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Hydrogen, as a clean energy carrier, presents a significant step toward sustainable energy solutions but faces challenges in storage due to its low energy density and high volatility. This study addresses the optimization of Type V hydrogen storage tanks by investigating the burst pressure performance of spherical, cylindrical, and toroidal shapes. Using finite element analysis (FEA) and first-order shear deformation theory, we examined how these geometries impact burst pressure outcomes across a range of composite materials and layup configurations. The materials tested included carbon T700/epoxy, Kevlar/epoxy, E-glass fiber/epoxy, and basalt/epoxy. Results demonstrate that the toroidal shape significantly outperforms spherical and cylindrical designs in stress distribution and burst pressure, with basalt/epoxy composites exhibiting superior burst pressure performance (12.7 MPa) compared to Kevlar/epoxy (10.8 MPa), E-glass fiber/epoxy (11.4 MPa), and carbon T700/epoxy (8.9 MPa). Kevlar/epoxy toroidal tanks outperform other materials in weight performance, having a structural performance index of 0.0305 Mpa.m3/kg and hydrogen density per unit mass of 0.0251 kg H 2 /kg. The stacking sequence [-45/45]s optimized stress distribution for the toroidal shape across all materials. The findings highlight that toroidal designs offer significant advantages for high-pressure hydrogen storage, providing efficient stress management and improved safety. This paper underlines the potential of toroidal vessels for enhancing hydrogen storage efficiency and emphasizes the importance of material selection and stacking sequences in achieving optimal burst pressure performance for international organization for standardization (ISO) certification. • Toroidal tanks show superior burst pressure over spherical and cylindrical designs. • The [-45/45]s stacking sequence optimizes stress distribution for toroidal tanks. • Basalt/epoxy composites outperform other materials in burst pressure performance. • Kevlar/epoxy toroidal tank outperforms others in weight performance. • Toroidal tanks offer efficient stress management and enhanced safety for hydrogen storage. [ABSTRACT FROM AUTHOR]

• A universal new yield criterion is established based on the Tresca yield criterion and the Mises yield criterion. • Various burst pressure prediction models are evaluated using a full-scale burst pressure test database. • The burst pressure model based on the new yield criterion offers the optimal approach for predicting burst pressure. Pipelines are a crucial transportation infrastructure for the long-distance transport of natural gas, oil, and other hydrocarbons, typically conducted through thin-walled pipes (D / t ≥ 20). Accurate prediction of the burst pressure of thin-walled pipelines is essential for their safe and reliable operation. To enhance the prediction accuracy of the burst pressure for defect-free, straight, thin-walled pipes, a new numerical integration yield criterion was proposed between the Tresca and Mises criteria, using the mean value of Simpson's numerical integration (MSI) as the equivalent shear stress. A new burst pressure prediction formula was then constructed using the MSI yield criterion. The burst pressure predictions based on different yield criteria were compared with experimental data. Additionally, the burst pressure curves of the new prediction formula were plotted, and the relative errors between the new prediction formula and four existing prediction formulas were analyzed and compared. The results indicate that the new burst pressure prediction formula using the MSI yield criterion closely matches the experimental data, with the best relative error result within a confidence interval of ±1.3 %. The Lord parameter curve and plane stress curve of the MSI yield criterion exhibit good consistency with the experimental data of various ductile metal materials. The new burst pressure formula established by incorporating the MSI criterion provides a safe, economical, and reliable theoretical foundation for the design, manufacture, inspection, and safety assessment of thin-walled pipelines in production practice. [ABSTRACT FROM AUTHOR]

The shift from metallic to composite pressure vessels for storing compressed natural gas (CNG) is driven by the goal of reducing environmental impact by using lighter higher-performing structures. This work focuses on enhancing the internal pressure strength of a type IV composite overwrapped pressure vessel (COPV) by optimising the stacking sequence of the overwrapping composite layers. Parametric finite element (FE) models are developed to reveal symmetry effects. In these models, both the thickness build-up and fibre angle variation at the turnaround zones are accurately modelled. Subsequently, the stacking sequence is optimised with the objective function of maximising burst strength. The parametric modelling demonstrates that representing the COPV as an axisymmetric continuum reduces computational costs in 5400× while yielding results comparable to full 3D continuum models. Experimental burst tests are carried out to validate the numerical predictions, and the difference in pressure between them is 12.6 %. • Development of lightweight composite pressure vessels for energy storage. • Realistic representation of fibre orientation and thickness build-up on the domes. • Four different symmetrical models to understand symmetry effects. • Computational models validated against manufacturing and testing. [ABSTRACT FROM AUTHOR]

This study aims to investigate the effect of the polymer pair meltdown process and mechanical properties using three different laser transparencies 20%, 30% and modulated, ranging from a minimum 27% to a maximum 47%. The cross-sections of joints were analysed with an optical microscope. Burst pressure was performed to evaluate the strength of welded joints produced with different laser welding process parameters. Welding parameters, scanning speed and meltdown were varied and their influence on the quality of the polymer joint was recorded and evaluated. With the increase of meltdown, a more molten volume of polymer can be seen in the cross-section area. It was shown that with the increase of meltdown, the formation of pores occurred due to the high energy concentration obtained within each laser scan passing across the weld seam. The decrease of burst pressure in all polymer pairs was observed with 0.33 mm and 0.34 mm targeted meltdown. Burn marks and burned lines were observed in joints with 20% laser transparency. Modulated laser transparency influenced non-homogeneous temperature distribution inside the joint, which influenced the formation of heat-affected zones (HAZ) and pores. A study of the influence of cooling time on joint formation showed that it is possible to variate total meltdown while changing cooling time until the joint is solidified. • Within the increase of meltdown, bigger weld flash occurred inside weld seam. • Peak weld strength observed at specific meltdown values. • The decrease of weld strength is influenced by defect formation inside seam. • Non-homogeneous melting, HAZ observed with modulated laser transparency polymers. • Total meltdown can be controlled by modulating cooling time. [ABSTRACT FROM AUTHOR]

• Use of rupture discs as safety protection for water heat pipe blackbody radiation sources. • Analyzed theoretical models for rupture discs in water heat pipes and performed burst pressure fitting calculations. • Experiments were conducted on the high temperature and pressure of water heat pipe with rupture discs. • The experiment confirms the theoretical analysis, with a maximum deviation of 4.50% at room and 3.74% at high temperature. Integrating heat pipe technology into blackbody radiation sources significantly enhances thermal consistency and accuracy. Nonetheless, at elevated temperatures, pressure fluctuations in water heat pipe blackbody systems may induce catastrophic failures. This issue was addressed by theoretically conceptualizing, engineering, and implementing rupture discs designed to alleviate pressure under predetermined conditions, thereby enhancing system safety. A water heat pipe blackbody source equipped with rupture discs was constructed, and a series of relevant empirical tests were executed. The burst pressure measured under standardized hydraulic evaluation reached 5.65 MPa, closely matching the theoretically calculated burst pressure of 5.60 MPa, with a minimal deviation of 0.88 %, thus confirming the model's precision. Under extreme testing conditions at 260 °C and 4.80 MPa, the rupture disc burst prematurely at 3.66 MPa due to rapid heating. However, in step heating scenarios, the rupture disc's performance was within 4 % deviation from the theoretical predictions, demonstrating its reliability. [ABSTRACT FROM AUTHOR]

• Investigated failure pressure of composite pipelines with different corrosion sizes. • Elucidated damage process of corroded pipelines rehabilitated by the Kevlar liners. • Evaluated the rehabilitative effect of Kevlar liners on offshore pipelines. Offshore pipelines transport oil and natural gas that contain different corrosive contaminants, leading to internal corrosions. The presence of internal metal loss problems can significantly degrade the load-bearing capacity and reliability of pipelines over time. To address this issue, a Kevlar liner, offering a more accessible and cost-effective solution, is employed for repairing corroded pipelines. However, a quantitative assessment of the rehabilitating effect of Kevlar liner has been lacking. This study performed an investigation of the burst pressure of internal corroded pipelines reinforced with the Kevlar liner through a combination of experimental testing and finite element numerical simulations. While previous research primarily concentrated on single external defect, this study has investigated the burst pressure of pipelines in the presence of both single and dual internal corrosion defects. The results indicated that the presence of two corrosion defects further decreases the burst pressure of the pipelines. This study examined the reinforcement mechanism of Kevlar liner, revealing that it largely postpones the stress development in the corrosion zone and thereby enhances the ultimate internal pressure load-bearing capacity of the pipelines. Moreover, the contact stress resulting from the friction between the Kevlar liner and the steel pipeline contributes to the overall improvement in the load-bearing capacity of the corroded offshore pipelines. [ABSTRACT FROM AUTHOR]

The determination of the pressure-bearing performance of hydrogen storage tanks (HST) is integral to enhancing their operational safety and risk management capabilities. In this study, an inaugural development of low-cost critical failure pressure (BP c) prediction model for small samples was proposed, which was based on a combination of the fuzzy grey relational analysis (FGRA) and GM(1,N). Specifically, a total of 15 of BP c -related factors were proposed for analysis and projections based on the data from bonfire tests. Results from the FGRA indicated burst pressure was most closely linked to the initial filling pressure (R ij1 = 0.939) of tanks under fire scenario. The normal working pressure (R ij2 = 0.924) and the elasticity modulus (R ij3 = 0.871) also demonstrating significant impacts. Furthermore, three GM(1,N) prediction models which could estimate BP c with multi-factor coupling were developed. Increasing the number of input feature factors could enhance the predictive capability of GM model. The GM(1,16) had optimal prediction performance among the models, achieving a prediction accuracy of 99.8 %. As well, the mean absolute error (MAE) was 0.799 MPa while the mean absolute percentage error (MAPE) was 1.56 %. This paper offered a novel option for establishing the HST critical failure criterion safely and efficiently. • Obtained factors on design features, physicochemical, and external thermal load. • Clarified the main controlling factors which affected critical failure pressure. • Developed GM(1,N)-based models to predict critical failure pressure. • Suggestions on the safety of hydrogen storage tanks in service were proposed. [ABSTRACT FROM AUTHOR]

Steel pipelines are increasingly essential for many applications, including the transport of oil, natural gas, and soon hydrogen gas. Steel pipelines are subject to harsh operating conditions. Corrosion is considered to be the most common type of failure in steel pipelines. This report focuses on corrosion and assessment in gas and oil pipelines. The most common method of repairing corroded pipelines by composite repair is included in the review. Based on conservative codes and deterministic and reliable FEM approaches, different tool designs and models of corroded pipelines without and with repair are summarized and compared. The evaluation of defects in determining the failure pressure of pipelines and the study of the contribution of composite wrap repair to corroded pipelines are discussed. • Review paper. • Failure pressure prediction of corroded pipelines. • Repairing corroded pipelines. • Composite wrap contribution based on synthetic and natural fibers. • Conservative codes, deterministic and reliability FEM design of corroded pipelines approaches. [ABSTRACT FROM AUTHOR]

Subsea production system occupies an important position in the development of deep-sea resources. As a key part of the subsea production system, the safety and reliability of the pipeline system of the subsea production system is crucially important. In recent years, with the development of artificial intelligence technology, the use of machine learning algorithms for large-scale complex pipeline system to provide a possibility of safety assessment. This paper collects the burst pressure of the pipeline in the experiments and uses various machine learning methods to evaluate and predict. The XGBoost model with the best performance after preliminary selection, and the accuracy of this method is improved through hyperparameter optimization with Bayesian principle. The improved XGBoost model are explained based on the Forward Feature Selection method and SHAP analysis, compared with commonly pipeline industry standards. The results show that the improved XGBoost model can significantly improve the prediction of the burst pressure and can effectively assess the structural integrity and reliability of pipelines. Moreover, the influencing factors of the burst pressure of the pipeline are analysed, and it is concluded that t (thickness of the pipeline), L (length of corrosion) are the two most important factors influencing the pipeline burst pressure. • Different machine learning methods are compared and it is found that the XGboost model has the best predictive performance. • The improved XGboost model is explained based on the Forward Feature Selection method and SHAP analysis. • The improved XGboost model is compared with existing industry standards. [ABSTRACT FROM AUTHOR]

• Burst pressure has a significant effect on the hazard of hydrogen explosion venting. • The damage area of the venting flame increases with the increase of burst pressure. • Mastering dynamic evolution is the effective means of achieving explosion protection. • Mastering explosion protection mechanisms is essential for the hydrogen development. A series of experiments are carried out to investigate the effect of burst pressure on hydrogen explosion venting in a 20 L square vessel. Pressure buildup and flame evolution are recorded using piezoelectric pressure transducers, high speed camera, high speed infrared camera and schlieren system. The results show that both the maximum explosion pressure (P max) inside and outside the vessel increase with the increasing burst pressure, and the P max in the external space decreases rapidly with the increase of the distance from the vent port. Compared to the burst pressure of 0 kPa, the P max inside the vessel and at 1200 mm increased by 79.1 % and 153.6 %, respectively, when the burst pressure was 325 kPa. The venting flame surface during the propagation is smoother with the increasing burst pressure, the width and area of the flame also increases. There is little effect of burst pressure on the maximum flame propagation distance (L max), but with the increase of burst pressure, the flame propagation time is shortened and the average propagation velocity is increased. The venting flame propagation time is shortened from 5.0 ms to 3.5 ms with the burst pressure increases from 0 kPa to 325 kPa. The high temperature zone of venting flame is mainly distributed in the flame front, while the maximum flame temperature (T max) gradually increases with the increase of burst pressure. The increase in burst pressure results in an increase in the turbulence intensity inside the vessel and an advance in the time to stabilization inside the vessel. Furthermore, the moment at which flow backflow occurs at the vent port is advanced from 16.5 ms to 8.5 ms with the increase in burst pressure. [ABSTRACT FROM AUTHOR]

• Finite element modeling approach of pipeline elbows is validated by full-scale burst tests. • A revision factor is coupled with the original PCORRC model to predict burst pressure of corroded elbows. • Finite element results are employed to derive the revision factor. • Improved accuracy of the PCORRC-based elbow burst model compared to existing models. The thinning of pipeline walls, resulting from corrosion, reduces their capacity to withstand internal pressures. Accurate prediction of the remaining strength of corroded pipelines is important to prioritize mitigation efforts for critical defects. While burst pressure models for straight pipelines have been well established, the research on the burst capacity of pipeline elbows is still limited, and most studies were established on rectangular-shaped corrosion. This study focuses on developing a new model for assessing the burst capacity of elbows containing single semi-elliptical corrosion, based on extensive three-dimensional elastic-plastic finite element (FE) analysis validated by full-scale burst tests of straight and elbow pipelines. The Pipe CORRosion Criterion (PCORRC) method, originally developed for straight pipelines, was re-calibrated to predict the remaining strength of corroded pipeline elbows. A revised factor was introduced to account for hoop stress variations caused by elbow curvatures. Results indicate that the revised model offers observable accuracy improvement over the existing models reported in the literature. The proposed model will improve the integrity management of corroded elbows. [ABSTRACT FROM AUTHOR]

• A 3D finite element model of wound pressure vessel with voids is established. • The 3D damage failure analysis is conducted considering pore defects. • A good agreement exists between predicted burst pressure and experimental data. • Void defects result in the deterioration of damage behavior of wound composites. • Providing experiences for reliability evaluation of wound composites with voids. Composite pressure vessels are promising solution for storing compressed gas with the high strength/stiffness to weight ratio, but the accurate modeling of mechanical behavior under high pressure remains a huge challenge considering manufacturing-induced void defects. The void generating method is developed to construct the finite element model with voids explicitly constructed. A three-dimensional(3D) progressive damage model complied with the user-defined material subroutine (UMAT) is performed to predict the void defect introduced damage behavior and burst pressure of composite pressure vessels. It indicates that the predicted burst strength agrees well with experimental value, and with the pressure increasing, the damage of composite layers initially appears in the matrix of middle cylinder section and region near the equator. The matrix damage is dominant at the outset, then achieves a balance with the fiber damage, and finally comes in second until the burst failure of the composite pressure vessels. The void defects will result in the damage initiation, evolution and final failure of composite layers, and the clustered voids will deteriorate the local damage status, but will not change the general damage trend. The present damage failure analysis scheme can provide theoretical guidance for reliability evaluation of composite pressure vessels with void defects. [ABSTRACT FROM AUTHOR]

Low temperature and high pressure line pipes are widely used in hydrogen storage, air separation plant, liquefied natural gas (LNG) transportation etc. The material properties of pipes at low temperature are different from those at room temperature. If the medium in the pipe is corrosive, it will cause the pipe wall thickness to decrease. However, the failure pressure of the corroded hydrogen storage pipeline at extremely low temperature is lacking of adequate understanding. In this paper, we provided a novel failure pressure equation of the mild steel line pipe with corrosion defects at extremely low temperature. Firstly, a mechanical model of the line pipe with corrosion defects is established. And then, an analytical solution of the mechanical model is obtained based on elastic theory. Next, a failure pressure equation of the corroded hydrogen storage pipeline at extremely low temperature is developed. In the end, the accuracy of the failure pressure equation is verified by comparing with finite element method (FEM). The results suggest that the calculated value of the failure pressure equation is consistent with that of FEM. This paper provides a theoretical basis for the safety assessment of low temperature hydrogen storage pipeline. The new equation presented in this paper can provide useful guidance for the design of low temperature and high pressure pipelines. • Burst pressure equation of corroded pipe at low temperature is presented. • Burst pressure of corroded pipe at low temperature is calculated numerically. • It is beneficial to predict burst pressure of corroded pipe at low temperature. [ABSTRACT FROM AUTHOR]

For exploring the pipe damage and blast failure mechanical behavior under the slips clamped operation is of critical importance in oil & gas production safety, the thick-walled cylinder hypothesis and elastic-plastic mechanics theory are applied to analyze pipe damage mechanical behavior under the slips clamped while the elliptical crack hypothesis and fracture damage mechanics theory are used to describe the pipe bite marks geometric characteristics. Further, the functional relationship between the bite mark and the slip structural parameters is determined and provides methods to estimate the burst pressure of the pipe with the bite mark. An experimentally validated FEM is used to study pipe blast failure mechanical behavior and the simulation results indicated the blast failure usually occurs in the two long narrow zones with a certain distance from the endpoint on both sides of the bite marks zone and the burst pressures obtained based on the proposed analytical model are in good agreement with the numerical results but relatively conservative. Furthermore, the sensitive parameters research indicates that the slip tooth space, tooth up and down inclination angle have an almost negligible effect on the pipe burst pressure, the pipe burst pressure decreases with the increases of bite-mark depth, slip teeth number, and edge thickness. • Pipe damage and bite-marks characterization under slip clamped are analyzed. • Functional relationship between the pipe burst pressure and the slip structural parameters is determined. • Blast failure behavior of pipe with slip bite marks is studied based on the verified FEM. • The slip structure effect on the burst pressure of the pipe with bite marks were discussed. [ABSTRACT FROM AUTHOR]

Double carcass floating hoses (DCFHs) are extensively utilized in offshore oil and gas transportation, with the outer carcass serving as an effective means to minimize or entirely prevent leakage of conveyed fluid. This study employs a combined approach involving numerical simulation and full-scale burst experiments to investigate the mechanical-structural behavior and failure mechanisms of DCFHs with inner diameter of 600 mm subjected to internal pressure and tension. By using rebar elements and embedded element method, a nonlinear large-deformation finite element model for DCFHs under internal pressure and tensile loads was established. The accuracy and effectiveness of the finite element analysis is validated against full-scale experimental results. Python programming language is employed to create the script used in the parametric modeling of DCFHs with ABAQUS software. The impact of varying parameters such as inner diameter, helix steel wire pitch, number of cord layers beneath the helix steel wire, and winding angles were analyzed for DCFHs under burst pressure. Based on the classical thick-walled cylinder ultimate internal pressure theory, a fitting formula for predicting the burst pressure of DCFHs is proposed. This paper provides valuable insights in the structural design and application of DCFHs under ultimate internal pressure loads. • Bursting failure mechanisms of DCFHs have been investigated by experiments and numerical simulations. • Investigations into two bursting failure modes are conducted with varying parameters of DCFHs. • The bursting pressure of DCFHs was studied using a Python-based parametric model with varying parameters. • A burst pressure prediction formula for DCFHs was proposed. [ABSTRACT FROM AUTHOR]

In the conventional method of analysis for the remaining strength assessment of a corroded pipeline, von Mises failure criterion is used. This continuum-based modelling approach is unable to assess the cracking of the pipeline. In this study, a fracture mechanics approach is used for the assessments of burst pressures of pipelines with corrosion only defects, pipelines with crack-like defects and pipelines with crack-in-corrosion defects. The fracture mechanics approach with the J -integral was found to simulate successfully the burst pressures obtained from rapture tests of pipelines with corrosion only defects and crack-in-corrosion defects. The conventional von Mises stress-based approach and design equations can reasonably be used for predicting the burst pressures of pipelines with corrosion only defects. However, the fracture mechanics approach is required for pipelines with crack-like defects and crack-in-corrosion defects. A parametric study is presented with calculations of the J -integrals for pipelines with crack-in-corrosion defects for various crack depths and crack lengths. • A numerical study on the burst pressure assessment of corroded pipelines using a fracture mechanics approach is presented. • The fracture mechanics approach is found to model effectively the cracking and the failure of the pipelines. • The assessment using J-integral criteria provided a better prediction of the burst pressures for corroded pipelines. • The study reveals that a fracture mechanics approach is required for pipes with crack-like and crack-in-corrosion defects. • Calculation of J-integrals for pipes with crack-in-corrosion defects for various crack depths and crack lengths are presented. [ABSTRACT FROM AUTHOR]

The burst strength of tube and casing is important to the storage and development of hydrogen gas and natural gas. Studies on the current classic models to calculate burst pressure of tube and casing show that they are not suitable to predict the burst pressure of tube and casing under modern manufacturing technology level due to without considering the effects of radius-thickness ratio and practical service environment (capped-end condition and capped-open conditions). Hence, for the thin-wall (20＜D/t＜40) tube and casing, based on the deformation instability and finite strain theory, this paper has established the equations to calculate burst pressure of thin-wall pipe under capped-end condition and capped-open conditions by adopting the power-law constitutive relation. For the thick-wall (5 ≤ D/t ≤ 20) tube and casing, based on the failure criterion of through-wall yield, the unified algorithms of burst pressure for thick-wall pipe under capped-end condition and capped-open condition have been derived by adopting unified strength theory. The burst pressure model which can calculate the burst pressure of thick-wall pipe under modern manufacturing technology level, has been presented combining with weighting twin shear stress yield criterion. Numerical and experimental comparisons show that the calculated results of this equation are closest to the test data, and its accuracy and reliability are obviously superior to other models, and the service environment of tube and casing has a great impact on the burst pressure. • Burst pressure models are investigated under capped-end and capped-open condition. • Burst pressure model of thin-wall pipe is established based on finite strain theory. • Burst model of thick-wall pipe is established based on weighting yield criterion. • Unified algorithm of burst pressure for thick-wall tube and casing is presented. [ABSTRACT FROM AUTHOR]

• Investigate the burst pressure of thin-walled pipe elbows. • Derive analytical burst models using the Tresca, von Mises and ASSY criteria. • Propose modified Goodall model that is highly accurate. • Extensive parametric finite element analyses carried out for model validation. This paper is focused on the development of burst pressure models for thin-walled pipe elbows subjected to internal pressure. Three analytical burst pressure models are derived based on the Tresca, Mises, and ASSY yield criteria, respectively. A modified Goodall model is further proposed with markedly improved accuracy in burst pressure predictions compared with the original Goodall model. The proposed models are validated using full-scale burst tests of pipe elbows reported in the literature and parametric finite element analyses carried out in the present study. The accuracy of the proposed models is also compared with that of analytical burst pressure models reported in the literature. [ABSTRACT FROM AUTHOR]

Abstract The search for novel, more compliant vascular grafts for the replacement of blood vessels is ongoing, and predictive tools are needed to identify the most promising biomaterials. A simple analytical model was designed that enables the calculation of the ratio between the ultimate stress (σ ult) and the elastic modulus (E). To reach both the compliance of small-diameter coronary arteries (0.0725%/mmHg) and a burst pressure of 2031 mmHg, a material with a minimum σ ult /E ratio of 1.78 is required. Based on this result and on data from the literature, random electrospun Polyurethane/Polycaprolactone (PU/PCL) tubular scaffolds were fabricated and compared to commercial ePTFE prostheses. PU/PCL grafts showed mechanical properties close to those of native arteries, with a circumferential elastic modulus of 4.8 MPa and a compliance of 0.036%/mmHg at physiological pressure range (80–120 mmHg) for a 145 μm-thick prosthesis. In contrast, commercial expanded polytetrafluoroethylene (ePTFE) grafts presented a high Young's modulus (17.4 MPa) and poor compliance of 0.0034%/mmHg. The electrospun PU/PCL did not however reach the target values as its σ ult /E ratio was lower than expected, at 1.54, well below the calculated threshold (1.78). The model tended to overestimate both the compliance and burst pressure, with the differences between the analytical and experimental results ranging between 13 and 34%, depending on the pressure range tested. This can be explained by the anisotropy of random electrospun PU/PCL and its slightly non-linear elastic behavior, in contrast to the hypotheses of our model. Impermeability tests showed that the electrospun scaffolds were impermeable to blood for all thicknesses above 50 μm. In conclusion, this analytical model allows to select materials with suitable mechanical properties for the design of small-diameter vascular grafts. The novel electrospun PU/PCL tubular scaffolds showed strongly improved compliance as compared to commercial ePTFE prostheses. Highlights • Simple analytical model proposed to select materials for vascular graft design. • Model predicted compliance and burst pressure based on materials properties. • Ratio of ultimate stress to elastic modulus reached 1.78 for small-diameter grafts. • Electrospun PU/PCL grafts exhibited mechanical properties close to native arteries. [ABSTRACT FROM AUTHOR]

The Tresca and von Mises criteria are two classic yield criteria for metals. While the von Mises criterion has been widely implemented in commercial finite element analysis (FEA) software package, the Tresca yield criterion in the context of the associated-plastic flow rule is not available in any well-known FEA packages such as ABAQUS and ANSYS. In this study, the Tresca yield criterion as well as the associated plastic flow and hardening rules are implemented in a user-defined material model (UMAT) in commercial FEA package ABAQUS based on the return-mapping technique. The consistent tangent operator for the Tresca criterion is also implemented in the UMAT model to facilitate the computation of the tangent stiffness matrix during the Newton-Raphson iteration for solving the nonlinear global equilibrium equations in the plastic domain. The constitutive integration algorithm for the Tresca UMAT is written in the principal stress space, which markedly simplifies the implementation. The implemented Tresca UMAT model is validated by theoretical solution and full-scale burst tests of both pristine and defected pipes. Furthermore, based on the Tresca-based and von Mises-based FEA predictions, a new formula is proposed to accurately predict burst pressure of thin-walled corroded pipes. • Implement the Tresca plasticity model as a UMAT subroutine in ABAQUS. • Employ the return-mapping algorithm in the principal stress space. • Verify the implemented UMAT using burst pressures of thin-walled pipes. • Recommend a new equation for evaluating the burst pressure of defected pipes. [ABSTRACT FROM AUTHOR]

Highlights • Effects of axial force and bending moment on the burst pressure of corroded pipelines are studied. • Burst pressure is significantly reduced under compressive axial force and closing bending moment. • Developed failure loci considering axial forces, bending moments and internal pressures. • The failure loci are found to depends on corrosion depths and load combinations. • The failure loci can be used for burst pressures assessment with known axial force and bending moment. Abstract The remaining strength of corroded pipeline is generally assessed considering the internal pressure only. However, pipelines are often subjected to axial forces and bending moments due to external loadings, which may significantly reduce the burst pressure of the pipeline. This paper presents a study using finite element analysis on the effects of axial forces and bending moments to the burst pressures of corroded pipelines. It is revealed that the compressive axial force and the closing bending moment, causing compression in the corroded area, affect the burst pressure most significantly. Considering the axial compression and closing bending moment, failure loci of combined bending moments and internal pressures are developed for different axial forces. The developed failure loci can be used for assessing the burst pressure of corroded pipelines subjected to axial forces and bending moments. [ABSTRACT FROM AUTHOR]

Highlights • The defect depth played a more dominant role in pipe burst than did the defect length. • The pipe burst pressures were reduced approximately 20–30% after a 30 MPa axial tensile load was added. • Burst pressures were much lower in the general defect tests compared to the groove defect tests with the same defect depth. • Failure began as instantaneous ductile rupture and extended as brittle rupture. • The higher the burst pressure, the stronger the BLEVE effect. Abstract Highly pressurized injection pipelines in CO 2 flooding often suffer from different types of corrosion defects and mechanical stresses and can easily cause serious damage to the environment. Currently, the descending rule of pipe burst pressures under different defect parameters and tensile loads has not been studied systematically. In this study, a section of injection pipe was used to simulate the burst process of pipe with groove and general corrosion defects. The crack appearance showed that the fracture began at the centre of the longitudinal defect line as an instantaneous ductile rupture and then extended along both sides as a rapid brittle rupture under high stress. The burst pressure in the groove corrosion defect tests showed that the defect depth played a more dominant role in pipe burst than the defect length did, and when a 30 MPa axial tensile load was added, the pipe burst pressure was reduced approximately 20–30%. In general corrosion defect tests, the burst pressures were generally much lower than the groove corrosion defect tests produced, and when adding the axial tensile load, the burst mode changed. Moreover, the value of the burst pressure can be a sign of BLEVE (boiling liquid expanding vapor explosion) severity. [ABSTRACT FROM AUTHOR]

Integration of forward osmosis (FO) and osmotically assisted reverse osmosis (OARO) provides low energy consumption and controlled fouling for brine treatment. This study explains the membrane properties required for cost–optimal OARO-based systems. A detailed model accounting for the relationship between burst pressure, permeate spacer gap, and structural parameters of OARO membranes was implemented with woven and non-woven spacers. Results indicate that the tradeoff between internal concentration polarization (ICP) and permeate–side pressure drop in OARO stages is a crucial consideration for optimal membrane element design. Due to the lower ICP of no-woven spacers, a system using non-woven spacers yielded lower levelized cost of water (LCOW) and specific energy consumption (5.83 $ / m 3 and 11.65 kWh / m 3 , respectively) as compared to the system with woven spacers (7.31 $ / m 3 and 9.90 kWh / m 3 , respectively) for dewatering a stream of 75 g/L salinity with 70 % water recovery. Sensitivity analysis shows that increasing the maximum pressure in OARO membranes requires a higher membrane structural parameter, aggravating ICP; however, the elevated driving force mitigates adverse effects of ICP. Moreover, a 15 % reduction in LCOW can be achieved if the membrane replacement factor of RO and OARO is reduced from 15 % to 5 %, which accounts for mitigated fouling. [Display omitted] • An integrated system of FO, RO, and OARO technologies is investigated. • Membrane properties are overviewed for osmotically assisted membrane–based systems. • Burst pressure was calculated using module mechanical properties. • Concentration polarization and permeate–side pressure drop dominate the losses. • Thicker membranes tolerating higher pressure best reduce cost despite higher ICP. [ABSTRACT FROM AUTHOR]

• Predicting the burst pressure of corroded oil and gas pipelines via machine learning algorithms. • The specifics of the datasets used to construct the machine learning models that estimate the pressure at which corroded oil and gas pipes would burst. • The limits of existing machine learning methods are investigated. • Details about organizations and institutions that generate datasets have been added. A comprehensive evaluation of the integrity of oil and gas pipelines subjected to corrosion defect is required for forecasting health & safety actions. If corrosion is ignored, it may have significant repercussions on a person's health, finances, and the environment. The preponderance of failure pressure prediction research uses numerical simulations and industry-specific codes. However, the complexity and magnitude of deteriorated pipe systems make machine learning based technologies such as artificial neural networks, support vector machines, deep neural networks, and hybrid supervised learning models more suited. Current ML research techniques that predict burst pressure lack a comprehensive review. This research aims to evaluate the present ML techniques (methodology, variables, datasets, and bibliometric analysis; Most active researchers, journals, regions around the world and institution). Based on the results the most widely used machine learning model is ANN followed by SVM but still they have some major limitations such as overfitting and generalization, but other machine learning models such as random forest and ensemble models along with theory guided models have been utilized even though still a very little research has been carried out. The most commonly datasets used to build these models are either experimental or numerical simulations conspiring of inputs and outputs as geometry and pipe material-based parameters such as pipe diameter, material grade, defect depth-breadth-length, and wall thickness. Most of these datasets have been built by known institutions such as PETROBRAS, KOGAS, BRITISH PETROLEUM and Waterloo university. In addition, this analysis revealed research limitations and inadequacies, including data availability, accuracy, and validation. Finally, some future recommendations and opinions are presented such as collaboration between institutions to share the dataset, providing more practical models such as physics informed machine learning and digital twins in the field. [ABSTRACT FROM AUTHOR]

• A mechanical model of the pipelines with asymmetrical defects is established. • With the change of defect shape, the burst pressure is like a saddle surface. • A burst pressure equation of pipelines with asymmetrical defects is proposed. As an efficient and inexpensive tool, pipelines are widely used in the transportation of hydrogen, carbon dioxide, oil and gas. The subsea pipelines are inevitably corroded because of the transportation environment and medium. The scholars have studied burst pressure of pipelines with simple corrosion defects, However, there are many research gaps in the burst pressure analysis of pipelines with complex corrosion defects. In this paper, the burst pressure of subsea pipelines with asymmetrical corrosion defects is studied. Firstly, a model of pipelines with asymmetrical and external corrosion defects is established. Then, the finite element method is conducted to analyze the burst capability of subsea pipelines with asymmetrical corrosion defects. Next, a novel method of simplifying asymmetrical corrosion defects is proposed. In the end, a modified DNV equation is presented to predict the burst pressure of subsea pipelines with asymmetrical corrosion defects. This study can provide a novel idea for obtaining the burst pressure of subsea pipelines with complex corrosion defects. [ABSTRACT FROM AUTHOR]

Exact solutions of burst pressure for defect-free, thick-walled cylindrical pressure vessels with capped ends are developed using the flow theory of plasticity in terms of the Tresca, von Mises, and Zhu-Leis yield criteria. The material is assumed to obey a power-law strain hardening rule, and the finite strain theory is adopted to describe large plastic deformation. On this basis, internal pressure is obtained as a complex polynomial function of effective strains on the inside and outside surfaces of the pressure vessel with the use of the Bernoulli numbers. At burst failure, the effective strains and stresses on the inside and outside surfaces are first determined, and then three flow solutions of burst pressure are obtained as a power series function of the diameter ratio (D o /D i), strain hardening exponent (n), and ultimate tensile stress (UTS). The power series solution is confirmed to agree well with the exact flow solution of burst pressure in a closed-form for each yield criterion, and the results show that the von Mises flow solution is an upper bound prediction, the Tresca flow solution is a lower bound prediction, and the Zhu-Leis flow solution is an intermediate prediction of burst pressure. Two sets of full-scale burst test data are then utilized to evaluate and validate the proposed flow solutions of burst pressure for both thin-walled pipes and thick-walled cylindrical pressure vessels. • This paper developed three exact solutions of burst pressure for thick-walled cylinders using the flow theory of plasticity in terms of the von Mises, Tresca, and Zhu-Leis yield criteria. • Three power series solutions were obtained using the Bernoulli numbers for thick-walled cylinders and then confirmed to be equivalent to the proposed flow solutions of burst pressure in a closed form for the three yield criteria. • Results showed that the von Mises flow solution is an upper bound prediction, the Tresca flow solution is a lower bond prediction, and the Zhu-Leis flow solution is an intermediate prediction of burst pressure for thick-walled cylinders. • Two datasets of burst pressure tests were utilized to evaluate the closed-from exact solutions of burst pressure and confirmed that the Zhu-Leis flow solution can predict an accurate result that matches best with burst pressure data on average for both thin and thick-walled pressure vessels. [ABSTRACT FROM AUTHOR]

• This paper developed an exact solution of burst pressure for thick-walled pipes using the flow theory of plasticity in terms of the average shear stress yield criterion (or Zhu-Leis criterion). Similarly, two other exact solutions of burst pressure for thin-walled pipes were also developed for the von Mises and Tresca yield criteria. • A power series solutions was first obtained using the second Bernoulli numbers for thick-walled pipes and then confirmed to be equivalent to the proposed flow solutions of burst pressure in a closed form for each yield criterion. • Results showed that the von Mises flow solution is an upper bound prediction, the Tresca flow solution is a lower bond prediction, and the Zhu-Leis flow solution is an intermediate prediction of burst pressure for thick-walled pipes. • Two datasets of full-scale burst pressure tests were utilized to evaluate the closed-from exact solutions of burst pressure and confirmed that the Zhu-Leis flow solution is the best model that can predict an accurate result to match best with burst pressure data on average for both thin and thick-walled pressure pipes. This paper develops an exact solution of burst pressure for defect-free, thick-walled pipes using the flow theory of plasticity in terms of the average shear stress yield criterion (or Zhu-Leis yield criterion). The pipe steel is assumed to obey the power-law strain hardening rule, and large plastic deformation is described by the finite strain theory. On this basis, internal pressure is obtained as a power series function of the effective strains on the inside and outside surfaces of the thick-walled pipe with use of the second Bernoulli numbers. At burst failure, the Zhu-Leis flow solution of burst pressure is determined as a power series solution, and the burst effective strains, the burst effective stresses, and the burst pressure are functions of the diameter ratio (D o / D i), strain hardening exponent (n), and ultimate tensile strength (UTS). Similarly, the Tresca and von Mises flow solutions of burst pressure are also determined as a power series solution in terms of the Tresca and von Mises yield criteria. A general closed-from exact solution of burst pressure is then proposed for the three yield criteria, and the results showed that the proposed exact solution matches well with the power series solution for each yield criterion. Moreover, the von Mises flow solution is an upper bound prediction, the Tresca flow solution is a lower bound prediction, and the Zhu-Leis flow solution is an intermediate prediction that agrees well with the finite element analysis results of burst pressure for thick-walled pipes. Two datasets of full-scale burst tests are then utilized to evaluate and validate the proposed flow solutions of burst pressure for both thin and thick-walled pipes. [Display omitted] [ABSTRACT FROM AUTHOR]

The burst pressure of commonly used ductile steel pipes in oil and gas industries, i.e. X52 and X60, is measured under internal pressure loading. The pipes were machined with circular and boxed defects at different orientations to simulate actual metal loss defects. Defect shapes and orientations were investigated in detail to study how they affect the failure behaviour of interacting defects. The experimental burst pressure results were compared with those obtained using existing analytical methods from Design Codes. Comparison of the results showed conservatism in the existing analytical methods which may potentially lead to unnecessary plant shutdowns and pipe repairs. The outcome of the experimental tests revealed that the shapes of the defects have very small influence on the defect interaction behaviour. The burst tests interestingly showed that the defect orientation has an important effect on defect interaction. Defects oriented in the hoop and diagonal directions showed no defect interaction even when spaced by a distance of one wall thickness, while defects oriented in the longitudinal directions showed that defects interact even when the spacing is up to six wall thickness but the interaction fades away for defects spaced at longer distances. [ABSTRACT FROM AUTHOR]

Abstract This paper investigates the influence of widely-spread randomly-distributed pits on the pressure carrying capacity of pipes using nonlinear finite element models for pitting colonies of Grades 1, 2 and 3 of Part-6 of API 579-1/ASME FFS-1 (FFS). Burst pressure predictions for pipes suffering from pitting with increasing severity are obtained and compared with those determined from lower levels of assessment provided in FFS. Upon re-evaluation of standard tabulated values for remaining strength factor (RSF) by means of limit load analysis using FEA for colonies with uniform pit depths, results of Level-1 assessment became more aligned with overall merit of FFS conservatism. For Level-2 assessment, the current investigation showed the need to modulate the conservatism of local thinned areas (LTA) approach. Despite the validity of adopting the LTA check within Level-2 assessment of pitting colonies, the final outcome of the combined RSF is highly conservative compared to RSF estimated by FEA. Highlights • Thin-walled pipes containing random pitting corrosion colonies are assessed using levels 1, 2 and 3 of FFS procedures. • Level-3 assessment is conducted using nonlinear FEA where corrosion pits are modeled by shell elements with reduced thickness. • Good correlation between P L obtained by the TES method and P F obtained by the ligament stress criterion. • RSF values adopted in FFS code for pits with uniform depth should be corrected in order to ensure more realistic level-1 assessment. • Consideration of local thin areas (LTAs) in Level-2 assessment provides realistic but highly conservative estimates of RSF. [ABSTRACT FROM AUTHOR]

The present study proposes a method to predict the burst pressures (BPs) of type III filament winding carbon fiber-reinforced plastic (CFRP) composite pressure vessels considering the inhomogeneity of carbon fiber packing through experimental work and simplified mechanical models reflecting the evolution of local damage in the CFRP layers. Vessels that had different carbon fiber volume fractions (Vfs) were prepared and tested to measure their BPs. The inhomogeneity of carbon fiber packing was evaluated using Weibull probability based on the microscopic observation of CFRP cross-sections in the virgin vessels. Detailed stress analyses of pressurized composite vessels considering the carbon Vf were conducted. Unstable fracture of the hoop layer was demonstrated by a simplified mechanical model combined with the inhomogeneity of the carbon Vf and de-bonding between the fiber and matrix. About 20% difference in the BP was measured between tested vessels with and without glass fiber-reinforced plastic layers over CFRP layers. The proposed method for predicting the BP based on the constant stress model enables consideration of the development of local fiber breaking prior to catastrophic fracture and to quantitatively estimate the change in the BP due to the difference in Vf. [ABSTRACT FROM AUTHOR]

• The vent failure time of the polyester cover shows an n-shape trend with thickness. • Acoustic waves are observed before the vent cover failure. • The temperature characteristics of external flame have been investigated. Explosion venting is an effective way to reduce the hazards of gases and dust fuel explosion in a confined space. Since there is little attention paid to the thermal radiant damage produced by the vented flame, the surface temperature distribution for hydrogen-air mixtures with different burst pressures (P v) is investigated in a large L/D ratio duct. The high-speed shadowgraph imaging system, pressure testing system and infrared thermal imager are used to record the explosion venting process. The P v and the thickness (δ) of the polyester vent cover are in the direct ratio, while the vent failure time shows a nonlinear relationship with the δ. Five internal overpressure peaks (P 1 , P 2 , P 3 , P Ref , P neg) are distinguished. With the addition of P v , P 1 increases gradually, while P 2 disappears in some higher P v. The external flow field is obtained and discussed in detail. The cases of lower P v with the unburned gas escaping from the vessel can sustain a high flame speed, whereas other cases only involve a flame jetting process with a relatively low speed. The high-temperature (>500 ℃) duration shows an 'M' shape with the P v. Besides, the safety distances to prevent humans from suffering thermal radiant damage have been determined. [ABSTRACT FROM AUTHOR]

• Pipeline residual strength prediction method based on HTLBO-DELM is proposed. • The interactions of parameters on pipeline residual strength are investigated. • Multiple adjustment strategies are used to optimize the TLBO algorithm. • The hybrid TLBO algorithm is applied for optimizing the parameters of DELM model. Residual strength prediction of defective pipelines is critical to pipeline reliability assessment, which can affect the remaining useful life of pipelines. In this paper, we propose a novel method for predicting residual strength of defective pipelines based on deep extreme learning machine (DELM). To obtain the high accuracy, the hybrid teaching-learning-based optimization (HTLBO) algorithm with multiple adjustment strategies is designed to improve the DELM model. The experimental data of pipeline burst pressure is selected for the training and validation of proposed method. The interactions of input parameters on residual strength are investigated using response surface method. After comparisons of key model parameters, the optimal model is established to ensure the prediction accuracy. Through the validation of benchmark functions, the HTLBO performs well in convergence and optimization performance. The prediction results show that the proposed method has higher precision than other models, and it can predict the residual strength within the relative error of 6%. This study can provide a basis for reliability engineering and transportation safety of defective pipelines. [ABSTRACT FROM AUTHOR]

This work provides a new systematic evaluation method to assess the interaction between adjacent corrosion defects and its effect on the integrity of pipelines. First, a finite element (FE) model of a pipeline containing adjacent defects (defects in longitudinal, circumferential and diagonal alignments) was developed. Then, the detailed relationships between defect spacing, and geometry, as well as the burst pressure of the pipe were investigated. At last, an interaction identification criterion applicable to asymmetrical defects was proposed, whose accuracy and reliability of the criterion were validated by FE simulations. The results show that the arrangement of corrosion affects the effect of interaction between adjacent defects. Regarding defects in longitudinal and circumferential alignments and with different depths, the increase of defect spacing strengthens the interaction between defects. For diagonally and circumferentially aligned defects with an identical depth, interaction strength tends to decrease first and then increase with the rise of defect spacing. An increase in defect depth exacerbates the interaction between adjacent corrosions. Similarly, an increase in the length of the shorter defect enhances the interplay between defects, which thus reduces the burst capacity of the pipe. When the length of the longer defect in adjacent defects increases, the interaction between the defects will be weakened, and the burst pressure of the pipeline is mainly dominated by the longer defect. Diagonally aligned defects show the strongest interaction effect when their overlapped distance in axial projection equals the sum of depths of adjacent defects, followed by defects in a longitudinal alignment. Besides, defects in a circumferential alignment have little effect on the failure pressure of the pipe. It is expected that the proposed interaction assessment criterion for adjacent defects with different arrangement types can provide a reference for assessing the integrity of pipelines with cluster corrosion defects. • A novel interaction assessment method applicable to asymmetrical defects and diagonally aligned defects was proposed. • The relationships between defect spacing, defect geometry and the burst capacity of corroded pipelines were clarified. • The arrangement with the most significant interaction for various alignments of defects was determined. • The developed interaction criterion shows a high accuracy in identifying the interacting defects. [ABSTRACT FROM AUTHOR]

Failure of pipeline is often caused by corrosion. It affects the health, safety, environment and economy considerably. To prevent pipeline failure, it is necessary to focus on the corrosion and pressure of the structures. Burst pressure is a key factor to assess the integrity of a pipeline. There are three means to determine burst pressure. These are lab testing, evaluation criteria and the Finite Element Method (FEM) modeling. However, the results of the burst pressure assessment using evaluation criteria are too conservative compared to the results of an actual pipe burst experiment and FEM modeling. The objectives of this paper are to analyze the changing trend of burst pressure of pipelines with different defect dimensions; to compare the FEM results with those of the evaluated criteria (DNV model) to indicate the conservative property; to revise the DNV model and verify its validity with actual burst experiments. The revised DNV model predicts burst pressure more reliably that could result in better engineering design of pipelines. [ABSTRACT FROM AUTHOR]

Corrosion defects occur very often on the internal and external surfaces of pipelines, which may result in a serious threat to the integrity of the pipelines. Numerous studies investigated failure behavior of corroded pipelines with single corrosion defects. However, few studies focus on interacting corrosion defects. Interacting defects are defined as defects with certain proximity that interact to reduce the overall strength of a pipeline. In the present study, the failure behavior of pipelines with interacting corrosion defects was studied using a finite element method, and then a solution was proposed to predict burst pressure using an artificial neural network. The solution was validated by experimental results in previous studies and compared with other existing assessment solutions to prove its applicability and efficiency. [ABSTRACT FROM AUTHOR]

Pipelines are the fifth type of transportation, which has the highest efficiency and the least environmental damage for gas or oil transmission. Recently, the pipeline failures due to corrosion defects have attracted people's attention in maintaining pipeline integrity. Based on the double circular arc (DCA) model and elastic-plastic theory, an analytical solution of the corroded pipelines under internal and external pressures was obtained. And then, a new burst pressure equation of the corroded pipelines with high strength was further provided according to the von Mises criterion and previous equations. Compared with previous equations, this equation greatly extends the application scope and increases the calculation accuracy. The accuracy of our equation is validated by comparing with the full-scale experimental data. The effects of the thickness to diameter ratio, corrosion ratio and yield strength on the burst pressure are carefully investigated. The results reveal that when the thickness to diameter ratio is less than 0.1, the calculated results show a good agreement with the experimental data for the corroded and high strength pipes. Our research can provide a foundation for replacing the corroded pipelines at the bottom of the sea. In addition, our research is beneficial for the engineering design and integrity assessment of oil and gas pipelines. [ABSTRACT FROM AUTHOR]

• ethanol lock impacts the chain organization. • ethanol lock increases the kinking ability. • stress and strain at break lower after ethanol lock. • Performances higher than normative requirements. The impact of ethanol locks on the mechanical performances of central venous catheters was compared to that of aqueous-based locks. Several mechanical tests were performed to evaluate catheter behavior: kinking radius measurements, burst pressure, and tensile tests. Different polyurethanes were studied to assess the impact of radio-opaque charge and polymer chemical composition on catheter behavior. The results were correlated to swelling measurements and calorimetric measurements. In particular, ethanol locks have a higher impact on long contact time than aqueous-based locks: stresses and strains at break were lower, and kinking radii were higher. However, for all catheters, the mechanical performances remain much higher than the normative requirements. [ABSTRACT FROM AUTHOR]

• This paper presents a hybrid approach model for predicting the burst pressure of corroded pipelines. • A new feature space with physical meaning is constructed. • The proposed fusion mechanism makes full use of the prior knowledge in the Tresca criterion and the predictive ability of ensemble learning. • LightGBM is used to build a predictive model, and the Tree-structured Parzen Estimator algorithm is used for hyper-parameter search. • This paper establishes a burst pressure dataset of full-scale corroded pipelines ranging from low strength to high strength. Accurate prediction of the burst pressure of corroded pipeline is of great significance to pipeline design, reliability analysis and maintenance decision. This paper presents a novel hybrid approach model for predicting the burst pressure of corroded pipelines. First, a new feature space with physical meaning is constructed based on the pipeline geometry, the size of corrosion defects, and the mechanical properties of materials. Then, a fusion mechanism combining empirical formula and ensemble learning is proposed, which makes full use of the prior knowledge in the Tresca criterion and the predictive ability of ensemble learning. The prediction model is built using the Light Gradient Boosting Machine, and the hyper-parameters are tuned using the Tree-structured Parzen Estimator algorithm. Finally, a burst pressure dataset of corroded full-scale oil and gas pipelines ranging from low strength to high strength is established to verify this model. The prediction results demonstrate that the hybrid approach model can significantly improve the prediction accuracy. And compared to other ensemble learning methods such as random forest and XGBoost, the accuracy of this model proposed in this paper is the highest. The correlation coefficient is 0.98163, the mean square error is 0.98087 MPa, the mean absolute error is 0.66500 MPa, and mean absolute percentage error is 0.04480. The model also provides feature importance, enhancing the interpretability of the model. In addition, further experiments demonstrate that this model has good adaptability to corroded pipelines of different strengths grade and obvious advantages compared with the calculation results of five traditional empirical formulas. [ABSTRACT FROM AUTHOR]

For a type IV hydrogen storage vessel, the complexity of the mechanical system is a result of the increased number of thin-layered composites and geometrical details at dome parts, which significantly prolongs the computation time for traditional numerical analysis and optimal design. In this work, a framework couples machine learning (ML) and finite element (FE) analysis is proposed for a 70 MPa type IV vessel. Providing an approach that allows the winding parameters optimization process to include the corresponded feasible dome geometry. High-fidelity FE models are established and different failure modes are included. The artificial neural network (ANN) is developed and coupled with the FE models, where the irregularity of directional material distribution on both cylindrical and dome regions is adequately considered during the optimization process. Winding parameters extended by practical production modifications such as transition areas and layer ending adjustments are introduced to the modified input layer of ANN, to ensure the integrality of the complex geometrical details. The computational cost is greatly reduced with satisfying accuracy compared to FE analysis, where the optimized lay-up scheme could be obtained with a prediction error of less than 2% on the damage state function. The associated simulation results show an obvious improvement in mechanical response under designed burst pressure. Particularly, the prototypical vessels are further produced to carry out comparative experiments, which indicate that the burst pressure of the type IV vessel has been improved from 145 MPa to 157.74 MPa. This is also consistent with the numerical prediction of burst pressure using Hashin failure criteria and progressive damage analysis. [Display omitted] • ANN-based machine learning (ML) algorithms is used to optimize 70 MPa type IV vessel. • The irregularity of directional material distribution in dome regions is well considered. • Transition areas and layer-ending adjustments are introduced to the modified input layer of ANN. • Multiple failure modes and mechanical performances are considered to evaluate the outputs. [ABSTRACT FROM AUTHOR]

Accurate prediction of the burst pressure is essential for structural integrity assessment of pipelines. Current design codes and models for residual burst pressure assessment of pipelines with surface corrosion defects are only applicable to axially orientated defects. Theoretical and empirical models for the prediction of burst pressure of thin-walled pipes with pre-existing localised and arbitrarily oriented surface corrosion defect are proposed. The theoretical model is based on power-law hardening and J2 flow theory while the empirical model is derived from nonlinear finite element analysis results of the burst pressure. Burst pressure experiments are used to validate the model predictions. The theoretical and empirical models are found to be reliable in predicting the effect of defect width, length, and orientation on the burst pressure. • Theoretical and empirical burst pressure prediction models are developed. • The models quantify effect of defect geometry and orientation on burst pressure. • Burst pressure experiments are used to validate the model predictions. • Axial defect is more detrimental to burst pressure than circumferential defect. [ABSTRACT FROM AUTHOR]

Pillow plates represent an efficient type of heat transfer equipment with a high degree of flexibility in terms of manufacturing and applications. Their thermo-hydraulic behaviour has been the focus of numerous scientific investigations over the last decade. However, along with the realisation of the thermal task, it is also important to ensure an adequate level of operational safety when designing equipment based on pillow plates. At present, for the approval of a pillow plate based apparatus, an experimental proof of the permitted operating pressure must be provided in accordance with the regulatory standards. In this process, this pressure is calculated from the burst pressure, which must be determined in time-consuming and cost-intensive experiments. For this reason, we propose a new approach in which the burst pressure of pillow plates is determined numerically based on the finite element methods, eliminating the need for experiments. Furthermore, the simulation results were used to derive equations for calculating the burst pressure and the maximum achievable inflation height of pillow plates made of the aluminium alloy EN AW- 5083. This part of the work has been motivated by the findings of a preliminary study showing a more than 25% thermal resistance reduction of counterflow operated pillow plate heat exchangers when the pillow plates are made of aluminium instead of the standard material stainless steel. • Novel finite element based approach for determination of burst pressure and maximum achievable inflation height of pillow plates. • The approach was successfully validated against experimental burst tests. • Technically relevant pillow plates are proven to be manufacturable from aluminium (EN-AW 5083). • Design equations for burst pressure and maximum achievable inflation height for pillow plates from aluminium. [ABSTRACT FROM AUTHOR]

Reproducing both the mechanical and biological performance of native blood vessels remains an ongoing challenge in vascular tissue engineering. Additive-lathe printing offers an attractive method of fabricating long tubular constructs as a potential vascular graft for the treatment of cardiovascular diseases. Printing hydrogels onto rotating horizontal mandrels often leads to sagging, resulting in poor and variable mechanical properties. In this study, an additive-lathe printing system with a vertical mandrel to fabricate tubular constructs is presented. Various concentrations of gelatin methacryloyl (gelMA) hydrogel were used to print grafts on the rotating mandrel in a helical pattern. The printing parameters were selected to achieve the bonding of consecutive gelMA filaments to improve the quality of the printed graft. The hydrogel filaments were fused properly under the action of gravity on the vertical mandrel. Thus, the vertical additive-lathe printing system was used to print uniform wall thickness grafts, eliminating the hydrogel sagging problem. Tensile testing performed in both circumferential and longitudinal direction revealed that the anisotropic properties of printed gelMA constructs were similar to those observed in the native blood vessels. In addition, no leakage was detected through the walls of the gelMA grafts during burst pressure measurement. Therefore, the current printing setup could be utilized to print vascular grafts for the treatment of cardiovascular diseases. • A vertical additive-lathe printing system offers an attractive method to print long tubular constructs. • This method can be employed to print uniform wall thickness vascular grafts using hydrogels. • The hydrogel filaments bonded properly with each other under the action of gravity resulting in good-quality tubular grafts. • No leakage was detected through the walls of the printed constructs during the burst pressure testing. • The anisotropic properties of printed grafts were found to be similar to those observed in the native blood vessels. [ABSTRACT FROM AUTHOR]

Corrosion is one of the major causes of damage in offshore and onshore pipes. Based on the double circular arc (DCA) model and the average shear stress yield (ASSY) criterion for isotropic hardening materials, a new burst pressure equation for corroded pipes is developed in this paper. The ASSY criterion is a weighted average of the maximum shear stress and the octahedral shear stress and it is adopted to predict the burst pressure of the pipelines with corrosion defects. The accuracy of our predictive equations is validated respectively by both the ideal and corroded pipes. Firstly, the burst pressure equation of a corroded pipe is degraded into an ideal pipe's. Then we compare the calculated results with the full-scale experimental data. The calculated results are consistent with the experimental data for the ideal pipes. Again, we make a comparison of the predicted burst pressures of corroded pipes with the ones from the elastic-plastic finite element method (FEM) and the experiment. The calculated results show a good agreement with the numerical calculations and experimental data for the corroded pipes. Our research reveals that the corrosion defects can decrease the burst pressure for a pipe; the yield criterion and the strain hardening exponent are crucial to accurately capture the burst pressure. Our research is beneficial to evaluate the integrity of the corroded pipes. [ABSTRACT FROM AUTHOR]

A study has been carried out to predict the static burst pressure in closed thick-walled unflawed cylinders using finite element analysis (FEA). The failure of the cylinder purely by ductile fracture mode is considered in the analysis. Thick-walled cylinders of different diameter ratios (K=outer diameter/inner diameter, ranging from 1.5 to 6) have been investigated. The commercially available ANSYS FEA code has been used, for carrying out an implicit elasto-plastic analysis of the cylinders considering the geometric and material nonlinearities. The Arc-length algorithm available in ANSYS code has been employed to overcome the solution convergence problem, due to tangent singularity at limit state. The FEA predicted static burst pressure for thick-walled cylinders over the considered range of diameters ratios i.e., K=1.5 to 6, showed good agreement with Svensson burst model. The implication of using elastic-perfectly plastic model for the prediction of static burst pressure has also been investigated. [ABSTRACT FROM AUTHOR]

Welded pipes containing corrosion may lead to catastrophic situations during transportation of gas. Appropriate methods are needed to assess defective pipelines for integrity assessment. Corroded girth and seam welds were studied for the effect of corrosion length and depth on the burst pressure of API X70 pipe. Full-scale hydrostatic burst pressure tests and finite element analysis (FEA) were performed to investigate the burst pressure resulting from the corroded girth and seam welds. The experimental results were used to validate the finite element model, which considered the 3D elastic–plastic behavior. The FEA predicted burst pressures were compared with the ASME B31G, Modified ASME B31G, DNV RP-F101, and PCORRC standards in order to derive a proper equation for evaluation of corroded seam and girth welds. [ABSTRACT FROM AUTHOR]

Moderate to weak mechanical properties limit the use of naturally-derived tissue sealants for dynamic medical applications, e.g., sealing a lung leak. To overcome these limitations, we developed visible-light crosslinked alginate-based hydrogels, as either non-adhesive methacrylated alginate (Alg-MA) hydrogel controls, or oxidized Alg-MA (Alg-MA-Ox) tissue adhesive tissue sealants, which form covalent bonds with extracellular matrix (ECM) proteins. Our study investigated the potential for visible-light crosslinked Alg-MA-Ox hydrogels to serve as effective surgical tissue sealants for dynamic in vivo s ystems. The Alg-MA-Ox hydrogels were designed to be an injectable system, curable in situ. Burst pressure experiments were conducted on a custom-fabricated burst pressure device using constant air flow; burst pressure properties and adhesion characteristics correlated with the degrees of methacrylation and oxidation. In summary, visible light crosslinked Alg-MA-Ox hydrogel tissue sealants form effective seals over critically-sized defects, and maintain pressures up to 50 mm Hg. [ABSTRACT FROM AUTHOR]

High pressure vessels with winding lamination of [90°/±15°] were manufactured adopting a vinylester and an epoxy resin reinforced with carbon fibres. An experimental setup was design to test the vessels up to the burst pressure. The tests results demonstrate a higher ultimate pressure of the carbon/vinylester composite vessel with respect to the epoxy reinforced counterpart. The full field strain measurements by the digital image correlation technique show a delayed of the initiation and propagation of the damage in the carbon/vinylester. Moreover, the carbon/vinylester vessel performed more homogeneous strain distribution with less and shorter hoop cracks than the carbon/epoxy one, as observed also with an X-ray micro tomography system, a laser microscope and a scanning electron microscope. [ABSTRACT FROM AUTHOR]

This work focuses on the fiber winding design and fabrication method of a carbon fiber wound composite pressure vessel with HDPE liner. The design parameters of the fiber winding layers, the fiber winding tensions, and the pre-charge pressures of the liner were studied. The hoop and helical winding layers were designed, and a finite element analysis model was established by combining the cubic spline thickness prediction method. A progressive damage analysis based on the Hashin failure criterion and the Camanho degradation criterion was conducted. The failure mode and the burst pressure of the vessel were obtained. By analysis of the critical buckling load of the liner and the design of the winding tensions, the pre-charge pressure was obtained by combining with the equivalent temperature method. A composite pressure vessel was fabricated and a burst test was carried out to verify the effectiveness of the design method and the fabrication process. • Critical buckling load of the liner and winding tension of the fiber were analyzed. • Pre-charge pressure was obtained by combining with an equivalent temperature method. • Failure mode and burst pressure were well simulated by progressive damage analysis. • Effectiveness of the design method and winding process of the vessel was verified. [ABSTRACT FROM AUTHOR]

To solve the problem of insufficient accuracy of the existing prediction models of burst pressure for defect-free straight pipes, a new yield criterion that can effectively reflect the deformation characteristics of pipeline materials is established by the mathematical extrapolation method, and a theoretical model of burst pressure for defect-free straight pipes is then derived. By comparing each yield criterion with the experimental data, the new yield criterion is found to be between the TSS criterion and the Tresca criterion, and is in good agreement with the experimental data. On this basis, a theoretical model for predicting the burst pressure of defect-free straight pipes is constructed by using this criterion, and the burst pressure under other yield criteria are also derived. The normalized burst pressures based on different yield criteria are given and compared with the full-size test data. It is found that the new yield criterion has the highest approximation degree to the test data since the average relative error is just 1.154% and the maximum error is no more than 10.801%. The model in this paper can meet the requirement of predicting the burst pressure of a defect-free straight pipe, which is of great significance to the structural design and safety assessment. • A new yield criterion that can describe the material deformation characteristics well is established. • A theoretical model that by using the new yield criterion can provide the best results of burst pressure. • The ultimate bearing capacity can be improved by selecting the pipe with low hardening, big wall thickness or small diameter. [ABSTRACT FROM AUTHOR]