Pipe Fragments Research Articles

Formation of silicated layer of austenitic pipe steel with different pipe sizes

Tubular furnaces of hazardous production facilities are unique technical devices, and serve for open fire heating of various process media to relatively high temperatures. Some of the furnaces, such as pyrolysis furnaces, hydrogen conversions are also reactors that serve to decompose the hydrocarbon feedstock into separate components. The most important element of the structure is a tubular coil. The effect of high temperatures and working media on the coil metal inevitably leads to metal degradation by forming various defects, changing the structure and mechanical properties for the worse. One of the most unfavorable moments is considered saturation of the surface layers of the metal with carbon or another - carburization of the metal. When the metal is carburized, its embrittlement occurs and the probability of brittle destruction increases. All this can lead to frequent shutdown of furnaces for repairs and significant costs. One way to contain the active diffusion of carbon into the metal may be to silicate the surface of the coil elements using different silicating mixtures, since silicon can effectively delay carbon incorporation. In this work, studies are carried out on the peculiarities of the formation of a silicated layer in fragments of pipes with dimensions of 160x6 mm, 32x2 mm, 57x4 mm made of steel 08Kh18N10T depending on the holding time in the silicating mixture.

A novel method for spatially-resolved thermal conductivity measurement by super-resolution photo-activated infrared imaging

Thermal conductivity measurements play a crucial role in most areas of the applied physical sciences, thereby constantly demanding for new non-invasive methods capable of providing high-resolution spatial mapping of absolute thermal conductivities on heterogeneous samples ranging from solid-state bulk materials to low-dimensionality structures. In this work, we lay the theoretical foundations and provide the experimental demonstration of a novel method for quantitative thermal conductivity mapping at tunable ∼10-μm resolution, by non-contact infrared photo-activated thermography. Starting from Fourier’s heat transfer law, we surmise a universal dependence of the thermal response of a laser-irradiated sample on its thermal conductivity, irrespectively of density and specific heat capacity. We demonstrate such a dependence over the three conductivity decades 0.1–100 W/mK by finite-element numerical simulations, and exploit it for proof-of-principle single-point thermal conductivity measurements on both thermally thick and thermally thin reference solid samples. We exemplify the feasibility of space-resolved measurements on eighteenth-century tin organ pipe fragments, where the product of the thermal conductivity times the sample thickness, imaged at 40-μm sub-diffraction resolution, is pointed out as a relevant parameter for the non-destructive characterization of the sample conservation state. By coupling temperature maps with the extraction of thermal properties at high spatial resolution, our approach significantly expands the capability of state-of-the-art infrared imaging technology in fully capturing the compositional heterogeneity and/or functional state of the imaged materials.

Evaluating the Load-Bearing Capacity of a Section of the Orenburg-Zainsk Main Gas Pipeline Using Static and Cyclic Loading Methods

This paper examines the operability of the Orenburg-Zainsk main gas pipeline, which has been in operation since 1971 and has various general defects, as well as specific defects such as internal corrosion-induced delaminations and blisters of various geometric shapes. The design parameters of the gas pipeline section and the characteristics of the pipe metal have been studied. Hydraulic tests were performed on the pipe fragments in the form of sample barrels to determine the load-bearing capacity in order to evaluate the operability of the gas pipeline. There were three types of sample barrels: those made from pipes with internal blistering and delamination, from pipes with invisible defects, and from emergency stock pipes. A cyclic test was performed on one sample according to the developed method. The theoretical analysis of the load-bearing capacity of the gas pipeline was performed according to the accepted design model.

The impact of internal stratifications on the performance of oil and gas pipes

The work investigated pipes of the main gas pipeline with a service life of more than 45 years. Initially, this gas pipeline was designed for the technological purposes. It was intended to remove associated gases generated during the purification of methane from acidic impurities, but subsequently, as production was modernized, it was transferred to purified natural gas transport. Nevertheless, the presence of corrosive components in the transported gas during the initial period of operation of the gas pipeline led to the appearance of structural defects in the form of delamination in the pipe wall. The purpose of the study was to evaluate the performance of defective pipes based on a set of laboratory and bench tests. During the construction of the pipeline, imported longitudinal welded pipes made from steel of strength class X53 and X56 were used. The study of the chemical composition and mechanical properties of pipe steel did not reveal significant deviations of these characteristics from normalized values. It was noted that the content of non-metallic inclusions was high, but acceptable for pipes Ø 1020 mm. Based on an analysis of the modes of gas transport through the gas pipeline over the past 10 years, a model of its operation has been formed, which includes alternately repeating combinations of amplitude and pulsation loading cycles. To carry out life tests, a research stand was constructed containing pipe fragments with extended zones of internal stratifications. Test results showed that delamination up to 1.5 m2 in size and/or up-to 3.5 m in length, as an independent type of defects, do not significantly affect the performance of the pipes.

Formation of Tubular Carbonates within the Seabed of the Northern South China Sea

A remarkable exposure of tubular authigenic carbonates was found on the seafloor in the Dongsha area of the South China Sea (SCS). The tubular carbonates, around 2–3 cm in diameter and usually less than 10 cm in length, represent broken fragments of once-larger pipes that now protrude from muddy sediments. The morphology, carbon and oxygen stable isotope compositions, and trace and rare earth element contents of the carbonates were analyzed to decipher the mode of carbonate formation. The tubular carbonates exhibit a dark brown coating of iron and manganese hydrous oxides, indicating prolonged exposure to oxic bottom waters. The carbonate content of the micritic pipes falls between 12.5 and 67.3 wt.% with an average of 42.0 wt.%, suggesting formation within the sediment. This inference is supported by trace and rare earth element patterns including a moderate enrichment of middle rare earth elements. Low δ13C values (as low as −50.3‰, Vienna Pee Dee Belemnite (VPDB)) suggest that carbonate precipitation was induced by the anaerobic oxidation of methane. The unusually positive δ18O values of the carbonates (as high as +5.3‰, VPDB) are believed to reflect the destabilization of locally abundant gas hydrate. Taken together, it is suggested that pipe formation was initiated by sediment-dwelling organisms, such as crustaceans or bivalves. The burrows subsequently acted as conduits for upward fluid migration. The lithification of the sediment directly surrounding the conduits and the partial filling of the conduits with carbonate cement resulted in the formation of tubular carbonates. Turbidity currents, sediment slumps, or the vigorous emission of fluids probably induced the fragmentation of tubular carbonates within the sediment. The carbonate fragments had been further subjected to winnowing by bottom currents. This study provides insight into the interaction of megafauna burrowing with fluid migration and carbonate formation at hydrocarbon seeps, highlighting the role of bottom currents and mass wasting on the formation of fragmented tubular carbonates.

Microplastic acts as a vector for contaminants: the release behavior of dibutyl phthalate from polyvinyl chloride pipe fragments in water phase.

The pollution of contaminants brought by plastic fragments is worth paying attention in the study of microplastic. The additives, like phthalates (PAEs), introduced during manufacture, are physically dispersed and can easily release into environment. Polyvinyl chloride pipes are widely used in China, and DBP is also a typical kind of additives in PVC materials. Here, the release behavior of DBP from PVC plastic pipe fragments was investigated in water environment under different conditions. Low-density polyethylene (LDPE) passive sampler was used to monitor the contents of DBP. The curve of DBP concentration started from the first increasing stage until a short equilibrium after 45 days' incubation followed by a second increasing part. The release kinetics and the rate-limiting step were discussed. For the whole migration period, the release process was better fitted to pseudo-second order which was participated by both intraparticle and plastic-water film diffusion processes while the two separated parts had different results. Moreover, light, smaller fragments, and higher temperature could all accelerate the release rate and increase the migration amount of DBP. The effect of temperature was the most significant of all, and higher temperature showed more significant effects. Besides, DBP tended to migrate in a long-time continuously. However, the release of additives will be promoted by various physical and chemical processes in nature compared to laboratory tests. Consequently, microplastic (plastic fragments with sizes smaller than 5 mm) with additives acts as a vector for pollutants, and will bring more threat to both environment and organisms.

Study of the mechanical properties of the gas pipeline metal after long-term operation in conditions of the North

The residual strength and technical condition of the material of 530-mm steel pipe (14KhGS) of main gas pipeline are estimated to ensure the safety of long-term operation of pipelines in climatic conditions of the North. The mechanical properties are determined using standard methods of mechanical testing in laboratory conditions. A full-scale pressure test up to failure is used to determine the actual values of the fracture toughness and safety factor of the pipe. Full-scale tests were carried out on a test bench, a computer-measuring complex which displayed the reaction of the object to the load. A pipe fragment was cut from the linear part of the main gas pipeline and welded with spherical plugs. The outer surface of the pipe was notched along the pipe axis. The depth of the notch was calculated such that the breaking load on the ligament section at the notch site corresponded to the working pressure of the gas pipeline. No significant changes in the mechanical properties of the pipe metal were revealed in the absence of visible corrosion and deformation damage during long-term operation of the pipe in the North. Impact tests did not reveal embrittlement of the metal of the tested pipes. Full-scale tests of a pipe with an artificially applied defect made it possible to calculate the value of the critical stress intensity factor, which allowed us to estimate the residual strength of a pipe with a longitudinal crack. The value of the strength criterion of the fracture mechanics indicates the preservation of a sufficiently high viscosity of sheet metal pipes. Similar tests of the pipes (of other size and made of other materials) operating in the main gas pipelines should be continued taking into account temperature ranges and material degradation after long-term operation.

The assessment of the individual resource of the welded joint during repairs of the technological pipeline

The relevance of research is due to the necessity to develop recommendations for assessing the “individual” resource of welded joints of technological pipelines using non-destructive testing methods for the timely detection of welds with the smallest resource to ensure reliable operation of equipment and the inadmissibility of premature failure in the weld zone. The task is to develop recommendations for determining “individual”resource of welded joints of technological pipelines with a different level of edge displacement and imperfection by introducing correction factors into the modified Coffin-Manson equation based on the mechanical characteristics of the yield strength and strength, determined as a result of static tensile testing of samples of various sections of welded joints with maximum acoustic and magnetic signals according to the results of flux-probe and ultrasonic non-destructive testing. For research, 6 pipe fragments were selected made of steel 20 with dimensions of 159×7 mm and a length of 45 mm each. Fragments were welded together by different types of welding with different displacements of the edges of the welded elements. The authors developed recommendations for assessing the “individual” resource of welded joints of technological pipelines. It is shown that the introduction of correction factors depending on the amount of offset of the edges of the welded joint allows to increase the accuracy of the predicted durability of individual welds by 4% for manual and 11% for semi-automatic welding, respectively.

Investigation of mechanical properties of the main gas pipeline material during a long-term operation in conditions of the North

The article presents the results of the investigation of the mechanical properties of the base metal and welded joints of the underground main gas pipeline with a diameter of 529 mm operating in permafrost soils. Test samples were cut from pipe fragments of different sections of the Taas-Tumus-Yakutsk gas pipeline after fifty years of operation. The investigated pipes were made of 09G2S low-alloy steel. The obtained results of the mechanical testing of the samples were compared with the data of the certificates for pipes, which were determined based on the results of spectral analysis. A decrease in the values of relative elongation and impact strength of the base metal has been established is comparison with the data of the certificate. The investigation of changes in the properties of pipe steels during long-term operation has made it possible to evaluate the technical condition of the pipe material and to develop forecasts regarding the prospects for the further safe operation of existing gas pipelines.

Determining influence of natural and man-made factors on safe performance of trunk pipelines

The paper discusses the relevance of ensuring environmentally safe pipeline operation by identifying natural and industrial hazards and the potential impact. An operating trunk pipeline running west to east across a specific territory (constituent entity) was given as an example to show areas likely exposed to the most dangerous destructions. These are natural and man-made pipeline crossovers and intersections designated by the authors as ecologically fragile areas (EFAs). For a natural/industrial impact identification methodology, relevant hazards were identified and classified by the exposure degree for each gas pipeline EFA. Given geodynamic changes, the data collected were to be updated after each change. The article outlines the new methodology also suitable for territorial cartographic zoning subject to hazard factors. An area to be affected by degradation processes of an accident is determined by using the radii of thermal impact and scatter of pipe fragments. Such data help compute flora and fauna damage and, for the best scenario, damage prevented. The key points of this survey may be used to developing computer programs to compute an aggregate hazardous impact on an operating pipeline and simulate emergency scenarios. The practical utility consists in assuring proper EFAs monitoring for timely prevention of accidents.

The use of magnetic flaw detection to control the offset of the edges of the welded joints of technological pipelines

The task was set of developing recommendations for identifying areas of displacement of the edges of the welded joints of abutting pipes, as well as identifying potentially dangerous sections of welded joints of technological pipelines by changing the normal component of the constant magnetic field. For research, 24 pipe fragments made of steel 20 with a length of 45 mm each were selected. The authors developed recommendations for identifying the presence and zone of displacement of the edges, as well as identifying potentially dangerous sections of welded joints of technological pipelines using the flux-gate control method. It is proposed to use the obtained maximum values of the normal component of the constant magnetic field for the objective detection of edge displacement zones and the determination of potentially hazardous areas. It was shown that the normal component of the constant magnetic field, is quite sensitive both to the displacement of the edges of the welded joints of the pipes and to the quality of the weld, its geometry, defectiveness and determines the above indicators with various characteristic values.

CHANGE OF ULTRASONIC WAVES SPEED SPREADING IN A MATERIAL OF THE REACTION FURNACE COIL DURING OPERATION PROCESS

Pyrolysis, or steam cracking, is the main process used to produce olefins. Thermal decomposition of organic compounds occurs in highly alloyed coils. Operating conditions of the furnaces are considered the most aggressive in terms of the influence on the metal pipes, on the one hand a chemically active product, and on the other a rigid thermal effect. High carbon activity on the inner surface of the pipe, where chemical reactions occur, leads to the formation and deposition of coke on the inner surface of the reaction tubes. Coke deposition increases fuel consumption, reduces furnace productivity, and also leads to intense diffusion of carbon into the metal. The outer surface of the pipe is also exposed to high temperatures and furnace gases, resulting in a decarburization process. Diffusion processes, in turn, lead to a change in the structure of steel and the formation of carbides and intermetallic compounds, which were not in the composition of the material in the delivery state. Essentially, «new» steel arises, and as a result of phase transformations of the material, the operational characteristics of the reaction furnace coil change. To protect the coil from destruction, an industrial safety examination is carried out, according to the results of which the residual resource is estimated. When assessing the residual life, the basic information is the measured wall thickness, which is carried out according to STO SA-03-004-2009. However, this approach does not cover thickness control over the entire surface area of the coil. Often, the most prone to degradation of the material areas are not controlled, so the definition of these areas with modern non-destructive testing methods is necessary. It was shown earlier that ferromagnetic properties and magnetic methods of measurement are sensitive to potentially dangerous zones in the surface layers of coils after operation, so it is proposed to control the wall thickness in those places where magnetic properties are manifested. Wall thickness measurement requires calibration of the ultrasound velocity, which is usually selected from reference sources. However, this does not take into account the fact that the speed of ultrasonic waves during operation changes. Therefore, it remains vital to determine the true wall thickness, as this will provide more accurate results in assessing the residual life. In this regard, as the object of the study there were selected fragments of pipes of the pyrolysis reaction furnace of steel 20Х25Н20С2, which were in operation 0, 750, 1300, 8000 and 10000 h. The article shows the results of the study of the regularities of changes in the speed of ultrasonic longitudinal waves, which were measured by the thickness of the coil surface before and after removal of the surface layer exhibiting ferromagnetic properties of the reaction tube material. The analysis of the measurement results showed that the speed of ultrasound in the wall material decreases with increasing duration of operation. It was found that upon reaching 10,000 h, this reduction was 16 %, compared with the delivery condition. It was also recorded reduction in ultrasonic velocity up to 8 % in the complete removal of the carbonized and decarbonized layers from the surface of the metal pipe. In order to determine the causes that affect the decrease in the speed of ultrasound in the wall of the coil, metallographic studies were conducted, which showed that structural changes occur in the bulk part. The formation of a large number of voids was found in the near-surface area, and in the bulk of the identified pairs, which play a major role in reducing the longitudinal ultrasonic waves. The results of the research can be applied in the assessment of the technical condition and the development of the rejection criterion of reaction furnace coils.

CHANGES IN GEOMETRY OF COILS OF REACTION FURNACES AND REDISTRIBUTION OF THE MAGNETIC FIELD ON THEIR SURFACE DURING OPERATION

A feature of most steels of the austenitic class is that they belong to paramagnetic materials and react weakly to an external magnetic field. One of the features of the changes occurring in the structural material is the formation of magnetic properties in the surface layers of the walls of the coil pipes, and the longer the operation, the higher the magnetisation value. On the one hand, this fact allows us to interpret the changes occurring in steel, on the other hand, it indicates this phenomenon as a diagnostic method that can identify structural changes with a non-destructive method and record the onset of the ultimate state of the material. The change in the properties of steel in the process of force and temperature loading has a complex multiparameter character, and therefore the study of this phenomenon includes several stages. At the first stage, the patterns of changes in the pipe geometry and the associated redistribution of the magnetic field in the surface layer during operation were examined. Analysis of previous studies shows that as a result of high-temperature cracking of hydrocarbons, active centers appear, the recombination of which leads to the formation of high molecular weight paramagnetic compounds, and coke is formed when interacting with the surface of the pipe. Coke deposits are irregular, impair heat transfer to the moving stream through the pipe wall, and lead to the launch of an autocatalytic process of intense diffusion of carbon into the metal. The formed carburized layer has physicomechanical properties that differ from the base metal of the coil pipes. This leads to a local stress concentration at the boundary of the carburized layer. On the other hand, the deterioration of heat exchange with a vaporliquid flow leads to an increase in temperature on the outer surface. At the same time, the processes of steel decarburization and scale formation with scale detachment are intensified. The detachment of corrosion products leads to thinning of the pipe wall and local overheating in places of thinning. The above shows that over time, wear is intensified and, thus, various processes of loss of form stability are realized. Studies presented in this paper have shown that the greatest thinning of the pipe wall is associated with the maximum manifestation of magnetism. Measurement of the outer and inner radius of the pipe before operation showed that its values are within the limits established by regulatory documents. However, after the operation of the coils, an ovality is formed, which, when compared with the results of the strength of a constant magnetic field, shows that in the zones where the greatest changes in the radius of the tubes occurred, the largest increase in the constant magnetic field was recorded. When measuring the distribution of the magnetic field in all the investigated fragments of pipes, both from the inner and from the outer surface, it was revealed that there are zones with extremely high values. In this case, the longer the operation time, the more the values of the constant magnetic field from the external and internal surfaces correlate. Thus, during the operation, the resulting physico-chemical changes in the coils of the reaction furnaces influenced the formation of ferromagnetic properties in the surface layers of pipes. The main influence on the distribution of parameters of magnetic characteristics in coils was made by the introduction of carbon and the formation of new phases with ferromagnetic properties. These changes caused an increase in the stresses in the pipes, which accelerated the creep process, led to local thinning and a change in the radius of the pipes.

A Study of the Influence of Operating Conditions on the Degradation of the Structure of Steel 14MoV63

The results of the study of the microstructure and properties of the manufactured pipe fragments of steel pipe lines 14MoV63 are given. The deterioration of the structure of the steel during operation and changes in mechanical properties are considered

IMPROVING THE CENTRIFUGAL PUMP DESIGN AND CHANGING THE STRENGTH OF OPERATION

Background Currently, the share of electric centrifugal pump (EСP) units, which operate in a periodic mode, is growing in the production structure at a marginal fund. In this mode, the pump flow varies from the maximum value at the beginning to the minimum at the end of the pumping period. The trend towards such dynamics is explained by the fact that the fund of low-yield wells is growing in Western Siberia, where EСP is the main mechanized method of production. When oil is being produced in marginal wells, it is often necessary to encounter such a problem, when the dynamic level of the gas-liquid mixture can drop to a critical level. In this case, the pump flow is reduced, and the pressure developed by the pump is insufficient to overcome the hydrostatic pressure of the liquid column in the tubing. In this case, the pump stops pumping fluid and an inevitable failure of the pumping unit occurs due to a motor burnout. In addition, an increase in EСP operating in automatic periodic switching on mode leads to a significant reduction in well production. Aims and Objectives The aim of the work is to introduce a device for stabilizing the pressure at the inlet to the EСP station, which would discharge part of the oil product back to the pump through the annulus without stopping the equipment. In order to ensure reliable operation of this structure, the material was tested for strength and durability, taking into account the redistribution of stresses and changes in properties during operation. Results The tests of samples from pipe fragments of steel 40X with a service life of 57, 378, 1035 days showed a decrease in the tensile strength and yield strength by 20 % and 6 %, respectively. The distribution of hardness over the cross section of the wall of the tested pipe fragments showed that the core is harder than the edges of the wall, while as the operation progresses there is a slight hardening. Impact test results showed a significant reduction in toughness by 73 %. Fatigue tests carried out according to the circular curvature with rotation, revealed a decrease in fatigue life. The analysis of the device for stabilizing the pressure at the inlet to the ESP revealed that the most loaded unit is the overlap mechanism, which forms the hydraulic channel between the tubing cavity and the annular space. The calculation the action of the axial compressive load and the internal pressure of this node showed that the resulting loads in the stress concentration zones do not exceed the allowable values.

Distribution of Magnetic Field Parameters in the Surface Layer of the Material of Reaction Furnace Coils after Operation Period

One of the main reasons for the limited service life period of the reaction furnace coils is the carburization of the surface layers, which leads to a decrease in the performance characteristics of the pipe material, decrease in plasticity, generation of internal stresses, change in the metal structure. Therefore, monitoring the state of coils surface in order to detect critical parameters of the carburized layer thickness, using non-destructive methods of control is relevant. The results of the distribution of magnetic parameters over the depth of the carburized layer in the fragments of pipes made of steel 20Х25Н20C2, operated under furnace conditions at high temperatures, for 1300, 6000, 8000, 10000 hours are presented in the article. Analysis of the results showed that the magnetic properties are manifested only in the surface layers of the reaction furnace tubes. At the same time, the longer the service life period, the deeper is the layer exercising the magnetic properties and the higher in this layer the values ​of the constant magnetic field intensity. Analysis of magnetic properties distribution in all studied pipe fragments, both from the inner and from the outer side, showed the non-uniformity of the constant magnetic field intensity distribution, while zones of extremely high values ​are observed. The layer-by-layer surface removal in these zones with the determination of the resultant constant magnetic field intensity showed that there are critical values of the carburization depth, after which a sharp increase of this parameter is registered. These results can be used as a method for carburization depth determination, and also used to develop criterion for rejecting coils of reaction furnaces.

Damage areas during emergency depressurization of a gas pipeline

Main gas pipelines are classified as energetically stressed objects. With an increase in their service life, there appears a need to model emergency breaks and analyze the distribution of the damaging factors of the accident. The main gas pipelines often run near residential areas and cross various communications, therefore possible accidents with gas emissions and damaging factors can negatively affect both the environment and the population. An emergency rupture of a gas pipeline section is numerically modeled in this article. The calculations of intensity of accidental gas emissions outflow and distribution of the accident damaging (the length of the methane jet in unlimited airspace, the range and height of the scattering of the soil and pipe fragments were found). The parameters of free jets of exhaust gas were determined. Such calculation is required during investigation of accidents and development of documents related to the environmentally safe operation of pipeline transport. In case of gas non-ignition, it disperses in the atmosphere with the formation of gas zones. The study of the influence of velocity, density and pressure on the emergency gas emission allows us to determine possible gas contamination zones. Graphs of distribution of static and total pressure over the ejection height, distribution of velocities along the axis of the ejected jet and along the axis of the pipeline were obtained. The ability to evaluate the parameters of free jet flow of natural gas (methane) from a damaged pipeline: the total flow rate, total pressure and flow rate at the rupture point is relevant in solving applied environmental safety problems of gas transportation facilities.

ИССЛЕДОВАНИЕ СТАТИЧЕСКИХ И ДИНАМИЧЕСКИХ ХАРАКТЕРИСТИК ГИДРОРАСКАЛЫВАЮЩЕГО УСТРОЙСТВА

In the work current importance of creation of hole electro driven pulse seismic sources for treatment of productive collectors of oil and gas deposit in order to hydrocarbons extraction intensification is justified. Study results of transfer center of strike pulses to extracting column are represented. The center is represented with hydrocleaving device. Objectives of the work are: establishing of dependences of plunger dies thrust force of hydrocleaving device on static pressure of working liquid in chamber, discovering of optimal values of hydrostatic pressure for provision of maximal pressure pulses in the chamber. Analytical dependence of thrust force on pressure in the chamber is obtained. Values of static strain of pipe fragment with diameter 122mm and wall thickness 9 mm under action of calculated thrust force are determined by methods of numerical simulations. Strains of fragment of the same pipe are experimentally studied under action of prototype thrust force. It is established that at pressure in the chamber up to 10MPa pipe strain at action axis is elastic up to 1mm. Repeatability of physical and numerical measurements is within 10%. With further increasing of the pressure up to 40 MPa the strain is elastic plastic up to 2.2mm. Using the method of physical simulation, it is established that pressure pulses in hydrocleaving device reach maximal values (up to 12 MPa) when values of preliminary static pressure are from 17 MPa up to 21MPa. However, increasing of strike energy above 180 J do not influence on value of pulse pressure significantly. Previously the devices of such type were not studied and were not applied in dynamic working modes. In the work recommendations for construction change of hydrocleaver for improvement of its dynamic parameters are formulated.

THE GENESIS OF BUNDLES IN METAL PIPES: INFLUENCE ON DANGER OF THESE DEFECTS AND METHODS OF IDENTIFICATION

Background For the rational planning and execution of repair work, it is accepted to be guided by the principle of objects servicing according to their technical condition. This principle has been used in the operation of oil and gas pipelines, however, an analysis of the approaches implemented in this case shows that it is often only formally observed. It can be clearly seen in the example of the bundles of metal pipes. Such defects are fairly common, but the existing standards for assessing the quality of pipes, in fact, do not recognize them as representing a real threat to the carrying capacity of the pipeline, at least if the stratification is flat. An analysis of existing studies of the genesis of the formation of metal bundles shows that at present it is customary to distinguish two types of similar defects: metallurgical and hydrogen. To extend these ideas, an assumption was made about the effect on the formation of stratification of the aging process of the metal. From a theoretical point of view, this is justified by the fact that aging, characterized by the segregation of carbides along grain boundaries, leads to metal embrittlement, which increases the likelihood of stratification. Aims and Objectives Establishing the causes of bundles formation and their effect on the risk of these defects. Methods Optical (microscope NIKON MA200) and electron microscope (Jeol JEM-200CX microscope) microscopy of various metal zones, standard mechanical tests of the templates being studied (InstronSI-1M coper, SHIMADZU EHF-EV200K2-040-1A X-ray spectroscopy of splitting zones (spectrometer JEOLJPS-9010MX). Results The article presents the results of complex experimental researches of pipe fragments with bundles. It is established that besides to the known types of bundles, caused by metallurgical liquation and hydrogen embrittlement, there is another one - caused by the aging process in metal, which, as the hydrogen type of bundles, leads to drop the performance properties of metal in the defective zone. Also was evaluated the possibility to identify of different types of bundles by non-destructive methods.

Biomolecular archaeology reveals ancient origins of indigenous tobacco smoking in North American Plateau

Chemical analysis of residues contained in the matrix of stone smoking pipes reveal a substantial direct biomolecular record of ancient tobacco (Nicotiana) smoking practices in the North American interior northwest (Plateau), in an area where tobacco was often portrayed as a Euro-American-introduced postcontact trade commodity. Nicotine, a stimulant alkaloid and biomarker for tobacco, was identified via ultra-performance liquid chromatography-mass spectrometry in 8 of 12 analyzed pipes and pipe fragments from five sites in the Columbia River Basin, southeastern Washington State. The specimens date from 1200 cal BP to historic times, confirming the deep time continuity of intoxicant use and indigenous smoking practices in northwestern North America. The results indicate that hunting and gathering communities in the region, including ancestral Nez Perce peoples, established a tobacco smoking complex of wild (indigenous) tobacco well before the main domesticated tobacco (Nicotiana tabacum) was introduced by contact-era fur traders and settlers after the 1790s. This is the longest continuous biomolecular record of ancient tobacco smoking from a single region anywhere in the world-initially during an era of pithouse development, through the late precontact equestrian era, and into the historic period. This contradicts some ethnohistorical data indicating that kinnikinnick, or bearberry (Arctostaphylos uva-ursi) was the primary precontact smoke plant in the study area. Early use likely involved the management and cultivation of indigenous tobaccos (Nicotiana quadrivalvis or Nicotiana attenuata), species that are today exceedingly rare in the region and seem to have been abandoned as smoke plants after the entry of trade tobacco.