Technical Specifications TU Research Articles

Особенности технического регулирования технических устройств

The article examines the issues of identification of technical devices: cartridge filters of natural gas, the procedure of their compliance with current requirements of industrial safety as well as how the assessment affects the service life of a device in the future. Specific attention has been paid to two technical regulations of the Customs Union (TR TU 032/2013 and 010/2011) defined as basic documents for cartridge filters. The scope of application of technical regulations and their main provisions have been considered. The main properties of natural gas cartridge filters have been described. The fact of the production of natural gas cartridge filters by different manufacturing plants in accordance with different production standards (Technical Specifications TU 3683-001-28494535—2018 and GOST 34347—2017) and the availability of different documents confirming the compliance with safety requirements provided by technical regulations ТР ТС 032/2013 and TR TU 010/2011 is mentioned. Technical devices have been identified; as a result, it has been detected that monotypic devices may differ after the identification in accordance with TR TU: «pipelines and valves of the design pressure exceeding 0.05 MPa, nominal diameter exceeding 25 mm designed for compressed, liquefied, and dissolved under pressure gases and vapors and used for working media of group 1» or «vessels designed for compressed, liquefied, and dissolved under pressure gases and vapors used for working media of group 1» as well as «pipeline industrial valves» or «air separation and rare gas units». The impact of the results of the conformity assessment of technical devices for their service life has been analyzed. Regulatory documents establishing the requirements for the operation of technical devices have been specified. The results of the analysis have revealed significant differences within the process of registration, accounting, and commissioning of technical devices. The authors believe that the root cause of different approaches to the assessment of conformity affecting the service life of technical devices in the future is the different approaches to the development of their technical certificates.

Mastering the production of special types of pipes made of ferritic-martensitic steels, taking into account the peculiarities of the microstructure and properties

The main results of the development of a technology for the production of special types of pipe products, carried out taking into account the features of the microstructure, the laws of phase and structural transformations, as well as the resistance to plastic deformation in a wide temperature range of steels of the ferritic-martensitic class of grades EP450-Sh and EP823-Sh, are presented. The microstructure was studied with determination of the grain size, the content of non-metallic inclusions and fraction of the main structural components depending on the heating temperature for quenching. Using the Gleeble 3800 multifunctional complex, the resistance to fracture deformation at high temperatures was determined. In the laboratory of JSC RusNITI, physical modeling of the cold rolling process in a two-roll stand was carried out according to the oval-oval calibration scheme in the mode of successive increase in reduction. On the basis of the studies carried out for the steel grades under study, were developed the modes for pressing stock hot-pressed pipes with dimensions of 133.0×14.0 and 89.0×7.0 mm; cold rolling of both large-scale samples of round pipes and stock pipes intended for subsequent production of hexagonal pipes; final heat treatment of pipes of round and hexagonal sections, ensuring compliance with the requirements of technical specifications. As part of the project direction, PJSC TMK developed and implemented, through inter-plant cooperation with JSC VTZ, TMK-INOKS Ltd. and JSC RusNITI, a new technology for manufacturing hexagonal pipes according to the hot pressing – cold deformation scheme (rolling, profiling), whereby large-scale samples of new types of pipes for special purposes were obtained from EP450-Sh and EP823-Sh steel grades. The results obtained are used to form a set of technical requirements for the new type of high-tech pipe products, presented in technical specifications TU 420-2021, TU 422-2021, TU 423–2021.

Досвід впровадження адитивних технологій при ремонті деталей ГТД зі сплава ЕП 648 ВІ (ХН50ВМТЮБ-ВІ) в умовах серійного виробництва

Technology has been developed for repairing the nozzle assembly (SA) casing in the D-18T engine by additively growing the damaged part by microplasma surfacing with a powder of EP648VI (KhN50VMTYUB-VI) alloy. Traditionally, a part with such damage was rejected. The cost of replacing a damaged part with a new one is about 200 thousand hryvnias. The article discusses the equipment and features of the growing technology using the method of microplasma multilayer surfacing. Additive growth of the cut-damaged part was carried out on a STARWELD 190 H robotic installation for microplasma powder surfacing using EP648 VI alloy powders with a 63–163 micron fraction. After growing, heat treatment (aging at 700 ºС, exposure for 16 hours), mechanical processing, and quality control of the grown part were carried out. To create an evidence base to determine the possibility of installing a repaired part on the engine, a set of studies was carried out, which included the determination of the chemical composition of samples grown using a technology similar to repair, metallographic studies, and mechanical tests. As a result, it was found that the chemical composition of the deposited metal meets the requirements of the technical specifications TU 14-1-3046-97 "Bars made of heat-resistant alloy grade KhN50VMTYUB (EP648), and the microstructure of the deposited metal after heat treatment is a γ - solid solution with the presence of carbides, carbonitrides and a small amount of γ´ phase, which corresponds to the normally heat-treated state of the EP 648 VI (KhN50VMTYUB-VI) alloy and the level of mechanical properties of the grown alloy with subsequent serial heat treatment (aging at 700 ° C, holding for 16 hours) not lower than the level of the forging used at serial production of a part. The economic effect of the introduction of this technology is shown, which is more than 100 thousand hryvnias (about 23% of the cost of a new part).

Performance of Surface Layers Applied by New Powder Wire in Highly Abrasive Wear

The influence of chromium (in high concentrations) as a reducing agent in the manufacture of Fe–C–Si–Mn–Cr–Ni–Mo powder wire is studied. Metal layers are applied to St3 steel plates under An-26S flux, with preliminary heating of the basic metal to 250–300°C. Powder wire (diameter 5 mm) manufactured on a laboratory machine is applied by means of an ASAW-1250 welding system, in the following conditions: current 420–520 A; voltage 28–32 V; welding rate 7.2–9.0 m/h. After surfacing, the metal is cooled to room temperature. In producing the powder wire, the filler consists of PZhV1 iron powder (State Standard GOST 9849–86); FS75 ferrosilicon powder (State Standard GOST 1415–93); FKh900A high-carbon ferrochrome powder (State Standard GOST 4757–91); FMn78(A) carbon ferromanganese (State Standard GOST 4755–91); PNK-1L5 nickel powder (State Standard GOST 9722–97); FMo60 ferromolybdenum powder (State Standard GOST 4759–91); FV50U0.6 ferrovanadium powder (State Standard GOST 27130–94); PK-1U cobalt powder (State Standard GOST 9721–79); and PVN tungsten powder (Technical Specifications TU 48-19-72–92). Within the chosen concentration ranges, carbon, manganese, chromium, molybdenum, nickel, and to some extent vanadium increase the hardness of the applied layer and also decrease the wear rate of the samples. The low viscosity of the matrix prevents the retention of tungsten carbide at the surface. Consequently, wear occurs not by uniform abrasion of the surface but by the extraction of high-strength carbon particles from the matrix. As a result, new cracks are formed in the matrix, which accelerates its wear. Multifactorial correlational analysis yields dependences of the hardness and wear resistance of the applied layer on the mass content of the elements in the Fe–C–Si–Mn–Cr–Ni–Mo powder wire. These dependences may be used to predict the hardness and wear resistance of the applied layer with change in its chemical composition.

Reduction of Tungsten from Its Oxide in Surfacing by Means of Powder-Core Wire

The influence of introducing tungsten and tungsten concentrate in powder-core wire on the structure, microhardness of the structural components, hardness, and wear of the applied metal layer is studied. For surfacing, tungsten-bearing powder wire (types H and E in the IIW classification) is produced in the laboratory. The fillers employed are KR-1 silicon powder (State Standard GOST 2169–69); MR-0 manganese powder (State Standard GOST 6008–82); PKhA-1M chromium powder (Technical Specifications TU 14-1-1474–75); VEL-1 vanadium (Technical Specifications TU 48-0533–71); PNK-1L5 nickel (State Standard GOST 9722–97); PAP-1 aluminum (State Standard GOST 5494–95); PVT tungsten (Technical Specifications TU 48-19-72–92); and PZhV-1 iron powder (State Standard GOST 0489–96). In some wire, tungsten powder is replaced by KSh-4 tungsten concentrate (State Standard GOST 213–83), produced by OAO GK AIR. The carbon-bearing reducing agent employed is gas-purification dust from aluminum production. Its composition is as follows: 21.00–43.27 wt % Al2O3, 18–27 wt % F, 8–13 wt % Na2O, 0.4–6.0 wt % K2O, 0.7–2.1 wt % CaO, 0.50–2.48 wt % SiO2, 2.1–2.3 wt % Fe2O3; 12.5–28.2 wt % Ctot; 0.03–0.90 wt % MnO, 0.04–0.90 wt % MgO, 0.09–0.46 wt % S, and 0.10–0.18 wt % P. The wire (diameter 5 mm) is produced on laboratory equipment. An ASAW 1250 system is used for surfacing, in the following conditions: Is = 400–450 A; Uarc = 32–36 V; Vs = 24–30 m/h. In surfacing, five metal layers are applied, under a layer of AN-26S flux and flux based on slag from silicomanganese production. The chemical composition of the applied metal is determined, and metallographic data are obtained: the size of the former austenite grain, the size of the martensite needles, and the content of nonmetallic inclusions are determined. Wear tests are conducted, and the hardness and microhardness are measured. The use of tungsten concentrate instead of tungsten powder in surfacing is shown to be possible in principle. The degree of tungsten extraction is calculated. For type-H wire, the replacement of tungsten powder by tungsten concentrate does not increase the content of nonmetallic inclusions in the metal layers applied; the primary austenite grain size is decreased. For type-E wire, the use of tungsten concentrate tends to decrease the primary austenite grain size and the size of the martensite needles and also increases the microhardness of martensite within the applied layer. The replacement of tungsten powder by tungsten concentrate in class-H wire considerably increases the hardness and wear resistance of the applied layer.

Flux-Cored Wire for the Surfacing of Parts Subject to Wear

Flux-cored wire of Fe–C–Si–Mn–Cr–Ni–Mo composition (type A in the International Institute of Welding classification) is developed for the surfacing of abrasively worn parts. In the laboratory, multiple surface layers are applied to plate samples, with preliminary heating to 350°C and subsequent (after surfacing) slow cooling. An ASAW-1250 welding tool with the new wire is used for surfacing: six layers are applied to a 09Г2С steel plate. Instead of amorphous carbon, the wire consists of dust containing carbon and fluorine, with the following composition: 21–46% Al2O3, 18–27% F, 8–15% Na2O, 0.4–6.0% K2O, 0.7–2.3% CaO, 0.5–2.5% SiO2, 2.1–3.3% Fe2O3, 12.5–30.2% Ctot, 0.07–0.90% MnO, 0.06–0.90% MgO, 0.09–0.19% S, and 0.10–0.18% P. The filler is a powder: PZhV1 iron powder (State Standard GOST 9849–86); FS75 ferrosilicon powder (State Standard GOST 1415–93); FKh900A high-carbon ferrochrome powder (State Standard GOST 4757–91); FMn78(A) carbon ferromanganese powder (State Standard GOST 4755–91); PNK-1L5 nickel powder (State Standard GOST 9722–97); FMo60 ferromolybdenum powder (State Standard GOST 4759–91); FV50U0.6 ferrovanadium powder (State Standard GOST 27130–94); PK-1U cobalt powder (State Standard GOST 9721–79); and PVN tungsten powder (Technical Specifications TU 48-19-72–92). Analysis of the applied layer shows that, within the ranges studied, carbon, chromium, molybdenum, nickel, manganese and, to a small extent, vanadium both increase the surface hardness and slow sample wear. Increasing the tungsten concentration somewhat increases the surface hardness but decreases the wear resistance. The low ductility of the matrix prevents the retention of tungsten carbides at the surface and so, rather than uniform surface wear, what is observed is crumbling of strong carbide particles from the matrix, with the formation of cracks that facilitate additional wear. The introduction of cobalt in the batch does not markedly affect the hardness and surface wear: the matrix obtained is more ductile but less hard. With no hard carbide particles in the matrix, the introduction of cobalt is deleterious. Multifactorial correlation analysis yields dependences of the hardness and wear resistance of the applied layer on the content of elements in the Fe‒C–Si–Mn–Cr–Mo–Ni–V–Co flux-cored wire.

Quality of the Seam in Welding under Flux by Means of Barium–Strontium Carbonatite

The use of barium–strontium carbonatite in the modification and refining of ferrocarbon alloys is considered. Its use in welding fluxes is proposed. That possibility is analyzed for the example of BSK-2 barium–strontium modifier (Technical Specifications TU 1717-001-75073896–2005) produced by OOO NPK Metalltekhnoprom, with the following composition: 13.0–19.0% BaO, 3.5–7.5% SrO, 17.5–25.5% CaO, 19.8–29.8% SiO2, 0.7–1.1% MgO, 2.5–3.5% K2O, 1.0–2.0% Na2O, 1.5–6.5% Fe2O3, 0–0.4% MnO, 1.9–3.9% Al2O3, 0.7–1.1% TiO2, and 16.0–20.0% CO2. A production technology is proposed for a flux additive containing 70% barium–strontium carbonatite and 30% liquid glass. Several welding-flux compositions based on slag from silicomanganese production are tested. The flux additive is introduced in quantities of 1, 3, and 5%. The specifics of welding under the proposed welding fluxes are determined. The chemical composition of the fluxes, the slag crusts, and the metal in the weld seam are determined by X-ray spectral analysis. The weld seams are studied metallographically. It is possible in principle to use barium–strontium carbonatite as a refining additive to welding fluxes; it also provides a protective atmosphere for the welded metal. By introducing barium–strontium carbonatite, the content of nonmetallic inclusions (nondeforming silicates, point oxides, and brittle silicates) in the weld seam may be reduced, and the desulfurizing properties of the welding fluxes may be enhanced. The introduction of up to 5% barium–strontium carbonatite in welding fluxes based on silicomanganese slag ensures that the metal in the weld seam has ferrite–pearlite structure of Widmanstatten type. The grain size is slightly reduced here: from a score of 4 to 4–5.

Glass-filled polyurethane materials produced by fiber composite spraying

By using polymer composites in auto parts, the vehicle mass may be considerably reduced, with improvement in the dynamic properties and load capacity of the vehicle and also in its fuel consumption and tailpipe emissions. In the present work, recommendations are made for improving the performance of glassfilled polyurethane materials produced by fiber composite spraying. To that end, the thermal stability, impact strength, high-temperature strength, and Shore D hardness are determined in accordance with Technical Specifications TU 2292-010-14682925–2014. The sound absorption and UV resistance of the composites are also determined.

Electrowelded straight-seam high-strength pipe for structural use

Technical Specifications TU 1381-068-00186654–2016 have been developed for large-diameter electrowelded straight-seam high-strength pipe used in special-purpose structures, including those that operate in severe climatic conditions. Pipe made from thick sheet with a low impurity content by thermomechanical rolling with accelerated cooling is characterized by low-temperature strength, crack resistance, thermal stability, and resistance to fatigue-crack propagation. Such pipe resists mechanical aging and withstands seismic shocks. Research data permit the formulation of Technical Specifications TU 1381-068-00186654–2016 such that the special-purpose structures made from electrowelded straight-seam pipe will operate reliably.

Operation of imported rail on the East Siberian Railroad

Japanese R65 rail is metallographically analyzed after operation in the East Siberian Railroad. Its chemical composition complies with Technical Specifications TU 0921-239-01124323–2007 for the steel used in the production of 350LDT rail. The macrostructure of the metal is of satisfactory quality. The tensile mechanical properties, hardness, and impact strength at +20°C determined on samples from the nonoperational chamfer of the rail head are consistent with Technical Specifications TU 0921-239-01124323–2007 for the steel used in the production of 350LDT rail. The impact strength at negative temperatures does meet the corresponding requirements. The content of nonmetallic inclusions is low. However, exogenous inclusions are present at unacceptable levels. The microstructure of the Japanese rail sample consists of sorbite and plate pearlite, whose dispersity declines on moving away from the surface. In operation of the rail, thin inclined cracks (depth 1.1 mm) form at the surface of the working chamfer in the rail head; in addition, lateral wear is considerable (up to 15 mm).

MODERNIZATION AS A WAY TO IMPROVE THE USE OF UNIVERSAL CARS

Purpose. The main design requirements of the modernized cars are those allowing reduction of operating costs and improvement of economic efficiency of their use. Due to the relevance of this subject the work presents the complex of conducted research, which will allow in prospect to use the universal flatcar, converted according to the Technical specifications TU 3182-065-71390252-2911 for container service. The research includes: evaluation of strength, fatigue safety of the design elements and conformity assessment of the strength characteristics of the modernized flatcar elements to the regulatory documents. Methodology. The analysis covers the use of specialized and universal rolling stock for transportation of containers, as well as the issues of modernization of universal cars. The strength of the flatcar bearing structure is evaluated based on the complex of numerical and experimental studies. The experimental part includes the static, repair load and impact tests. The car strength qualities and the fatigue safety are evaluated on the basis of calculated and experimental data. Findings. The conducted static, repair load and impact tests, given the quasi-static longitudinal forces, allowed the evaluation of the car structure strength according to the regulatory documents. The calculated and experimental data make it possible to assess the fatigue safety of structural elements. The present work is completed by obtaining the results that allow performing reasonable re-equipment of universal flatcars with baseplates with fitting stops to fasten the containers. Originality. The results of calculated and experimental studies showed that the modernized flatcars meet the conditions of strength and have sufficient fatigue safety factor. This makes it possible to recommend the re-equipment of universal flatcars for all car-repair enterprises that submitted the prototypes. Practical value. The complex of works was conducted that demonstrated the possibility of re-equipment of universal flatcars for the transportation of large containers. Part of the car fleet, kept in reserve, with little material costs can be transferred to the operational fleet. The modernization – re-equipment of universal flatcars with stationary specialized devices will increase the car usability coefficient.

Production of hexahedral pipe blanks from centrifugally cast 04Х14ТЗР1Ф (СЧ82) steel billet for the nuclear industry

A new production technology for centrifugally cast 04Х14ТЗР1Ф boron-steel has been developed. In addition, technology has been developed for the production of hot-rolled 290 × 12 mm pipe from such blanks on a TPU 8-16″ system with Pilger mills and for the conversion of such pipe to hexahedral pipe blanks (dimensions 257 +2/–3 × 6 +2/–1 × 4300 +80/–30 mm). The hexahedral pipe blanks produced by this means meet the requirements on the geometric dimensions, mechanical properties, and intercrystallite corrosion in Technical Specifications TU 14-3-1630–89 for the manufacture of racks used in holding tanks at nuclear power plants and in spent-fuel transportation.

Production of seamless pipe in a pilger mill with new groove configurations

New groove configurations for the pilger mill reduce the nonuniformity of sleeve deformation on transition from the striker to the polishing section and enhance pipe quality. The rolling of 08X18H10Tsteel-Ш pipe blanks (produced by electroslag remelting) by the new method to obtain intermediate pipes is considered. Machining of the intermediate pipes—boring and turning—produces commercial pipe of diameter 530 and 630 mm corresponding to Technical Specifications TU 14-3R-197–2001.

Regulating the macrostructure of continuous-cast billet

The macrostructure of 10, 20, 09Γ2C, and дб steel billet (diameter 150 and 220 mm) is investigated. Regardless of the casting parameters and grade of steel, the metal in the continuous-cast billet studied contains sections distributed randomly over the length that are characterized by impermissible central porosity in tests. The nonuniform distribution of this defect over the length of the billet is due to unstable solidification of the central zone and is not eliminated in continuous casting of the steel. The research permits the adoption of a new edition of Technical Specifications TU 14-159-324-2012 for continuous-cast billet, with requirements on the extent of the central porosity.

Production of cold-rolled strip from low-alloy 10ЮA steel

A new production technology for cold-rolled sheet from low-alloy steel is proposed for a sheet-rolling shop at OAO MMK; the steel is smelted in accordance with Technical Specifications TU 14-4-1333-2002.

Catalytic activity of ferroalloy slags

869 Slags obtained in ferrous metallurgy may poten� tially be used as catalysts in the deep oxidation of poly� cyclic aromatic hydrocarbons from metallurgical pro� duction (1). Accordingly, it is of interest to study the catalytic properties of ferroalloy slags. In the present work, we investigate the catalytic properties of ferroalloy slags in the deep oxidation of polycyclic aromatic hydrocarbons. The output of ferroalloy slags in the Common� wealth of Independent States is more than 5 million t/yr. Slags obtained in the production of ferrochrome alloys differ in chemical and mineralogical composi� tion and in physicochemical properties. The following ferrochrome slags are formed: regular carbon slags, lowcarbon and carbonfree refining slags, and mod� eratecarbon converter slags (2, 3). Structurally, the slags consist of highrefractory spinels, forsterite, and glass saturated with spinel inclusions. The slags con� tain 2-4% chromospinelide (Mg, Fe)O ⋅ (Cr, Al)2O3; 10-15% spinel MgO ⋅ Al2O3; 15-20% forsterite 2MgO ⋅ Si 2 O 3 ; 50-55% glass; up to 1% metallic beads (Cr, Fe); and 0.7-1.0% sulfide phase FeS-CrS. The slags from silicochrome production contain a small quantity (0.3-0.5%) of chromium oxides; its basic components are oxides of silicon, aluminum, and cal� cium. Analysis of the chemical composition and physico� chemical properties of ferroalloy slags suggests that converter slags from the production of moderateand lowcarbon ferrochrome are the best for the catalysis of deep oxidation. Such slags contain the greatest quantity of catalytically active oxides: up to 70% chro� mium oxides and 2% iron oxides. In the present work, we investigate moderatecarbon ferrochrome slag from Aktyubinsk ferroalloy plant. In smelting manganese alloys, slag that is rich in manganese oxide (14.0-52.5%) is formed, as we see in the table (2, 4). Slag from the production of lowphos� phorus manganese corresponds to Technical Specifi� cations TU 14�11�85-73, and contains at least 65% manganese. Manganese slag is formed from the reduc� tion products of higher manganese oxides and fluxing additives (quartzite). The basic components of this slag are manganese oxide MnO (up to 60%), silica SiO 2 (up to 30%), alumina Al2O3 (up to 3%), calcium oxide CaO (up to 4%), and magnesium oxide MgO (up to 3%). Up to 3% K2O and Na2O are present. The melting point of the slag is around 1208°C. In smelting silicomanganese, slag containing 14-17% MnO is formed. The slag mainly consists of silicate of close� packed manganese-calciumsilicate glass of busta� mite type (CaO ⋅ MnO ⋅ 2SiO2); metal beads are present. The slag from the production of carbon and moderatecarbon ferromanganese consists mainly of oxides of manganese (40-50%), silicon (25-35%), alu� minum (0.9-3.0%), and calcium (7-23%). In mineral� ogical composition, the slags consist mainly of tephroite (2MnO ⋅ SiO 2 ) and forsterite (2MgO ⋅ SiO 2 ), with small quantities of bustamite (CaO ⋅ MnO ⋅ 2SiO 2 ). Analysis of the chemical and mineralogical com� position indicates that all the manganese slags consid� ered contain catalytically active oxides; their content is greatest in lowphosphorus manganese slag. All the slags are tested in deep catalytic oxidation.

Vibration-and noise-absorbing polymer composites used in manufacturing

194 Highly efficient polymers are required in manufac turing. Polymer composites are widely used in structural, protective, adhesive, vibration damping, and other manufacturing materials characterized by excellent strength and also by deformational, anticorrosive, and thermophysical properties. In vibrationally active equipment, harmful vibra tions impair the reliability. An effective means of pre venting such vibration is the use of vibration and noise absorbing materials based on polymer compos ites in structures subject to dynamic loads [1, 2]. Experiments have been conducted on the following matrix composites: ED 20 epoxy resin (State Stan dard GOST 10587–84); polyethylene polyamine (Technical Specifications TU 2413 357 00203447– 99), dibutylphthalate (GOST 8728–88), 540 M888 polyester resin, peroxide 1 (a solution of methylethyl ketone peroxide in dimethylphthalate), simple polyes ter (Sarel A 04), and polyisocyanate (Sarel B 04). The Vibration and Noise Absorbing Polymer Composites Used in Manufacturing

Production of cold-rolled sheet of increased strength

In sheet-rolling shop 5 at OAO Magnitogorskii Metallurgicheskii Kombinat (MMK), a production technology for 0.8–3.0 × 1180–1250 mm cold-rolled annealed strip made of 08γCЮT steel (strength class 275 according to Technical Specifications TU 14-1-3764-84) has been developed. Such sheet is used in stamping auto components. Technological parameters such that the product meets customer requirements on surface quality and mechanical properties are established.

Improving the annealing of cold-rolled 65Γ steel to comply with the ISO/TU 16949:2002 standard

Production processes are evaluated on the basis of statistical process control (SPC) in order to ensure that cold-rolled strip made from 65Γ steel corresponding to Technical Specifications TU 14-4-1382-86 complies with the ISO/TU 16949:2002 standard. The statistical applicability and degree of controllability of SPC are determined, and corrections are introduced in the technology.

Refractory fiber from natural starting materials

The feasibility was demonstrated of producing refractory fiber from high-alumina chamotte of calcined Arkalyk clay. The fiber properties conform to the requirements of Technical Specifications TU 14-8-107-74.