The classical water hammer model omits bending and inertial effects in the pipe wall. The validity of such assumptions for buried and covered pipes is assessed by developing a one-way coupled water hammer model based on an axisymmetric thin shell pipe finite element that captures bending and inertial effects. A finite/infinite pipe element formulation is developed to capture the stiffness contribution

The present paper studies stress, temperature and heat dependence of creep rupture life of 9Cr-1.8W-0.5Mo-VNb (Gr. 92) steel with creep rupture data of 4 heats reported in National Institute for Materials Science Creep Data Sheet 48B. In creep of Gr. 92 steel there are four regions, H, M, L and G, showing different stress and temperature dependence of creep rupture life. Creep rupture life of Gr. 92

The effect of NRB on the corrosion behavior of X80 pipeline steel in the soil extract solution of Shenyang was studied using polarization curve, electrochemical impedance spectroscopy, weight-loss tests and scanning electron microscope. The results show that NRB accelerates the corrosion rate of steel and promotes the formation of pitting holes on the surface of steel. XPS results show that the types

This paper provides a solution for a functionally graded hollow cylinder by using a novel numerical solution technique. The cylinder has an arbitrary elastic property along the radial direction. The cylinder is divided into N layers. The assumed Young's modulus in radial direction is approximated by the many power functions along layers. For an individual layer, two undetermined constants are involved

The requirements for materials and their strength significantly increased with the new generation of coal fired power plants operating at steam temperatures of up to 620 °C. Therefore, new materials were introduced to fulfill the defined needs. During the commissioning process of the first plant many cracks occurred in welds of T24 material. The cracks showed clear characteristics of stress corrosion

The ball valve has been widely used in many industries. Adjustable ratio is a core parameter of the valve design, which characterizes the adjustment accuracy of the valve. Type-V ball valves on the market due to limitations of machining process, the highest adjustable ratio is only approximately 30–50. This study designs a special adjustable ball valve with ultra-high adjustable ratio, and analyzes

Probabilistic assessments allow the uncertainties present in reactor design and operation to be understood and reflected in the quantification of reliability. Increased awareness of the limitations of deterministic structural integrity assessments have highlighted that the unquantified margins do not provide an adequate measure of component risk. The R5 procedure is a “UK nuclear power industry standard

BS 7910 provides guidance on the fitness for service of a flawed component. It covers a wide variety of metals in broad applications, thus the integrity of many components in various safety critical industries depends on it. Its detailed and rigorous validation, therefore, is of utmost importance. In this study, validation of the fracture assessment procedures of BS 7910 is carried out through the

The main coolant piping material Z3CN20.09 M was heat treated at 400 °C for 18,000 h and then the fracture behavior has been studied. To understand the effect of in-plane constraint on fracture behavior, J-R curves were determined by the pre-cracked specimens with a wide range of crack depth ratios. And the stretch zone width (SZW) values were measured by experimental method and finite element method

In this study, the microstructure and microhardness of low alloy steel A508 welded with 309/308L stainless steel are investigated. The microstructure evaluations show that the heat affected zone of the A508 base metal changes, from tempered bainite to an uneven mixture of bainite and martensite, depending on the intensity of the heat flow from the welding process. Different recrystallization processes

Based on the study of pressure pulsation fluid characterization, the present study investigates the impact generated by high-pressure pulsating fluid on pipeline fittings’ sealing characteristics. In the meanwhile, it analyzes the influence of the internal fluid pulsation amplitude and fluid pulsation at different pressures on pipeline fittings sealing characteristics. A comparative study on the research

Pipe elbows (bends) are considered critical pressurized components in the piping systems and pipelines due to their stress intensification and the effect of bend curvature. They are prone and hence more exposed to different corrosion failure modes than straight pipes. Late detection of such elbow damages can lead to different dangerous and emergency situations which cause environmental disasters, pollution

For transmission of high-pressure corrosive fluids, it is required to pipe that with both anti-corrosive and high strength material. One of the economical and reliable approaches is the use of Tight Fit Pipe (TFP). Tight Fit Pipe is a double-walled pipe, where a corrosion-resistant alloy liner is fitted inside a carbon steel outer pipe through a thermal-hydraulic manufacturing process. TFP is manufactured

The paper presents the detailed microstructure study and mechanical behavior of P91 welded joint produced by gas tungsten arc welding process (GTAW) using the dissimilar nickel grade superalloy Inconel 718 filler (ERNiFeCr2). The microstructural changes in the weld fusion zone (WFZ) and heat-affected zone (HAZ) were also studied for varying heat treatment conditions. The effect of the Inconel 718 filler

Hydrogen economy considers hydrogen as a substantial fraction of a nation's energy and services. This could happen in the future if hydrogen can be produced from domestic energy sources economically and in an environmental-friendly manner. Hydrogen can also be used as fuel in stationary fuel cell systems for buildings, emergency power or distributed generation. Hydrogen transport is generally made

The hydrogen-assisted cracking (HAC) behavior of 2205 duplex stainless steel is investigated via experimental testing and computational modelling, with specific focus on developing a predictive methodology for the coupled effects of hydrogen diffusion and stress. The effects of duration and stress level on hydrogen-assisted fracture in the dual-phase microstructure are characterized via tensile testing

The present paper provides engineering estimates for plastic J-integral and crack opening displacement (COD) of a non-idealized axial through-wall crack (TWC) in pipes based on detailed 3-dimensional finite element (FE) analyses. The behaviors of plastic J-integral and COD of a non-idealized axial TWC in typical pressurized pipes in nuclear power plants were systematically investigated. The FE model

This paper reports research on the thermal buckling and post-buckling of vertical steel tanks under heat induced by a nearby burning tank. A two-layer solid flame model is adopted and a heat transfer analysis is carried out to compute temperatures in the target tank. The temperatures are used as input in the structural analysis based on a geometrically nonlinear analysis and temperature-dependent properties

In the field of pressure vessel design, much research has been done to predict the structural behaviour of round nozzles connected to spherical and cylindrical structures. This has been motivated by the fact that the majority of pressure vessels in industry have round bodies, as these are better suited to withstanding pressure. A large demand however also exists for flat-sided pressure vessels with

Temporary production storage is largely needed in the oil and gas industry, thus, storage tanks that have the capability to sustain the normal operation condition are needed. The American Petroleum Institute (API) specification 12F provides twelve shop-welded tank designs that can accommodate storage and operational pressure needs of the facility requires temporary production storage. The nominal capacity

The paper presents a model of describing three-dimension parametric vibrations of a simply supported pipe conveying pulsating fluid. The three-dimensional motion equation of the system is a set of two nonlinear partial differential equations developed on the basis of Euler-Bernoulli beam theory, geometric nonlinearity and Kelvin-Voigt damping model. The three-dimensional motion equation is discretized

Risk-based inspection (RBI) offers the most cost-effective operation and maintenance strategy for minimizing overall risks and making financial and safety improvements within a power plant. Risk assessment may also benefit decision-making with regards to plant design and equipment manufacturing processes. The purpose of this study is to propose a quantitative RBI methodology that can be applied to

Damage performance and annual frequency of exceedance are the focus of probabilistic safety assessment for nuclear power plant structures. However, conventional displacement-based global damage index and classical method for calculating the annual frequency of exceedance of the nuclear containment structure suffers from some limitations and deficiencies. Based on seismic energy balance concept, an

The aim of this research was to compare the effect of 80 000 h exploitation time in high temperature on mechanical properties and microstructure of X10CrMoVNb9-1 (P91) power engineering steel for pipes. The specimens obtained from two pipes: new, as-received and after exploitation were subjected to fatigue loadings to compare their mechanical responses. Additionally, the uniaxial tensile tests on both

Pipeline is an important and valuable infrastructure for transporting oil and gas which expanding a long distance and working in a corrosive environment. Consequently, corrosion becomes one of the most critical threads for metal material pipeline. The high internal pressure in an oil and gas pipeline is the additional factor leading to the high risk of bursting. Various models predicting the burst

The burn-through of in-service welding is affected by pipeline structure, welding procedure and the pressure of the internal medium, etc. It is a high-temperature failure process under the coupling action of structure field, temperature field, and stress field. Predicting the critical burn-through pressure of in-service welding is a challenging problem. In this paper, the existing burn-through criteria

Although polyethylene (PE) pipelines have been extensively used in engineering fields, very little effort has been devoted to their abilities against blast loads. In the present study, numerical method is used to predict the dynamic performance of buried small-diameter PE pipelines under subsurface localized explosion. The effectiveness of a numerical model was firstly evaluated to entirely replicate

Flow behavior of a metal during hot deformation is influenced by physical phenomena such as work hardening, dynamic recovery and dynamic recrystallization. Effects of these phenomena on flow stress can be expressed through various semi-empirical models. To find unknown parameters of these semi-empirical models, one can use a process such as system identification in the way that the difference between

High-density polyethylene (HDPE) pipes are widely used in urban natural gas pipelines. Thermal butt fusion (BF) welds are the weakest components of pipelines. Welding joint aging causes degradation of the PE thermal BF joint material properties. Using the nonlinear ultrasonic technique as a nondestructive testing (NDT) method was proposed for evaluating aging damage. Nonlinear ultrasonic measurements

In recent years, the occurrence of numerous intentional and accidental explosions in buried pipelines, especially in oil and gas pipelines, has been turned to a proper subject of research. The present research, for the first time, studies the utilization of GFRP for reducing the deformation of buried and internally pressurized steel pipes against explosions through the non-linear three-dimensional

From a fatigue point of view, the second most important WWER (Water-Water Energetic Reactor) pressure vessel component (after closure studs) are the primary nozzles. These parts are included in the in-service inspection performed every 4 years when non-destructive testing techniques like ultrasonic, eddy-current and dye-penetration methods are applied. After the determination of the severity of fatigue

Thin-walled circular tubes have been widely used in space lattice structures and other industrial areas. Steel tubes are prone to corrosion during their service life, significantly reducing their loading capacity and threatening the structural safety. This work aimed to investigate the residual moment capacity of corroded circular steel tubes (CSTs) subjected to compression force. The second-order

Sv 07Kh25N13 is austenitic stainless steel used in nuclear industry. Due to its excellent corrosion resistance in the environment of WWER type nuclear reactor primary circuit, it is applied as anticorrosive cladding of the reactor pressure vessel. In this paper, results of detailed experimental research of failure behaviour of the cladding are presented. Static fracture toughness values J0.2 exhibited

Polyethylene (PE) pipes are often used for transporting gas and water, which play an important role in lifeline engineering. Such pipes, especially with notches, scratches or cracks, can be subject to actions inflicted by nature or man-made factors. To ensure that the pipes can continue to operate, even after being subjected to foundation settlement, it is necessary to study the fracture behavior of

In recent years, a large number of surface cracks caused by stress corrosion cracking (SCC) have been reported in dissimilar metal welds of light water reactors. For some of these cracks, the depth (a) is greater than the half-length (l/2). Upon the detection of cracks, the integrity of cracked components should be assessed in accordance with the fitness-for-service (FFS) codes such as the ASME Boiler

The idea that the stress-strain curve satisfies different ordinary differential equations in its different segment is proposed and implemented. In contrast to the classical Ramberg-Osgood law, the model establishes the dependence of stress on deformation. For each segment of the deformation curve, a differential equation is formulated that corresponds to the physics of deformation in this section.

The development of leakage and strength of a metallic bolted flange joint are investigated in this work. Finite element analyses in 2D and 3D have been developed using ANSYS to study a steel flange and bolt with an aluminium gasket. The pressure-penetration criterion (PPNC) in ANSYS has been used to model fluid leakage propagation between the flange and the gasket. Validation was performed with a benchmark

Since creep strength reduction of mod.9Cr-1Mo steel welds in long-term creep was confirmed experimentally, residual life prediction for Type IV creep failure has been an important theme in Ultra Super Critical (USC) plants after long-term service. The mechanism of Type IV creep failure within the fine-grained heat affected zone (FGHAZ) is twofold; an increase in number density of creep voids of a size

The work deals with the cyclic behavior of 304 L and 316 L austenitic stainless steels subjected to stress or strain control. Particular attention is being given to the analysis of situations where the cyclic loading under a given amplitude was preceded by inelastic pre-deformation. The obtained results show that the cyclic stress-strain curve is not unique, as it depends on the maximum strain range

Local corrosion poses a big threat to the integrity and safety of steel pipelines. Investigation of the failure pressure of buried pipelines containing multiple corrosion defects subjected to earthquakes is vital for pipeline safety. In-line inspection (ILI) data is introduced to estimate and update the 3D random corrosion growth model, embedded in the development of a nonlinear finite element analysis

In order to provide direction guidance for the heat loss of steam pipeline and ensure the safe and energy-saving operation of steam pipe network, it is very important to realize rapidly and accurate diagnosis of high-temperature area of the pipeline. This paper is aimed at the problem of the complicated working environment of the steam pipe, which causes the infrared image obtained have strong background

The structure of unbonded flexible riser is very complex. It is very necessary to propose an efficient mechanical model. Applying the principle of minimum total potential energy, the theoretical model under axially symmetrical load is proposed in this paper. The geometric relationship between adjacent layers is introduced into the model by two methods (penalty function method and Lagrange multiplier

Gas tungsten arc welding (GTAW) joints of nuclear power main pipelines were subjected on accelerated thermal ageing tests until 30000 h to investigate long-term ageing effect on fracture property. The results indicate that fracture toughness values JIC and JSZW of both base metals and welded metals decreases clearly and fracture mode transits subsequently from typical ductile to brittle fracture with

In spite of the increasing use of FRP composites in bolted flange joints and the good knowledge of these structures and their material behavior the procedure used for their design is that of metallic flanges. There is a major concern to appropriately address the anisotropic behavior of composite materials in FRP flange design. Therefore, it is necessary to revisit this procedure by implementing a more

The mechanical properties of the G115/Sanicro25 dissimilar steel welded joints were characterized by room temperature tensile and microhardness. The microstructures of fine-grain heat affected zone (FGHAZ) and base metal (BM) in the G115 steel side were characterized by optical microscopy, SEM, TEM, and XRD. The results show that as the strain increases, weld beam first yields and hardens, the stress

The present study uses advanced numerical tools to examine the mechanical behavior of steel pipe bends (elbows), subjected to strong cyclic loading, associated with repeated plastic deformations of alternate sign. The elbows are modeled with finite elements, accounting for the measured elbow geometry and the actual properties of steel elbow material. The main feature of the present work is the simulation

The girth-weld joint of a pipeline can be divided into three parts: base metal, heat affected zone, and weld metal. This study investigates the local mechanical properties of X80 and Q235 girth-welded joints. Microscopic observations and micro-hardness measurements were carried out, and it was observed that the metallographic structure and hardness gradients of each region were evidently different

Narrow gap welds have been increasingly used in pressure vessels and pipe components due to their unique advantages. A recent comprehensive investigation into residual stress distributions in narrow gap is presented in this paper, covering component wall thickness from 1” (25.4 mm) to 10” (254 mm), component radius to wall thickness ratio from 2 to 100, and linear welding heat input from low (300 J/mm)

The use of high strength steels is penalised by the current regulations of pressure vessel codes. Simulation studies could enhance the data basis for exploring more suitable design functions or safety factors. Damage mechanics are able to provide an adequate description of ductile failure on small-scale experiments. The article presents a modelling concept for scale-bridging damage mechanics models

A simplified mechanical analysis is carried out for a specific closure system of a pressure vessel, consisting of a segmented locking ring, partially inserted into an annular groove; the ring portion radially protruding from the slot supports the vessel bottom; sealing is achieved by placing a copper gasket between the ring and the bottom. Several formulae useful for design purposes are derived. In

Acoustic emission (AE) based method is a very promising passive measurement technique for detection of faults and incipient damage in in-service structures. Considering the advantage of detecting even the weak acoustic signals emitting from in-service critical infra-systems for characterizing the fault/damages/leakage in the structures, AE technique is considered to be one of the efficient NDT techniques

Experimental investigation of the integrity of casing pipes, used in the oil drilling rigs, withdrawn after about 70,000 h of service, has been conducted, together with numerical simulation. Pipes were manufactured by the high frequency contact welding (HF) of API J55 steel. The influence of corrosion damage is investigated by means of pressure test of a pipe with different damage levels made by machining

Return mapping algorithms are popular procedures for evaluating elasto-plastic material behaviour. This paper presents a dedicated return mapping algorithm for thin walled pipes and vessels with Von Mises plasticity and isotropic hardening, for which it can be assumed that the hoop stress is constant. This applies for example to pipe line sections during offshore laying operations. In the algorithm

In the present endeavor, a Gleeble thermo-mechanical simulator has been used to simulate subzones of the heat-affected zone (HAZ) of boron-free P91 and boron-modified P91B steels to investigate the influence of boron on microstructure and mechanical properties. The prior austenite grain (PAG) size remained similar to that of parent metal in the fine-grained heat-affected zone (FGHAZ) and inter-critical

Fatigue life of plate and shell heat exchangers has been determined by experiments. Tests occurred with the aid of a pneumatic-hydraulic setup in which plate pack samples were internally pressurized by water. The samples were exposed to cyclic pressure loads varying from ambient to service pressure in the range 1.0–1.4 MPa, typical operating pressure range of crude oil production sites. Stress determination

A novel creep life assessment methodology is proposed in this paper that uses periodic and routine inspection data in conjunction with online operational data and other computed parameters, such as the ‘rate of change’, and where applicable correlations with data from small specimen tests on ex-service materials. The proposed methodology is critically implemented by the introduction of a life assessment

This study describes a simplified procedure to estimate the Weibull stress parameter, m, using cleavage fracture toughness values measured from testing high constraint fracture specimens. The estimation procedure builds upon the conventional toughness scaling methodology (TSM) based on the Weibull stress coupled with the weakest link model to correct measured toughness distributions for high constraint