Pipe Samples Research Articles

Review and recommendations for structural testing of buried gravity storm drain pipes and culverts

Buried pipes are important components of the underground infrastructure. Structural failure of these pipes is costly, socially and environmentally disruptive. To prevent such incidents, a deep understanding of the soil–pipe interaction system behavior is needed. Currently, two common standard methods are available for the structural testing of pipes: parallel-plate loading test and three-edge bearing test, in which the effects of surrounding soil and distributed load on the pipe sample are ignored. However, in the available design methodologies the effect of bedding and load distribution is considered though empirical factors. As of today, there is no standard test method available for structural testing of pipes considering the effect of soil–pipe interaction system. Therefore, the objectives of this paper are to present a literature review of full-scale structural testing methods of relatively large diameter gravity pipes ranging from 36 in (90 cm) and larger, and suggest a general soil–pipe test procedure for structural evaluation of large diameter gravity pipes, such as culverts. Discussions are made for selection of a soil–pipe structural testing condition, loading method, loading rate, loading configurations, and required instrumentations for capturing and recording test results.

Water deoxygenation using a hollow fiber membrane contactor to prevent pipe corrosion for sustainable management of district heating systems: A pilot-scale study

Dissolved oxygen (DO) is a key factor affecting pipe corrosion in district heating systems (DHS). This study demonstrated effective deoxygenation of water in a DHS using a hollow fiber membrane contactor (HFMC) via systematic investigation from lab-to pilot-scale. First, deoxygenation efficiency was evaluated in a lab-scale HFMC with varying operating parameters including an effective membrane area, flow rate and feedwater temperature. Based on the results from the lab-scale investigation, a pilot HFMC system was designed with capacity of 1 m3 per day. To achieve a permeate DO concentration below 10 μg L−1 at feedwater temperatures of 20–60 °C, the vacuum degree needed to be lower than the saturated water vapor pressure of 10–120 Torr. In addition, the primary foulant for membrane fouling was organic matter in the make-up and district heating (DH) return water. A significant change in corrosion response was observed for pipe steel in the DHS after deoxygenation. Immersion tests for 14 days indicated that weight loss values had greatly reduced by the deoxygenation process from 39.3 to 1.3 mg cm−2 and from 21.9 to 2.1 mg cm−2 for steel pipe samples immersed in the make-up water and the DH return water of the DHS, respectively. This improved corrosion resistance from deoxygenation was interpreted by electrochemical analysis. As such, this study offers a pilot-scale demonstration of the feasibility of a hollow fiber membrane-based deoxygenation process as an effective tool to prevent the corrosion of steel pipes.

Mid Infrared Tomography of Polymer Pipes

Mid-infrared signals in the 2–5 μm wavelength range have been transmitted through samples of polymer pipes, as commonly used in the water supply industry. It is shown that simple through-transmission images can be obtained using a broad spectrum source and a suitable camera. This leads to the possibility of tomography, where images are obtained as the measurement system is rotated with respect to the axis of the pipe. The unusual 3D geometry created by a source of finite size and the imaging plane of a camera, plus the fact that refraction at the pipe wall would cause significant ray bending, meant that the reconstruction of tomographic images had to be considered with some care. A result is shown for a thinning defect on the inner wall of a polymer water pipe, demonstrating that such changes can be reconstructed successfully.

Interaction of Calcium Carbonate with Nanobubbles Produced in an Alternating Magnetic Field.

Nanobubbles have been widely studied for their use in water treatments. Conventional methods for producing nanobubbles require significantly high levels of electric power. A system that involves inducing an alternative magnetic field (AMF) in flowing water has been developed, which has relatively low power requirements compared to other methods. Experimental results are presented that indicate nanobubbles are generated by this AMF system. These results include ζ potential measurements in deionized water, light scattering observations, and nanoparticle tracking analysis (NTA) measurements of object size and relative scattering intensity for water containing 5 × 10-4 M CaCO3. The NTA results also suggest the formation of nanobubble-nanoparticle clusters. Finally, an earlier work is reviewed which demonstrated that this AMF treatment led to the removal of tubercles on the inner walls of pipe samples. This prior result is discussed in light of the present evidence of nanobubble formation and a hypothesis is proposed based on the dissolution of CaCO3 as a result of nanobubble-nanoparticle clustering.

Ремонт наплавкой при дефектах металла трубы и сварных соединений

Cladding repair is the one of the most simple and least expensive repair technologies. It refers to both permanent and temporary repair methods. It reduces work costs and time of repair works while retaining the quality required by the statutory requirements. With the help of cladding repair, a significant number of defects of corrosion-mechanical origin can be eliminated. The problem of improving this technology is of utmost importance. The purpose of the present research is to develop the technology for effective and safe cladding repair of such defects as corrosion damages of pipe metal and such welded connection defects as incomplete groove filling, undercut, pores, strikes, slag inclusion. The following problems were solved to reach this goal: research of thermal cycles in the course of cladding, research of cladding modes, development of multipass repair technology, determination of allowable defect parameters, and detection of methods for optimal quality control of repaired areas. The specialists performed testing of full-scale pipe samples and circular joint of pipes, imitating the surface defects after cladding repair. The test results did not reveal the damage of metal and welded connection areas. Cladding repair allows recovering bearing capacity of pipeline to design level. This technology can be used in the works on shutdown pipelines and on pipelines under operation.

Structural evaluation of invert-cut circular and arch shape corrugated steel pipes through laboratory testing

Culverts are important components of highway infrastructure. They are structurally designed to support earth and live traffic loads. Corrugated steel pipes (CSPs) are widely used as culverts in North America in different geometries. However, due to the corrosive nature of the stormwater passing through the culverts, it is common to find CSPs with partially or entirely lost inverts. Dependent on site, depth of cover and embedment conditions, invert deterioration would not necessarily result in culvert failure. This paper presents the results of a laboratory testing campaign that evaluates the structural capacity of two circular CSPs and their equivalent arch CSP through the application of a vertical static loading. The circular pipe samples had a length of 6 ft (1.82 m) and a diameter of 60 in. (1.52 m). The same length arch pipe sample had a span of 71 in. (1.8 m) and a rise of 47 in. (1.19 m). The invert of the arch and one of the circular CSPs were cut to simulate heavily corroded culverts in service. The pipe samples were embedded under two feet (0.6 m) of cover using one foot (0.3 m) of sand and one foot (0.3 m) of coarse aggregates on top, simulating a base course layer of pavement. The results of testing showed that the invert-cut circular CSP was highly dependent on its ring stiffness. While, the invert-cut arch CSP took advantage of its arch geometry and was able to resist the applied load without significant loss in the sample pipe’s horizontal dimension.

Laboratory testing of invert-cut corrugated metal pipes renewed with polymeric spray applied pipe lining

Buried culverts are important components of highway infrastructure. Most large culverts are built decades ago from corrugated metal or reinforced concrete materials and now have reached their design life. A variety of renewal techniques can be utilized to enhance load carrying capacity of the existing deteriorated culverts and extend their design life. Spray applied pipe lining (SAPL) is a trenchless renewal methodology that applies layers of liner on the interior surface of the deteriorated host culvert. The SAPL’s substances generally fall into two categories: cementitious and polymeric materials. Currently, there is no standard method available for structural design of SAPLs that resulting in various methods being applied by SAPL vendors. To provide the essentials for development of a design methodology for SAPLs, the objective of this paper is to examine the structural performance of full scale soil box testing of 60 in. (1.5 m) diameter circular invert deteriorated (invert-cut) corrugated metal pipes (CMPs) renewed with three different thicknesses of polymeric SAPL. The inverts of the CMPs were cut to simulate an invert deteriorated culvert in service condition and maximize the applied static load on the SAPL. The pipe samples were backfilled with loose SP soil and buried under two feet (0.6 m) of soil cover. The performances of SAPL renewed CMPs were compared with a same size invert-cut bare CMP under the same testing configuration. The results indicated that depending on thickness of the polymeric SAPL, application of this method could improve the structural capacity of a fully deteriorated invert CMP culverts up to 80%.

Расчетные и экспериментальные исследования прочности натурных образцов труб с дефектами «потеря металла» и «вмятина с риской»

The article contains the comparative results of the experimental and calculated research of the strength of a pipeline with such defects as “metal loss” and “dent with groove”. Two coils with diameter of 820 mm and the thickness of 9 mm of 19G steel were used for full-scale pipe sample production. One of the coils was intentionally damaged by machining, which resulted in “metal loss” defect, the other one was dented (by press machine) and got groove mark (by chisel). The testing of pipe samples was performed by applying static internal pressure to the moment of collapse. The calculation of deterioration pressure was carried out with the use of national and foreign methodical approaches. The calculated values of collapsing pressure for the pipe with loss of metal mainly coincided with the calculation experiment results based on Russian method and ASME B31G. In case of pipe with dent and groove the calculated value of collapsing pressure demonstrated greater coincidence with Russian method and to a lesser extent with API 579/ASME FFS-1. In whole, all calculation methods demonstrate sufficient stability of results, which provides reliable operation of pipelines with defects.

USING GEOPOLYMER COMPOSITES FOR HEAT AND CORROSION RESISTANT PIPES

This research studied the use of carbon fiber reinforced geopolymer composites as corrosion resistant pipe material. Geopolymer material is a general term for material synthesized from fly ash. Fly ash is an industrial by-product (coal combustion residue) with high silica content (SiO2) and Alumina content (Al2O3). In addition, there are also other elements in a relatively small percentage. This material will compound like cement if activated with Sodium Silicate. This study aims to obtain the optimum composition for high quality mechanical properties. The method used is to synthesize material with various elemental compositions. Furthermore, a mechanical test (bending test) is performed to see the effect of each element to be optimized. Besides that, a physical test in the form of SEM-EDX was also conducted to see the microstructure. Materials with optimum composition have been fabricated as pipes with centrifugal casting process. Mechanical testing of pipe samples is done by hoop tensile strength test. The test results show that the strength of geopolymer composites can achieve 58 MPa.

Stress Distribution in Pipe Samples of Gas Pipelines with Welded Joints

Напряжения в зоне термического влияния и сварного соединения связаны с наличием внутренних напряжений, возникновение которых связано с различными причинами. Основными из них являются неравномерность нагрева и усадки сварного шва, а также структурные изменения металла и околошовной зоны в процессе сварки. Эти напряжения могут складываться с эксплуатационными напряжениями, что в свою очередь приводит к ускорению скорости зарождения трещин в зоне сварного соединения. Произведена оценка двухосных напряжений в основном металле и в зоне сварных соединений магистральных трубопроводов на основе явления акустоупругости с использованием трех типов волн различных поляризаций (продольной и двух поперечных с ортогональной поляризацией) и электромагнитно-акустического преобразования ввода-приема ультразвуковых волн.В осевом направлении ближе к краям вырезки значения напряжений ниже, чем по центру, что объясняется уменьшением напряжений при удалении связей. Похожая картина наблюдается для окружного σ2 направления. В образцах со сварным соединением наблюдается резкое уменьшение значения относительных напряжений в зоне термовлияния сварного соединения по сравнению с напряжениями в области основного металла.

Failure analysis of AISI 304 stainless steel pipeline transmission a petrochemical plant

This paper presents the failure analysis of AISI304 stainless steel pipeline that was fabricated by welding and used for CO2 transmission in a petrochemical plant. After a years of satisfactory operation, significant cracking was observed adjacent to the weld joints of valve and pipeline. The failure investigation was carried out on welded pipe samples using optical and fractography, micro hardness measurements, XRF and XRD testing. The hardness test results show faults occur in the HAZ region. Fractured surface macrostructure and morphology analysis shows inter-granular brittle fracture mode. The inter-granular fault begins with the presence of very intensive inter-granular corrosion, especially on the outer metal surface and progressively propagates to the inside of the metal. The results of XRD found peak of carbide from the secondary phase of SS 304 austenite steel. The material experienced sensitization that is indicated by the presence of carbides at the grain boundary.

The Mechanical Performance of Pipe Based on Fiberglass Reinforced with Plastic Waste (FRPW) Composites

The project research present the mechanical performance of pipe based on fiberglass reinforced with plastic waste (FRPW) in plant application system. The use of FRPW able to reduce corrosion problem faced by oil and gas industry. In this study involved four types of combination ratio of fiberglass reinforced with plastic waste (FRPW) of 1.0: 0.5; 1.0:1.0; 1.0:1.5; and 1.0:2.0. The fabrication process started with grinding process of plastic waste into small size in the range of 0.1 mm. Fiberglass then reinforced with plastic waste by mixed with resin and hardener with ratio of 2: 1 and poured into the cylinder mould. There is a possibility fiberglass from 10-40% by weight result in substantial increase in elastic modulus, accompanied by an increase in strength with reduced ductility 1.0 of ratio. The tensile test showed clearly exhibited that 1.0 of plastic waste reinforced fiberglass with stand the higher maximum force value of 2.69 kN. For the bending test ratio of 1.0 of plastic waste withstand the higher bending strength at 5.29 kN. Ratio of 1.0 FRPW is more suitable for produced pipe in plant application system due to matrix-reinforcement bonding for each pipe sample after conducting tensile strength. The result obtained that ratio 1.0 of FRPW shown good matrix-reinforcement bonding.

The influence of a porous, compliant layer with overlying discrete roughness elements as exhaust pipe wall on friction and heat transfer

The purpose of this work is to experimentally establish the combined influence on the flow and thermal resistance of an exhaust pipe wall formed by a porous, compliant layer with overlying discrete roughness elements exposed to the pulsating exhaust gas flow of a combustion engine. Through measuring the streamwise pressure drop over and radial temperature differences in different pipe samples for a range of flow states with different Reynolds numbers and non-dimensional pulsation frequencies, the effects were discerned. The configurations of the sample walls covered a range of mesh pitches, compliant-layer densities, and compliant-layer compression ratios. The (non-sinusoidally) pulsating exhaust gas flow spanned the following range: Reb (= ubD/νb) = 1⋅ 104 - 3⋅ 104, Tb = 500 - 800 ∘C, ω+(= omega nu _{b} / u_{tau }^{2} ) = 0.003 - 0.040. The friction factors were found to be effectively constant with Reynolds number and non-dimensional pulsation frequency while the variation with insulation density/compression was not significant. Additionally, for both mesh pitches, the measured friction factors were in line with those reported in literature for similar geometries with steady flow and solid walls. Together this indicates that neither compliance nor the pulsations in the exhaust gas flow significantly affect the friction for this configuration. Comparison of the samples based on the derived thermal resistance showed a similar influence of the fluid-wall interface as for the friction. Additionally a distinct influence of compression, independent of the insulation density, was observed that increases with increasing temperature. It was concluded that the increased resistance was due to additional radiation resistance because of fibre reorientation due to compression.

Influence of unevened grains of metal on the mechanical properties of seamless hot – rolled pipes.

Seamless hot – rolled pipes are a popular metal product on the world market. During operation, pipelines are subjected to cyclic loads associated with temperature fluctuations, vibrations near compressor stations, and pressure drops in the transformed medium. One of the ways to ensure high performance properties is to manage the quality of pipe metal, including that laid in the process of metallurgical production. All the basic physical and mechanical properties of metal materials are structurally sensitive and significantly depend on both the grain size and the degree of uniformity of the grain structure, that is, on the different grain sizes. For metallographic research, samples of pipes with the size of 70,0×12,5 mm of S460NH steel were selected with satisfactory (#1) and unsatisfactory (#2) results of the impact. It was found that the inhomogeneous (multi – grained) microstructure in sample #2 was the reason for obtaining unsatisfactory results of the impact. As a result, it was found that one of the most important characteristics that can guarantee stable and satisfactory results of mechanical characteristics, in particular the impact performance, is a homogeneous grain structure.

Obtaining Hollow Semifinished Products Based on Copper Alloys for Electrical Purposes by Means of Screw Rolling

A process for obtaining semifinished products in the form of pipes made of copper alloys for electrical purposes by means of screw rolling is proposed. The results of experimental piercing and rolling of tube samples made of Cu–0.75Cr alloy billets with a diameter of 45 mm are presented. The samples, 43.5 × 10.0 mm in size, obtained after piercing with the use of a two-roll screw rolling mill, have exact geometrical dimensions: the deviation of the outer diameter at the front end is less than 1%, that at the rear end is less 2.4%, the relative nonuniformity of pipe wall thickness at the front end amounts to 0.3–0.5%, and that at the rear ranges within 0.5–1.0%. The pierced pipe samples have been rolled by using a three-roll minimill for radial-shear rolling (RSR) with a different total reduction level; the samples have been obtained with an outer diameter of 30, 25, and 18 mm. The reduction process has been analyzed from the standpoint of stability and deformation of the mouth of pipe. In the case of a 30% relative reduction of the outer diameter, the rolling without a mandrel is accompanied by an increase in the wall thickness. The deviations of the inner diameter are within permissible limits. The experiments performed for obtaining samples based on the Cu–0.75Cr alloy by means of screw piercing and reduction using an RSR mill show that this technique could be implemented in industry. At the same time, in order to obtain a quality product, it is necessary to more exactly determine the deformation parameters (deformation level and reduction mode). Different variants for the heat treatment (HT) of the pipe samples and the effect of the HT mode exerted on the electrical conductivity and hardness are considered. After piercing, the samples exhibited a conductivity of 59.3% IACS. The maximum electrical conductivity of 76.7% IACS has been obtained for the samples after quenching from a temperature of 1020°C and aging at 450°C for 3 h. The results of this work show that it is fundamentally possible to obtain semifinished products based on copper alloys for electrical purposes by means of screw rolling.

A study of thermal performance change of cryogenic heat pipes by wick structures for wide range of working fluid filling ratio

In this research the performances of nitrogen cryogenic heat pipes with different wick structures were compared under the condition of a wide range of heat load and several filling ratios. The heat pipes tested are commercially available ones, which were originally designed for room temperature applications using water as a working fluid. For the present research, working fluid, water, was replaced by liquid nitrogen. Heat pipe samples with three types of wicks, namely, axial grooves (G), sintered metal (S), and the combination of them (SG), were tested for comparing the thermal performance of the heat pipes with different wick structures, which is characterized by the effective thermal resistance Rth . The experimental data of the maximum heat transport capability Qmax was compared with theoretical predictions on the basis of the capillary limit for each wick structure. Under high filling ratio condition, wide range of heat load was supplied to investigate the variation of the thermal resistance including such operations as dry-out state and the state where liquid puddle was formed in the pipe. The result indicates that the thermal performances of heat pipes with three kinds of wick structures are ordered as follows in descending order; SG, S and G wick.

Напряженно-деформированное состояние трубопровода под воздействием комбинированной нагрузки

Theoretical and experimental study of the stress-strain state of a pipeline under the influence of two types of loads was carried out: 1) bending force in vertical plane; 2) combined action of bending force in vertical plane and internal pressure. The experiments were performed on a pipe sample: steel grade Ст3, outside diameter 114 mm, wall thickness 4.5 mm, length 0.94 m. Hoop and longitudinal strains were measured in different areas of the pipe sample wall under the bending force in the vertical plane. To determine other parameters of the pipe stress-strain state the theories of thick-walled and thin-walled cylindrical shell, the Hooke’s law, the Zhuravsky–Vlasov formula for calculating the greatest shear stress in a circular tube, the principle of superposition were used. The distributions of the stress-strain state parameters (hoop, longitudinal, radial strains; hoop, longitudinal, shear stresses; von Mises stress) of the pipe sample wall around the perimeter of different pipe cross sections are found. It is revealed that hoop and shear stresses have a significant effect in the considered cases of loading. The values of hoop and shear stresses should be taken into account when calculating von Mises stress and assessing strength of the main pipeline according to the maximum-distortion-energy theory.

Obtaining hollow semi-finished products from copper alloys for electrical applications by screw rolling method

The article proposes a process for obtaining semi-finished products in the form of pipes made of copper alloys for electrical applications using the screw rolling method. The paper presents the results of experimental piercing and rolling of pipe samples made of Cu–0.75Cr copper alloy billets with a diameter of 45 mm. The 43.5×10.0 mm samples obtained after piercing using a two-roll screw rolling mill had exact geometrical dimensions: outer diameter deviation at the front end was up to 1 %, at the back end – up to 2.4 %; relative variation in wall thickness at the front end was 0.3÷0.5 %, at the rear end – 0.5÷1.0 %. Then pierced pipe samples were rolled using a three-roll radial-shear rolling (RSR) mini mill with a different total degree of reduction – samples were obtained with an outer diameter of 30, 25 and 18 mm. The reduction process was analyzed from the point of view of internal hole stability and deformation. In case of 30 % relative reduction of the outer diameter, rolling without a mandrel is accompanied by wall thickening. In this case, inner diameter deviations are within acceptable limits. The experiments on obtaining samples from the Cu–0.75Cr alloy by screw piercing and reduction in the RSR mill show that this scheme can be implemented in principle in industry. At the same time it is necessary to define more exactly deformation parameters (degree of deformation, choice of reduction scheme) to obtain a quality product. Various options for heat treatment (HT) of the obtained pipe samples and the effect of the HT method on electrical conductivity and hardness are considered. Samples after piercing had a conductivity of 59.3 % IACS. The maximum electrical conductivity of 76.7 % IACS was obtained on samples after quenching from a temperature of 1020 °C and aging at 450 °C for 3 h. The results of the work show the fundamental possibility of obtaining semi-finished products from copper alloys for electrical purposes using the screw rolling method.

Active SHM for composite pipes using piezoelectric sensors

Composite materials, in addition to the high specific mechanical properties, have properties enabling their applications in high-pressure, high-temperature (HPHT) and corrosive environment as occurs in deep water. Their use for manufacturing pipelines and offshore risers can provide relevant performance advantages over steel such as lower weight, improved fatigue capacity, corrosion resistance and higher strain limits. However, composite materials are more complex to use in design than metallic materials due to their anisotropic properties and lack of accurate failure prediction models. Thus, a continuous in-situ and in real-time Structural Health Monitoring (SHM) of composite components would be necessary and useful to promote their use in a wider range of operational conditions. In this work, an FRP pipe sample was instrumented with Piezoelectric Wafer Active Sensors (PWAS) used either as passive receivers or as transmitters of guided waves for active health monitoring in pitch-catch configuration. The propagation properties of guided waves in glass fibres reinforced composites were studied by developing MATLAB scripts, running FE simulation and experiments. The numerical and experimental signals were post-processed in MATLAB by Short Time Fourier Transform (STFT) in order to evaluate their frequency and time-frequency content. Furthermore, the guided waves were used to detect artificial defects imposed on the structure identifying their location. Several testcases were studied to find out the limitations and the most suitable conditions of using guided waves for defects monitoring in a composite pipe. The work proposes effective methods for pipe structural health evaluation by non-destructive techniques and ultrasonic guided waves.

Avaliação do Comportamento dos Parâmetros Cinéticos da Reação de Oxidação do Biodiesel em Contato com Ligas Metálicas Durante o Armazenamento

Biodiesel has low oxidative stability due to the high content of unsaturated esters in its composition, and its degradation can occur due to exposure to air, humidity, light, heat, contaminants by microorganisms and in the presence of metals. This study aims to evaluate the influence of alloys of carbon steel, steel 1020 and sample of industrial pipe in biodiesel storage. The sample of biodiesel in contact with the pipe sample presented lower values of the induction period and, consequently, higher rate constants, accelerating biodiesel degradation. The biodiesel in contact with carbon steel and steel 1020 showed a lower degradation when compared to the industrial pipe sample. The biodiesel in the presence of the carbon steel alloy presented higher oxidative stability that of the sample in the presence of steel 1020. Some samples presented more complex oxidation reactions with deviations of the linearity described by Arrhenius.