A thermal-metallurgical-mechanical model was developed to study the effects of dilution in each weld pass for multipass gas tungsten arc and submerged arc welding in low alloy steel (i.e. SA508) plates. Hardness distributions and residual stresses were measured on the transverse sections perpendicular to the welding direction of the manufactured weldments. The predicted hardness and residual stresses

In this paper, reference stress based J estimation equations are presented for circumferential constant-depth surface and through-wall cracked cylinders with the radius to thickness ratio ranging from three up to seventy. The equations are developed based on extensive finite element (FE) analysis results. Firstly it is shown that application of existing J estimation equations is limited to thick-walled

This paper assesses the uncertainties in the structural reliability levels of thick high strength pipelines with active corrosion defects subjected to internal pressure. A general burst strength model and other applicable to thick high strength pipes are adopted and their predictions uncertainty over a wide range of corrosion defect depths is assessed by Monte Carlo simulation. A 3-parameter lognormal

As a result of the catastrophic damage to society, the economy and the environment induced by pipeline fire and explosion accidents, determining the impact distance of a natural gas pipeline has attracted increasing attention. In this paper, first the impact distances of some typical natural gas pipeline fire and explosion accidents are statistically reviewed. Then, a 3D natural gas pipeline jet fire

This study aims to assess the accuracy of various modelling methodologies in predicting creep-fatigue damage (dcf) and cycles-to-crack-initiation (Ni) of Alloy 617 at 850 °C and 950 °C. In the decoupled methodologies, four creep damage models were employed: (i) the time fraction (TF), (ii) ductility exhaustion (DE), (iii) stress-modified ductility exhaustion (SMDE), and (iv) strain-energy density (SED)

The paper presents the method of modeling the elastic deformations of expanded graphite, a material used as flexible filling in spiral wound gaskets. Five methods (from A to E) were proposed, by means of which the mean values of the effective elasticmodulus were determined on the basis of the experimentally determined stress-strain characteristics of expanded graphite. The values determined in this

Creep crack growth (CCG) behaviors of 9Cr–1Mo heat resistant steel under different stress states, such as the different initial crack lengths, two/three dimensional stress states, different side groove depths and angles are investigated by the numerical method. The results show that decreasing the initial crack length can increase the specimen life. Affected by the higher stress tri-axiality in the

Lifeline engineering plays an important role in the development of human society and economy. A large number of seismic damage events show that the buried polyethylene pipeline is easy to be damaged under the earthquake action, however, the research on the seismic vulnerability of the buried polyethylene pipeline is still lacking. In this paper, the seismic vulnerability of buried polyethylene pipeline

The nuclear reactors can undergo different forms of asymmetric operating conditions with one or more reactor coolant pump (RCP) fails or pressurized thermal shock (PTS) occurrences which can influence the life of reactor vessels. So, accurate descriptions of the heat transfer and the coolant flow within a nuclear reactor for the safety and performance concerns are always desirable. In this paper, computational

This paper presents an analytical study on the buckling of cylindrical shells under arbitrarily distributed axial loads. It has three main innovation points. First, different from the previous studies, the axial loads need not be assumed to be specific forms beforehand and be simple ones such as cosine type, which are arbitrary in this paper (including continuous and discontinuous distributions). Second

The paper presents a result of the numerical investigation into the buckling behaviour of geometrically imperfect cone-cylinder transition subjected to external pressure. The models are assumed to be made from the Hiduminium alloy (HE-15). Various initial geometric imperfections such as eigenmode imperfection and Single Load Indentation (SLI) imperfections were superimposed on the perfect cone-cylinder

Polypropylene (PP) plastic pipes have recently gained widespread application in non-pressurized gravity pipes used for seawater intake lines in the petrochemical industry. These pipes consist of a solid wall base pipe, on which an outer reinforcement called the omega-profile is spirally winded and hot fusion bonded. The omega-profile is usually filled with grout to provide on-bottom stability for subsea

Fatigue fracture in pipelines is the major failure mode during the service of oil and gas pipeline transportation. Welded joints, as the weakest region of a line-pipe, should be paid more attention firstly. Due to the need to remove the weld reinforcement at the beginning and end of each part of the pipeline for connection, it is necessary to study the fatigue properties of the welded joints before

In this paper, the effect of inertia on the steady-state velocity of propagating cracks in modern high toughness pipeline steel was investigated. The steel grades examined in this work were American Petroleum Institute Standard X70 and X100. A tensile plate model, simplified from the geometry of a pipe, was studied using the finite element code ABAQUS 6.14–2. The cohesive zone model (CZM) was used

Prior research has shown that additive manufacturing (AM) can be used to make functional and end-use components, however the absence of design guide has led to restricted use of AM in industry. This research aims to redesign a pressure reducer valve integrated into an end-cap as a subcomponent of composite pressure vessel (CPV), which is manufactured by AM. First, a number of design criteria are defined

The concept of sandwich pipes for subsea applications has been studied independently of an available connection to joint the pipe segments. Therefore, it is necessary to propose and study the design of a pipe segment connection to build a continuous sandwich pipeline. The reported research work suggests using threaded connections of integral type with square teeth and metal-to-metal sealing. The threaded

Subsea steel pipes are often used to form extensive networks for transporting oil and gas over large distances. Such pipes can be subjected to actions characterised by high loading rates and intensities stemming from high-mass low-velocity collisions. To ensure that such networks continue to operate, even after being subjected to impact loads, it is essential that the behaviour of the pipes is characterised

The paper presents the results of research on the microstructure and mechanical properties of TP347HFG steel after long-term service. The test samples for research were taken from the coil of a boiler superheater serviced for 105 000 h at a steam pressure of 12.5 MPa at the temperature of 540 °C. The tests have shown that the process of long-term service of the steel mostly contributed to the processes

An artificial neural network (ANN) model was developed to predict tensile and impact properties of a submerged arc helical welded (SAHW) pipeline steel API X70 based upon its chemical composition. Weight percent of the elements was considered as the input, while the tensile and Charpy impact properties were considered as the outputs. Scatter diagrams and two statistical parameters (absolute fraction

This work presents methodologies for the examination of uncertainties in plant loading conditions for incorporation in probabilistic creep-fatigue (CF) crack initiation assessments. These approaches are based on the use of plant data for transient (TR) as well as steady-operating (SO) conditions, with both potentially having large contributions towards creep-fatigue damage. Conventionally, the stress-states

Stress corrosion cracks detected in austenitic stainless pipes were circumferential cracks at inside of the pipes. Failure stresses for the cracked pipes were developed by net-section stress concept. Limit Load Criterion provided by the ASME Code based on the net-section stress concept can estimate fully plastic collapse stress, which is called as failure stress. Local Approach of Limit Load Criteria

Externally wrapped carbon fiber reinforced polymer (CFRP) composites are effective to repair a defective steel pipe. In the present study, the pipes of defects with different hoop lengths were repaired with CFRP and different putty was used to fill the defects. The effects of defect dimensions and putty mechanical properties on the burst performances of the repaired pipes were investigated through

Corrosion induced degradation of fracture toughness in buried cast iron pipes is a serious concern for structural integrity and smooth operation of buried pipes. External corrosion of pipes is fundamentally governed by the corrosivity of soil which may vary depending on the type of soil and its specific properties. While the corrosion assessments of pipes buried in soil can provide realistic behaviour

This paper compares systematic finite element results with reference stress based J estimation equations for pressurised axial surface and through-wall cracked cylinders with the radius-to-thickness ratio ranging from five up to seventy. It is found that, for the reference stress, the use of the Tresca limit pressure given in R6 provides satisfactory results for all cases considered; for both inner

The degradation of high energy piping systems is very complex to simulate due to the many variables that influence the useful lives of such systems. Estimation of the extent of degradation is however important in the maintenance planning process. In this research the use of data driven machine learning techniques to deal with this complex problem is investigated. A hybrid recurrent neural network is

Cracks caused by water hammer are one of the most common destructive forms in water supply pipeline systems. Unlike developed cracks, incipient cracks are not likely to be found, as they do not leak under normal running conditions. However, as a potential threat, the incipient cracks may rapidly develop under severe water hammer effects. To investigate the features of incipient cracks and their effects

Grade 92 heat-resistant steel is an important material for ultra-supercritical units. The degradation of the P92 properties affects the safety of structural components during long-term service. In this paper, the microstructural evolution of P92 depending on different service times was quantitatively studied using scanning electron microscopy and transmission electron microscopy. The effect of each

Metal dusting takes place in carbon-supersaturated gaseous atmospheres at temperatures comprised between 400 and 800 °C and is most commonly encountered in steam reforming processes such as hydrogen production from methane. It can lead to a severe loss of metal, resulting in high-cost maintenance and serious safety issues. Aluminide coatings are known to protect Fe and Ni based alloys under these conditions

A universal solution procedure has been developed for solving a wide range of thermal ratcheting problems beyond those covered by Bree Diagram or modified Bree Diagrams. Both thermal and pressure cyclic loading histories considered can be in-phase or out-of-phase with a prescribed phase shift. Material strain hardening behavior is modeled through a modified Ramberg-Osgood stress-strain relationship

This paper presented the effect of the complex crack shape on crack driving forces and crack tip stress fields, via experimental and numerical analysis results of the complex cracked tension (CC(T)) specimens. Fracture tests using CC(T) specimens are conducted using SA508 Gr.1a low-alloy steel, from which detailed crack shapes are measured before crack initiation and after crack growth. It is found

This paper deals with an evaluation of mechanical properties and microstructures of similar and dissimilar narrow gap orbital welds of martensitic steels P91 and P92 after long-term laboratory ageing at elevated temperatures (650, 675 and 700 °C, 5000 to 30 000 h). Conclusions of this assessment are the kinetic dependencies of structural and mechanical properties changes during long-term exposure to

Aim of the paper is to understand the effect of microstructural features of SA508 Grade 3 Class I low alloy steel (LAS) on short crack propagation rate under cyclic loading. The complex upper bainitic microstructure of this LAS consists of low angle bainitic ferrite lath boundaries and high angle prior austenite grain boundaries (PAGBs). Compared to bainitic ferrite lath boundaries, the PAGBs provided

In this work, the unified constraint-based FAD (failure assessment diagram) assessment methodology has been investigated and developed for ductile fracture in cracked pipes. Two unified constraint parameters Ap and Ad are utilized to incorporate both in-plane and out-of-plane constraints. The results show that the FAD approaches based on two-parameter K-Ap and K-Ad can predict similar fracture initiation

The current work has been performed to characterize the heterogeneous P91 welded joint. The gas tungsten arc welded (GTAW) P91 welds joint has been prepared using the dissimilar Inconel 617 filler. The P91 welded plates have been subjected to post-weld normalizing and tempering (PWNT) heat treatments for varying normalizing temperature in the range of 950–1150 °C. To homogenize the microstructure across

This paper presents an investigation of the potential of extended finite element method (XFEM) implemented in Abaqus standard software, with maximum principal strain and fracture energy as damage parameters for analysis of crack propagation and prediction of burst pressure in pipelines. Models of API 5L X60 pipe were calibrated first, using data from single edge notched tension test and then using

Nuclear containment structure plays a critical role of providing the leak proof boundary for preventing radioactive material leak into the environment during severe accident conditions. There is a growing demand to quantify the failure probability of containment structure under severe accident conditions. This paper mainly focuses on fragility analysis and performance evaluation of containment structure

As part of recent work on the structural behaviour of toroidal shells, this paper presents results of a numerical study on the buckling resistance of a closed toroidal vessel with a doubly-symmetric parabolic-ogival cross-section, subjected to uniform external pressure. The analysis was carried out on both geometrically perfect and imperfect elastic steel shells, and boundary conditions resulting in

Presently most structural integrity assessment procedures still allow the use of Charpy-V notch impact tests as a measure of fracture toughness. The use is generally made through some more or less reliable correlations between standard Charpy-V notch energy and fracture toughness or tearing resistance. A problem arises if the structure has such a geometry that standard size Charpy-V notch specimens

This work describes the framework to model ductile damage based on phenomenological stress-modified critical strain criterion (SMCS) coupled with a softening law to predict the onset of ductile initiation and ductile propagation in typical fracture specimens, extracted from a flat plate made of ASTM A285 Gr. C steel. A very detailed and well-illustrated methodology has been developed for the identification

The well-established benefits of compressive residual stresses over the fatigue lifetime constantly motivate engineers to scrutinize these trapped stresses in mechanical/civil structures. This research deals with characterization of thermal residual stresses in fiber reinforced polymer (FRP) tubes. Three important thermo-mechanical parameters, namely “cooling temperature”, “CNT reinforcement” and “tube

This paper is dedicated to providing a detailed limit load analysis for 180° pipe bends under bending moment using three dimensional finite element (FE) method considering geometric nonlinearity. Results show that FE results for 180° pipe bends are all lower compared to those for 90° pipe bends, especially for pipe bends with thin wall and small bend radius (R/r = 1.5, r/t = 50). However, for pipe

Fluid–structure interaction (FSI) and wave propagation in engineering structures can cause severe damage to piping systems or fluid machines, inducing serious accidents. In these phenomena, the mechanism of structural damage depends on the wave propagation across the fluid–solid interface. Previous studies reported that disagreements between the induced pressure value on the solid–fluid movable interface

In order to study the impact of surface explosion load such as terrorist attacks and disasters on buried pipelines, the field experimental study of the dynamic response characteristics of buried pipelines under surface explosion load was carried out by means of explosion experiment of on-site pre-buried pipelines and explosives, combined with blasting vibration and dynamic strain monitoring. The attenuation

A large portion of natural gas is transferred through transmission pipelines. For these facilities, in the United States, external corrosion has led to more than 1700 failures in the past decades, causing a property damage of approximately $189 M. Such numbers highlight the importance of maintaining such facilities in safe conditions to postpone corrosion failure. Given such criticality, addressing

Stick-slip affects torque-preload relationship during bolted joint tightening process. Its occurrence is not always possible to avoid and it can lead to an unreliable joint. In this study, tightening process was investigated and, in a first approach, modeled through theoretical analysis. In a second approach, experimental data was explored statistically using Analysis of Variance (ANOVA) and F-Test

In this paper, the ratcheting phenomena in the tubesheet of a heat exchanger, which made of modified 9Cr–1Mo steel, has been investigated. The nonlinear isotropic/kinematic hardening model (combined model) is used to investigate the progressive strains due to the cyclic pressure and temperature loading. Therefore, three series of tests were carried out at different temperatures (room temperature, 300