Pipeline Repair Research Articles

Stress distribution analysis of composite repair with Carbon Nanotubes reinforced putty for damaged steel pipeline

Composite pipeline repair systems involving infill material and composite wrapper are a common method of enhancing the integrity of damaged oil and gas pipelines. Composite wrappers can be theoretically optimised by minimising the layers of wrapper whilst reinforcing the infill material; i.e., putty. Integrating nanomaterial into putty to enhance its strength is a novel approach to provide secondary layer protection of damaged pipelines. A finite element model simulating a composite repaired pipe was developed to investigate the influence of reinforced Carbon Nanotubes putty on the system's overall repair performance and behaviour. The result was verified with a previous experimental hydrostatic burst pressure test and industrial standard resulting in less than a 15% error margin. The result shows the damaged artificial pipe segment filled with two different putties, namely Grout A and Grout B, ruptured at 32.22 MPa and 32.93 MPa, respectively. The reinforced putty improved the load-bearing capacity of the repaired pipe by a marginal increment of 2.2%. It demonstrated a better load-transfer and load-sharing mechanism than the common composite repair system. The recorded burst failure of the repaired pipe was less abrupt, thus minimising the sudden rupture of the pipeline by acting as a secondary layer of protection in the event of a composite wrapper failure.

Preparation and properties of a magnetorheological material used for pipeline and pressure vessel damage repair

Rapid repair of damaged pressure vessels and pipelines has always been a key technology in the study of safe storage and transportation. In this study, a magnetorheological material with curing and bonding abilities which can be combined with strong magnet as a rapid repair technology, was prepared by using surface modified carbonyl iron powder and epoxy resin. The reaction process and structure of the material were studied by infrared spectroscopy analysis, X-ray diffraction analysis, X-ray photoelectron spectroscopy and scanning electron microscopy. The optimum ratio was determined by orthogonal experiment, and mechanical experiments was designed to explore various mechanical properties of the material. The repair effect of the material was tested by a simplified simulation model, and the mechanism was also explained by numerical simulation.

Evaluation method for acoustic underwater propulsion systems.

Acoustic underwater propulsion systems based on bulk acoustic waves and surface acoustic waves have been studied. In this study, an acoustic propulsion system that consists of a 2.065-MHz thickness-vibration-mode lead-zirconate-titanate ultrasonic transducer is evaluated. A prototype swimmer is designed and fabricated. The admittance difference of the transducer in water and air is investigated. The vibration amplitude of the transducer is measured to evaluate transducer performance. The acoustic radiation force is calculated to describe acoustic propulsion. The zero-speed propulsion (ZSP) force and no-load speed (NLS) are measured in water. Swimmer movement starts at a NLS of 6.1 mm/s and a ZSP force of 0.2 mN for an input voltage and input power of 12.4 V peak to peak and 0.4 W, respectively. Although the average efficiency of the acoustic propulsion system is 69% in water, the overall movement efficiency of the swimmer is less than 1% because of fluid resistance and wire traction. Based on admittance, acoustic propulsion calculations, ZSP force, NLS measurements, and efficiency analysis, an evaluation method is proposed for optimizing swimmers with an acoustic underwater propulsion system. Small size, high power density, and simple structure of an acoustic propulsion system with an ultrasonic transducer make such systems suitable for applications such as pipeline inspection and repair.

Saturation diver fatality due to hydrogen sulphide while working on a subsea pipe line

In the offshore oil industry, Multipurpose Support Vessels with extensive diving capability are used for inspection, maintenance and repair of subsea pipelines. The diving industry has developed systemic safety checks and strict regulatory control after a number of fatal accidents in early years. However, accidents do continue to occur and, when involving divers in the water, are often fatal. Hydrogen sulphide (H2S), called ‘sour gas’ in an oil field, is produced by the action of anaerobic bacteria on sulphate containing organic matter. A highly toxic gas, it remains a constant danger for offshore oil industry workers who must remain vigilant. Crude oil and gas produced in these oilfields is called ‘sour crude’ and pipelines carry this crude with varying content of dissolved H2S to shore for processing. Divers are routinely called to attend to leaking pipelines and come in contact with this crude. Their hot water suits and umbilical lines are often covered with crude containing dissolved H2S. There is always a possibility that these may enter and contaminate the bell environment. Such a case leading to fatality is reported here.

Physicochemical modification of heat-shrinkable epoxy polymers

An approach to the physicochemical modification of heat-shrinkable epoxy-diane polymers was considered, these polymers being used as couplings for the repair of polymer pipelines for various functional purposes. The purpose of the modification is to stabilize and improve the performance of the end couplings that are heat-shrinkable. We assessed the prospects of preparation of the products of various profiles by forming cross-linked polymers in a highly elastic state by plunger extrusion via creating favorable conditions for the orientation of interstitial fragments in epoxy-diane polymers. The starting epoxy-diane composition contained rigid and elastic components. The polymers fabricated by hardening of these compositions have both a glass transition temperature, which is convenient for operation, and high deformability in glassy and highly elastic states. We investigated the tensile strength, the elastic modulus, the failure deformation and the flaring deformation of the inner diameter of the preform of epoxy-diane polymers. Physical modification of a liquid filled epoxy-diane composition before mixing with a hardener was performed by using low-frequency ultrasonic treatment. We analyzed the results associated with the effect of combined ultrasonic treatment on the physical-mechanical and service properties of heat-shrinkable epoxy-diane polymers filled with short glass fibers.

Numerical Study on the Effect of Defect Length upon Burst Capacity of Composite Repaired Pipe

Pipeline system is one of the essential infrastructures in oil and gas industries as it is used to transport oil and gas over long distance. However, pipelines will undergo damages and deteriorations after being used for some years, especially when corrosion occurs. Corrosive pipes will experience reduction in wall thickness resulted a lower remaining strength of the pipe, and consequently lead to failure once the remaining strength unable to withstand the desired operating pressure of the pipe. Therefore, additional strength from repairing job needs to be provided, for instance, by using fibre-reinforced polymer (FRP) composites. Unlike the corroded pipeline assessment codes, the pipeline repair codes that are used to design composite repair system of corroded pipe do not include the defect geometries such as defect length. In this study, burst pressure of the composite repaired pipeline with different defect lengths and the effect of the defect length upon the burst capacity of composite repaired pipe are investigated. The study is carried out by finite element analysis on various defective pipes with different defect length sizes. The results show that the difference of the burst pressure subjected to various defect lengths is 15.59% and this had proved that there is effect of defect length upon the burst capacity of composite repaired pipe. This finding can be very useful for optimizing the existing repair design.

Excavator implement for pipeline repair

The article presents an option to improve the design of the equipment of an excavator of the 3 dimensional group. The equipment is intended for selective repair of the pipeline by an excavator, without involving other road construction equipment (for example, a pipeline). The proposed version of the design of the working body allows you to increase the speed of repair of the pipeline, by reducing the time required to change equipment, its relocation, which as a result reduces the cost of repair work. The main idea is to supplement the main equipment of the excavator with a structure consisting of three teeth, forming, in conjunction with the bucket, a gripping mechanism. To confirm the operability of the proposed design, theoretical studies were carried out aimed at determining the stability of the machine for the most dangerous design operating positions, and the permissible sizes (pipe sizes) were established, with which the stability of the machine is maintained.

Calculation of an inhomogeneous polymer thick-walled cylindrical shell taking into account creep under the action of temperature load

The article presents the calculation of a polymer thick-walled cylindrical shell taking into account creep under the action of an uneven temperature field. The relevance of the work lies in the widespread introduction of polymer pipes in the repair and construction of heating pipelines, sewerage systems, water supply systems. The problem is solved in an axisymmetric setting under conditions of plane deformation. The calculation is based on the nonlinear Maxwell - Gurevich equation, which is widely used in the calculations of polymer structures.

Effect of water flow and depth on fatigue crack growth rate of underwater wet welded low carbon steel SS400

Abstract Underwater wet welding (UWW) is widely used in repair of offshore constructions and underwater pipelines by the shielded metal arc welding (SMAW) method. They are subjected the dynamic load due to sea water flow. In this condition, they can experience the fatigue failure. This study was aimed to determine the effect of water flow speed (0 m/s, 1 m/s, and 2 m/s) and water depth (2.5 m and 5 m) on the crack growth rate of underwater wet welded low carbon steel SS400. Underwater wet welding processes were conducted using E6013 electrode (RB26) with a diameter of 4 mm, type of negative electrode polarity and constant electric current and welding speed of 90 A and 1.5 mm/s respectively. In air welding process was also conducted for comparison. Compared to in air welded joint, underwater wet welded joints have more weld defects including porosity, incomplete penetration and irregular surface. Fatigue crack growth rate of underwater wet welded joints will decrease as water depth increases and water flow rate decreases. It is represented by Paris's constant, where specimens in air welding, 2.5 m and 5 m water depth have average Paris's constant of 8.16, 7.54 and 5.56 respectively. The increasing water depth will cause the formation of Acicular Ferrite structure which has high fatigue crack resistance. The higher the water flow rate, the higher the welding defects, thereby reducing the fatigue crack resistance.

Study of contact forces in the bearing part of the protective coating of underground pipelines in gravel and cobbles

In the construction and operation of underground pipelines, the feasibility of engineering methods of protecting the insulation coating from external mechanical impacts should be based on the existing loads. When an underground pipeline is laid on coarse gravel and very coarse soil, the analysis of the support forces at the base of the pipeline is a pressing issue. In particular, the difficult conditions for the construction, reconstruction, repair and operation of underground pipelines include cases when the pipeline route passes through sections of rocky soils. Discrete rocky conditions include large grain content in the form of coarse gravel, cobbles, and boulders. The article analyzes the influence of the size of foundation soil components on the magnitude of force arising in the protective coating of the support part of an underground pipeline depending on the unevenness of the soil and its granulometric composition. One of the directions for studying the distribution of contact-mechanical interaction in granular soils is a discrete model. The distinction of the discrete medium model is that individual elements of its structure are viewed as mechanically interacting bodies. Structural elements are particles of bulk material that can be considered as spheres. The results of modeling the contact problem using the discrete (granular) model of the base of the pipeline are presented. It was found that with the same diameter size and depth of burial, the force varies depending on the pipe diameter chosen in the project (for a pipe of 1420 mm, the maximum difference was 23%). In the case of unevenness of the ground, the force in the supporting part can increase by 3-5 times. The conditions of stability and strength of underground pipelines are formulated taking into account the discreteness of the base particles.

Опыт оценки экономической эффективности планирования мероприятий по диагностике, техническому обслуживанию и ремонтам магистральных газопроводов в существующих информационно-управляющих системах ПАО “Газпром”

Опыт оценки экономической эффективности планирования мероприятий по диагностике, техническому обслуживанию и ремонтам магистральных газопроводов в существующих информационно-управляющих системах ПАО “Газпром”

Research on Damage Assessment of Buried Standard and Carbon‐Fibre‐Reinforced Polymer Petroleum Pipeline Subjected to Shallow Buried Blast Loading in Soil

Buried petroleum pipelines may encounter threats from blast loading due to terrorist attacks, accidental explosions, and artificial blasting during in‐progress construction. Carbon‐fibre‐reinforced polymer (CFRP) is often used for the repair and reinforcement of buried petroleum pipelines. It is meaningful and necessary to distinguish the different responses and establish an effective damage assessment method for standard petroleum pipelines and CFRP‐supported petroleum pipelines buried in soil under blast loading. In this study, under fixed end constraints, experimental analysis and numerical simulations were combined to assess the damage of a standard petroleum pipeline and a CFRP petroleum pipeline buried in soil under blast loading. The results showed that, for a scaled distance of 0.19 m/kg1/3, plastic deformation occurred on the surfaces of the two pipelines facing the explosive. The antiexplosion performance of the CFRP pipeline was better than that of the standard pipeline, and the CFRP sheets had a positive effect on the protection of the buried petroleum pipeline during the buried blast loading. Furthermore, based on pressure‐impulse damage theory and with consideration of the feasibility under real circumstances, two pressure‐impulse damage evaluation curves for standard and CFRP pipelines facing explosive loads were established separately based on a new critical ratio of the dent depth and length. Finally, based on the two pressure‐impulse damage evaluation curves and the new critical ratio, two pressure‐impulse damage criteria for these two buried petroleum pipelines were defined. Moreover, with the two pressure‐impulse damage evaluation curves, mathematical formulae for the two different buried petroleum pipelines were established to generate pressure‐impulse diagrams. With the established formulae, the damage to the standard buried pipeline and the CFRP pipeline could be evaluated effectively. Damage to other similar standard pipelines or CFRP pipelines buried in soil with different design parameters due to shallow buried blast loading could also be evaluated using this method.

Damage evolution mechanism of buried pipeline crossing reverse fault

Fault caused by earthquake is harmful to buried pipelines. Long-distance transportation pipelines will inevitably cross the seismic fault zones. In this paper, a numerical simulation model of X80 pipeline under reverse faulting with a crossing angle of 60° was established. Damage evolution mechanism of buried steel pipeline was analyzed. Effects of internal pressure and diameter-thickness ratio on the stress, strain and displacement of pipeline were discussed. The results show that the buckling phenomenon is more severe in the hanging wall than that in the footwall for reverse fault. For non-pressure pipeline, local collapse occurs on the compression side. When the pipeline wall buckles, the axial stress is released, and high-stress is mainly concentrated on the collapsed position. For pressure pipeline, the internal pressure aggravates the buckling degree. Then, wrinkles appear on the compression side. The results can provide a reference for anti-seismic construction, repair and maintenance of buried pipeline.

Deformation Inspection and Safety Assessment Method of Buried Flexible Pipeline in Service

The working performance of buried flexible pipelines is connected with the pipe- soil interaction; the weak stiffness of backfill leads to large long-term pipeline deformation and even structural failure. Spangler’s formula is a theory for macroscopic evaluation of pipeline deformation, which cannot reflect the deformation state of various parts around the pipe from a microscopic view. A large number of engineering practices have shown that when the macro radial deformation of the flexible pipe is not large, it is also possible that the local geometric size of the pipeline may change suddenly in the microscopic view. Combining with a diversion project, a laser scanning and piecewise elliptic curve fitting combined method was proposed to measure the empty pipeline deformation in this paper. The deformation pattern of the flexible pipeline was analysis. And then, the analysis results were verified by the elastic wave test and material test data. Based on the deformation inspections, the internal force and related reliability of pipe structure were calculated. Finally, the structural safety of each pipe was assessed to guide the replacement, repair and reinforcement of pipeline.

Experimental measurement of dynamic loading and numerical analysis of gas pipeline damaged by corrosion

The paper presents the results of the expert works in the area of diagnostics, repair, and reconstruction of the steel pipelines of the transit gas pipeline (TP) on Slovak territory. One part of our work included dynamic measurements of a steel casing pipe located under the railway. This pipeline was damaged by corrosion and it was necessary to evaluate its safety.

Calculation of water hammer on the pressure pipeline of modernized irrigation pumping station

One of the main factors to provide reliable and safe operation of irrigation pump station – prevent possible occurrence of water hammer. In order to determine the magnitude of water hammer’s method of characteristics (moc), wave characteristic method (wcm), graphical analytical and simplified methods of calculations are used. During the design for the construction of the new pump station surge analysis should be carried out using accurate calculation methods moc or wcm using special computer software. At the same time, should the modernization of existing pump station is taking place with the installation of the same equipment, then simplified calculations method can be used. But care must be taken to take in to account all the factors that might increase the risk of occurrence and with the higher magnitude of water hammer: reduced inertia of pumping set’s moving parts, replacement of shutting valves to different types, replacement of air valves to different types, reduction of hydraulic losses after discharge pipeline repair works and etc. Existing simplified calculation methods to calculate water transients in pump stations was modified to take in to account these factors. Based on the proposed method surge analysis calculations had been carried out at modernized pump station “Kizil-tepa”. Comparison of calculation results performed by simplified method and wcm using «KY-Pipe 2018-Surge program-version 9.014» has shown a good similarity in the magnitude of maximal positive pressures.

Development of a Nonlinear Dependence for Determining the Stress-Strain State of the Pipeline-Composite Bandage System

The range of applications of polymeric materials in the oil and gas industries is expanding every year. For example, at present, a number of industrial enterprises are engaged in the production of various tape polymer composite structures that are used to repair pipelines. They are widely used due to the significant advantages of polymeric materials over steel such as low costs, low weight, corrosion resistance and strength. Moreover, most of the operated pipelines are about to reach their standard service life. In the course of technical diagnostics, a significant number of defects of mechanical origin from external influences are constantly revealed. Repair work on pipelines must fully restore the bearing capacity of the site. Therefore, the use of polymer materials for pipeline repair is an important task. Here, we propose to use polymer composite bandages, which will increase the overhaul period. However, a coherent methodology for choosing a material and calculating the required thickness of this structure is not available in the literature, and, therefore, the purpose of this work was to develop such a methodology, as well as to assess the stress-strain state of pipeline-bandage systems. The method presented in this work takes into account the possible anisotropy of the shroud material in the longitudinal and transverse directions and the possibility of plastic deformation of the pipeline material in the annular direction. This work is based on the following assumptions: (a) bilinear dependence of stress on deformation for steel; (b) plastic deformations of the band material are absent; and (3) absolute adhesion between the pipeline and the band. The paper presents the analysis of the market of polymeric materials for pipeline repair, their key properties, and the minimum thickness of the band made of these materials was calculated for various values of the stress concentration coefficient.

Wave Scattering from Step Discontinuities in a Water Pipeline Waveguide: Analytical Modeling and Discontinuity Material Influence

Step discontinuities, which are formed in pipeline repair and maintenance, will introduce additional wave scattering in the pipeline diagnosing work. Therefore, an analytical model is established in this paper to investigate the longitudinal wave scattering from a step discontinuity and the influence of discontinuity material on the scattering characteristics in water pipelines. In the model, axial wavenumber, displacement and stress profiles of the unblemished pipeline and discontinuity sections are calculated by a multi-layered cylindrical waveguide model. To concatenate these sections and predict the overall influences of the discontinuity, the mode matching method is applied by enforcing the flexible axial boundary conditions with an extended bi-orthogonality relation. Based on the established model, numerical calculations are carried out to investigate the reflection/transmission characteristics when discontinuity material and attenuation are considered. Both finite element method (FEM) software and laboratory experiments are also conducted for modeling verification: the maximum root mean square errors of the predicted reflection and transmission coefficients are 0.01 and 0.1 compared with FEM and experiment results, respectively. It indicates the proposed model is accurate in predicting the wave scattering from a step discontinuity in a water pipeline with the influence of discontinuity material accounted for. In addition, this pure analytical model introduces advantages in computational cost when modeling long pipelines compared with existing FEM packages.

Research on the influence of cutting parameters on chips in the process of diamond bead cutting pipeline steel

Diamond bead wire is an important engineering equipment in the repair of submarine oil and gas pipelines. In the process of cutting pipeline steel with diamond bead, the chip shape affects its wear condition, which in turn affects the cutting efficiency. In this paper, based on the principle of displacement damage evolution, the simulation model of diamond grains was established, and the influence of cutting parameters on chip shape and residual stress was studied by dynamic simulation. The results show that: When the cutting speed of diamond grains is 23 m/s, the critical cutting depth for granular chips is 16 μm, and the residual stress value is the minimum; When the cutting depth of diamond grains is 16 μm, the range of cutting speed that produces granular chips is 23 m/s ~ 26 m/s. Secondly, a cutting simulation model of electroplated diamond bead was established, and the influence of density on chip shape was studied. The results show that: With the increase of the grain density, the chip size becomes larger and larger, and the chips gradually change from granular chips to ribbon chips (continuous chips). Finally, the correctness of the simulation results was verified, and the best cutting parameters were determined through cutting experiments.

Definitive repair of pipelines in operation in corrosive environments

Definitive repair of pipelines in operation in corrosive environments