacture of gaskets, drive belts. The front side of the skin has a shiny surface, the inside is a non-smooth and non-shiny surface called bakhtarma.
Scutched flax (GOST 10330-76) in the form of a strand impregnated with red lead or whitewash, diluted with natural drying oil, is used as a sealant in threaded pipe joints through which water is transported with a temperature of up to 105 o C.
FUM - fluoroplastic sealing materials manufactured in the form of a tape 10-25 mm wide and 0.08-0.12 mm thick and a cord. The tape is used to seal threaded joints of pipelines DN £ 65 mm, the cord is used to seal locknuts, and also as a stuffing box packing in valve and valve types. They should be white or some other light color. Small spots and separate inclusions are allowed. The surface of the tape and the cord should be equal, without tears or bulges.
FUM is made from fluoroplastic - 4D (80-83%), softened with vaseline oil (17-20%). Fluoroplast - 4D does not dissolve in any of the known solvents, it is resistant to all alkalis and other aggressive media. The FUM seal is water-resistant and can withstand temperatures from - 60 o C to + 200 o C.
Tape and cord are supplied in coils weighing 300-600 g, packed in polyethylene bags, films or impregnated wrapping paper.
Natural linseed and hemp varnish (GOST 7931-76) is used for preparing red lead putty, diluting primer and thick-grated paints, as well as for impregnating cardboard gaskets.
The viscosity of drying oil (at 20 ° C) should be in the range of 26 -320 according to the VZ-4 viscometer. After settling for 24 hours, the drying oil should have complete transparency, and the sludge should not be more than 1% by volume. The time for complete drying of a thin layer of drying oil applied with a brush to a plate at an ambient temperature of 18-22 ° C and a relative humidity of 60-70% is no more than 24 hours.
Lead white thickly grated (GOST 12287-77) is a paste consisting of a mixture of lead white, heavy spar and drying oil or raw linseed or sunflower oil, and are produced in three grades: MA-011, MA-011 - N - 1 and MA - 011 - N - 2. Lead white, diluted with natural drying oil, can serve to impregnate a flax strand used as a sealant in threaded joints of heating pipelines with a coolant temperature of up to 105 ° C and hot water supply pipelines.
Densely grated zinc white (GOST 482-77) is a paste of dry zinc white, mashed on natural linseed oil or vegetable oils with the addition of a desiccant; 7 brands are produced: M-00 special; M-00; M-0; B-2-00; B-2-0; В-4-00; B-4-0.
This white is intended for coloring various surfaces and is used after dilution with natural or semi-natural drying oil to a paint consistency.
Zinc white, diluted with natural linseed oil, is used to impregnate a flax strand used as a sealant in threaded joints of cold water pipelines.
Red lead (GOST 19151-73) is a heavy powder of bright red-orange color, produced in five grades: M-1, M-2, M-3, M-4, M-5. Red lead, diluted with natural drying oil (2 mass parts of red lead and 1 mass part of drying oil), serves to impregnate a flax strand used as a sealant in threaded joints of heating pipelines with a coolant temperature of up to 105 ° C, hot water supply and gas supply pipelines.
3.2. Stuffing materials
Stuffing boxes (GOST 5152-77), designed to operate in a wide range of pressures and temperatures of water, steam, gases, combustible and corrosive media, are used to ensure the density of individual nodes of valves and various designs.
Depending on the working conditions, 3 types of packings are used: braided, rolled and ring.
Braided packings are made of cotton, hemp, jute, linen, asbestos cords of various weaves - with a core, reinforced or unreinforced, dry or impregnated with antifriction and other compounds (talc, graphite, rubber, fluoroplastic). They are designed for a maximum temperature of 100 ° C - 400 ° C, a pressure of 4.5-20 MPa and for use in the following media: air, industrial and drinking water, salt solutions, water vapor, inert vapors and gases.
Rolled packing is made by rolling up cords of cotton, rubberized, asbestos fabric. They are designed for a maximum temperature of 100 ° C - 400 ° C, a pressure of 10-20 MPa and use for industrial water and superheated and saturated steam.
Ring packings are solid-rolled or split multi-layer shaped rings made of rubberized asbestos fabric, vulcanized and graphitized. They are designed for a temperature of 300 ° C, a pressure of 20 MPa, and are used for air, industrial water and steam.
Graphite (GOST 4596-75) is a crystalline substance of steel-gray color, soft and greasy to the touch, produced in the form of tokenized powder and in the form of flakes. Flaked graphite is used to impregnate stuffing box packing and paronite gaskets. Graphite mixed with natural drying oil is called graphite paste. This paste is used to lubricate nipples and nipple nipples when assembling sectional cast iron boilers.
3.3. Lubricants, drying oils and paints
Lubricants are used to ensure normal operation, reduce friction and prevent wear of moving and rotating parts of sanitary equipment, devices and fittings, in particular self-lubricating ones, as well as for temporary protection of metal surfaces from corrosion.
Lubricants are classified into lubricating oils (liquid materials) and greases.
Lubricants and lubricating oils are produced for universal and special purposes, while the area and conditions of their use are regulated by the relevant standards and specifications.
Industrial oil (spindle) grades 12 and 20 in accordance with GOST 20799-75 is used to lubricate rubbing parts of mechanisms and wet the filtering surfaces of oil filters. Compressor oil grade 12 (M) in accordance with GOST 1861-73 is used to lubricate parts of compressors and blowers. Viscin and perfume oils are used to absorb dust in filters of ventilation systems.
Greases (greases) are a thick ointment and are used in case of impossibility or difficulty in supplying liquid lubricant to lubricate units and parts. These lubricants are divided into three types: synthetic (from artificial fats), fatty (from natural vegetable and animal fats), emulsion (from oils mixed with rosin). Solid oils are used for the lubrication of ball and roller bearings, for corrosion protection and for the preservation of machined metal surfaces. Fatty grease, grade US in accordance with GOST 1033-73, is used to lubricate fans and other mechanisms at a temperature of no more than 60 o C. Graphite grease BVN-1 in accordance with GOST 5656-60 is used to lubricate the mating surfaces of steel pipes subject to temperature changes during operation. Technical petroleum jelly and K-17 conservation lubricants are used for the preservation and corrosion protection of the metal surfaces of sanitary equipment.
The purpose of paints and varnishes is to protect products from corrosion and give them a decorative look.
The following requirements are imposed on paints and varnishes: the ability to firmly adhere to the surface of the painted product, the presence of the necessary mechanical strength, hardness and elasticity, resistance to water, oil products, sunlight, retention of their qualities at low and high temperatures, water resistance, the ability to dry quickly and provide the required color.
Depending on the purpose, paints and varnishes are divided into three groups: primers designed to ensure a strong bond between the painted surface and the paint and varnish coating; putties designed to level the painted surface; paints (varnishes, enamels) intended to form the outer layer of the coating.
Primers are either specially made formulations (suspensions of pigments, solvents and fillers), or a mixture of paint and drying oil. The primer is applied in a thin layer, therefore its viscosity (density) should be significantly lower than the viscosity of the coating itself.
Putties are a thick liquid or paste that is a mixture of primer, solvent, pigment and filler (chalk, gypsum, kaolin).
Paints are classified into oil paints, varnishes and enamels.
Oil paints are a paste consisting of a dye, a small amount of solvent and special impurities. Before use, oil paints must be diluted with linseed oil or solvent. Varnishes are a solution of resin in oil or an easily evaporating solvent with the addition of special impurities. Enamels are finely ground dyes diluted on varnish.
Oksol drying oil (GOST 190-68) is a substitute for natural drying oil made by compaction of linseed oil, blowing it with air in the presence of a desiccant and then adding a solvent (white spirit). It is used for diluting thick-grated paints.
Primer GS-2020 (GOST 4056-63 *) is a suspension of pigments (red lead and zinc oxide) and filler (talc) in phthalic varnish with the addition of solvents, drier and stabilizer. Used for priming metal surfaces. The primer film is resistant to temperature changes from -40 o C to + 60 o C. Drying time at a temperature of 100-110 o C is no more than 35 minutes, at a temperature of 18-23 o C - no more than 48 hours. It is applied with a paint sprayer, brush, dipping. In order to obtain a working viscosity, the primer is diluted with a solvent, xylene or a mixture of one of these solvents with white spirit.
Red iron dry (GOST 8135-74) is a natural mineral pigment, consisting mainly of iron oxide. Depending on the purpose, two grades are produced: A - for the manufacture of primers, enamels and oil paints; B - for the manufacture of adhesive paints, colored asbophane and asbestos products.
Thick-grated colored oil paints (GOST 8292-75) and special (GOST 18596-73) are a paste made from a mixture of dry pigments and a filler rubbed onto natural drying oil or its substitutes. They are used after dilution with linseed oil to a working viscosity to cover the outer surfaces of products in order to protect them from corrosion and give them a distinctive color. These coatings are weather resistant. Apply by spray, brush, dipping, blasting or electrostatic spraying. In the latter case, white spirit or turpentine is added to the paint. Drying of paint at a temperature of 18-22 ° C is carried out within 24 hours, at a temperature of 100 ° C - within 2 hours.
Varnish BT-577 and paint BT-177 are manufactured in accordance with GOST 5631-70 *. Varnish BT-577, which is a solution of black resins and vegetable oils in organic volatile solvents, is used to cover metal surfaces, as well as in the manufacture of BT-177 paint. The latter is a suspension of aluminum powder in BT-577 varnish.
It is prepared immediately before application to the surface by introducing 15-20% aluminum powder into the BT-577 varnish. The paint is intended for anticorrosive and decorative coating of metal surfaces, on which it is applied with a paint sprayer. The time of practical drying at a temperature of 18-23 ° C of varnish BT-577 is 24 hours, of paint BT-177 - 16 hours, and at a temperature of 100 ° C, respectively, no more than 20 and 30 minutes. Lacquer coatings have a reduced weather resistance, however, they are resistant to prolonged exposure to temperatures up to 20 o C. The introduction of aluminum powder increases the weather resistance and heat resistance of the coating. In order to improve the protective properties, hot drying is recommended.
Turpentine is used to dilute the drying oil, and solvent, white spirit, xylene are used to dilute the primer and oil paints.
To degrease the metal before coating with paint and varnish, it is recommended to clean it with white spirit or a mixture of caustic soda with trisodium phosphate, water glass.
To cover air ducts of ventilation systems operating in aggressive environments, perchlorovinyl enamels are used that are resistant to acid vapors, alkalis and other aggressive environments. Enamel grades are selected depending on the operating conditions of the air ducts.
3.4. Drive belts
Drive belts are used to transfer movement from the drive (electric motor) to the working mechanism (fan, pump) and change the number of revolutions of the mechanism in relation to the drive.
Depending on the material from which they are made, drive belts are divided into textile, leather and rubber-fabric.
In sanitary installations, as a rule, rubber-fabric V-belts are used.
Driving V-belts (GOST 1284-68 **) consist of cord fabric or cord, wrapping fabric and rubber, joined together by vulcanization. The calculated belt length corresponds to the circumference at the level of the calculated belt width, measured under tension, is 400-18000 mm. V-belts are produced in the form of rings. In cross section, it has the shape of a trapezoid.
3.5. Acceptance, transportation and storage of auxiliary materials
Acceptance of auxiliary materials is carried out in accordance with the rules given in the relevant standards for each material, which also contains recommendations for their storage and transportation.
It is advisable to store materials for sealing threaded joints in small packaging (0.5-1 kg), and a strand in special metal or wooden boxes. These conditions ensure the safety and quality of the materials used and the reliability of the connections. Packaging, transportation and storage of sealing materials should ensure the prevention of contamination and moisture of all materials and freezing of some materials (drying oil, thick-grated fillers); surface preservation; prevention of folds, folds and sticking, which is ensured by smearing with graphite, sheet materials and ready-made gaskets; protection of paronite and rubber from direct sunlight and heat radiation from heating devices. In this case, twisting and knotting of fibrous materials should not occur.
Because lubricants, drying oils and paints are flammable, they should be stored in separate rooms equipped with fire extinguishing means.
Refractory and thermal insulation materialsFor cladding (lining) of boiler units, red brick, various refractory and heat-insulating materials are used.
Red brick is made from a mixture of kaolin clay (A1203) and sand (Si02) by firing blanks at a high temperature. Red brick is used for laying foundations, hogs, outer walls of lining, vaults and other elements exposed to temperatures no higher than 700 ° C.
Refractory materials used for masonry in boilers include fireclay bricks, high-alumina and chromite refractories, refractory fireclay concrete. The main controlled properties of refractories include: refractoriness, thermal stability, slag resistance, as well as structure density, gas permeability, thermal conductivity.
Refractoriness is characterized by the softening temperature at which deformation of the sample occurs without load, as well as the temperature of the onset of deformation under a load that creates a compressive stress of 0.2 N / mm2 (2 kg / cm2).
Thermal resistance is determined by the change in the mechanical strength of the refractory at temperature stresses arising from changes in heating and cooling.
Slag resistance is characterized by the loss of mass of the refractory under the action of a high-temperature gas medium and slag.
Fireclay bricks and fireclay products are most widely used as refractory materials for boiler units. They are used for the lining of the combustion chamber and gas ducts in areas of high (up to 1,400 ° C) temperatures.
Fireclay brick is made of refractory clay, consisting of 50 ... 65% silica (Si02), 30 ... 45% alumina (A1203), with a total content of up to 5% lime (CaO), magnesia (MgO) and titanium dioxide ( Tyu2).
High-alumina refractories are made from high-alumina raw materials on a clay bond; during firing in the furnace, the material is sintered. Depending on the type of product, the content of A1203 can be 45 ... 75%. According to the content of A1203, the refractoriness of the material varies within 1 750 ... 2 000 ° C. High-alumina materials have high thermal stability, slag resistance and high resistance to deformation under load. This type of refractory is widely used as a protective coating for furnace lining to reduce their wear.
Refractory chamotte concrete is used for the manufacture of refractory wall lining slabs, as well as suspended vaults.
Insulating heat-resistant materials are characterized by low density and thermal conductivity. These materials include diatomite brick - used to insulate the hot parts of the boiler unit operating at temperatures up to 900 ° C.
For insulation of hot surfaces of pipelines, fittings, gas-air ducts, equipment, etc. lightweight insulating materials are used: asbestos, asbestos, diatomite foam, diatomite brick, glass and slag wool, sovelite, etc. Asbestos is used in the form of asbestos fiber, asbestos sheet or cord and is used at operating temperatures up to 500 ° C.
Interlining and stuffing materials
Gasket materials are used when installing fittings to seal flange connections. Asbestos, technical rubber sheets, parasite, cushioning cardboard are used as cushioning materials.
Asbestos is used at the junctions of sections of cast iron boilers to seal nipples, explosive safety valves, fittings seals, etc.
Technical rubber sheet is used for the manufacture of gaskets between the flanges of the water supply, gas pipeline, between the sections of radiators.
Paranit is a cushioning material based on asbestos, rubber and fillers, used in the form of sheets with a thickness of 0.4 ... 6 mm, withstands pressure up to 5 MPa (50 kgf / cm2) and temperatures up to 450 ° C. It is used to seal flange connections of steam lines, hot water lines, and medium and high pressure gas lines.
Cushioning cardboard is used for gaskets on cold water pipelines. Before installing between the flanges, the gaskets are moistened with water and boiled in oil.
Packing Materials - Various gland packing and mastics that are used to prevent vapor or liquid from escaping through the gland gaps.
The stuffing box materials must have a low coefficient of friction, high resistance to wear at high temperatures. The stuffing boxes are made in the form of a braided cord made of cotton, linen or hemp yarn, as well as an asbestos cord impregnated with antifriction mastic.
Stuffing materials
Stuffing boxes (GOST 5152-77), designed to operate in a wide range of pressures and temperatures of water, steam, gases, combustible and corrosive media, are used to ensure the density of individual nodes of valves and various designs.
Depending on the working conditions, 3 types of packings are used: braided, rolled and ring.
Braided packings are made of cotton, hemp, jute, linen, asbestos cords of various weaves - with a core, reinforced or unreinforced, dry or impregnated with antifriction and other compounds (talc, graphite, rubber, fluoroplastic). They are designed for a maximum temperature of 100 ° C - 400 ° C, a pressure of 4.5-20 MPa and for use in the following media: air, industrial and drinking water, salt solutions, water vapor, inert vapors and gases.
Rolled packing is made by rolling up cords of cotton, rubberized, asbestos fabric. They are designed for a maximum temperature of 100 ° C - 400 ° C, a pressure of 10-20 MPa and use for industrial water and superheated and saturated steam.
Ring packings are solid-rolled or split multi-layer shaped rings made of rubberized asbestos fabric, vulcanized and graphitized. They are designed for a temperature of 300 ° C, a pressure of 20 MPa, and are used for air, industrial water and steam.
Graphite (GOST 4596-75) is a crystalline substance of steel-gray color, soft and greasy to the touch, produced in the form of tokenized powder and in the form of flakes. Flaked graphite is used to impregnate stuffing box packing and paronite gaskets. Graphite mixed with natural drying oil is called graphite paste. This paste is used to lubricate nipples and nipple nipples when assembling sectional cast iron boilers.
Lubricants, drying oils and paints
Lubricants are used to ensure normal operation, reduce friction and prevent wear of moving and rotating parts of sanitary equipment, devices and fittings, in particular self-lubricating ones, as well as for temporary protection of metal surfaces from corrosion.
Lubricants are classified into lubricating oils (liquid materials) and greases.
Lubricants and lubricating oils are produced for universal and special purposes, while the area and conditions of their use are regulated by the relevant standards and specifications.
Industrial oil (spindle) grades 12 and 20 in accordance with GOST 20799-75 is used to lubricate rubbing parts of mechanisms and wet the filtering surfaces of oil filters. Compressor oil grade 12 (M) in accordance with GOST 1861-73 is used to lubricate parts of compressors and blowers. Viscin and perfume oils are used to absorb dust in filters of ventilation systems.
Greases (greases) are a thick ointment and are used in case of impossibility or difficulty in supplying liquid lubricant to lubricate units and parts. These lubricants are divided into three types: synthetic (from artificial fats), fatty (from natural vegetable and animal fats), emulsion (from oils mixed with rosin). Solid oils are used for the lubrication of ball and roller bearings, for corrosion protection and for the preservation of machined metal surfaces. Fatty grease, grade US in accordance with GOST 1033-73, is used to lubricate fans and other mechanisms at a temperature of no more than 60 o C. Graphite grease BVN-1 in accordance with GOST 5656-60 is used to lubricate the mating surfaces of steel pipes subject to temperature changes during operation. Technical petroleum jelly and K-17 conservation lubricants are used for the preservation and corrosion protection of the metal surfaces of sanitary equipment.
The purpose of paints and varnishes is to protect products from corrosion and give them a decorative look.
The following requirements are imposed on paints and varnishes: the ability to firmly adhere to the surface of the painted product, the presence of the necessary mechanical strength, hardness and elasticity, resistance to water, oil products, sunlight, retention of their qualities at low and high temperatures, water resistance, the ability to dry quickly and provide the required color.
Depending on the purpose, paints and varnishes are divided into three groups: primers designed to ensure a strong bond between the painted surface and the paint and varnish coating; putties designed to level the painted surface; paints (varnishes, enamels) intended to form the outer layer of the coating.
Primers are either specially made formulations (suspensions of pigments, solvents and fillers), or a mixture of paint and drying oil. The primer is applied in a thin layer, therefore its viscosity (density) should be significantly lower than the viscosity of the coating itself.
Putties are a thick liquid or paste that is a mixture of primer, solvent, pigment and filler (chalk, gypsum, kaolin).
Paints are classified into oil paints, varnishes and enamels.
Oil paints are a paste consisting of a dye, a small amount of solvent and special impurities. Before use, oil paints must be diluted with linseed oil or solvent. Varnishes are a solution of resin in oil or an easily evaporating solvent with the addition of special impurities. Enamels are finely ground dyes diluted on varnish.
Oksol drying oil (GOST 190-68) is a substitute for natural drying oil made by compaction of linseed oil, blowing it with air in the presence of a desiccant and then adding a solvent (white spirit). It is used for diluting thick-grated paints.
Primer GS-2020 (GOST 4056-63 *) is a suspension of pigments (red lead and zinc oxide) and filler (talc) in phthalic varnish with the addition of solvents, drier and stabilizer. Used for priming metal surfaces. The primer film is resistant to temperature changes from -40 o C to + 60 o C. Drying time at a temperature of 100-110 o C is no more than 35 minutes, at a temperature of 18-23 o C - no more than 48 hours. It is applied with a paint sprayer, brush, dipping. In order to obtain a working viscosity, the primer is diluted with a solvent, xylene or a mixture of one of these solvents with white spirit.
Red iron dry (GOST 8135-74) is a natural mineral pigment, consisting mainly of iron oxide. Depending on the purpose, two grades are produced: A - for the manufacture of primers, enamels and oil paints; B - for the manufacture of adhesive paints, colored asbophane and asbestos products.
Thick-grated colored oil paints (GOST 8292-75) and special (GOST 18596-73) are a paste made from a mixture of dry pigments and a filler rubbed onto natural drying oil or its substitutes. They are used after dilution with linseed oil to a working viscosity to cover the outer surfaces of products in order to protect them from corrosion and give them a distinctive color. These coatings are weather resistant. Apply by spray, brush, dipping, blasting or electrostatic spraying. In the latter case, white spirit or turpentine is added to the paint. Drying of paint at a temperature of 18-22 ° C is carried out within 24 hours, at a temperature of 100 ° C - within 2 hours.
Varnish BT-577 and paint BT-177 are manufactured in accordance with GOST 5631-70 *. Varnish BT-577, which is a solution of black resins and vegetable oils in organic volatile solvents, is used to cover metal surfaces, as well as in the manufacture of BT-177 paint. The latter is a suspension of aluminum powder in BT-577 varnish.
It is prepared immediately before application to the surface by introducing 15-20% aluminum powder into the BT-577 varnish. The paint is intended for anticorrosive and decorative coating of metal surfaces, on which it is applied with a paint sprayer. The time of practical drying at a temperature of 18-23 ° C of varnish BT-577 is 24 hours, of paint BT-177 - 16 hours, and at a temperature of 100 ° C, respectively, no more than 20 and 30 minutes. Lacquer coatings have a reduced weather resistance, however, they are resistant to prolonged exposure to temperatures up to 20 o C. The introduction of aluminum powder increases the weather resistance and heat resistance of the coating. In order to improve the protective properties, hot drying is recommended.
Turpentine is used to dilute the drying oil, and solvent, white spirit, xylene are used to dilute the primer and oil paints.
To degrease the metal before coating with paint and varnish, it is recommended to clean it with white spirit or a mixture of caustic soda with trisodium phosphate, water glass.
To cover air ducts of ventilation systems operating in aggressive environments, perchlorovinyl enamels are used that are resistant to acid vapors, alkalis and other aggressive environments. Enamel grades are selected depending on the operating conditions of the air ducts.
Sealing, insulation and upholstery materials
In the manufacture and operation of machines, it becomes necessary to seal the contact points of some parts with each other. In addition, the ability of storage batteries to support very high amperage values (hundreds of amperes), as well as the presence of high voltage in the ignition system (20 ... 30 kV) predetermined high requirements for insulating materials.
The use of upholstery materials improves the appearance of the cab, interior, body, and increases comfort.
Consider the sealing, insulation and upholstery materials used in the automotive industry.
Sealing materials are divided into two groups - cushioning and stuffing.
Gasket materials are used when it is necessary to seal the detachable parts of the engine, transmission housings and other assemblies. Spacers are sometimes used to adjust the clearances or forces in contact pairs.
Stuffing materials are used to seal gaps between moving pairs of parts, as well as to protect friction units from dust, dirt and water.
Sealing materials are classified into paper, asbestos, rubber, felt, cork, and plastic. Sometimes soft materials such as aluminum, lead and copper are used as sealing materials.
Paper cushioning materials include paper itself, cardboard, fiber and parchment. Paper materials with a thickness of up to 0.5 mm and a specific gravity of up to 250 g / m 2 are conventionally referred to as paper, and a larger mass and thickness - to cardboard. Cardboards are distinguished into cushioning, packaging, construction, decorative, etc.
Interlining cardboard is a relatively elastic, oil and petrol resistant material, produced with a thickness of 0.2 ... 1.5 mm. The surface of the cardboard sheet must be flat and the thickness constant over the entire area.
Technical cardboard or drawing paper is used as a substitute for liner board. To increase their porosity, they are moistened with hot water until saturated and then dried. The pores are filled with impregnation for 20 ... 25 minutes heated to 60 ... 70 0 With vegetable oil or drying oil.
Parchment- transparent oil-proof moisture resistant paper. It is obtained as a result of processing non-glued paper with sulfuric acid, followed by its neutralization with an alkali solution.
Fiber- a cushioning material obtained by processing non-glued paper or cardboard with a zinc chloride solution, which gives the material high strength, as well as oil and petrol resistance. When operating the nodes, it must be borne in mind that high hygroscopicity (up to 60 ... 65%) leads to the fact that the fiber warps when moistened.
Fiber is available in several brands:
FSV - special, high-strength (for the manufacture of especially durable products);
FT - technical, for the manufacture of parts in mechanical engineering and instrument making;
FE - electrical, for the manufacture of electrical insulating parts;
KGF - castor-glycerin, is used as a sealing material that protects against leaks of water, oil, kerosene and gasoline.
The fiber is made in the form of sheets with a width of 1.1 ... 1.4 m and a length of 1.7 ... 2.3 m, a thickness of 0.4 ... 25.0 mm and a density of at least 1100 kg / m 3.
A common disadvantage of paper cushioning materials is low heat resistance. At temperatures above 130 ... 140 0 С, paper and cardboard lose flexibility, become brittle, at 180 0 С carbonization (blackening) begins, and at 240 ... 250 0 С, the paper fibers are completely decomposed.
Asbestos- a natural mineral (chrysotile asbestos). It has a fibrous structure, capable of splitting (fluffing) into the finest flexible and strong fibers, which are diamond-shaped whiskers. The density of lumpy asbestos is 2000 ... 2500 kg / m 3, and asbestos products without fillers - 1000 ... 2000 kg / m 3. Asbestos does not burn, heat-resistant, good dielectric. Easily withstands heating up to 300 0 С, and at 386 0 С it loses adsorbed water, which reduces its strength and flexibility (reversible phenomenon). When heated to more than 450 0 C, water is lost irreversibly. The process ends at 700 ... 800 0 С, asbestos becomes fragile, easily crushed into powder. The strength of asbestos depends on temperature: from 315 ... 320 kgf / cm 2 at 20 0 С to 70 ... 80 kgf / cm 2 at 600 0 С.
Depending on the length of the fibers, asbestos is classified into nine grades with different purposes. So, for the manufacture of fabrics, cords, gland packing threads, insulating rovings, woven tapes and similar textiles, asbestos of grades AK is used; 1st, 2nd and 3rd hard texture and 2nd grade of semi-hard texture (with a fiber length of 6 ... 18 mm).
For the manufacture of paronite, electronite, asbestos cardboard and asbestos paper, grades of the 3rd and 4th semi-hard and soft texture are used.
For the production of asbestos cardboard and other insulating products, the 6th grade of asbestos (fiber length 1 ... 2 mm) is used, and the 7th and 8th grade are intended for the manufacture of various asbestos-cement products and as heat-insulating filling (fiber length no more than 1 mm).
Asbestos, as having high heat resistance, is used as a sealing material operating at elevated temperatures (exhaust manifold gaskets, muffler). When using asbestos as gaskets for engine block (cylinder) heads, it is enclosed in a copper or steel shell (foil) to prevent contact with hot gases. Damage to the shell leads to contact, loss of constitutional (part of) water and rapid destruction.
For various auxiliary equipment, asbestos cardboard, asbestos cords and threads, paronite, as well as crushed asbestos for thermal insulation works are used.
Asbestos board and paper are used for fire protection, thermal insulation, electrical insulation and sealing.
Asbestos cardboard is produced in the form of sheets with a thickness of 2 ... 10 mm and dimensions of about one square meter. Density 1000 ... 1300 kg / m 3, coefficient of thermal conductivity (for 20 ... 100 0 С) - 0.13 kcal / m × h × hail.
Asbestos paper produced in rolls 0.25 ... 1.0 mm thick, 670 ... 1150 mm wide.
Paronite- cushioning sheet material made of rolled asbestos with a rubber (with sulfur) binder and mineral fillers in the ratio: 60 ... 75% - 12 ... 13%. Clay, feldspar, talc, etc. are used as mineral fillers.
Paronite is used as gaskets for camshaft gear covers, flanges for oil receiver tubes, water pump, fuel sump, etc.
Paronite is produced in the following brands:
PON - general purpose;
PMB - oil and petrol resistant;
PA - reinforced with steel mesh.
Sheet thickness 0.4 ... 3 mm, length - up to 3 m and width - up to 1.5 m.
Asbestos fabrics are used for thermal insulation, production of fire-resistant overalls and blankets, stuffing box packing, production of asbestos laminate. To increase strength, cotton fibers are added to asbestos fabrics, reinforced with brass wire or glass threads. The width of asbestos fabrics is 1040 ... 1550 mm, the thickness is 1.2 ... 3.8 mm.
Asbestos cords and threads- are used for stuffing box packing and heat-insulating windings. Three types of cords are produced:
asbestos cord made of twisted asbestos threads;
asbestos cord made of combed asbestos and cotton fibers, braided with asbestos cords;
asbestos cord with a core of magnesia and asbonites, also braided with asbestos threads (for thermal insulation of surfaces with temperatures up to 550 ... 600 0 С; thermal conductivity coefficient 0.080 ... 0.150 kcal / m × h × hail).
Asbestos tapes serve for thermal and electrical insulation. Thickness 0.4 ... 1.4 mm, width 13 ... 250 mm.
Asbestos sheets are used for cutting shaped gaskets. Six brands, dimensions: length 215 ... 875 mm, width 500 and thickness 1.4 ... 1.75 mm.
It should be noted that recently, for reasons of reducing the harmful effect on humans, the volume of use of asbestos products has been decreasing.
Cork gasket materials- obtained by pressing cork oak bark groats and used to seal joints operating at low stress in the environment of water or oil products:
engine valve box covers;
fuel pump filter cups;
crankcase ventilation filter;
engine crankcase;
block head covers;
rocker covers, etc.,
and as a stuffing box for a needle bearing.
Cushion felt is a sheet material made from wool fibers. Technical felt is subdivided:
fine-haired;
semi-coarse;
coarse.
Felt is a porous material in which air pores account for at least 75% of the volume. The density of the felt is 200 ... 430 kg / m 3.
Felt possesses high heat-, sound-insulating and shock-absorbing properties. Thermal resistance of felt does not exceed 75 0 С.
Felt wool fibers are destroyed by the action of fungi and moths, unstable against alkalis, but resistant against acids.
