Industry standard
OST 26-04-312-83
Methods for degreasing equipment. General requirements for technological processes
(put into effect by letter of the Technical Department of the Ministry of Chemical Engineering dated November 29, 1983 N 11-10-4/1685)
Validity period established from January 1, 1985. Replaces OST 26-04-312-71 This standard applies to cryogenic, cryogenic-vacuum equipment and equipment working with oxygen, including medical oxygen, nitrogen and other air separation products, and establishes general technological requirements for methods of removing fatty contaminants from the surface of products (degreasing). The standard does not establish requirements for the processes of depreservation of products. Explanations of terms used in this standard are given in Reference Appendix 1.
| 1. General provisions 2. Technical requirements 3. Safety requirements 4. General technological requirements 5. Quality control of degreasing Appendix 1 Explanation of terms Appendix 2 Features of degreasing various types equipment 1. General provisions 2. Degreasing of air separation units 3. Degreasing of cryogenic vessels, cylinders and transport tanks 4. Degreasing of liquid oxygen pumps 5. Degreasing of gasification plants 6. Degreasing of cryogenic cold gasifiers like GKH 7. Degreasing of oxygen compressors 8. Degreasing of pipelines and hoses 9. Degreasing fittings and instruments Appendix 3 Requirements for solvents Appendix 4 Preparation of baths with aqueous cleaning solutions, their control and adjustment 1. Preparation of baths 2. Monitoring and adjustment of baths |
1. General Provisions
1.1. Degreasing of equipment must be carried out if the content of fatty contaminants on the surface exceeds the norms established by regulatory and technical documents, technical documentation (drawings, technical specifications and operational documentation), during manufacture, installation, repair and operation. The standards for equipment working with gaseous oxygen are established according to GOST 12.2.052, for equipment working with liquid oxygen - according to OST 26-04-1362, for cryogenic-vacuum equipment - according to OST 26-04-2600. The method and means of degreasing are indicated in the technological documentation. The operational documentation indicates the method, means and frequency of degreasing or the criteria determining the need for degreasing. Depending on the design features of the product, it is possible to indicate the degreasing method in technical documentation(drawings, technical specifications), if this method is the only one guaranteeing the required quality of degreasing, or limit the use of certain methods. 1.1.1. Excluded from July 1, 1987 1.2. The procedure for degreasing equipment during manufacturing should be established by instructions and technological processes developed at the manufacturer in accordance with the requirements of this standard. When carrying out installation or repair work, the procedure and technological process for degreasing, developed in accordance with the requirements of this standard, must be determined by the organization carrying out the installation or repair work; degreasing during operation is carried out in accordance with the operational documentation. Change No. 1 , approved by the Deputy Minister of Chemical and Petroleum Engineering on January 4, 1987, amendments were made to paragraph 1.3 of this OST, which come into force on July 1, 1987. 1.3. Degreasing of individual parts before assembly or products after assembly at the manufacturing plant and during installation may not be carried out if during the manufacturing process the parts from which the product is assembled were degreased or underwent chemical or galvanic treatment in accordance with GOST 9.305 (lightening, passivation, galvanizing, etc. .p.), and surface contamination was prevented during storage and assembly. If grease stains get on parts with galvanic coatings, they can be degreased by wiping with aqueous detergent solutions at a temperature not exceeding 40°C. It should be taken into account that this may damage the appearance of the coating. 1.4. Equipment that meets the requirements of technical documentation for the content of fatty contaminants on the surface, has confirmation in the passport and arrived at the installation site with intact plugs and in intact packaging is not subject to degreasing during installation. 1.5. Features of degreasing various types of equipment are given in recommended Appendix 2. 1.6. Compliance of the content of fatty contaminants with the established standards is confirmed by a mark in the control route map, in the technological data sheet of the product or in other technical documentation. Based on these documents, notes are added to the product passport, for example: “The content of fatty contaminants does not exceed the standards established by GOST 12.2.052” * or “degreased.”1.7. The preparation and implementation of all degreasing work must be supervised by a responsible person appointed by written order of the administration, who must be fully responsible for compliance with degreasing technology, timely technical control and safety of work.2. Technical requirements
2.1. Material requirements
2.1.1. Solvents or aqueous cleaning solutions should be used to degrease equipment. The need to use solvents or aqueous cleaning solutions must be indicated in the technological documentation.
2.2. Solvents
2.2.1. Solvents are divided into two groups: Group 1 - fireproof, used for degreasing assembled products both at manufacturing plants and during equipment operation. Group 2 - fire and explosion hazardous, used for degreasing products by wiping, subject to subsequent complete removal solvents from the internal cavities of low-fat products. When using solvents of group 2, conditions must be observed to ensure fire and explosion safety, in accordance with clause 3.9. The used solvents of groups 1 and 2, used at a temperature of 10-20 ° C, depending on the detergent and physicochemical properties, are given in table. 1. Change No. 1, approved by the Deputy Minister of Chemical and Petroleum Engineering on January 4, 1987, introduced changes to subclause 2.2.2 of this OST, which come into force on July 1, 1987. 2.2.2. When degreasing materials other than those indicated in the table. 1, tests should be carried out for corrosion compatibility with solvents and for residual content of fatty contaminants.
Scope of solvents
Table 1
|
Name of solvents |
Residual content of fatty contaminants, mg/m 2, no more |
Application area |
Group 1 |
Freon 113 GOST 23844 | Freon 114B2 GOST 15899 | Trichlorethylene GOST 9976 |
For products made of steel, cast iron, copper and alloys based on iron, copper and nickel |
Tetrachlorethylene TU 6-01-956 | Trichlorethylene GOST 9976 with stabilizer STAT-1-1% TU 6-01-927 |
For products made of steel, cast iron, copper, aluminum and alloys based on iron, copper, nickel, aluminum |
Tetrachlorethylene TU 6-01-956 with stabilizer STAT-1-1% TU 6-01-927 |
Group 2 |
Nefras S2-80/120 and SZ-80/120 GOST 443 |
For products made of any metals and alloys |
Nefras-S 50/170 GOST 8505 (distilled) | Gasoline solvent for the paint and varnish industry (white spirit) GOST 3134 |
For preliminary removal of grease stains from products made of any metals and alloys |
Permissible content of fatty contaminants
2.2.6. When repeated degreasing, solvents containing fatty contaminants of no more than 50 mg/dm 3 should be used. In the following, solvents that meet the above requirements are called pure. 2.2.7. The use of the CTAT-1 stabilizer is mandatory when degreasing products made of aluminum and its alloys and is preferable when degreasing other metals.2.3. Aqueous cleaning solutions
2.3.1. Fireproof non-toxic aqueous cleaning solutions are used for degreasing assembled and disassembled products, the design of which ensures the possibility of completely draining the solution and removing its residues by rinsing with water, both at manufacturing plants and during installation and operation of equipment. Change No. 1, approved by the Deputy Minister of Chemical and Petroleum Engineering on January 4, 1987, introduced changes to subclause 2.3.2 of this OST, which come into force on July 1, 1987. 2.3.2. The compositions of aqueous washing solutions, technological modes and scope of application, indicating the materials, are given in table. 3. Instructions for the preparation of baths with aqueous solutions, their control and adjustment are given in mandatory Appendix 4. Table 3
Compositions of aqueous cleaning solutions and degreasing modes
|
Compositions of aqueous cleaning solutions |
Degreasing modes |
Residual content of fatty contaminants, mg/m2 |
Application area |
components of aqueous cleaning solutions and detergents |
quantity, g/dm 3 |
temperature °C |
degreasing ratio |
Composition 1 |
twice |
For products made of steel, cast iron, copper and alloys based on iron, copper and nickel |
Sodium phosphate, (trisodium phosphate), |
Detergent* |
Sodium hydroxide (caustic soda) |
Sodium liquid glass |
Detergent* |
Composition 2 |
twice |
For products made of steel, cast iron, copper, aluminum and alloys based on iron, copper, nickel, aluminum |
Sodium liquid glass |
Detergent* |
For products made of steel, cast iron, copper and alloys based on iron, copper and nickel, with increased requirements for the absence of precipitation on their surface |
Technical sodium nitrite |
Sodium phosphate (trisodium phosphate) |
Detergent* |
Detergent ML-72 |
Synthetic detergent MS-8 |
Detergent KM-2 |
For products made of steel, cast iron, copper, aluminum and alloys based on iron, copper, nickel, aluminum |
twice |
For products made of steel, cast iron, aluminum and alloys based on iron, nickel, aluminum |
Technical synthetic detergent VIMOL |
For products made of copper and its alloys |
Technical detergent TMS-31 |
For products made of steel, cast iron and alloys based on iron, nickel, aluminum |
Technical detergent Vertolin-74 |
once |
Technical detergent Vertolin-74 |
twice |
For products made of steel, cast iron, copper and alloys based on iron, copper and nickel |
once |
For products made of aluminum and its alloys |
Aluminum alloy degreaser (OCA) |
twice |
For products made of steel, cast iron, copper and alloys based on iron, copper and nickel |
Household detergents** |
3. Safety requirements
3.1. Safety requirements during the degreasing process must comply with GOST 12.3.008. 3.2. When working with components of aqueous cleaning solutions and solvents, you should comply with the safety requirements set out in the regulatory and technical documents for the substances used, given in Table. 1 and 3. 3.3. When carrying out degreasing of cryogenic vessels, if the presence of a person in them is required, the requirements of the “Temporary standard instructions for organizing the safe conduct of gas-hazardous work at enterprises of the Ministry of Chemical Industry of the USSR” approved by the State Mining and Technical Inspectorate of the USSR and the MHP of the USSR must be observed. Before carrying out work on degreasing cryogenic vessels that have been in use, they must be heated to temperatures in the range of 12-30°C and ventilated. Work should be carried out only when the oxygen content in the air inside the vessels ranges from 19 to 23%. The organization carrying out degreasing must approve instructions for carrying out this work in accordance with the established procedure. 3.4. Degreasing of individual parts by immersing them in baths of solvents should be carried out in devices with a closed or semi-closed degreasing cycle, equipped with local ventilation and preventing the release of solvent vapors into the air production premises. In this case, it is necessary to create continuity in the process of degreasing, drying and unloading parts. Solvent should be drained from equipment and baths into closed vessels through pipelines. 3.5. When degreasing equipment with solvents of group 1 (see clause 2.2.1.), it is necessary to ensure the tightness of the equipment in which degreasing is carried out. 3.6. Air emissions after drying and blowing must comply with GOST 17.2.3.02. 3.7. Ventilation of premises must ensure that air requirements are met working area in accordance with GOST 12.1.005. Table 4Maximum permissible concentrations of solvents in the air
|
Name of solvents |
Maximum permissible concentration value, mg/m 3 |
Hazard Class |
Trichlorethylene |
Tetrachlorethylene |
Freon 113 |
Freon 114B2 |
Gasoline solvent for the rubber industry (in terms of C) |
Nefras-S 50/170 |
White spirit (in terms of C) |
4. General technological requirements
4.1. The degreasing process consists of the following operations: - preparation for degreasing; - degreasing; - removal of residues of used degreasers. 4.2. Preparation for degreasing. 4.2.1. Before degreasing, the equipment must have a temperature from 12°C to 30°C. If it is technically necessary to carry out degreasing at lower or higher temperatures, in each specific case, a special technological process must be developed. Safety valves and instrumentation should be removed from the equipment and degreased separately. 4.2.2. Products coated with preservative lubricants must be depreserved in accordance with OST 26-04-2138 before degreasing with aqueous cleaning solutions or solvents. 4.2.3. Before degreasing with solvents, in order to avoid corrosion, the products must be thoroughly dried. 4.3. Degreasing. 4.3.1. Degreasing with solvents and aqueous cleaning solutions is carried out using the following methods: - filling the internal cavities of products; - immersion in baths; - circulation of solvents or washing solutions in the washed products; - condensation of solvent vapors in the washed products; - blast cleaning; - rubbing; - ultrasonic cleaning. 4.3.2. Selecting a degreasing method according to clause 4.3.1. produced depending on the size of the degreased products and available technical means degreasing. It is preferable to degrease the products before assembly, taking into account the requirements of clause 1.3. 4.3.3. Degreasing by filling the internal cavities of products or immersion in baths is used for individual parts or assembly units, as well as for small-sized products, and is carried out using solvents and aqueous washing solutions. The solvent must remain in the degreased products for at least 30 minutes. The presence of the solvent in the products should not exceed 1.5 hours. Degreasing with aqueous cleaning solutions is carried out twice with intermediate and final rinsing. hot water (60-80°C), the solution temperature is indicated in the table. 3. Products should be kept in each bath with aqueous cleaning solutions for 30 minutes, in baths with hot water - 15 minutes. Degreasing time with composition No. 2, table. 3 - 15 minutes. Keeping products in contact with aqueous cleaning solutions should not exceed 2 hours. 4.3.4. The method of circulating solvents or aqueous cleaning solutions is used for degreasing pipelines, hoses, as well as assembled products, the design of which allows the circulating solution to wash all surfaces to be degreased (tubular heat exchangers, etc.). Degreasing by circulation is carried out in the product with solvents or washing solutions, the circulation speed is from 0.5 to 1.0 m/s. When circulating the solvent, the following conditions must be met: - circulation duration is at least 20 minutes. and no more than 1.5 hours; - the amount of circulating solvent is not less than the volume of the product, while washing the entire degreased surface with the solvent must be guaranteed; - the need for repeated degreasing is determined based on the results of analysis of the solvent drained from the product (see clause 5.3.). When circulating the cleaning solution, the following conditions must be met: - circulation duration is at least 30 minutes, but not more than 2 hours; - the amount of circulating aqueous washing solution is not less than the volume of the products, while washing the entire degreased surface with the solution must be guaranteed; - degreasing should be done twice with intermediate and final rinsing with hot water. 4.3.5. The degreasing method by condensation of solvent vapor is used for degreasing cryogenic vessels, pipelines, hoses and is performed by supplying solvent vapor heated to the boiling point to the degreased cavities, and subsequent condensation of the vapor on the degreased surface. Condensate is drained from the equipment. The solvent poured into the evaporator is not subject to requirements for the content of fatty contaminants in accordance with paragraphs. 2.2.5. and 2.2.6. Solvent consumption for one-time degreasing is 5-10 dm 3 per 1 m 2 of degreasing surface. Degreasing ends when the content of fatty contaminants in the condensate drained from the product is no more than 20 mg/dm 3, however, in any case, the solvent consumption must be at least 5 dm 3 /m 2. 4.3.6. The jet cleaning method is used for degreasing individual products or internal surfaces of vessels and is carried out by applying a solvent or aqueous washing solution to the surface to be degreased with a jet under high pressure through special nozzles that ensure washing of the entire surface to be degreased. The amount of solvent or aqueous washing solution supplied to the degreased surface must be at least: for solvents 25 dm 3 / m 2, for washing solutions 50 dm 3 / m 2. When degreasing using the jet method, intermediate rinsing with hot water is not necessary. 4.3.7. The rubbing method is used in the absence of special equipment or more effective ways degreasing. This method is used for degreasing large-sized products, cryogenic vessels, if they have hatches, and for small-sized products, subject to free access to the degreased cavities and is carried out by repeatedly wiping the degreased surfaces with napkins with cut edges, moistened with a hot aqueous washing solution at a temperature of 40-45 °C. Provided that safety requirements are met, it is allowed to use freon 113 and freon 114B2 or group 2 solvents for wiping small-sized products. 4.3.8. The ultrasonic cleaning method should be used to degrease products with complex configurations. Degreasing is carried out with group 1 solvents or hot aqueous cleaning solutions (see Tables 1, 3) in special ultrasonic baths. The duration of degreasing is 10-15 minutes. After degreasing with aqueous cleaning solutions, the products are washed with hot water. 4.4. Removing residues of used degreasers. 4.4.1. Removal of solvent residues from products after degreasing them is carried out by blowing with compressed air or nitrogen, according to clause 2.3.7. For group 2 solvents, only nitrogen is used. The gas used for purging must be heated to a temperature of 60-70°C. By the end of the purging, the gas at the outlet of the apparatus should have a temperature of at least 40-50°C. The duration of purging depends on the size and shape of the products being degreased and on the physicochemical properties of the solvents. Blowing should be carried out until the solvent odor is completely removed. The purge procedure is the same as when warming up equipment from a cold state. It is necessary to prevent the entry into the room of air contaminated with solvent vapors. 4.4.2. Products intended for storing and transporting medical oxygen should be purged until there is no solvent vapor in the gas; during control purge, no more than double gas exchange in the product should be ensured within 1 hour. 4.4.3. Residues of aqueous cleaning solutions should be removed by washing the products with hot drinking water at a temperature of 70-80°C. Washing is stopped if there is no foam in the water and the medium reacts neutrally (RN-6-8) when checked with universal indicator paper according to TU 6-09-1181. 4.4.4. After degreasing the products with aqueous washing solutions using the “wiping” method, remove the remaining solution by wiping with cloths moistened with warm water at a temperature of 35-40°C. Wiping the surface with napkins moistened with water ends when there are no traces of foam on the surface being wiped or on the napkins. The pH of the last rinse water should be 6-8. 4.4.5. Before drying items, the water must be completely drained. Particular attention should be paid to the complete removal of water from internal cavities and pockets. Dry metal products washed in water until moisture is completely removed by blowing with compressed air at a temperature of 100-120°C, and assembly units with non-metallic parts at a temperature of 70-80°C. By the end of the purge, the air temperature at the outlet of the apparatus should be no more than 10-15°C lower than the supply air temperature. Natural drying of parts of simple configurations and open surfaces is allowed in compliance with safety regulations. The interval between the end of washing and drying of the product should not exceed 10-15 minutes. Spots of white deposits from aqueous cleaning solutions are allowed with an area of no more than 10% of the surface of the washed products.5. Quality control of degreasing
5.1. Quality control of degreasing and technological parameters is carried out during development of the technological process, as well as at the request of the quality control department or the customer’s representative. In the absence of control, the quality of degreasing must be guaranteed by compliance with the adopted technology. 5.2. The need to control the degreasing of products, the percentage of controlled products and the chosen methodology must be specified in the technological documentation. 5.3. Depending on the method of degreasing and the design of the product, the quality of degreasing is controlled by directly determining the content of fatty contaminants on the surface of the product after degreasing or indirectly, by determining the content of fatty contaminants in the solvent before control degreasing and in the drained product after control degreasing, or on the surface of “witnesses”. " fat-free at the same time as the product. Solvent consumption during control degreasing is 20-30% of the amount required for a single degreasing of the product. 5.4. Quality control of degreasing is carried out in accordance with OST 26-04-2574. 5.5. The temperature of solutions, the temperature and composition of gases is monitored by universal measuring instruments (thermometers, gas analyzers of any type). ______________________________ * Example entry is preferred.Annex 1
Information
Explanation of terms
|
Explanation |
|
|
Degreasing |
Technological operation of reducing the content of fatty contaminants to the standards established by regulatory and technical documents or technical documentation. |
|
Low-grease equipment |
Equipment, the content of fatty contaminants on the surface of which complies with the standards. |
|
Pollution |
According to GOST 24869. |
|
Grease contamination |
Pollution consisting of mineral oils and other fatty substances. |
|
The amount of grease contamination per unit surface of the product. |
Appendix 2
Features of degreasing various types of equipment
1. General Provisions
1.1. Equipment operating with oxygen that complies with GOST 5583 and GOST 6331 is not degreased during operation, with the exception of liquid oxygen evaporators and other equipment in which fatty contaminants may enter the oxygen. 1.2. Equipment operating with oxygen containing 0.01 mg/dm3 of fatty contaminants or more must be degreased after the amount of fatty contaminants calculated by the formula reaches the normWhere S- inner surface of the vessel, m2; v- volume of oxygen poured or pumped into the vessel, dm 3; C - content of fatty contaminants in oxygen, mg/dm 3 ; n- number of fillings of the vessel; m- permissible content of fatty contaminants according to OST 26-04-1362 or GOST 12.2.052, mg/m 2. The equipment passport or other document must record the amount of oxygen passed and the content of fatty contaminants in it. Amendment No. 2 has supplemented this appendix with clause 1.3 1.3. The need to degrease oxygen equipment can be determined using test degreasing. If the design of the product allows, control degreasing should be carried out in places where fatty contaminants are most likely to be deposited and accumulated. The equipment may not be degreased if the oil content does not exceed the values regulated by the regulatory and technical documents specified in clause 1.1. of this standard.
2. Degreasing of air separation units
2.1. Degreasing of separation units assemblies is carried out only with solvents of group 1 (see Table 1) of the standard. The use of group 2 solvents for these purposes is not permitted. 2.2. The amount of solvent required for degreasing depends on the size of the separation unit and the degree of contamination with oil. The approximate amount of solvent required for one-time washing of some blocks is given in table. 1. Table 1Approximate solvent consumption for one-time washing of air separation units
2.3. To avoid corrosion, all separation unit apparatus must be thoroughly dried before degreasing with solvents. 2.4. Before degreasing air separation units, the equipment must be checked for leaks and any detected leaks must be eliminated. 2.5. Degreasing of communications and internal cavities of heat exchangers is carried out by circulating the solvent in the washed cavities for 1-1.5 hours. 2.6. Degreasing of devices (condensers, bottom column cube, regenerators, etc.) is carried out by filling with solvent up to 3/4 of the volume, followed by bubbling with air or nitrogen for 1-1.5 hours or by condensing solvent vapors. 2.7. Adsorbers are degreased after removing the adsorbent from them by wiping the adsorber body and basket. It is not allowed to degrease acetylene adsorber assemblies. 2.8. Degreasing of the filter elements of expander filters is carried out with aqueous washing solutions, for example, in washing machines, or by circulating the solvent through the filter element in a special device. Degreasing the filter fabric by hand washing in a solvent is not allowed.3. Degreasing of cryogenic vessels, cylinders and transport tanks
3.1. Vessels of liquid medical oxygen are degreased when fatty contaminants are detected in liquid oxygen in an amount of 0.01 mg/dm 3 or more, confirmed in five consecutive analyzes. 3.2. Vessels and cylinders are degreased by filling up to 1/3 of the vessel with solvent, followed by rotation or rocking in a special device. The specified equipment can also be degreased with a hot aqueous cleaning solution, filling the equipment with it or washing its walls using the jet method. 3.3. To degrease transport tanks and vessels, the method of condensation of solvent vapors can be used. Before degreasing transport tanks and vessels using this method, their component evaporators should be removed and degreased separately. Solvent vapor is supplied to the vessel, preheated to a temperature of 30-40°C, through a “fill-empty” valve. Air is forced out of the vessel through the gas release valve during the first hour of solvent vapor supply. The condensate flows into the lower part of the vessel. If the pressure in a transport tank or vessel when supplying solvent vapor rises above 0.05 MPa (0.5 kgf/cm2), the vessel should be cooled by blowing with cold air or nitrogen until the outlet gas temperature drops to a temperature of 293- 298 K (20-25°C), then continue degreasing. The condensate is drained and the content of fatty contaminants is determined. Degreasing is completed when the content of fatty contaminants in the drained solvent is no more than 20 mg/dm 3 . 3.4. Vessels and cylinders with hatches can be degreased by washing their walls with a jet method or wiping the inner walls of the vessels with cloth napkins moistened with a hot aqueous cleaning solution; after wiping, the remaining solution is drained through the bottom drain. The evaporator and bottom drain communications are washed again with a clean solution. 3.5. When degreasing vessels using the “wiping” method, the following rules must be observed: - before carrying out degreasing work, a vessel that has been in use must be warmed up in accordance with clause 3.3. standard; - workers performing degreasing must be instructed on the rules and safe methods of working inside closed equipment; - the person responsible for degreasing must inspect the work site and make sure that the vessel is warmed up and prepared for work; - when working, the requirements of the “Temporary Standard Instructions for Organizing the Safe Conduct of Gas Hazardous Work at Enterprises of the USSR Ministry of Chemical Industry”, approved by the USSR State Mining and Technical Supervision Authority and the USSR MHP, must be observed.4. Degreasing liquid oxygen pumps
4.1. Parts of liquid oxygen pumps are degreased by immersion in baths, preferably with aqueous cleaning solutions, in accordance with the instructions in paragraph 4.3.3. standard 4.2. Communications to the pump are degreased by circulating an aqueous cleaning solution or solvent or condensing solvent vapors in accordance with the instructions in Section 8. 4.3. Flake graphite is degreased with a solvent in a separate vessel. After thorough mixing, the solvent is drained, and the graphite is poured out and dried in the open air or in an oven until the smell of the solvent is completely removed.5. Degreasing of gasification plants
5.1. Vessels of warm and cold gasifiers are degreased by filling them with a solvent, followed by bubbling nitrogen or air. 5.2. Evaporators of gasification plants are degreased by circulating solvents through them. The frequency of degreasing of evaporators operating with liquid oxygen in accordance with GOST 6331 is determined by formula 1, clause 1.2. in this case, the content of fatty contaminants in oxygen is assumed to be 0.01 mg/dm 3 . Degreasing of gasifiers at a pressure of 15 MPa (150 kgf/cm2) must be carried out at least after 1000 hours of operation of the installation.The numbering of points is given in accordance with the source
5.4. After degreasing and purging the gasifier with medical oxygen, the gaseous product is released into the atmosphere for 1 hour without increasing the pressure.6. Degreasing of cryogenic cold gasifiers type GKH
6.1. When the gasifier operates on oxygen in accordance with GOST 6331, control degreasing of one of the evaporators is carried out after the mass of oxygen, determined by the formula, has passed through the gasifier installation:Where M- mass, t; F- internal area of the gasifier panel, m2. Control degreasing is carried out with solvents of group 1 of table. 1 standard in an amount of 20-30% of the total volume poured. After control degreasing, the content of fatty contaminants in the solvent is determined in accordance with OST 26-04-2574. 6.2. Degreasing of the remaining evaporators is carried out if the content of fatty contaminants exceeds the permissible standards according to 26-04-1362. Degreasing is carried out using the circulation method with a solvent of group 1 of the table. 1 standard. 6.3. When using oxygen containing fatty contaminants of more than 0.01 mg/dm 3, the gasifier (tank, fitting cabinet, evaporators and pipelines) is degreased after the mass of oxygen determined according to clause 1.2 has passed through the tank. 6.4. Degreasing of gasifier tanks is carried out by condensation of solvent vapors in accordance with clause 4.3.5. standard Evaporators are degreased using the solvent circulation method. Degreasing ends when the content of fatty contaminants in the drained condensate is no more than 20 mg/dm 3 .6.5. The spindle groups of fittings are degreased by wiping with aqueous cleaning solutions. 6.6. Degreasing of spindle groups of fittings with solvents of group 1 of table. 1 standard is not allowed. Degreasing evaporators with aqueous cleaning solutions is not allowed. 6.7. After degreasing, the gasifier is purged until all remaining solvent is removed. The complete removal of solvents must be verified by analysis. The medical oxygen gasifier should be purged until there is no solvent vapor in the gas during control purging (no more than 2 mg/m3). 6.8. When using oxygen in a gasifier in accordance with GOST 6331, degreasing of the tank, fitting cabinet and pipelines is not carried out.
7. Degreasing oxygen compressors
7.1. Small parts are degreased according to clause 4.3.3. standard 7.2. Degreasing of valves with solvents should only be done in disassembled form. 7.3. Large parts, for example, a cylinder, cover, rods, pistons, etc., are degreased in baths with an aqueous cleaning solution or solvent, or by wiping the surfaces with napkins moistened with low-toxic solvents (see clause 4.3.7 of the standard) or hot water detergent solution. 7.4. Shell-and-tube refrigerators, moisture separators, receivers and other containers are filled 1/3-1/2 of the volume with solvent, after which edging is performed. If parts are degreased after re-preservation, it is necessary to wash the parts two or three times with a solvent. It is recommended to degrease these devices by condensing solvent vapors or washing them with a hot washing solution (see clause 4.3.5 of the standard). 7.5. Coil refrigerators are degreased with a solvent or hot washing solution using the circulation or filling method (see clause 4.3.4.; 4.3.3. of the standard). 7.6. After degreasing, the compressor must be run in air or nitrogen for 2 hours. 7.7. Degreasing of oxygen turbocompressors is carried out in accordance with RTM 26-12-43.8. Degreasing of pipelines and hoses
8.1. The need to degrease assembled pipelines with a pressure above 4.0 MPa (40 kgf/cm2) is determined by the technical documentation; the decision on degreasing is recommended to be made after monitoring the open ends of the pipeline, in accordance with OST 26-04-2574. 8.2. Liquid oxygen pipelines are checked for the presence of fatty contaminants at least once a year, in the case when oxygen with a content of fatty contaminants exceeding the requirements of GOST 6331 is transported through it. Areas with the lowest flow rate are subject to a control check for the presence of fatty contaminants, and with a uniform flow - entrance areas. Control is carried out in accordance with section 5 of the standard. If the standard OST 26-04-1362 is exceeded, the entire pipeline is subjected to degreasing. 8.3. When degreasing by immersion in baths, pipes are placed in special baths filled with aqueous cleaning solutions or solvents and maintained in accordance with the instructions in clause 4.3.3. standard 8.4. For degreasing by circulation, the pipelines are connected to a special system equipped with a pump, through which aqueous cleaning solutions or solvents are pumped (see clause 4.3.4 of the standard). 8.5. Degreasing the inner surface of pipes using the filling method is carried out as follows: technological plugs are installed at the ends of the pipes. Solvent is poured into the plug through the corresponding fitting, after which the fitting is closed, and the pipes or hoses are laid horizontally. The pipes should remain in a horizontal position for 10-20 minutes, during which time they should be turned 3-4 times to wash the entire inner surface with solvent. Pipes filled with solvent can also be moved in special rockers or turning mechanisms. 8.6. Sections of the installed pipeline are degreased by circulating a solvent or aqueous cleaning solution. 8.7. The approximate solvent consumption required for one-time degreasing of the inner surface of one linear meter of pipe is calculated using the formula:
(2)
Where Q- solvent consumption, dm 3 /m; D- internal diameter of the pipe, cm. Solvent consumption for one-time degreasing of pipes is given in table. 2. Table 2
Solvent consumption for one-time degreasing of pipes
Continuation of the table. 2 Continuation of table. 2 8.8. Small sections of pipelines can be degreased by wiping or jetting an aqueous cleaning solution using special devices. 8.9. During installation, the outer surfaces of the ends for a length of 0.5 m are wiped with napkins soaked in a solvent or aqueous washing solution and dried in the open air. 8.10. All parts intended for connecting hoses to the container must be degreased by wiping if they were possibly contaminated during storage. 8.11. The hoses of medical oxygen tanks are degreased along with the vessel. 8.12. Fat-free sections of pipelines to be stored or transported must be plugged and sealed. 8.13. Pipeline sections subjected to chemical passivation or other types of chemical surface treatment before assembly may not be degreased if the requirements of clause 1.3 are met. standard 8.14. Sections of pipelines and hoses that were degreased during manufacture, received for installation with plugs and have the appropriate marks in the passport, are not degreased. 8.15. Pipeline assemblies are not subject to degreasing at pressures up to 4.0 MPa (40 kgf/cm2), if sections of pipelines before assembly or pipeline assemblies were cleaned of scale, slag, etc. by etching, sandblasting and shot blasting. 8.16. Main pipelines and inter-shop oxygen pipelines, pressure up to 1.6 MPa (16 kgf/cm2), assemblies are not degreased if, before connecting individual pipes, a visual inspection confirms the absence of stains of greasy contaminants on the surface of the pipelines, for which a report must be drawn up .9. Degreasing of fittings and devices
9.1. Degreasing is carried out after manufacturing, before installation and after repair, i.e. in cases where contamination of the fittings was possible. 9.2. The fittings are degreased in disassembled form with aqueous cleaning solutions. It is possible to pre-wipe with a cloth soaked in white spirit or kerosene. In this case, special attention should be paid to fire safety measures. 9.3. In case of technical necessity, it is allowed to degrease the fittings without disassembling. To determine the possibility of degreasing purchased fittings without disassembling, it is recommended to degrease, dry, and then disassemble and check for residual grease content. If the residual content meets the standards, in accordance with clause 1.1. standard, in the future the fittings can be degreased without disassembling. Particular attention should be paid to the oil seal and its packing. 9.4. When degreasing fittings without disassembling, one should take into account the compatibility of all materials from which the fittings are made, especially seals, with the detergents used. 9.5. The fittings are not subject to degreasing before installation if degreasing was carried out at the manufacturer (which must be confirmed by accompanying documents or appropriate branding) and the packaging is not damaged. 9.6. Gaskets made of rubber, paronite, fiber, fluoroplastic oil seal rings, parts made of fiberglass, polycarbonate and textolite are degreased by wiping with aqueous detergent solutions and rinsed with water. 9.7. Asbestos used for stuffing box fittings is degreased by calcination at a temperature of 300°C for 2-3 minutes. 9.8. Degreasing of instruments for measuring flow and pressure is carried out in accordance with OST 26-04-2158.Appendix 3
Mandatory
Requirements for solvents
Incoming control|
Indicator name |
Control method |
1. Appearance | Colorless, transparent liquid | Determined visually | 2. Content of mechanical impurities and water | Must be transparent and free of foreign impurities suspended and deposited on the bottom of the cylinder | Pour the solvent into a glass cylinder with a diameter of 40-50 mm | 3. Reaction of the environment | The aqueous layer should not turn pink | The solvent in an amount of 15 cm 3 is placed in a separating funnel, 40 cm 3 of distilled water is added and shaken for 3-5 minutes; after settling, the aqueous layer is drained and methyl orange 0.1% aqueous solution is added to it | 4. Oil content | Section 2 of the standard, table. 2 | According to OST 2 6-04-2574 |
Appendix 4
Mandatory
Preparation of baths with aqueous cleaning solutions, their control and adjustment
1. Drawing up baths
1.1. The amount of each component provided for in the recipe is calculated based on the composition of the bath and its useful capacity. The components of the solution, depending on local conditions, can be dissolved separately in auxiliary vessels or directly in the bath in which degreasing is carried out. Dissolution is carried out by heating to a temperature of 60-70°C with vigorous stirring of the solutions with mechanical stirrers or air bubbling. 1.2. After drawing up the bath, determine the total alkalinity of the freshly prepared composition according to the method given below.2. Control and adjustment of baths
2.1. General requirements
2.1.1. Control analyzes of the composition of aqueous washing solutions in degreasing baths are carried out at least 2 times a week by determining the total alkalinity of the solution. Baths are adjusted based on the results of control tests. A general change of the aqueous cleaning solution with regular loading of the bath is carried out once a week. 2.1.2. When using baths, do not allow contamination to accumulate on the surface of the solutions. Regularly remove grease from the surface using special devices (with a holey spoon or mesh) or special grease traps. 2.1.3. Before taking a sample of the solution for control analysis, it is necessary to bring the solution to the desired level and mix.
2.2. Determination of the total alkalinity of a solution
Change No. 1, approved by the Deputy Minister of Chemical and Petroleum Engineering on January 4, 1987, introduced changes to subparagraph 2.241 of this appendix, which come into force on July 1, 1987.Amendment No. 2 amended subclause 2.2.1 of this appendix 2.2.1. Reagents, solutions and utensils used: - hydrochloric acid, according to GOST 3118, 0.1 m solution; - methyl orange indicator according to TU 6-09-5171, 0.1%; - distilled water, according to GOST 6709; - conical flasks, according to GOST 25336, with a capacity of 250 cm 3; - measuring pipettes, according to GOST 1770, with a capacity of 100 cm 3; - measuring burette, according to GOST 1770, with a capacity of 25 cm3. 2.2.2. To carry out the determination, 5 cm 3 of a cooled aqueous washing solution is placed in a conical flask with a capacity of 250 cm 3, diluted with water to 100 cm 3, 2-3 drops of methyl orange solution are added and titrated with 0.1 N HCl until the yellow color changes to pale pink. 2.2.3. The total alkalinity of the solution in terms of NaOH in g/dm 3 is calculated using the formula:
Where q- amount of 0.1 N solution HCl, spent on titration, cm 3; 0.004 - solution titer HCl, G; TO- correction to the titer of 0.1 N solution HCl;m- amount of solution taken for analysis, cm3.
2.3. Bathtub adjustments
2.3.1. Based on the results of control tests, the baths are adjusted if the total alkalinity of the solution decreases by more than 20%. 2.3.2. When making adjustments, add all components of the solution to the bath. The amount to be added is calculated based on the main component, which determines the total alkalinity of the solution. For example, according to a control analysis of a bath of the composition: NaOH - 10 g; Na 3 PO 4 -15 g; Na 2 SiO 3 -2 g; OP-7 - 2-3 g; H 2 O - 1 dm 3 total alkalinity decreased by 35%. When adjusting, it is necessary to add to the bath at the rate of 1 dm 3: NaOH - 3.5 g; Na 2 SiO 3 - 0.7 g; Na 3 PO 4 - 5.2 g; OP-7 - 0.7-1 g. Change No. 2 introduced changes to this ListChange No. 1, approved by the Deputy Minister of Chemical and Petroleum Engineering on January 4, 1987, introduced changes to this List that come into force on July 1, 1987.
List of reference normative and technical documents (NTD)
|
Designation |
Name |
Sheet (page) |
GOST 9.010-80 |
ESZKS. Compressed air for spraying paints and varnishes. Technical requirements. Rules and methods of control |
GOST 9.305-84 |
E S 3 KS. Metallic and non-metallic, inorganic coatings. Operations of technological processes for obtaining coating |
GOST 12.1.001-83 |
SSBT. Ultrasound. General safety requirements. |
GOST 12.1.004-85 |
SSBT. Fire safety. General requirements. |
GOST 12.1.014-84 |
SSBT. Work area air. Method for measuring the concentration of harmful substances using indicator tubes. |
GOST 12.1.016-79 |
SSBT. Work area air. Requirements for methods for measuring concentrations of harmful substances. |
GOST 12.1.019-79 |
SSBT. Electrical safety. General requirements. |
GOST 12.2.052 -81 |
SSBT. Equipment working with oxygen gas. General safety requirements |
GOST 12.3.008-75 |
SSBT. Production of metallic and non-metallic inorganic coatings. General safety requirements. |
GOST 12.4.011-89 |
SSBT. Protective equipment for workers. Classification. |
GOST 12.4.026-81 |
SSBT. Signal colors and safety signs |
GOST 17.2.3.02-78 |
Protection of Nature. Atmosphere. Rules for establishing permissible emissions of harmful substances by industrial enterprises |
Trisodium phosphate. Technical conditions. |
Nefrases S2-80/120 and SZ-80/120. Technical conditions. |
GOST 1770-74E |
Laboratory glassware. Cylinders, beakers, flasks. Technical conditions. |
GOST 22 63-79 |
Technical sodium hydroxide. Technical conditions. |
GOST 2874 -82 |
Drinking water. Hygienic requirements for quality control. |
GOST 3118-77 |
Hydrochloric acid. Technical conditions. |
GOST 3134-78 |
Gasoline solvent for the paint and varnish industry. Technical conditions. |
GOST 4328-77 |
Reagents. Sodium hydroxide. Technical conditions. |
GOST 4753-68 |
Kerosene for lighting. Technical conditions. |
GOST 5583-78 |
Oxygen gas, technical and medical. Technical conditions. |
GOST 6331-78 |
Liquid oxygen technical and medical. Technical conditions. |
GOST 6709-72 |
Distilled water. |
GOST 8505-80 |
Nefras-S 50/170. Technical conditions. |
GOST 9293 -74 |
Nitrogen gaseous and liquid. Technical conditions. |
GOST 9337-79 |
Sodium phosphate 12-water. Technical conditions. |
GOST 9976-83 |
Technical trichlorethylene. Technical conditions. |
GOST 2533 6-82 |
Laboratory glassware and equipment. Type, main parameters and dimensions. |
GOST 10652-73 |
Disodium ethylenediamine salt - N, N, N¢, N¢ tetraacetic acid, 2-water (Trilon-B). |
GOST 13078-81 |
Liquid sodium glass. Technical conditions. |
GOST 15899-79 |
Freon 114B2. Technical conditions. |
GOST 19906-74 |
Technical sodium nitrite. Technical conditions. |
OST 26-04-13 62-75 |
OST 26-04-2138-81 |
Temporary anti-corrosion protection of products. |
OST 26-04-2158-78 |
SSBT. Flow and pressure measuring instruments. Safety requirements for use in gaseous oxygen environments. |
OST 26-04-2574-80 |
Gases, cryogenic products, water. Methods for determining the content of mineral oils. |
OST 26-04-2578-80 |
Gases, cryogenic products. Chromatographic method for determining impurities in chlorofluoroorganic solvents. |
OST 26-04-2600-83 |
Cryogenic equipment. General technical conditions. |
RTM 26-12-43-81 |
Degreasing of centrifugal oxygen compressors. |
TU 6-01-927-76 |
Trichlorethylene stabilizer (STAT-1). |
TU 6-02-640-80 |
Nonionic drug syntamid-5. |
TU 6-09-1181-76 |
Universal indicator paper for determining pH 1-10 and 7-14. |
TU 6-09-5171-84 |
Methyl orange indicator (sodium para-dimethylanino-azobenzenesulfonic acid) |
TU 6-01-956-86 |
Tetrachlorethylene (perchlorethylene) |
TU 6-14-577-88 |
Detergent preparation syntanol DS-10 |
TU 6-15-978-76 |
Synthetic detergent NS-8. |
Drug KM-2. |
TU 38.103 62-87 |
Surfactant NEONOL AF9.12 |
TU 38-10761-75 |
Synthetic detergent Vimol. |
Technical detergent Vertolin-74. |
TU 38-107113-78 |
Technical detergent TNS-31. |
TU 38.50724-84 |
Degreasing of equipment designed to work with liquid oxygen
from "Safety when working with liquid oxygen"
During the manufacturing of oxygen equipment parts, their storage in production conditions, assembly and installation of the product, the surfaces of the parts may become contaminated with organic and flammable substances (oil, grease, etc.). In addition, many parts of oxygen equipment components are coated with a preservation lubricant during storage. Contact with liquid oxygen of such equipment without first cleaning its surfaces from organic substances (degreasing) can lead to detonation or fire of the organic substance film - liquid oxygen system. Cleaning oxygen equipment from organic and flammable substances is achieved by degreasing individual parts before assembly, assemblies or the entire product after installation.The equipment is also degreased during its operation within the time limits established by the design and technological documentation. The degree of degreasing of equipment must be such that the thickness of the layer of fatty contaminants on surfaces in contact with oxygen does not exceed values at which combustion and detonation are impossible.
The procedure for degreasing oxygen equipment, the requirements for detergents and solvents, and the cleanliness of degreasing surfaces in contact with oxygen are regulated by the industry standard OST 26-04-312-71 Oxygen equipment. Degreasing methods. Materials used.
Based on their ability to create flammable and explosive mixtures with air and oxygen, solvents are divided into two groups. The first category includes fire and explosion-proof hazardous solvents that are used to degrease parts, assemblies and assembled products. Solvents belonging to the second group are explosive and fire hazardous when in contact with liquid oxygen, and their vapors, when mixed with air and gaseous oxygen, can form flammable and explosive systems. Such solvents can only be used under conditions that ensure their complete removal from the internal cavities of degreased units and parts.
Aqueous cleaning solutions are used for degreasing individual parts, fittings, pipelines and the entire product when their design provides the possibility of completely draining the cleaning solution and removing its residues by rinsing with water.
The duration of surface cleaning and the quality of degreasing depend on the temperature of the aqueous cleaning solutions. The most effective is degreasing at a solution temperature of 60-80 °C.
If oil is detected in liquid oxygen in an amount of more than 0.4 g/m3, confirmed in five consecutive analyzes (GOST 6331-68), degreasing of the blocks should be carried out immediately.
Air separation units intended for the production of medical oxygen are degreased immediately when oil in liquid oxygen is detected in an amount of 0.01 g/m3 or more, confirmed in five consecutive analyzes. Degreasing of air separation units need not be carried out within the time limits specified above if the means of protecting the unit from oil ensured that during the entire period of operation of the unit after the next degreasing, the absence of oil in liquid oxygen within the sensitivity of the analysis method.
If there is no data for calculating the timing of degreasing, then degreasing should be carried out every 6 months.
For degreasing, carbon tetrachloride, trichloroethane, tetrachlorethylene, freon-113, as well as hot aqueous washing solutions are used.
Oxygen Dewar flasks should be degreased at least once every 6 months. Degreasing must be carried out with one of the solvents (see Table 39), for example, carbon tetrachloride, freon-113, etc. The solvent is poured in an amount of at least 1/3 of the capacity of the vessel being degreased. The neck is closed with a rubber stopper and the vessel is shaken, turning in different directions so that the entire surface of the inner vessel is irrigated with solvent. Washing should be carried out for at least 10 minutes, after which the solvent should be poured out, the vessel should be turned upside down and kept in this position for 1-2 hours, and then dried in a vertical position for 24 hours (at least).
Parts of liquid oxygen pumps that come into contact with oxygen are degreased before final assembly, after re-preservation or repair, as well as during operation of the product (for example, a gasifier) that includes the pump.
Gasifier evaporators are degreased by circulating a solvent through them. Degreasing must be carried out at least every 1000 hours of operation of the unit.
Liquid oxygen pipelines are degreased during manufacture or installation, after repairs, during which contamination of internal surfaces is possible, as well as during operation. If the oil content in the transported liquid oxygen exceeds 0.01 g/m, then the pipeline is degreased at least once a year.
After degreasing, any remaining solvent or aqueous cleaning solution must be removed from the equipment. This is achieved by blowing the product with nitrogen or air preheated to 60-70°C. To remove gasoline residues, only nitrogen is used.
The duration of purging depends on the size and shape of the products being degreased, as well as on the physicochemical properties of the solvent. Blowing should be carried out until the solvent odor is completely removed. Control of the completeness of removal of solvent vapors from the product is carried out according to the results of the analysis (OST 26-04-312-71).
Residues of cleaning solutions are removed by rinsing the product with water. Washing is stopped when the medium reaction is neutral (pH = 6-8) and there is no foam in the water. The neutrality of the medium is checked using a universal indicator piece of paper.
Before drying, water must be completely removed from parts and components. Drying is carried out with dry compressed air, followed by exposure in electrical cabinets at 100-120 ° (2) or dry hot compressed air at a temperature of 90-100 ° C. For parts of simple design, natural drying is allowed.
Carbon tetrachloride Trichlorethylene.
Kerosene (in terms of carbon). . Change No. 2 introduced changes to this OST
Industry standard
OST 26-04-312-83
Methods for degreasing equipment. General requirements for technological processes
(put into effect by letter of the Technical Department of the Ministry of Chemical Engineering dated November 29, 1983 N 11-10-4/1685)
Validity period established from January 1, 1985. Replaces OST 26-04-312-71 This standard applies to cryogenic, cryogenic-vacuum equipment and equipment working with oxygen, including medical oxygen, nitrogen and other air separation products, and establishes general technological requirements for methods of removing fatty contaminants from the surface of products (degreasing). The standard does not establish requirements for the processes of depreservation of products. Explanations of terms used in this standard are given in Reference Appendix 1.
| 1. General provisions 2. Technical requirements 3. Safety requirements 4. General technological requirements 5. Quality control of degreasing Appendix 1 Explanation of terms Appendix 2 Features of degreasing various types of equipment 1. General provisions 2. Degreasing of air separation units 3. Degreasing of cryogenic vessels, cylinders and transport tanks 4. Degreasing of liquid oxygen pumps 5. Degreasing of gasification plants 6. Degreasing of cryogenic cold gasifiers such as GKH 7. Degreasing of oxygen compressors 8. Degreasing of pipelines and hoses 9. Degreasing of fittings and instruments Appendix 3 Requirements for solvents Appendix 4 Preparation of baths with water washing solutions, their control and adjustment 1. Drawing up baths 2. Control and adjustment of baths |
1. General Provisions
1.1. Degreasing of equipment must be carried out if the content of fatty contaminants on the surface exceeds the norms established by regulatory and technical documents, technical documentation (drawings, technical specifications and operational documentation), during manufacture, installation, repair and operation. The standards for equipment working with gaseous oxygen are established according to GOST 12.2.052, for equipment working with liquid oxygen - according to OST 26-04-1362, for cryogenic-vacuum equipment - according to OST 26-04-2600. The method and means of degreasing are indicated in the technological documentation. The operational documentation indicates the method, means and frequency of degreasing or the criteria determining the need for degreasing. Depending on the design features of the product, it is possible to indicate the degreasing method in the technical documentation (drawings, technical specifications), if this method is the only one that guarantees the required quality of degreasing, or to limit the use of certain methods . 1.1.1. Excluded from July 1, 1987 1.2. The procedure for degreasing equipment during manufacturing should be established by instructions and technological processes developed at the manufacturer in accordance with the requirements of this standard. When carrying out installation or repair work, the procedure and technological process for degreasing, developed in accordance with the requirements of this standard, must be determined by the organization carrying out the installation or repair work; degreasing during operation is carried out in accordance with the operational documentation. Change No. 1 , approved by the Deputy Minister of Chemical and Petroleum Engineering on January 4, 1987, amendments were made to paragraph 1.3 of this OST, which come into force on July 1, 1987. 1.3. Degreasing of individual parts before assembly or products after assembly at the manufacturing plant and during installation may not be carried out if during the manufacturing process the parts from which the product is assembled were degreased or underwent chemical or galvanic treatment in accordance with GOST 9.305 (lightening, passivation, galvanizing, etc. .p.), and surface contamination was prevented during storage and assembly. If grease stains get on parts with galvanic coatings, they can be degreased by wiping with aqueous detergent solutions at a temperature not exceeding 40°C. It should be taken into account that this may damage the appearance of the coating. 1.4. Equipment that meets the requirements of technical documentation for the content of fatty contaminants on the surface, has confirmation in the passport and arrived at the installation site with intact plugs and in intact packaging is not subject to degreasing during installation. 1.5. Features of degreasing various types of equipment are given in recommended Appendix 2. 1.6. Compliance of the content of fatty contaminants with the established standards is confirmed by a mark in the control route map, in the technological data sheet of the product or in other technical documentation. Based on these documents, notes are added to the product passport, for example: “The content of fatty contaminants does not exceed the standards established by GOST 12.2.052” * or “degreased.”1.7. The preparation and implementation of all degreasing work must be supervised by a responsible person appointed by written order of the administration, who must be fully responsible for compliance with degreasing technology, timely technical control and safety of work.2. Technical requirements
2.1. Material requirements
2.1.1. Solvents or aqueous cleaning solutions should be used to degrease equipment. The need to use solvents or aqueous cleaning solutions must be indicated in the technological documentation.
2.2. Solvents
2.2.1. Solvents are divided into two groups: Group 1 - fireproof, used for degreasing assembled products both at manufacturing plants and during equipment operation. Group 2 - fire and explosion hazardous, used for degreasing products by wiping, subject to the subsequent complete removal of solvents from the internal cavities of degreased products. When using solvents of group 2, conditions must be observed to ensure fire and explosion safety, in accordance with clause 3.9. The used solvents of groups 1 and 2, used at a temperature of 10-20 ° C, depending on the detergent and physicochemical properties, are given in table. 1. Change No. 1, approved by the Deputy Minister of Chemical and Petroleum Engineering on January 4, 1987, introduced changes to subclause 2.2.2 of this OST, which come into force on July 1, 1987. 2.2.2. When degreasing materials other than those indicated in the table. 1, tests should be carried out for corrosion compatibility with solvents and for residual content of fatty contaminants.
Scope of solvents
Table 1
|
Name of solvents |
Residual content of fatty contaminants, mg/m 2, no more |
Application area |
Group 1 |
Freon 113 GOST 23844 | Freon 114B2 GOST 15899 | Trichlorethylene GOST 9976 |
For products made of steel, cast iron, copper and alloys based on iron, copper and nickel |
Tetrachlorethylene TU 6-01-956 | Trichlorethylene GOST 9976 with stabilizer STAT-1-1% TU 6-01-927 |
For products made of steel, cast iron, copper, aluminum and alloys based on iron, copper, nickel, aluminum |
Tetrachlorethylene TU 6-01-956 with stabilizer STAT-1-1% TU 6-01-927 |
Group 2 |
Nefras S2-80/120 and SZ-80/120 GOST 443 |
For products made of any metals and alloys |
Nefras-S 50/170 GOST 8505 (distilled) | Gasoline solvent for the paint and varnish industry (white spirit) GOST 3134 |
For preliminary removal of grease stains from products made of any metals and alloys |
Permissible content of fatty contaminants
2.2.6. When repeated degreasing, solvents containing fatty contaminants of no more than 50 mg/dm 3 should be used. In the following, solvents that meet the above requirements are called pure. 2.2.7. The use of the CTAT-1 stabilizer is mandatory when degreasing products made of aluminum and its alloys and is preferable when degreasing other metals.2.3. Aqueous cleaning solutions
2.3.1. Fireproof non-toxic aqueous cleaning solutions are used for degreasing assembled and disassembled products, the design of which ensures the possibility of completely draining the solution and removing its residues by rinsing with water, both at manufacturing plants and during installation and operation of equipment. Change No. 1, approved by the Deputy Minister of Chemical and Petroleum Engineering on January 4, 1987, introduced changes to subclause 2.3.2 of this OST, which come into force on July 1, 1987. 2.3.2. The compositions of aqueous washing solutions, technological modes and scope of application, indicating the materials, are given in table. 3. Instructions for the preparation of baths with aqueous solutions, their control and adjustment are given in mandatory Appendix 4. Table 3
Compositions of aqueous cleaning solutions and degreasing modes
|
Compositions of aqueous cleaning solutions |
Degreasing modes |
Residual content of fatty contaminants, mg/m2 |
Application area |
components of aqueous cleaning solutions and detergents |
quantity, g/dm 3 |
temperature °C |
degreasing ratio |
Composition 1 |
twice |
For products made of steel, cast iron, copper and alloys based on iron, copper and nickel |
Sodium phosphate, (trisodium phosphate), |
Detergent* |
Sodium hydroxide (caustic soda) |
Sodium liquid glass |
Detergent* |
Composition 2 |
twice |
For products made of steel, cast iron, copper, aluminum and alloys based on iron, copper, nickel, aluminum |
Sodium liquid glass |
Detergent* |
For products made of steel, cast iron, copper and alloys based on iron, copper and nickel, with increased requirements for the absence of precipitation on their surface |
Technical sodium nitrite |
Sodium phosphate (trisodium phosphate) |
Detergent* |
Detergent ML-72 |
Synthetic detergent MS-8 |
Detergent KM-2 |
For products made of steel, cast iron, copper, aluminum and alloys based on iron, copper, nickel, aluminum |
twice |
For products made of steel, cast iron, aluminum and alloys based on iron, nickel, aluminum |
Technical synthetic detergent VIMOL |
For products made of copper and its alloys |
Technical detergent TMS-31 |
For products made of steel, cast iron and alloys based on iron, nickel, aluminum |
Technical detergent Vertolin-74 |
once |
Technical detergent Vertolin-74 |
twice |
For products made of steel, cast iron, copper and alloys based on iron, copper and nickel |
once |
For products made of aluminum and its alloys |
Aluminum alloy degreaser (OCA) |
twice |
For products made of steel, cast iron, copper and alloys based on iron, copper and nickel |
Household detergents** |
3. Safety requirements
3.1. Safety requirements during the degreasing process must comply with GOST 12.3.008. 3.2. When working with components of aqueous cleaning solutions and solvents, you should comply with the safety requirements set out in the regulatory and technical documents for the substances used, given in Table. 1 and 3. 3.3. When carrying out degreasing of cryogenic vessels, if the presence of a person in them is required, the requirements of the “Temporary standard instructions for organizing the safe conduct of gas-hazardous work at enterprises of the Ministry of Chemical Industry of the USSR” approved by the State Mining and Technical Inspectorate of the USSR and the MHP of the USSR must be observed. Before carrying out work on degreasing cryogenic vessels that have been in use, they must be heated to temperatures in the range of 12-30°C and ventilated. Work should be carried out only when the oxygen content in the air inside the vessels ranges from 19 to 23%. The organization carrying out degreasing must approve instructions for carrying out this work in accordance with the established procedure. 3.4. Degreasing of individual parts by immersing them in baths of solvents should be carried out in devices with a closed or semi-closed degreasing cycle, equipped with local ventilation and preventing the entry of solvent vapors into the air of production premises. In this case, it is necessary to create continuity in the process of degreasing, drying and unloading parts. Solvent should be drained from equipment and baths into closed vessels through pipelines. 3.5. When degreasing equipment with solvents of group 1 (see clause 2.2.1.), it is necessary to ensure the tightness of the equipment in which degreasing is carried out. 3.6. Air emissions after drying and blowing must comply with GOST 17.2.3.02. 3.7. Ventilation of premises must ensure compliance with the air requirements of the working area in accordance with GOST 12.1.005. Table 4Maximum permissible concentrations of solvents in the air
|
Name of solvents |
Maximum permissible concentration value, mg/m 3 |
Hazard Class |
Trichlorethylene |
Tetrachlorethylene |
Freon 113 |
Freon 114B2 |
Gasoline solvent for the rubber industry (in terms of C) |
Nefras-S 50/170 |
White spirit (in terms of C) |
4. General technological requirements
4.1. The degreasing process consists of the following operations: - preparation for degreasing; - degreasing; - removal of residues of used degreasers. 4.2. Preparation for degreasing. 4.2.1. Before degreasing, the equipment must have a temperature from 12°C to 30°C. If it is technically necessary to carry out degreasing at lower or higher temperatures, in each specific case, a special technological process must be developed. Safety valves and instrumentation should be removed from the equipment and degreased separately. 4.2.2. Products coated with preservative lubricants must be depreserved in accordance with OST 26-04-2138 before degreasing with aqueous cleaning solutions or solvents. 4.2.3. Before degreasing with solvents, in order to avoid corrosion, the products must be thoroughly dried. 4.3. Degreasing. 4.3.1. Degreasing with solvents and aqueous cleaning solutions is carried out using the following methods: - filling the internal cavities of products; - immersion in baths; - circulation of solvents or washing solutions in the washed products; - condensation of solvent vapors in the washed products; - blast cleaning; - rubbing; - ultrasonic cleaning. 4.3.2. Selecting a degreasing method according to clause 4.3.1. produced depending on the size of the degreased products and the available technical means of degreasing. It is preferable to degrease the products before assembly, taking into account the requirements of clause 1.3. 4.3.3. Degreasing by filling the internal cavities of products or immersion in baths is used for individual parts or assembly units, as well as for small-sized products, and is carried out using solvents and aqueous washing solutions. The solvent must remain in the degreased products for at least 30 minutes. The presence of the solvent in the products should not exceed 1.5 hours. Degreasing with aqueous cleaning solutions is carried out twice with intermediate and final rinsing with hot water (60-80°C), the temperature of the solution is indicated in the table. 3. Products should be kept in each bath with aqueous cleaning solutions for 30 minutes, in baths with hot water - 15 minutes. Degreasing time with composition No. 2, table. 3 - 15 minutes. Keeping products in contact with aqueous cleaning solutions should not exceed 2 hours. 4.3.4. The method of circulating solvents or aqueous cleaning solutions is used for degreasing pipelines, hoses, as well as assembled products, the design of which allows the circulating solution to wash all surfaces to be degreased (tubular heat exchangers, etc. ). Degreasing by circulation is carried out in the product with solvents or washing solutions, the circulation speed is from 0.5 to 1.0 m/s. When circulating the solvent, the following conditions must be met: - circulation duration is at least 20 minutes. and no more than 1.5 hours; - the amount of circulating solvent is not less than the volume of the product, while washing the entire degreased surface with the solvent must be guaranteed; - the need for repeated degreasing is determined based on the results of analysis of the solvent drained from the product (see clause 5.3.). When circulating the cleaning solution, the following conditions must be met: - circulation duration is at least 30 minutes, but not more than 2 hours; - the amount of circulating aqueous washing solution is not less than the volume of the products, while washing the entire degreased surface with the solution must be guaranteed; - degreasing should be done twice with intermediate and final rinsing with hot water. 4.3.5. The degreasing method by condensation of solvent vapor is used for degreasing cryogenic vessels, pipelines, hoses and is performed by supplying solvent vapor heated to the boiling point to the degreased cavities, and subsequent condensation of the vapor on the degreased surface. Condensate is drained from the equipment. The solvent poured into the evaporator is not subject to requirements for the content of fatty contaminants in accordance with paragraphs. 2.2.5. and 2.2.6. Solvent consumption for one-time degreasing is 5-10 dm 3 per 1 m 2 of degreasing surface. Degreasing ends when the content of fatty contaminants in the condensate drained from the product is no more than 20 mg/dm 3 , but in any case, the solvent consumption must be at least 5 dm 3 /m 2 . 4.3.6. The jet cleaning method is used for degreasing individual products or internal surfaces of vessels and is carried out by applying a solvent or aqueous washing solution to the surface to be degreased with a jet under high pressure through special nozzles that ensure washing of the entire surface to be degreased. The amount of solvent or aqueous washing solution supplied to the surface to be degreased must be at least: for solvents 25 dm 3 / m 2, for washing solutions 50 dm 3 / m 2. When degreasing using the jet method, intermediate rinsing with hot water is not necessary. 4.3.7. The wiping method is used in the absence of special equipment or more effective degreasing methods. This method is used for degreasing large-sized products, cryogenic vessels, if they have hatches, and for small-sized products, subject to free access to the degreased cavities and is carried out by repeatedly wiping the degreased surfaces with napkins with cut edges, moistened with a hot aqueous washing solution at a temperature of 40-45 °C. Provided that safety requirements are met, it is allowed to use freon 113 and freon 114B2 or group 2 solvents for wiping small-sized products. 4.3.8. The ultrasonic cleaning method should be used to degrease products with complex configurations. Degreasing is carried out with group 1 solvents or hot aqueous cleaning solutions (see Tables 1, 3) in special ultrasonic baths. The duration of degreasing is 10-15 minutes. After degreasing with aqueous cleaning solutions, the products are washed with hot water. 4.4. Removing residues of used degreasers. 4.4.1. Removal of solvent residues from products after degreasing them is carried out by blowing with compressed air or nitrogen, according to clause 2.3.7. For group 2 solvents, only nitrogen is used. The gas used for purging must be heated to a temperature of 60-70°C. By the end of the purging, the gas at the outlet of the apparatus should have a temperature of at least 40-50°C. The duration of purging depends on the size and shape of the products being degreased and on the physicochemical properties of the solvents. Blowing should be carried out until the solvent odor is completely removed. The purge procedure is the same as when warming up equipment from a cold state. It is necessary to prevent the entry into the room of air contaminated with solvent vapors. 4.4.2. Products intended for storing and transporting medical oxygen should be purged until there is no solvent vapor in the gas; during control purge, no more than double gas exchange in the product should be ensured within 1 hour. 4.4.3. Residues of aqueous cleaning solutions should be removed by washing the products with hot drinking water at a temperature of 70-80°C. Washing is stopped if there is no foam in the water and the medium reacts neutrally (RN-6-8) when checked with universal indicator paper according to TU 6-09-1181. 4.4.4. After degreasing the products with aqueous washing solutions using the “wiping” method, remove the remaining solution by wiping with cloths moistened with warm water at a temperature of 35-40°C. Wiping the surface with napkins moistened with water ends when there are no traces of foam on the surface being wiped or on the napkins. The pH of the last rinse water should be 6-8. 4.4.5. Before drying items, the water must be completely drained. Particular attention should be paid to the complete removal of water from internal cavities and pockets. Dry metal products washed in water until moisture is completely removed by blowing with compressed air at a temperature of 100-120°C, and assembly units with non-metallic parts at a temperature of 70-80°C. By the end of the purge, the air temperature at the outlet of the apparatus should be no more than 10-15°C lower than the supply air temperature. Natural drying of parts of simple configurations and open surfaces is allowed in compliance with safety regulations. The interval between the end of washing and drying of the product should not exceed 10-15 minutes. Spots of white deposits from aqueous cleaning solutions are allowed with an area of no more than 10% of the surface of the washed products.5. Quality control of degreasing
5.1. Quality control of degreasing and technological parameters is carried out during development of the technological process, as well as at the request of the quality control department or the customer’s representative. In the absence of control, the quality of degreasing must be guaranteed by compliance with the adopted technology. 5.2. The need to control the degreasing of products, the percentage of controlled products and the chosen methodology must be specified in the technological documentation. 5.3. Depending on the method of degreasing and the design of the product, the quality of degreasing is controlled by directly determining the content of fatty contaminants on the surface of the product after degreasing or indirectly, by determining the content of fatty contaminants in the solvent before control degreasing and in the drained product after control degreasing, or on the surface of “witnesses”. " fat-free at the same time as the product. Solvent consumption during control degreasing is 20-30% of the amount required for a single degreasing of the product. 5.4. Quality control of degreasing is carried out in accordance with OST 26-04-2574. 5.5. The temperature of solutions, the temperature and composition of gases is monitored by universal measuring instruments (thermometers, gas analyzers of any type). ______________________________ * Example entry is preferred.Annex 1
Information
Explanation of terms
|
Explanation |
|
|
Degreasing |
Technological operation of reducing the content of fatty contaminants to the standards established by regulatory and technical documents or technical documentation. |
|
Low-grease equipment |
Equipment, the content of fatty contaminants on the surface of which complies with the standards. |
|
Pollution |
According to GOST 24869. |
|
Grease contamination |
Pollution consisting of mineral oils and other fatty substances. |
|
The amount of grease contamination per unit surface of the product. |
Appendix 2
Features of degreasing various types of equipment
1. General Provisions
1.1. Equipment operating with oxygen that complies with GOST 5583 and GOST 6331 is not degreased during operation, with the exception of liquid oxygen evaporators and other equipment in which fatty contaminants may enter the oxygen. 1.2. Equipment operating with oxygen containing 0.01 mg/dm3 of fatty contaminants or more must be degreased after the amount of fatty contaminants calculated by the formula reaches the normWhere S- inner surface of the vessel, m2; v- volume of oxygen poured or pumped into the vessel, dm 3; C - content of fatty contaminants in oxygen, mg/dm 3 ; n- number of fillings of the vessel; m- permissible content of fatty contaminants according to OST 26-04-1362 or GOST 12.2.052, mg/m 2. The equipment passport or other document must record the amount of oxygen passed and the content of fatty contaminants in it. Amendment No. 2 has supplemented this appendix with clause 1.3 1.3. The need to degrease oxygen equipment can be determined using test degreasing. If the design of the product allows, control degreasing should be carried out in places where fatty contaminants are most likely to be deposited and accumulated. The equipment may not be degreased if the oil content does not exceed the values regulated by the regulatory and technical documents specified in clause 1.1. of this standard.
2. Degreasing of air separation units
2.1. Degreasing of separation units assemblies is carried out only with solvents of group 1 (see Table 1) of the standard. The use of group 2 solvents for these purposes is not permitted. 2.2. The amount of solvent required for degreasing depends on the size of the separation unit and the degree of contamination with oil. The approximate amount of solvent required for one-time washing of some blocks is given in table. 1. Table 1Approximate solvent consumption for one-time washing of air separation units
2.3. To avoid corrosion, all separation unit apparatus must be thoroughly dried before degreasing with solvents. 2.4. Before degreasing air separation units, the equipment must be checked for leaks and any detected leaks must be eliminated. 2.5. Degreasing of communications and internal cavities of heat exchangers is carried out by circulating the solvent in the washed cavities for 1-1.5 hours. 2.6. Degreasing of devices (condensers, bottom column cube, regenerators, etc.) is carried out by filling with solvent up to 3/4 of the volume, followed by bubbling with air or nitrogen for 1-1.5 hours or by condensing solvent vapors. 2.7. Adsorbers are degreased after removing the adsorbent from them by wiping the adsorber body and basket. It is not allowed to degrease acetylene adsorber assemblies. 2.8. Degreasing of the filter elements of expander filters is carried out with aqueous washing solutions, for example, in washing machines, or by circulating a solvent through the filter element in a special device. Degreasing the filter fabric by hand washing in a solvent is not allowed.3. Degreasing of cryogenic vessels, cylinders and transport tanks
3.1. Vessels of liquid medical oxygen are degreased when fatty contaminants are detected in liquid oxygen in an amount of 0.01 mg/dm 3 or more, confirmed in five consecutive analyzes. 3.2. Vessels and cylinders are degreased by filling up to 1/3 of the vessel with solvent, followed by rotation or rocking in a special device. The specified equipment can also be degreased with a hot aqueous cleaning solution, filling the equipment with it or washing its walls using the jet method. 3.3. To degrease transport tanks and vessels, the method of condensation of solvent vapors can be used. Before degreasing transport tanks and vessels using this method, their component evaporators should be removed and degreased separately. Solvent vapor is supplied to the vessel, preheated to a temperature of 30-40°C, through a “fill-empty” valve. Air is forced out of the vessel through the gas release valve during the first hour of solvent vapor supply. The condensate flows into the lower part of the vessel. If the pressure in a transport tank or vessel when supplying solvent vapor rises above 0.05 MPa (0.5 kgf/cm2), the vessel should be cooled by blowing with cold air or nitrogen until the outlet gas temperature drops to a temperature of 293- 298 K (20-25°C), then continue degreasing. The condensate is drained and the content of fatty contaminants is determined. Degreasing is completed when the content of fatty contaminants in the drained solvent is no more than 20 mg/dm 3 . 3.4. Vessels and cylinders with hatches can be degreased by washing their walls with a jet method or wiping the inner walls of the vessels with cloth napkins moistened with a hot aqueous cleaning solution; after wiping, the remaining solution is drained through the bottom drain. The evaporator and bottom drain communications are washed again with a clean solution. 3.5. When degreasing vessels using the “wiping” method, the following rules must be observed: - before carrying out degreasing work, a vessel that has been in use must be warmed up in accordance with clause 3.3. standard; - workers performing degreasing must be instructed on the rules and safe methods of working inside closed equipment; - the person responsible for degreasing must inspect the work site and make sure that the vessel is warmed up and prepared for work; - when working, the requirements of the “Temporary Standard Instructions for Organizing the Safe Conduct of Gas Hazardous Work at Enterprises of the USSR Ministry of Chemical Industry”, approved by the USSR State Mining and Technical Supervision Authority and the USSR MHP, must be observed.4. Degreasing liquid oxygen pumps
4.1. Parts of liquid oxygen pumps are degreased by immersion in baths, preferably with aqueous cleaning solutions, in accordance with the instructions in paragraph 4.3.3. standard 4.2. Communications to the pump are degreased by circulating an aqueous cleaning solution or solvent or condensing solvent vapors in accordance with the instructions in Section 8. 4.3. Flake graphite is degreased with a solvent in a separate vessel. After thorough mixing, the solvent is drained, and the graphite is poured out and dried in the open air or in an oven until the smell of the solvent is completely removed.5. Degreasing of gasification plants
5.1. Vessels of warm and cold gasifiers are degreased by filling them with a solvent, followed by bubbling nitrogen or air. 5.2. Evaporators of gasification plants are degreased by circulating solvents through them. The frequency of degreasing of evaporators operating with liquid oxygen in accordance with GOST 6331 is determined by formula 1, clause 1.2. in this case, the content of fatty contaminants in oxygen is assumed to be 0.01 mg/dm 3 . Degreasing of gasifiers at a pressure of 15 MPa (150 kgf/cm2) must be carried out at least after 1000 hours of operation of the installation.The numbering of points is given in accordance with the source
5.4. After degreasing and purging the gasifier with medical oxygen, the gaseous product is released into the atmosphere for 1 hour without increasing the pressure.6. Degreasing of cryogenic cold gasifiers type GKH
6.1. When the gasifier operates on oxygen in accordance with GOST 6331, control degreasing of one of the evaporators is carried out after the mass of oxygen, determined by the formula, has passed through the gasifier installation:Where M- mass, t; F- internal area of the gasifier panel, m2. Control degreasing is carried out with solvents of group 1 of table. 1 standard in an amount of 20-30% of the total volume poured. After control degreasing, the content of fatty contaminants in the solvent is determined in accordance with OST 26-04-2574. 6.2. Degreasing of the remaining evaporators is carried out if the content of fatty contaminants exceeds the permissible standards according to 26-04-1362. Degreasing is carried out using the circulation method with a solvent of group 1 of the table. 1 standard. 6.3. When using oxygen containing fatty contaminants of more than 0.01 mg/dm 3, the gasifier (tank, fitting cabinet, evaporators and pipelines) is degreased after the mass of oxygen determined according to clause 1.2 has passed through the tank. 6.4. Degreasing of gasifier tanks is carried out by condensation of solvent vapors in accordance with clause 4.3.5. standard Evaporators are degreased using the solvent circulation method. Degreasing ends when the content of fatty contaminants in the drained condensate is no more than 20 mg/dm 3 .6.5. The spindle groups of fittings are degreased by wiping with aqueous cleaning solutions. 6.6. Degreasing of spindle groups of fittings with solvents of group 1 of table. 1 standard is not allowed. Degreasing evaporators with aqueous cleaning solutions is not allowed. 6.7. After degreasing, the gasifier is purged until all remaining solvent is removed. The complete removal of solvents must be verified by analysis. The medical oxygen gasifier should be purged until there is no solvent vapor in the gas during control purging (no more than 2 mg/m3). 6.8. When using oxygen in a gasifier in accordance with GOST 6331, degreasing of the tank, fitting cabinet and pipelines is not carried out.
7. Degreasing oxygen compressors
7.1. Small parts are degreased according to clause 4.3.3. standard 7.2. Degreasing of valves with solvents should only be done in disassembled form. 7.3. Large parts, for example, a cylinder, cover, rods, pistons, etc., are degreased in baths with an aqueous cleaning solution or solvent, or by wiping the surfaces with napkins moistened with low-toxic solvents (see clause 4.3.7 of the standard) or hot water detergent solution. 7.4. Shell-and-tube refrigerators, moisture separators, receivers and other containers are filled 1/3-1/2 of the volume with solvent, after which edging is performed. If parts are degreased after re-preservation, it is necessary to wash the parts two or three times with a solvent. It is recommended to degrease these devices by condensing solvent vapors or washing them with a hot washing solution (see clause 4.3.5 of the standard). 7.5. Coil refrigerators are degreased with a solvent or hot washing solution using the circulation or filling method (see clause 4.3.4.; 4.3.3. of the standard). 7.6. After degreasing, the compressor must be run in air or nitrogen for 2 hours. 7.7. Degreasing of oxygen turbocompressors is carried out in accordance with RTM 26-12-43.8. Degreasing of pipelines and hoses
8.1. The need to degrease assembled pipelines with a pressure above 4.0 MPa (40 kgf/cm2) is determined by the technical documentation; the decision on degreasing is recommended to be made after monitoring the open ends of the pipeline, in accordance with OST 26-04-2574. 8.2. Liquid oxygen pipelines are checked for the presence of fatty contaminants at least once a year, in the case when oxygen with a content of fatty contaminants exceeding the requirements of GOST 6331 is transported through it. Areas with the lowest flow rate are subject to a control check for the presence of fatty contaminants, and with a uniform flow - entrance areas. Control is carried out in accordance with section 5 of the standard. If the standard OST 26-04-1362 is exceeded, the entire pipeline is subjected to degreasing. 8.3. When degreasing by immersion in baths, pipes are placed in special baths filled with aqueous cleaning solutions or solvents and maintained in accordance with the instructions in clause 4.3.3. standard 8.4. For degreasing by circulation, the pipelines are connected to a special system equipped with a pump, through which aqueous cleaning solutions or solvents are pumped (see clause 4.3.4 of the standard). 8.5. Degreasing the inner surface of pipes using the filling method is carried out as follows: technological plugs are installed at the ends of the pipes. Solvent is poured into the plug through the corresponding fitting, after which the fitting is closed, and the pipes or hoses are laid horizontally. The pipes should remain in a horizontal position for 10-20 minutes, during which time they should be turned 3-4 times to wash the entire inner surface with solvent. Pipes filled with solvent can also be moved in special rockers or turning mechanisms. 8.6. Sections of the installed pipeline are degreased by circulating a solvent or aqueous cleaning solution. 8.7. The approximate solvent consumption required for one-time degreasing of the inner surface of one linear meter of pipe is calculated using the formula: (2)
Where Q- solvent consumption, dm 3 /m; D- internal diameter of the pipe, cm. Solvent consumption for one-time degreasing of pipes is given in table. 2. Table 2
Solvent consumption for one-time degreasing of pipes
Continuation of the table. 2 Continuation of table. 2 8.8. Small sections of pipelines can be degreased by wiping or jetting an aqueous cleaning solution using special devices. 8.9. During installation, the outer surfaces of the ends for a length of 0.5 m are wiped with napkins soaked in a solvent or aqueous washing solution and dried in the open air. 8.10. All parts intended for connecting hoses to the container must be degreased by wiping if they were possibly contaminated during storage. 8.11. The hoses of medical oxygen tanks are degreased along with the vessel. 8.12. Fat-free sections of pipelines to be stored or transported must be plugged and sealed. 8.13. Pipeline sections subjected to chemical passivation or other types of chemical surface treatment before assembly may not be degreased if the requirements of clause 1.3 are met. standard 8.14. Sections of pipelines and hoses that were degreased during manufacture, received for installation with plugs and have the appropriate marks in the passport, are not degreased. 8.15. Pipeline assemblies are not subject to degreasing at pressures up to 4.0 MPa (40 kgf/cm2), if sections of pipelines before assembly or pipeline assemblies were cleaned of scale, slag, etc. by etching, sandblasting and shot blasting. 8.16. Main pipelines and inter-shop oxygen pipelines, pressure up to 1.6 MPa (16 kgf/cm2), assemblies are not degreased if, before connecting individual pipes, a visual inspection confirms the absence of stains of greasy contaminants on the surface of the pipelines, for which a report must be drawn up .9. Degreasing of fittings and devices
9.1. Degreasing is carried out after manufacturing, before installation and after repair, i.e. in cases where contamination of the fittings was possible. 9.2. The fittings are degreased in disassembled form with aqueous cleaning solutions. It is possible to pre-wipe with a cloth soaked in white spirit or kerosene. In this case, special attention should be paid to fire safety measures. 9.3. In case of technical necessity, it is allowed to degrease the fittings without disassembling. To determine the possibility of degreasing purchased fittings without disassembling, it is recommended to degrease, dry, and then disassemble and check for residual grease content. If the residual content meets the standards, in accordance with clause 1.1. standard, in the future the fittings can be degreased without disassembling. Particular attention should be paid to the oil seal and its packing. 9.4. When degreasing fittings without disassembling, one should take into account the compatibility of all materials from which the fittings are made, especially seals, with the detergents used. 9.5. The fittings are not subject to degreasing before installation if degreasing was carried out at the manufacturer (which must be confirmed by accompanying documents or appropriate branding) and the packaging is not damaged. 9.6. Gaskets made of rubber, paronite, fiber, fluoroplastic oil seal rings, parts made of fiberglass, polycarbonate and textolite are degreased by wiping with aqueous detergent solutions and rinsed with water. 9.7. Asbestos used for stuffing box fittings is degreased by calcination at a temperature of 300°C for 2-3 minutes. 9.8. Degreasing of instruments for measuring flow and pressure is carried out in accordance with OST 26-04-2158.Appendix 3
Mandatory
Requirements for solvents
Incoming control|
Indicator name |
Control method |
1. Appearance | Colorless, transparent liquid | Determined visually | 2. Content of mechanical impurities and water | Must be transparent and free of foreign impurities suspended and deposited on the bottom of the cylinder | Pour the solvent into a glass cylinder with a diameter of 40-50 mm | 3. Reaction of the environment | The aqueous layer should not turn pink | The solvent in an amount of 15 cm 3 is placed in a separating funnel, 40 cm 3 of distilled water is added and shaken for 3-5 minutes; after settling, the aqueous layer is drained and methyl orange 0.1% aqueous solution is added to it | 4. Oil content | Section 2 of the standard, table. 2 | According to OST 2 6-04-2574 |
Appendix 4
Mandatory
Preparation of baths with aqueous cleaning solutions, their control and adjustment
1. Drawing up baths
1.1. The amount of each component provided for in the recipe is calculated based on the composition of the bath and its useful capacity. The components of the solution, depending on local conditions, can be dissolved separately in auxiliary vessels or directly in the bath in which degreasing is carried out. Dissolution is carried out by heating to a temperature of 60-70°C with vigorous stirring of the solutions with mechanical stirrers or air bubbling. 1.2. After drawing up the bath, determine the total alkalinity of the freshly prepared composition according to the method given below.2. Control and adjustment of baths
2.1. General requirements
2.1.1. Control analyzes of the composition of aqueous washing solutions in degreasing baths are carried out at least 2 times a week by determining the total alkalinity of the solution. Baths are adjusted based on the results of control tests. A general change of the aqueous cleaning solution with regular loading of the bath is carried out once a week. 2.1.2. When using baths, do not allow contamination to accumulate on the surface of the solutions. Regularly remove grease from the surface using special devices (with a holey spoon or mesh) or special grease traps. 2.1.3. Before taking a sample of the solution for control analysis, it is necessary to bring the solution to the desired level and mix.
2.2. Determination of the total alkalinity of a solution
Change No. 1, approved by the Deputy Minister of Chemical and Petroleum Engineering on January 4, 1987, introduced changes to subparagraph 2.241 of this appendix, which come into force on July 1, 1987.Amendment No. 2 amended subclause 2.2.1 of this appendix 2.2.1. Reagents, solutions and utensils used: - hydrochloric acid, according to GOST 3118, 0.1 m solution; - methyl orange indicator according to TU 6-09-5171, 0.1%; - distilled water, according to GOST 6709; - conical flasks, according to GOST 25336, with a capacity of 250 cm 3; - measuring pipettes, according to GOST 1770, with a capacity of 100 cm 3; - measuring burette, according to GOST 1770, with a capacity of 25 cm3. 2.2.2. To carry out the determination, 5 cm 3 of a cooled aqueous washing solution is placed in a conical flask with a capacity of 250 cm 3, diluted with water to 100 cm 3, 2-3 drops of methyl orange solution are added and titrated with 0.1 N HCl until the yellow color changes to pale pink. 2.2.3. The total alkalinity of the solution in terms of NaOH in g/dm 3 is calculated using the formula:
Where q- amount of 0.1 N solution HCl, spent on titration, cm 3; 0.004 - solution titer HCl, G; TO- correction to the titer of 0.1 N solution HCl;m- amount of solution taken for analysis, cm3.
2.3. Bathtub adjustments
2.3.1. Based on the results of control tests, the baths are adjusted if the total alkalinity of the solution decreases by more than 20%. 2.3.2. When making adjustments, add all components of the solution to the bath. The amount to be added is calculated based on the main component, which determines the total alkalinity of the solution. For example, according to a control analysis of a bath of the composition: NaOH - 10 g; Na 3 PO 4 -15 g; Na 2 SiO 3 -2 g; OP-7 - 2-3 g; H 2 O - 1 dm 3 total alkalinity decreased by 35%. When adjusting, it is necessary to add to the bath at the rate of 1 dm 3: NaOH - 3.5 g; Na 2 SiO 3 - 0.7 g; Na 3 PO 4 - 5.2 g; OP-7 - 0.7-1 g. Change No. 2 introduced changes to this ListChange No. 1, approved by the Deputy Minister of Chemical and Petroleum Engineering on January 4, 1987, introduced changes to this List that come into force on July 1, 1987.
List of reference normative and technical documents (NTD)
|
Designation |
Name |
Sheet (page) |
GOST 9.010-80 |
ESZKS. Compressed air for spraying paints and varnishes. Technical requirements. Rules and methods of control |
GOST 9.305-84 |
E S 3 KS. Metallic and non-metallic, inorganic coatings. Operations of technological processes for obtaining coating |
GOST 12.1.001-83 |
SSBT. Ultrasound. General safety requirements. |
GOST 12.1.004-85 |
SSBT. Fire safety. General requirements. |
GOST 12.1.014-84 |
SSBT. Work area air. Method for measuring the concentration of harmful substances using indicator tubes. |
GOST 12.1.016-79 |
SSBT. Work area air. Requirements for methods for measuring concentrations of harmful substances. |
GOST 12.1.019-79 |
SSBT. Electrical safety. General requirements. |
GOST 12.2.052 -81 |
SSBT. Equipment working with oxygen gas. General safety requirements |
GOST 12.3.008-75 |
SSBT. Production of metallic and non-metallic inorganic coatings. General safety requirements. |
GOST 12.4.011-89 |
SSBT. Protective equipment for workers. Classification. |
GOST 12.4.026-81 |
SSBT. Signal colors and safety signs |
GOST 17.2.3.02-78 |
Protection of Nature. Atmosphere. Rules for establishing permissible emissions of harmful substances by industrial enterprises |
Trisodium phosphate. Technical conditions. |
Nefrases S2-80/120 and SZ-80/120. Technical conditions. |
GOST 1770-74E |
Laboratory glassware. Cylinders, beakers, flasks. Technical conditions. |
GOST 22 63-79 |
Technical sodium hydroxide. Technical conditions. |
GOST 2874 -82 |
Drinking water. Hygienic requirements for quality control. |
GOST 3118-77 |
Hydrochloric acid. Technical conditions. |
GOST 3134-78 |
Gasoline solvent for the paint and varnish industry. Technical conditions. |
GOST 4328-77 |
Reagents. Sodium hydroxide. Technical conditions. |
GOST 4753-68 |
Kerosene for lighting. Technical conditions. |
GOST 5583-78 |
Oxygen gas, technical and medical. Technical conditions. |
GOST 6331-78 |
Liquid oxygen technical and medical. Technical conditions. |
GOST 6709-72 |
Distilled water. |
GOST 8505-80 |
Nefras-S 50/170. Technical conditions. |
GOST 9293 -74 |
Nitrogen gaseous and liquid. Technical conditions. |
GOST 9337-79 |
Sodium phosphate 12-water. Technical conditions. |
GOST 9976-83 |
Technical trichlorethylene. Technical conditions. |
GOST 2533 6-82 |
Laboratory glassware and equipment. Type, main parameters and dimensions. |
GOST 10652-73 |
Disodium ethylenediamine salt - N, N, N¢, N¢ tetraacetic acid, 2-water (Trilon-B). |
GOST 13078-81 |
Liquid sodium glass. Technical conditions. |
GOST 15899-79 |
Freon 114B2. Technical conditions. |
GOST 19906-74 |
Technical sodium nitrite. Technical conditions. |
OST 26-04-13 62-75 |
OST 26-04-2138-81 |
Temporary anti-corrosion protection of products. |
OST 26-04-2158-78 |
SSBT. Flow and pressure measuring instruments. Safety requirements for use in gaseous oxygen environments. |
OST 26-04-2574-80 |
Gases, cryogenic products, water. Methods for determining the content of mineral oils. |
OST 26-04-2578-80 |
Gases, cryogenic products. Chromatographic method for determining impurities in chlorofluoroorganic solvents. |
OST 26-04-2600-83 |
Cryogenic equipment. General technical conditions. |
RTM 26-12-43-81 |
Degreasing of centrifugal oxygen compressors. |
TU 6-01-927-76 |
Trichlorethylene stabilizer (STAT-1). |
TU 6-02-640-80 |
Nonionic drug syntamid-5. |
TU 6-09-1181-76 |
Universal indicator paper for determining pH 1-10 and 7-14. |
TU 6-09-5171-84 |
Methyl orange indicator (sodium para-dimethylanino-azobenzenesulfonic acid) |
TU 6-01-956-86 |
Tetrachlorethylene (perchlorethylene) |
TU 6-14-577-88 |
Detergent preparation syntanol DS-10 |
TU 6-15-978-76 |
Synthetic detergent NS-8. |
Drug KM-2. |
TU 38.103 62-87 |
Surfactant NEONOL AF9.12 |
TU 38-10761-75 |
Synthetic detergent Vimol. |
Technical detergent Vertolin-74. |
TU 38-107113-78 |
Technical detergent TNS-31. |
TU 38.50724-84 |
No.________ "__"______ 20__
Representative of the developer or customer_____________________________________________
(job title,
Representative of the person carrying out the construction, __________________________
(job title,
__________________________________________________________________________
surname, initials, details of the document on representation)
Representative of the person carrying out the construction on construction control issues_________________________________________________________________
(job title,
__________________________________________________________________________
surname, initials, details of the document on representation)
Representative of the person carrying out the construction, performing technical manual installation work, (chief engineer)______________________________
__________________________________________________________________________
Representative of the person preparing the project documentation______
__________________________________________________________________________
(position, surname, initials
__________________________________________________________________________
details of the document on representation)
Representative of the person carrying out the construction who carried out the work on degreasing the equipment, _______________________________________________
(position, surname, initials,
__________________________________________________________________________
details of the document on representation)
as well as other representatives of persons involved in defatting,_________________
__________________________________________________________________________
(position, surname, initials,
__________________________________________________________________________
details of the document on representation)
carried out process control and review of the results of degreasing of equipment, fittings, pipelines, assembly units and parts (hereinafter referred to as the product), presented ___________________________________________
(name of the person, actually
__________________________________________________________________________
presenting the product for degreasing)
and have drawn up this act as follows:
1. The product has been degreased:
a) technological equipment (apparatus, container, etc.)
b) fittings of the same type
c) pipeline, pipeline network
d) assembly unit, part
2. Accompanying documents presented________________________________________________
__________________________________________________________________________
__________________________________________________________________________
as well as design documentation for non-standard equipment________________
__________________________________________________________________________
(number, other details of the drawing, name of the design
__________________________________________________________________________
documentation, information about persons carrying out
__________________________________________________________________________
preparation of the design documentation section)
3. Documents are presented confirming the product’s compliance with the requirements for it, including:
a) for compliance with the requirements of technical documentation of manufacturers and design documentation of developers, technical regulations (norms and rules), other regulatory legal acts______________________________
(Name
__________________________________________________________________________
document of compliance, date, number, other details)
b) results of examinations, surveys, laboratory and other tests and work performed under construction control
__________________________________________________________________________
(name of document, date, number, other details)
4. The necessary tests and testing have been carried out___________________________
__________________________________________________________________________
(name of document, date, number, other details)
5. Documents confirming the quality of degreasing of the product from the manufacturer have been presented, _______________________________________________________________
__________________________________________________________________________
(name of document, date, number, other details)
6. Product manufactured (delivered)__________________________________________
(name of manufacturer (supplier, intermediary),
__________________________________________________________________________
name, number and date of issue of the state registration certificate, OGRN, TIN,
__________________________________________________________________________
postal details, telephone, fax - for legal entities;
__________________________________________________________________________
last name, first name, patronymic, passport details,
__________________________________________________________________________
place of residence, telephone, fax - for individuals)
7. Characteristics of the product subjected to degreasing of internal surfaces,_______________________________________________________________
(purpose of the product, technological
__________________________________________________________________________
the environment in the product, its condition and characteristics,
__________________________________________________________________________
requirements for cleanliness of internal surfaces)
8. A work permit has been presented to perform the work.
__________________________________________________________________________
(name of document, date, number, other details)
To prevent an explosion of an oxygen cylinder, you need to know exactly the residual pressure in it. To do this, you need to use a special oxygen manometer, which differs from other devices for measuring pressure in general and gases in particular. From this article you will learn how important it is to correctly install the pressure gauge on an oxygen cylinder.
Oxygen in cylinders is considered medicine, because it is widely used in medicine. Over the past 10 years, there have been about 50 cases of explosions of oxygen cylinders in the CIS, most of them in hospitals. Before explaining in detail the direct relationship between safety and the need to install a pressure gauge on an oxygen cylinder, let's understand the basic concepts.
Oxygen gas technical and medical non-flammable, non-toxic and non-explosive. But since it greatly increases the ability of other materials to burn, it becomes explosive when mixed with other gases. Contact of oxygen with fats and lubricants is very dangerous.
Oxygen balloon - The cylinder, made of steel, is intended for the transportation and storage of oxygen, is painted blue, and the cylinder must have the inscription “oxygen” in black.
Gas pressure gauge - a device for measuring pressure in a gas cylinder. For each type of gas, a pressure gauge designed specifically for it is installed on the cylinder.
I would like to dwell on the types of pressure gauges in more detail.
Types of pressure gauges.
To distinguish the housing of pressure gauges for different gases, they are painted in different colors: blue for pressure gauges for oxygen cylinders, white for acetylene and red for hydrogen. Also on the pressure gauge dial there may be a special inscription indicating the type of gas for which the cylinder is intended.
Pressure gauges are also divided by accuracy class: numbers 0.2; 0.6; 1.0; 1.5; 2.5; 4.0, in ascending order, shows decreasing accuracy of the device.
Absolute pressure gauges measure absolute pressure, while gauge pressure gauges measure the difference between the pressure in a system and atmospheric pressure.
Installation and operation of a pressure gauge on an oxygen cylinder.
Failure to comply with certain conditions when using gas pressure gauges can cause an explosion with serious consequences or destroy the device.
The pressure gauge for the oxygen cylinder must be securely attached to the cylinder during installation. Installation of the device is carried out only by pressing on the fitting using special keys. It is strictly forbidden to apply mechanical forces to the housing when installing the pressure gauge. When installing the pressure gauge, it is very important to thoroughly degrease it to prevent the oil from coming into contact with oxygen.
Pressure gauges on oxygen cylinders can only be used if the ambient temperature does not exceed 70 °C.
Why is it important to control the pressure in the oxygen cylinder?
Empty oxygen cylinders are filled with oxygen to a pressure of 150 kgf/cm2. Thus, with a filling pressure set for oxygen cylinders of 150 kgf/cm 2 and a temperature of 20 ° C, a cylinder with a capacity of 40 liters holds about 6 m 3 of gas. The actual value of the filling pressure of the cylinders is taken depending on the temperature in the filling room.
Explosions are most often caused by mixing oxygen with flammable gas. Gas enters the cylinder during gas welding work, when the pressure of oxygen in the cylinder is lower than that of the combustible gas and the latter flows into the oxygen cylinder.
Therefore, it is very important when accepting empty cylinders for filling to be sure to check the residual oxygen pressure in the cylinder (preferably at least 3 kgf/cm2) and check the presence of flammable gas in the cylinder using a sensitive gas leak detector on the outflowing stream.
Cylinders without residual pressure must be sent to an inspection point or pre-filled with nitrogen gas to a pressure of 3-5 kgf/cm 2, checked by the outflowing stream using a sensitive gas leak detector for the absence of flammable gas, and only after that, removing nitrogen gas and performing a preliminary “washing” " oxygen cylinder, send it for final filling.
Thus, proper selection of a pressure gauge and installation of it on an oxygen cylinder is an important safety condition when using an oxygen cylinder.