Strength Of Pipes Research Articles

ГИБРИДНАЯ ЛАЗЕРНО-ДУГОВАЯ СВАРКА ВЫСОКОПРОЧНЫХ ТРУБНЫХ СТАЛЕЙ КЛАССОВ ПРОЧНОСТИ API X80 И X120

The aim of the present work was to investigate the possibilities of hybrid laser arc welding regarding reliable production of longitudinal welds of high strength pipe steels X80 and X120 and to evaluate achievable mechanical properties of laser hybrid welds. The study focused on weld toughness examination in low temperature range up to -60 °C. SЮТЭКЛХО ПТХХОЫ ЦКЭОЫТКХЬ were identified in the context of this task. It could be shown that metal cored electrodes guaranteed sufficient Charpy impact toughness at low temperature for both investigated materials. Modern arc welding technologies such as modified pulsed spray arc were used to promote deeper Penetration of the filler material into the narrow laser welding gap. Edge preparation with a 14 mm deep root face was considered as optimum, because no penetration of the filler material could be detected beyond this depth limit and therefore any metallurgical influences on the weld metal properties through the welding wire could be excluded.

The influence of repeated loading on work of the steel fiber concrete drainage trays and pipes on the roads

The drainage system is one of the components of the road design. The condition of the subgrade and pavement depends on its effectiveness. The main structural elements of the drainage system on the roads are gutters and pipes. They are made of concrete or reinforced concrete. Under the influence of climatic factors and fluctuations of the vibration caused by the vehicles movement on the surface, it occurs destruction: formation of cracks, potholes, husking of concrete, destruction of protective layer of concrete, etc. It should be noted that these structures perceive the dynamic and thermal effects. The low fracture materials toughness poses the issue of searching ways of its increase. One solution of this problem is the use of dispersion-reinforced concrete gutters and pipes. The article presents the results of research strength, crack resistance and deformability of gutters and pipes using steel fiber reinforced concrete under the action of repeated loads

Heat Lump in Different Pavement Layer Using Ethylene Glycol as A Solar Heat Collector

Due to the hot weather in Malaysia, several studies being carried out regarding solar energy harvesting and use as a noble renewable energy. Therefore, researchers start developing various methods to utilize sun's heat as a renewable source of energy. Solar energy has been always concern researchers to develop most effective, durable and cheap methods and materials to be used as solar energy collectors in road pavements. Therefore, this study was conducted to determine the maximum heat area using ethylene glycol. The study was involved the field monitoring of the six samples of asphalt slab with stainless steel pipe with ethylene glycol and empty pipe act as the controlled sample. The pipe was arranged in three different depths of 50mm, 100mm and 150mm and keeping controlled the pipe diameter and the size of slab of 20mm and 300mm x 300mm respectively. These results show that the maximum heat extraction by the ethylene glycol was at a depth 150mm which was 51.2°C. The average percentage increments of the pipe with ethylene glycol for three days for pipe depth 50mm was 71%, while for pipe at depth 100mm and 150mm were 78% and 62% respectively. The ethylene glycol effect was more noticeable compare to the pipe without ethylene glycol and can store more heat. For the strength of pipe, the highest maximum load bearing capacity that can be supported by the stainless steel pipe was at depth 50mm and the second highest was at a depth 100mm while the third highest was at depth 150mm. So, the suitable depth to install the pipe with the consideration of both cases which was maximum heat gain and the maximum load that can be supported was at depth 50mm.

Failure and integrity analysis of casings used for oil well drilling

Abstract Drilling with casing (DwC) is an innovative method particularly widespread in deep shale plays, that reduces the time and cost of drilling stages. However, casings are not designed for this purpose, and still the pipes and connections are required to remain sealed in the well after sustaining a large amount of drilling cycles and possible damage. The investigations presented in this article were triggered by the failure of a 9 5/8″ diameter K55 seamless casing during drilling an oil well. Fractographic analyses identified fatigue crack nucleation and growth in the tube/coupling (T/C) transition zone. The failure analysis included physical and chemical material tests and numerical stress analyses at the T/C threaded joints when subjected to the loads logged during drilling. Fatigue cracks were found in other pipes that, although did not lead to fast fracture, would have caused leaking during subsequent well completion and production. The most relevant conclusion is that future integrity of casings used for drilling could not be assured. Reducing cyclic drilling stresses below the actual fatigue strength of pipes and connections is not easy task; the industry tendency is to go to slim-hole DwC, with ever increasing operating loads. Therefore, the economic feasibility of using heat treated casing and more sophisticated DwC designs are highlighted. Large grained tube steels and premium connections are found to be the most cost-effective alternatives to ensure the casing would survive the cyclic torque and compression stresses without serious damage.

Buckling Strength of Corroded Pipelines with Interacting Corrosion Defects: Numerical Analysis

Pipelines in the oil and gas industry are prone to extensive internal corrosion which leads to premature failures. Furthermore, corrosion defects within certain proximity interact to reduce the overall strength of a pipe and are termed as interacting corrosion defects. Pipelines may also experience complex loadings due to geotechnical movements such as landslides and internal pressure. Therefore, an understanding of the behavior of corroded pipelines under multiple loadings is important for the safe operation of pipelines. Extensive literature review indicates that major design codes only consider the effect of interacting corrosion defects on the burst pressure of pipes, with less attention paid to the structural behavior of steel pipes under multiple loadings. Therefore, this study focuses on the effect of interacting corrosion defects of equal depth on the local buckling strength of X46 steel pipes using the finite element analysis (FEA). Results showed that the corrosion defects interact to reduce the overall buckling strength of the pipe. Furthermore, circumferentially aligned corrosion defects are more critical than axially aligned corrosion defects, due to the greater loss of material along the circumference of the pipe. Besides, the effect of interactions of corrosion defects on the buckling strength decreases as the internal pressure increases. Lastly, as the depth of the defects increases, their interactions become more severe, which can significantly reduce the overall buckling strength of the steel pipe.

연료가스 배관용 탄소강관의 잔존강도에 대한 연구

연료가스 배관용 탄소강관의 잔존강도에 대한 연구

Influence of hydrothermal ageing on the compressive behaviour of glass fibre/epoxy composite pipes

The effects of hydrothermal ageing on the crushing behaviour of glass fibre-reinforced epoxy (GRE) pipes are discussed. Pipes with three different winding angles (±45°, ±55°, ±63°) were manufactured by filament winding process. The pipes were then hydrothermally aged in tap water at a constant temperature of 80°C for periods of 500, 1000, and 1500h. Uniaxial compressive tests were conducted on the virgin and aged samples using a universal testing machine in accordance with ASTM D695-10. The tests were also performed at temperatures ranging from room temperature (RT) at 25°C to 45°C and 65°C to study the response of the pipes at elevated temperatures. Scanning electron microscopy (SEM) images were captured and the relationship between the ageing period and strength of the GRE pipes was determined. The results indicate that the strength of the GRE pipes significantly decreases with increase in the temperature and ageing period. On the contrary, the strength increases as the winding angles decrease. The compressive strength of the pipes was also predicted using a Berbinau’s based model and was found to correlate well with the earlier obtained experimental results yielding a maximum variation of less than ∼25%.

Study of fatigue behavior of longitudinal welded pipes

During transport and storage of the various fluids, welded pipes are subjected to cyclic loading due to pressure fluctuations that often exceed the prescribed values for normal operation. These cyclic loading can significantly reduce the life of the pipes; as a result the design should be based on the fatigue strength not only on static resistance. In general the fatigue strength of pipes is dependent by strength, pipe geometry and surface quality. In case of the electric longitudinal welded pipes, the fatigue strength is significantly limited by concentration of residual stress and the size of existing defects in the weld seam. This paper presents the fatigue behaviour of the electric welded pipes by high frequency, under conditions that simulate real operating conditions pipes. Fatigue testing was performed on welded pipes made of micro alloyed carbon steels. Some of these pipes were previously subjected to a heat treatment of normalization, in order to also determine the influence of heat treatment on the fatigue strength of welded pipes. To determine and correlate the different factors affecting the fatigue strength, welded pipes were also subjected to various tests: tensile tests, impact tests, measurement of micro hardness, microstructural analysis by optical microscopy and scanning electron microscopy.

Effects of elevated temperatures on glass-reinforced epoxy pipes under multi-axial loadings

The effects of elevated temperatures on the performance of glass-reinforced epoxy (GRE) pipes under multi-axial loadings were investigated. Finite element software was used to develop the layers of the winding angle on GRE composite pipes. The simulations of the closed-ended pipes’ performance under internal pressure loadings of various hoop to axial stress interactions were observed, then the failure strength was illustrated in the form of a failure envelope. Five different stress ratios ranging from pure axial loading 0:1, 1:1, 2:1, 4:1 and pure hoop 1:0 were tested at elevated temperatures (room temperature (RT), 65°C and 95°C) respectively. The first ply failure (FPF) for GRE pipes was predicted based on Tsai–Wu failure criteria. The results show that the highest temperature reduced the strength of the GRE pipes since the hoop and axial stress decreased with increasing temperature and thus the mechanical properties of the GRE pipes were degraded with the increase of temperature. Both showed a strong dependence on the stress ratio and test temperatures. Moreover, as the temperature increases, the glass fibres become more ductile and cause the failure envelopes to shrink towards the origin and become slightly narrower to accommodate the increase in strength of the composite pipes. It is shown that the initial failure stress based failure envelope at elevated temperatures generally degraded, except for the 2:1 loading where the initial failure stress increased.

Rational finite element assisted design of precast steel fibre reinforced concrete pipes

There has been growing interest to introduce steel fibres in precast concrete pipes as a replacement for regular reinforcement. Several experimental studies have been conducted in order to determine the optimal fibre content for various pipe design scenarios. However, there is still need for more inclusive and comprehensible design approaches. This paper aims at developing a rational design tool for precast SFRC pipes. For this purpose, a non-linear 3D finite element model was developed to simulate the three-edge-bearing test. The model was verified using experimental data generated previously by the authors on full-scale SFRC pipes as well as other data available in the open literature. The model was capable of reasonably simulating the load-deformation curves of SFRC pipes tested using the three-edge-bearing method. The average error in model-predicted ultimate D-loads was about 6.5% on the conservative side. Subsequently, a parametric study was conducted. The pipe diameter, pipe wall thickness, fibre type and content, concrete compressive strength, and targeted pipe strength were the parameters under investigation. The findings of the parametric study were presented in a tabular form that can be used as a design aid supplementary to the ASTM C1765 standard.

Relating the structural strength of concrete sewer pipes and material properties retrieved from core samples

Drill core samples are taken in practice for an analysis of the material characteristics of concrete pipes in order to improve the quality of the decision-making on rehabilitation actions. Earlier research has demonstrated that core sampling is associated with a significant uncertainty. In this paper, the results of core samples are compared with the results of full-scale pipe cracking lab experiments. It is shown that the concrete of deteriorated sewer pipes shows a significant variability in material characteristics. Further it is shown that the formation of ettringite due to biochemical sulphuric corrosion is not necessarily limited to the crown of the pipe and also degradation of pipe material, measured by the carbonation depth, is occurring at the inside and outside of the pipe. It is concluded that tensile splitting strength and the carbonation depth are the two material property parameters of core sampling with a sufficiently high correlation (R2 > .90) with the structural strength of the pipe. The thickness of the remaining ‘healthy’ concrete material is the optimal parameter, as this requires the smallest sampling size.

Explosion loading on equipment from CFD simulations

Explosion studies using computational fluid dynamics (CFD) are performed on daily basis among safety consultants all over the world. The purpose of the explosion studies is usually to give guidance on required design strength of equipment, piping, blast walls or buildings. One key element is to translate the results from an explosion simulation, into actual forces on equipment. Major weaknesses exist in the current approaches for estimation of loads on small and medium sized equipment. In a previous work we demonstrated how loads on rectangular equipment could be estimated by combining free field form drag and pressure gradient. In the current work it is discussed how best to estimate loads onto other types of equipment including cylindrical pipes, pipe bundles and other shapes, and some comparisons and validation against large scale experiments are also included. The main findings of this work are the more accurate guidance on how best to extract explosion loads from simulations, including discussions on appropriate drag coefficients.

Optimization of Pulsed Current MIG Welding Parameters for Ultimate Tensile Strength and Hardness of ASTM A106 Pipes using Taguchi Technique

Optimization of Pulsed Current MIG Welding Parameters for Ultimate Tensile Strength and Hardness of ASTM A106 Pipes using Taguchi Technique

Investigation of Circular Woven Composite Preforms for Composite Pipes

Abstract The main traditional technique for commercial manufacturing of composite pipes is filament winding in which the winding angle and the discontinuity of the structure (caused by starting and ending points of the winding process) are two important matters of concern. In the present study, circular woven fabric with its orthogonal net-shaped continuous structure was produced from polyester yarns. Fabric was wet with epoxy and hand lay-up was used to manufacture the composite pipes. Composite pipes were subjected to internal hydrostatic pressure and their burst strength was recorded. In addition, tensile strength of flat laminas was assessed in the warp and weft directions. We estimated and analysed the failure strength of composite pipes using Tresca’s failure criterion and Finite Element (FE) modeling. The experimental burst strength was almost 23% more than the FE model and 77% more than the theoretical estimate.

Effects of steel properties on the local buckling response of high strength pipelines subjected to reverse faulting

The reverse fault is one of main threats faced by high strength gas pipelines, for the potential of leading to buckling failure in the pipe. A 3D finite element model was established in this study, in which the pipe was modeled by shell elements and the pipe-soil interaction relationship by spring elements. A suitable equivalent boundary condition is introduced at the ends of the pipe to simulate the remote end and reduce the model dimension. The mechanical behavior of the buckling process of the pipe was studied. 10 high strength pipe steel materials of 3 different APL 5L grades (X80, X90, X100) were taken into consideration to analyze the influences of the yield strength and the strain hardening parameter of the pipe steel material on the buckling behavior. Results show that, when buckling occurs in high strength steel gas pipelines under reverse fault displacement, the Mises stress in the buckling position of the pipe is about 1.1 times the yield strength of the pipe steel. The critical fault displacement and axial stress increase with the increase of the yield strength, and decrease with the increase of the hardening parameter, while both the yield strength and the hardening parameter have a small influence on the critical axial strain.

초고압 커먼레일 연료분사튜브 원재료 강성 최적화를 위한 인발 공정에서의 Die와 Plug 각도 변경에 따른 해석적 연구

Abstract : The study is actively being performed to increase fuel injection pressure of common rail system among countermeasures to meet the emission regulation strengthen of the Diesel engine. The common rail fuel injection tube in such ultra high pressure common rail system has the weakest structural characteristics against vibration that is generated by fuel injection pressure and pulsation during engine operation and driving. Thus the extreme durability is required for common rail fuel injection tube, and the drawing process is being magnified as the most important technical fact for strength of seamless pipe that is the raw material of common rail tube. In this respect, we analyzed the characteristic of dimension and stress variation of the ultra high pressure common rail fuel injection tube by variation of Die and Plug angle in drawing process. Based on the analysis, we tried to obtain the raw material strength of common rail fuel injection tube for applying to the ultra high pressure common rail system. As a result, Plug angle is more important than entry angle of Die and we could obtain the target dimension and strength of the ultra high pressure common rail fuel injection tube through optimization of Plug angle.

Investigating the Possibility of using Fiberglass Reinforced Polyethylene Pipe for the Transportation of Natural Gas

Background/Objectives: Historically the most applied pipe material for gas transportation is steel, but polyethylene and fiberglass are also used. The purpose of this article is to present the results of a comprehensive study of the possibility to use composite pipes. Methods: A multivariate experiment to refine the method for calculation of reinforced polyethylene pipes consisting of three layers was carried out using pipe samples specially prepared in the laboratory; the economic effect of composite pipes introduction during the construction of gas pipelines instead of traditional steel was analyzed on the basis of the calculation of net present value and profitability index using the industrial data for offshoot pipeline construction. Findings/Improvements: The literature and statistical data analysis shows an increase in the length of composite pipelines over the last 10 years and their defect-free; a classification of multilayer pipes offered by various manufacturers was first developed and proposed and a diagram of product characteristics is presented; advantages and disadvantages of using these pipes for hydrocarbon transport streams are shown. According to the laboratory experiment the regression coefficients for mathematical model of a composite pipe were obtained for the first time and the assumption of the joint participation of polyethylene and a reinforcing frame to ensure overall pipe strength was confirmed, as well as the method of calculating the critical pressure for a classical composite pipe was proposed and conclusions about the nature of the pipe wall destruction were represented. The profitability index of the project, built of composite materials, compared to the project, built of traditional materials, shows a higher efficiency of the former by 34%, which enables to reduce the costs of social projects without reducing investment totally. Application: The investigation results can be used in creating the methodological and regulatory base for the implementation of multi-layer composite pipes of different designs in the oil and gas industry.

Accelerated ageing of plastic jacket pipes for district heating

The axial shear strength of plastic jacket pipes consisting of a steel medium pipe surrounded by polyurethane insulation and a casing of polyethylene was determined after service life. Recalculation of the physical life to equivalent life at 120 °C with the respective Arrhenius equation showed the envelope of lifetime ends much earlier than stated as minimum requirement in EN253. A method to determine an apparent activation energy considering additionally the oxidative degradation of PUR in plastic jacket pipes is presented. Enabled gas exchange within accelerated ageing similar to 30 years of life time resulted in an apparent activation energy of 95 kJ/mol, and additionally a further degradation, obviously due to corrosion, was found.

The Design of Glass Fiber//Epoxy Composite Pipes by the Implementation of the Full Factorial Experimental Design

In the present work, the attempt was made to assess the applicability of the full factorial experimental design in predicting the hoop tensile strength of glass fiber/ epoxy resin composite pipes by using of a split disk specimens. Split disk tension tests, provide reasonably accurate information with regard to the apparent tensile strength of composite pipe.In the study we used a number of composite pipes with different fiber orientation, fiber tension and velocity of the winding. The composite pipes were made by using of filament winding technology includes winding of resin impregnated fibers into a tool and hardening of the wound structure. The preparation of the composite experimental samples was conducted in accordance with the 23 full factorial experimental design. The winding speed of the composites was taken to be the first factor, the second was the fiber tension and the third winding angle. The first factor low and high levels were set at 5,21 m/min and 21 m/min, respec­tively, for the second factor – at 64N and 110N, respectively, and for the third factor – at 100 and 900. To approxi­mate the response i.e. the hoop tensile strength of the composite pipes within the study domain (5,25 – 21) m/min x (64-110)N x (10 – 90)0, the first order linear model with the interaction was used. The influence of each individual factor to the response function was established, as well as the influence of the interaction of the two and three factors. We found out that the estimated first-degree regression equation with the interaction gave a very good approximation of the experimental results of the hoop tensile strength of composites within the study domain.

高窒素ステンレス鋼の高圧水素溶接配管の疲労強度評価

Hydrogen refueling infrastructure for fuel cell vehicles requires weld joints for high-pressure piping. Thus characterization of the effect of hydrogen on the fatigue strength of piping welds is necessary. Here, fatigue strength of the weld jointed pipe, which is made of high-nitrogen stainless steel XM19, was investigated. At first, a fatigue test method to simulate fatigue due to inner pressure cycle in an efficient way was developed. The microstructure of the weld metal was dendrite and small δ-ferrite grains. The fatigue strength of the hydrogen-charged specimen was the same as that of the uncharged one. There was no significant change in the fatigue fracture surfaces between the uncharged and hydrogen-charged specimen. The fatigue crack initiated from small defects like micro-porosity at inner surface of the weld metal.