High-pressure Pipeline Research Articles

A fully coupled fluid-structure interaction simulation of three-dimensional dynamic ductile fracture in a steel pipeline

Long running fractures in high-pressure pipelines transporting hazardous fluid are catastrophic events resulting in pipeline damage and posing safety and environmental risks. Therefore, the ductile fracture propagation control is an essential element of the pipeline design. In this study, a coupled fluid-structure interaction modelling is used to simulate the dynamic ductile fractures in steel pipelines. The proposed model couples a fluid dynamics model describing the pipeline decompression and the fracture mechanics of the deforming pipeline exposed to internal and back-fill pressures. To simulate the state of the flow in a rupturing pipeline, a compressible one-dimensional computational fluid dynamics model is applied, where the fluid properties are evaluated using a rigorous thermodynamic model. The ductile failure of the steel pipeline is described as an extension of the modified Bai-Wierzbicki model implemented in a finite element code. The proposed methodology has successfully been applied to simulate a full-scale pipeline burst test performed by British Gas Company, which involved rupture of a buried X70 steel pipeline, initially filled with rich natural gas at 11.6 MPa and −5 °C.

Theoretical analysis of braiding strand trajectories and simulation of three-dimensional parametric geometrical models for multilayer interlock three-dimensional tubular braided preforms

Multilayer interlock three-dimensional (3D) tubular braided composites have been widely used in propeller blades, high pressure pipelines, rocket nose cones and engine nozzles owing to prominent interlaminar shear properties, reliable damage tolerance and outstanding torsion performance. The prediction of the mechanical properties and the design of the fabric structures for the 3D braided composites are dependent on the trajectory distribution of strands and the geometrical model of the braided structure. This paper aims to build theoretical models for the braiding strand trajectories and presents a creative method to establish the parametric geometrical models for the multilayer interlock 3D tubular braided structures. Firstly, mathematical models of braiding strand trajectories are derived based on the analysis for the characteristics of carrier paths, the interlacing and interlocking of braided structures and the motion of braiding strands. The mathematical models are then developed to establish parametric expressions for multilayer interlock 3D tubular braided structures by the advanced development of UG NX®. In addition, the models of corresponding braiding strand trajectories and braiding structures can be obtained automatically in the simulation environment with the modification of design parameters. Finally, the established models are compared with the carbon fiber braided specimen. The results show that the innovative parametric geometric models of the multilayer interlock 3D tubular braided structures accurately describe the key characteristics of the preform.

Electromagnetic effect of lightning return stroke to buried energy pipelines

Direct lightning strike in the vicinity of buried high-pressure energy pipeline can cause damages to pipe coatings or to the metal pipe. This damage sometimes leads to explosions which may cause loss of consignments. This is also a risk to pipeline integrity and safety of the people working on the pipeline. Hence, lightning induced electromagnetic interference (EMI) on buried energy pipeline is a matter of serious concern. To protect buried metallic energy pipeline from the effects of direct lightning strikes near the pipeline to the ground, it is necessary to have comprehensive information about the lightning currents and the radiated electromagnetic fields. To obtain thorough information of lightning-induced effect on the buried pipeline, a computational model considering electrical parameters of soil, pipe and lighting strikes to carry out a simulation of buried pipeline under soil has been developed which can be used to identify parameters influencing the coupling phenomenon between pipeline and lightning strike. The E and H field was estimated at various distance and depth from the point of strike. The model is based on the finite difference time domain (FDTD) solution of Maxwell’s equations. Lightning current and other fields are calculated within soil with and without the presence pipe and the same has been done for pipe with and without corrosion coating. The results are then used to analyze the influence of various parameters of the studied system on the development of high breakdown potential around the pipeline. This paper then presents the impacts of the direct lightning strike to the ground on buried metallic energy pipeline with corrosion coating. The results showed that although ground conductivity, current rise time, burial depth of pipeline and the pipeline metallic property has an influence on the severity of impact, in case of coated pipe, the coating on pipeline plays a great role on the scale of impact lightning can cause on the pipeline. While coating prevents pipelines from corrosion, the very low conductive coating is also responsible for very high electric field above the pipe surface. This work will be very useful pipeline industry in selecting a coating with suitable impedance value so that buried pipeline can be protected from both corrosion and lightning strike.

Consequence modelling of CO2 pipeline failure

This paper describes the experimental investigation and Computational Fluid Dynamics (CFD) simulations of the dispersion of CO2 following high-pressure dense phase CO2 pipeline failure. A full-scale burst test was carried out to simulate a CO2 pipeline failure in the real world. The atmospheric dispersion of the CO2 following the explosive release was measured. The CFD models were validated against the experimental data. The models were then used to estimate the consequence distances related to CO2 dispersion following failure of pipelines with various diameters under different wind speeds. This approach provides a predictive formula for the consequence distances of CO2 transmission pipelines.

Investigation of Dynamic Phase Changes in High-Pressure Pipelines During Flexible CO2 Transport

Investigation of Dynamic Phase Changes in High-Pressure Pipelines During Flexible CO2 Transport

Fracture Control of the 2nd West to East Gas Pipeline in China

The 2nd West to East Gas Pipeline ( WEGP) is the first major pipeline project in China importing abroad natural gas and also the longest and largest gas transmission pipeline in the world with gas supply of Middle Asian natural gas and adjusting gas supply of domestic gas from Tarim Basin and Ordos Basin. Its total length is 9 000 kilometers, in which the total length of artery from Khorgos to Guangzhou is 4 900 kilometers. Its design throughput is 30 billion cubic meters per year. Designed maximum operation pressure is 12 MPa, largest diameter of pipe is 1219mm and highest steel grade is X80. To ensure the long-term safety and reliability in operation, fracture control program has been proposed through systematic research, including crack initiation control, brittle fracture control and ductile long-running fracture control. The requirement of arrest toughness of the 2nd WEGP had been studied on the basis of pipe full-scale burst test data base in the world, Battelle Two Curve (BTC) method and GasDecom software. Full-scale burst tests of X80 high-pressure gas pipeline had been successfully performed based on previous research results. The fracture control program was set up based on different fracture criteria and the principle of both safety and economy. The crack arrest ability of X80 spiral submerged arc welded (SSAW) steel pipe was firstly verified and a new correct factor of arrest toughness prediction was obtained. Results presented that the crack arrest ability of SSAW pipe is better than longitudinal submerged arc welded (LSAW) pipe. It lays a solid foundation for the safe operation of the X80 pipeline after construction and completion.

Risk Factors in a Process of Gas Supply Pipeline Construcion

The paper applies to the risk management in the specialized construction by the example of construction of a high-pressure gas supply pipeline. The specific character of the construction project has an impact on the scope and types of risks which may occur and adversely affect the outcome of the project. The paper aims to indicate the groups of technological tasks which need to be carried out when constructing a gas supply pipeline, the associated factor risks and the quality control method as a tool of mitigating the level of risk.

Hydrogen-Natural Gas mixture compression in case of transporting through high-pressure gas pipelines

When dealing with search for ideal energy production solutions, one of the direction may be the use of hydrogen based on excess electricity. Gaseous state and the existing gas network can be used to deliver it to customers. Quantity of hydrogen in the natural gas system would be different depending on its production, hence it should be sent as an additional component sent by pipeline next to natural gas. Due to the difference in its physicochemical parameters with respect to the characteristics of natural gas, the work of gas compressors at different hydrogen concentrations will be different. An additional aspect taken into account when considering the effect of hydrogen on the performance of the compressor is the change of the main parameters which characterizes the flow. It may turn out that they will also positively influence the work of compression needed in the same compressor stations. Such changes may in consequence lead to additional savings, some of which are described in this paper.

Assessment of in-service degradation of gas pipeline steel taking into account susceptibility to stress corrosion cracking

Stress Corrosion Cracking (SCC) is often identified as one of the predominant failure causes of high-pressure gas transmission pipelines. Long-term operation of pipelines causes degradation of mechanical properties of pipeline steel, including a significant decrease in brittle fracture resistance and resistance to SCC. For oil and gas pipeline steels, there are regulatory requirements for impact toughness, disregarding steel condition, namely as-received or serviced. However, SCC resistance of pipeline steels, being very important for structural integrity, is not regulated. In the present work a new method to evaluate in-service degradation of pipeline steels, taking into account increasing susceptibility of operated metal to SCC, was developed. To ensure a safe operation of gas pipelines, it is suggested that the minimum allowable value of SCC resistance characteristics, in particular, the threshold of J-integral based stress intensity factor for SCC Jscc, should be defined and regulated. It is quite difficult to input these characteristics into regulatory requirements, therefore the developed method is based on modification of regulated limit values of impact toughness for as-received and serviced metal conditions separately, taking into account increasing susceptibility of serviced steel to SCC. The method was applied to evaluate in-service degradation of API 5L X52 ferrite-pearlite pipeline steels. The developed method considers different SCC susceptibility of as-received and serviced pipeline steels and shows there are limitations in regulating the same limit value of impact toughness for as-received and serviced pipeline steels.

Acoustic Emission Response to Erosion-Corrosion and Creep Damage in Pipeline Systems

Pipeline system failures confirm that special attention must be paid to the main components of nuclear power plants in particular. One of the significant degradation factors in terms of integrity and residual life of these components is erosion-corrosion in piping systems and creep in high pressure pipelines of thermal power plants. This article deals with analysis of a set of steel samples with different degrees of degradation using acoustic emission method based on detection of elastic-stress waves in a material. Time domain and frequency domain characteristics of acoustic emission signals generated by different creep mechanisms are analyzed. The main task is to find a relationship between crack creation and propagation and acoustic emission response. Part of the solution is also the design and implementation of a diagnostic method for operation monitoring of the deterioration of the high-pressure piping systems at high temperature. The benefit should be a significant reduction in the risk of damage to important components and reduction of the probability of damaging pipe wall integrity potentially sensitive to erosion-corrosion.

Effect of formation water and hydrochloric acid on the physical and chemical properties of polymer materials of high pressure pipelines used for transportation of crude oil

The purpose of the work is to conduct a comparative analysis of the stability of two types of polymer coatings to the effects of formation water and hydrochloric acid based on the analysis of mechanical properties, thermal stability and surface morphology. To accomplish the task, modern physical-chemical methods were used: differential scanning calorimetry, microscopy, an electromechanical universal testing machine, a dilatometer. Simulation of the effect of water at elevated temperatures and pressures on the polymer coating samples was carried out in an autoclave-reactor, the study of the effect of acid was carried out in a glass beaker. On the basis of the work carried out, results were obtained that show similarities and differences in the behavior of the polymer samples studied. The change of the dynamic modulus of elasticity and the coefficient of linear thermal expansion with increasing temperature is investigated. In general, it has been shown that PE-RT polymer has better characteristics than PE polymer. However, both of them are stable to the exposure of formation water and hydrochloric acid and can protect corrosion of high pressure pipes connections.

Life cycle durability prediction of high-pressure pipelines under the impact of low-cycle loads

Life cycle durability prediction of high-pressure pipelines under the impact of low-cycle loads

Simple solutions for downslope pipeline walking on elastic-perfectly-plastic soils

Pipeline Walking is a phenomenon that occurs when high pressure and high temperature pipelines experience axial instability over their operational lifetime, and migrate globally in one direction. Existing analytical solutions treat the axial soil response as rigid-plastic but this does not match the response observed in physical model tests. In this paper, the authors develop a new analytical strategy using elastic-perfectly-plastic axial pipe-soil interaction, which leads to more realistic walking rate predictions. The new analytical methodology is benchmarked with a series of Finite Element Analyses (FEA), which constitutes a parametric study performed to test the proposed expressions and improve on the understanding of the influence of axial mobilisation distance.

Numerical simulation on fracture mechanics behavior of high-pressure gas pipeline

The numerical simulation could help to understand the fracture mechanics behavior of high-pressure gas pipeline. The calculation results show that the internal high pressure of gas provides a driving force for crack propagation and tube wall deformation when the pipeline cracks and expands. Therefore, the rapid crack propagation tends to occur when the steel pipe is driven by high-pressure gas. In the process of steel pipe crack extension, immense internal high-pressure gas spewed from rupture and expand rapidly, compressing the air to form a series of compression wave which propagate rapidly and superpose together to form a shock wave eventually. Because the explosive wave of the pipe rupture has a high directivity, the energy distribution of gas is not uniform during the releasing process. What’s more, in pipe blasting, the longer distance, the more the surface vibration velocity decreases. In the vicinity of explosion source, the decreasing trend of the peak vibration velocity is significant. The vertical vibration velocity at the same point is larger than the longitudinal and tangential vibration speed.

Numerical study of explosion of “propylene-air” mixture cloud in recessed cavity located near complex of bluff bodies

The paper deals with mathematical modelling of the process of an explosion of a cloud of reactive gases and its impact on the environment. The research may be relevant to ensure fire safety and to prevent explosion hazards at industrial production facilities that use reactive gas mixtures as a working medium and at high-pressure industrial pipelines used for their transportation. The goal of the study is to develop a computational technology for numerical modelling of shock waves propagation and to predict loads on civil structures. To describe the chemical processes in the explosion, a simplified mathematical model is proposed which based on the assumption of the infinite speed of chemical reactions. Using the model, a set of User Defined Functions is implemented in ANSYS Fluent and applied to solve a problem of a “propylene-air” cloud explosion inside the cavity located in the vicinity of two standalone buildings.

Subsea pipeline walking with velocity dependent seabed friction

With the increase in demand and supply gap in the oil and gas industry, new developments of oil and gasinfrastructure are moving into deeper water. This requires design and construction of long high temperature and high pressure pipelines from deep sea to shore. These pipelines are subjected to cyclic expansion during operating cycles. Accumulated axial movement due to repeated thermal cycles may lead to global displacement referred to as ‘walking’. Walking rates depend on the restraint associated with seabed friction. In conventional analyses, seabed friction is independent of the rate of thermal loading and expansion but it has been recognised that the sliding resistance between a pipe and the seabed varies with velocity, partly due to drainage effects. In this paper a numerical model is used to explore the effect of velocity-dependent seabed friction. A velocity-dependent friction model is implemented in commercial software ABAQUS and validated via single element and simple (flat seabed) pipeline cases. This model features upper and lower friction limits, with a transition that occurs as an exponential function of velocity. A parametric study is performed using differing rates of heating and cool-down in walking situations driven by seabed slope, SCR end tension and the difference between heat up and cool down rates. The walking behaviour is compared to cases with constant friction and solutions are proposed to express the velocity-dependent response in terms of an equivalent constant friction. These equivalent friction values can then be applied in existing simple solutions or more complex numerical analyses, as a short cut method to account for velocity-dependent friction.

Introducing Bentonite into the Environment in the Construction Stage of Linear Underground Investment Using the HDD Method

The study discusses the issue of introducing drilling fluid (bentonite) into the environment during the construction of linear underground investments, considering the example of the construction of the high-pressure gas pipeline, Czeszów—Kiełczów DN1000, which involved the use of the Horizontal Directional Drilling (HDD) method. The analyses concern the drilling stage as a low-waste technology, indicating the use and management of bentonite drilling fluid in a closed circulation cycle in the area of Pęciszów, poviat Trzebnica (Poland). The loss of drilling fluid in valuable natural areas during the construction stage of the gas pipeline has been analyzed. Drilling fluid is an element of the horizontal directional drilling technology (HDD). The analyzed area included a section of the route of the strategic gas pipeline, realized in June–July 2017 in an area of lowland ash and alder forest 91E0-3, a probable breeding site of the Bluethroat for a detailed description and common frog. The loss of the drilling fluid used in the drilling phase has been determined, depending on the type of soil and the related fraction as well as the possibility of treating the drilling fluid used to construct the drilling.

Crack tip opening angle during unstable ductile crack propagation of a high-pressure gas pipeline

A full gas burst test was conducted to clarify the CTOA history during ductile crack propagation in a high-pressure pipeline. The measurement results obtained by high-speed camera observation and image processing showed that the CTOA value remains constant during crack propagation despite the large changes in the crack velocity. The numerical results of a series of finite element analyses supported the intrinsic implications of the experimental results. Consequently, the validity of the constant CTOA criterion, which has the potential to improve the accuracy and efficiency of numerical simulations of unstable ductile crack propagation in a high-pressure pipeline, was verified.

Application of BS 7910 to high pressure pipelines

• Characteristics of high pressure steel pipelines that are relevant to use of BS 7910 are reviewed. • Issues when assessing fracture of axial and circumferential cracks in pipelines are described. • Alternative approaches from other standards compared to those of BS 7910. • Suggestions made for improvements in the next edition of the standard.

Intergranular stress corrosion cracking of steel gas pipelines in weak alkaline soil electrolytes

Abstract The paper presents an overview of the main types of stress corrosion cracking (SCC) of pipeline steels under operating conditions of high-pressure buried gas pipelines. Up to the present time, there have been cases of transgranular cracking in gas pipelines in near-neutral pH soil electrolytes in Russian territory. The present work studies fragments of pipes containing cracks as well as soil samples at the excavation sites of gas pipelines running through the territory of the Astrakhan region. It was found that the cracks formed as a result of SCC of pipe metal and are of intergranular character of propagation. It is also established that the chemical composition of the soil along the gas pipeline differs from the previously studied compositions of corrosive environments that encourage the development of intergranular SCC of pipeline steels.