In order to reduce the vibration of planar pipe systems assembled by multiple segments, bends and supports, an impedance synthesis method, which is based on the Timoshenko beam theory, is used to analyze vibration and wave propagation characteristics. Due to junction coupling at unanchored bends, there exists interesting hydraulic and structural wave transmission and reflection. By comparing the natural

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

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

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 model (TSM) based on the Weibull stress coupled with the weakest link model to correct measured toughness distributions for high constraint fracture

Water conductor system in hydro power plants experience water hammer or hydraulic transient events regularly and may cause damage of civil and mechanical components. Recently developed viscoelastic pipes such as Glass Reinforced Fibre Plastic (GRP) have been started in use to replace metallic pipes in hydro power and water supply plants. However, studies on combinations of metallic-viscoelastic pipeline

Recently, efforts have been made to apply the leak-before-break (LBB) design concept to the main steam line (MSL) piping in secondary systems of Korea standard nuclear power plants (KSNPs). In this study, the microstructures, mechanical properties, and consequential LBB margins of five candidate materials (SA335 Gr.P11/P22, SA508 Gr.3 Cl.2, SA508 Gr.3 Cl.1, and SA508 Gr.1A steels) were evaluated, and

The main interface docking seal (MID seal) is one of the key components in the developing low impact docking systems for future space vehicles, and its sealing property is crucial to the spacecrafts docking in space. A seal-on-seal structure is one of the mainstream designs of the MID seal, and is generally made of rubber materials that can adapt to the complex space environment. For the MID seal of

Corrosion of buried pipes is complex and difficult to model without considering corrosiveness of the soil. To estimate the external corrosion of buried and aged oil and gas pipelines, a Bayesian spectral analysis regression is proposed. The depth of the corrosion pit progression on a bare metallic pipe is linked to the soil factors that are assumed to influence its rate. The time the pipe is exposed

In recent years, a new variant of the GTAW process, commercially named TopTIG, has attracted interest in the industrial sector due to the possibility of increasing productivity and facilitating automated operation. In this technology, the main component is a special welding torch that allows the insertion of a wire tangentially, in a region closer to the tungsten electrode when compared to traditional

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

This study focused on the buckling of corroded spherical shells with wall-thickness reduction in local regions under a uniform external pressure. For spherical shells whose wall thickness was reduced owing to local corrosion on the outer surface, the effects of the shape, area, depth, and location of the reduction on the buckling properties were evaluated to identify the most dangerous case. Accordingly

In this study, a NC35 tool joint with double shoulder is considered as the research object and studied by finite element method (FEM) using nonlinear thermo-mechanical coupled model and implicit & explicit conversion method. Von mises stress field, temperature field, contact stress, and ultimate working torque of tool joint under different axial loads at high temperatures are calculated and compared

This research work describes the development of autogenous orbital gas tungsten arc welding for oxygen-free copper pipe. Neutral beam system for fusion devices consists of the different water-cooled component, which is designed and fabricated from pure copper to have the excellent thermal and electrical conductivity from the functionality point of view. Due to their application in a high vacuum along

There is a renewed interest to utilize the advantages of hot wire gas tungsten arc welding (HWGTAW) process in industrial area. This manuscript reports HWGTAW of pure nickel tubes of 4 mm thickness. Design of experiment (DoE) approach was adopted to bring down the number of the joints. Welding plan was executed according to 3 factors, 5 levels central composite design (CCD). Electrode current, wire

Many manufacturing processes can induce residual stresses in produced components for high-temperature application. Residual stresses, combined with the primary mechanical stresses, play an important role in structural integrity assessments of high-temperature components. In this paper the elastic and elastic-plastic creep behaviour of mechanically loaded shallow cracked SENB specimen in the presence

In this study, we examine the classical problem of unsteady fluid flow in a long pipeline, induced by reduction/growth in the fluid head. This problem was solved by using the symmetry properties of the water hammer equations, which enable us to transform the time and the space coordinates into one independent coordinate. In other words, the two partial differential equations which are characterized

Supercharged boilers are widely used as the core equipment of ship steam-power plants. A 1:1 model is built considering the connection details of tube-tubesheet joints. Furthermore, numerical simulation of stress field and fatigue life based on the DBA method is conducted. The results show that the maximum equivalent stress amplitude of 253.81 MPa appears on the tube-tubesheet joint of the tube plant

Boiler tubes used in power plants and manufacturing industries are prone to failure due to the harsh environment they operate in, usually involving high temperature, pressure, and some erosive-corrosive mechanisms. Among the wide range of failures associated with the tubes, localized external erosion continues to be a leading cause of tube leakages and unscheduled boiler outages in power plants and

An experimental study has been performed on a representative prototype-sized pipe bend made of SS 316 LN material to generate the relevant material parameters required for fatigue crack growth (FCG) simulation. Traditionally, FCG numerical simulation material parameters are generated based on specimen level test. In the literature there are many prototype pipe bend test results can be found. However

This paper studies the creep and damage behaviors of PMMA deep-sea manned submersible viewport windows under constant seawater pressure. First, the viscoelastic creep experiments of PMMA material specimens under four groups of tensile stresses (near 30 MPa) are performed. Second, we adopt the three-element spring/dashpot viscoelastic model to study the creep behaviors of the PMMA viewport windows without

Multiple repair welding of X20Cr13 martensitic stainless steel was performed using gas metal arc welding. The groove for repair welding was designed such that the heat affected zone (HAZ) of each repair welding sequence remained the HAZ of the previous repair (i.e. cyclic weld removal and repair welding was done). After post weld heat treatment, microstructure and mechanical properties of the HAZ were

Casing wear is a serious problem affecting casing integrity and casing strength, especially in ultra-deep wells, directional wells and horizontal wells. After casing is worn, degraded casing strength will lead to such hazardous problems as casing deformation, sustained casing pressure and even casing failure. Therefore, it is crucial and meaningful to predict residual casing strength and design casing

In this work we performed a structural integrity assessment of a riser pipe made of a material with a novel application, the API 5CT P110 steel, with superficial semi-elliptical cracks in the longitudinal position. The behavior of different crack size on a pipe under specific boundary conditions and pressure loads was studied. With the Finite Element Method, the Stress Intensity Factors along the crack

The study presented in this paper addresses the response of Metallic-Polymeric pipe configurations under water hammer events. The southern Tunisian water distribution network (WDN) is considered for the numerical studies. Hydraulic Transient in the branched WDN is initiated following an intermittent pump power stoppage. The numerical investigations were conducted using a viscoelastic model, which simulates

In this study, the effect of post-weld heat-treatment (PWHT) on the interface microstructure and its mechanical properties in the three-layered explosive welded (EXWed) SS321/AA1050/AA5083 joints fabricated with different stand-off distances were investigated. The welded specimens were heat-treated at 250 and 350 °C for 1000–10000 s. The microscopy studies exhibited that the AA5083/AA1050 interface

Accurate assessment of the burst pressure of corroded pipes is pivotal for pipelines integrity management and adequate decision-making and thus, meticulous selection of an appropriate prediction model is vital. Several burst strength models have been developed based on analytical, numerical and empirical analyses, often validated by full or small-scale experiments. This paper provides a comprehensive

This work analyses the deformation of high-loaded structures for problems of strength and safety. Determining the load safety factor typically requires a series of calculations with successively increasing loads, up to fracture. In cyclic loading, each calculation is a numerical modeling of the structure behavior during several (or several tens) cycles up to stabilization to estimate the damage accumulated

Guided waves based structural health monitoring systems have been proposed to ensure reliability and structural integrity of pipelines. These systems are designed with permanently attached transducers that are able to detect automatically early state damage that could occur during the lifetime of a pipeline. Actually, the transducers are responsible for generating ultrasonic guided waves signals which

The stratum settlement caused by underground mining is one of the main geological disasters that threaten and damage buried pipelines. Therefore, the mechanical behavior of buried pipe under stratum settlement is investigated in this paper. Effects of pipeline parameters, mining area parameters and inclination directions of mining area on mechanical behavior of the buried pipeline are discussed. The

The influence of creep damage on high cycle fatigue (HCF) in Alloy 617 M at 700 °C was investigated by incorporating periodic holds at the (maximum stress (σmax) during HCF cycling. The effect of creep damage in “HCF-creep interaction test” is reflected in the form of specimen failure at stress levels corresponding to the occurrence of run-out observed under pure HCF cycling. However, in-situ precipitation

Small punch (SP) creep test specimen with an elliptical surface crack was suggested for use with creep crack growth testing. Estimation equations for fracture parameters are needed. K-equation was derived previously for the crack in the SP specimen. In this study, estimation equations for J and C* were derived. 3D elastic-plastic finite element analyses were carried out to determine J value along the

The main purpose of the present research is the investigation of the stress and displacement distributions of the internally pressurized thick-walled hyperelastic cylindrical vessels or pressure pipes. The governing equations are derived by incorporation of the incompressible neo-Hookean and Mooney-Rivlin hyperelastic constitutive models into the direct hyperelasticity theory in the von Karman framework

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

It has recently been contemplated to use spherical caps as outer space energy concentrators. Adding toroidal segment to a cap gives a component known as torisphere which offers the necessary, space-relevant reinforcement of cap's rim. The current study addresses a range of issues related to the above shell. Buckling, affected by shape imperfections, being one of them, is studied numerically. Possible

In this study, fracture mechanics analysis was performed to calculate crack growth under very low cycle fatigue loading conditions. The calculation results are compared with 11 experimental datasets concerning through-wall cracked pipes made from three different materials under fully reversed large-amplitude cyclic loading. In the analysis, it was assumed that the crack growth rate under large-amplitude

Leak location using correlation-based acoustic method is a common practice in gas-filled pipelines, which will be extremely effective when the leakage-induced acoustic wave has a constant propagation speed. This premise is often not satisfied as result of multi-modal and dispersive nature which will cause acoustic speed to vary with frequency and modal type. In this work, the multi-modal identification

The structural reliability of a pipe-in-pipe system operating in deep-waters under high internal pressure and high temperature is assessed. First, the major failure modes are identified and the respective limit state functions are formulated. In particular, the collapse of the outer and inner pipes, the local buckling of the inner and outer pipes under combined loading, the burst of the inner pipe

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

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

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

For the heat resistance steel weld metal, special post-weld heat treatments need to be performed to maintain the creep resistance, improve the impact toughness, and relieve the welding residual stress. In this paper, firstly, the three factors affecting variability and lower values of toughness were revealed. Secondly, two different post-weld heat treatment (PWHT) methods have been used to improve

Primary creep regeneration (PCR) is an important phenomenon observed for some alloys loaded at high-temperature and under stress varying loading conditions. For example, for a specimen deforming in the secondary creep regime, a stress reversal might result in an enhanced creep rate upon reloading due to full/partial re-activation of the primary creep stage (i.e. primary creep regeneration). The extent

Ultrasonic guided wave based non-destructive testing is an effective method to inspect defects in long-distance pipe structures. This paper proposes a novel defect detection approach for the pipes using stochastic resonance of Duffing oscillator and ultrasonic guided waves. Stochastic resonance can improve the signal-to-noise ratio (SNR) in the output signal, because it can enhance the periodic component

ASTM E1820 and ISO 12,135 are the two main testing standards of fracture toughness. Choosing which standard to obtain more suitable fracture toughness is confusing in engineering fields, since there are some obvious differences between these two standards, such as blunting line, effective data and J-R curve equation. In this paper, fracture toughness tests of SS304 and Chinese SA508-III steel were

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

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

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

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 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

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