Steel Pressure Research Articles

Investigation on Mechanical Behaviors of Cold Stretched and Cryogenic Stretched Austenitic Stainless Steel Pressure Vessels

Austenitic stainless steel is widely used in pressure vessels for storage of liquid gas, such as LN2, LO2, LH2. To make wall thin and weight light, cold stretching technology is applied in cryogenic pressure vessel manufacture. Cold stretching is performed by pressurizing a vessel to a specific pressure and maintaining the pressure for a moment to produce a certain amount of plastic deformation, so that the yield strength of the vessel material could be strengthened after releasing the pressure. Cryogenic stretching is similar in principle to cold stretching, but the medium is liquid nitrogen instead of water in cold stretching. Cold stretching has been recorded in standards such as Cold-Stretching Directions 1991, AS 1210-Supp2-1999, EN 13458-2:2002, EN 13530-2:2002, ASME BPVC VIII-I Code Case 2596, ISO 20421-1:2006, ISO 21009-1:2008. Nevertheless, cryogenic stretching is not applied in pressure vessels manufacture due to lack for detailed investigation. To investigate mechanical behaviors of cold stretched and cryogenic stretched austenitic stainless steel pressure vessels, a series of tests for S30403 were performed at 20°C (temperature in which cold stretching proceeds) and -196°C (temperature in which cryogenic stretching proceeds), the difference of martensite transformation, strength and plasticity in which were compared. Finite element analysis method based on MISO model was used to simulate cold stretching process of pressure vessel, including the process of loading to strengthening pressure, unloading to no-load state and reloading to design pressure. Considering material properties difference, different types of strengthening pressure methods for cryogenic stretching were performed to confirm a rational strengthening pressure value. Mises equivalent stress, tresca equivalent stress, circumferential stress, axial stress and deformation were taken into consideration. The investigation has shown that compared with cold stretching, cryogenic stretching could improve material properties more significantly. In other words, pressure vessels could have thinner wall and lighter weight after cryogenic stretching.

Numerical Limit Load Analysis of 3D Pressure Vessel with Volume Defect Considering Creep Damage Behavior

The limit load of 3D 2.25Cr-1Mo steel pressure vessel structures with volume defect at 873 K is numerically investigated in the present paper, and limit load under high temperature is defined as the load-carrying capacity after the structure serviced for a certain time. The Norton creep behavior with Kachanov-Robotnov damage law is implemented in ABAQUS with CREEP subroutine and USDFLD subroutine. Effect of dwell time to the material degradation of 2.25Cr-1Mo steel has been considered in this paper. 190 examples for the different sizes of volume defects of pressure vessels have been calculated. Numerical results showed the feasibility of the present numerical approach. It is found that the failure mode of the pressure vessel depends on the size of the volume defect and the service life of the pressure vessel structure at high temperature depends on the defect ratio seriously.

탄템 GMA 용접공정의 표면비드높이 예측을 위한 STACO모델 개발에 관한 연구

One of the main challenges of the automatic arc welding process which has been widely used in various constructions such as steel structures, bridges, autos, motorcycles, construction machinery, ships, offshore structures, pressure vessels, and pipelines is to create specific welding knowledge and techniques with high quality and productivity of the production-based industry. Commercially available automated arc welding systems use simple control techniques that focus on linear system models with a small subset of the larger set of welding parameters, thereby limiting the number of applications that can be automated. However, the correlations of welding parameters and bead geometry as welding quality have mostly been linked by a trial and error method to adjust the welding parameters. In addition, the systematic correlation between these parameters have not been identified yet. To solve such problems, a new or modified models to determine the welding parameters for tandem GMA (Gas Metal Arc) welding process is required. In this study, A new predictive model called STACO model, has been proposed. Based on the experimental results, STACO model was developed with the help of a standard statistical package program, MINITAB software and MATLAB software. Cross-comparative analysis has been applied to verify the reliability of the developed model.

Model of Gas Flow Through Porous Refractory Applied to an Upper Tundish Nozzle

Argon gas commonly is injected into the liquid metal stream through the porous refractory walls in many metallurgical processes. In this work, a new model has been developed to investigate gas diffusion through heated porous refractory, including the effects of refractory geometry, the thermal expansion of the gas, temperature-dependent gas viscosity, and possible leakage into unsealed joints. A novel one-way-flow pressure boundary condition has been formulated and implemented to prevent unrealistic flow into the refractory. The complete model is validated with both analytical solutions of 1D test problems and observations of a water bubbling experiment. Then, to demonstrate practical application of this general model, argon gas flow is simulated through a double-slitted upper tundish nozzle during continuous steel casting with a slide-gate system. Realistic liquid steel pressure distributions with the bubbling threshold condition are applied on the inner surface. Parametric studies are conducted to investigate the effects of joint gas leakage, refractory conductivity, permeability, and injection pressure on the resulting gas distributions, gas mass flow rates, and leakage fraction. This new model of porous flow can serve as the first step of a comprehensive multiphase model system.

Ultrasonic stress evaluation through thickness of a stainless steel pressure vessel

This paper investigates ultrasonic method in stress measurement through thickness of a pressure vessel. Longitudinal critically refracted (LCR) waves are employed to measure the welding residual stresses in a vessel constructed from austenitic stainless steel 304L. The acoustoelastic constant is measured through a hydro test to keep the pressure vessel intact. Hoop and axial residual stresses are evaluated by using different frequency range of ultrasonic transducers. The welding processes of vessel shell and caps are simulated by a 3D finite element (FE) model which is validated by hole-drilling method. The residual stresses calculated by FE simulation are then compared with those obtained from the ultrasonic measurement while a good agreement is observed. It is demonstrated that the residual stresses through thickness of the stainless steel pressure vessel can be evaluated by combining FE and LCR method (known as FELCR method).

Research on the Fatigue Assessment Method for Steel Pressure Vessels Containing Surface Defects

Defects have great influence on the safe running of pressure vessels, and the safty assessment for in-service pressure vessels containing defects can realize safe and economical operation of presure vessles.Aiming at the fatigue assement of defect in steel pressure vessels,the fatigue assement method is studied and a primary program can be uesd to calculate fatigue crack propagation and life prediction is programed based on GB19624.The comparison between test and calculated results indicates that the method provided is suitable for fatigue assessment of defects.Combining the test results and cricical conditonds, the presient approach can provide a basis for the fatigue safety assessment and the reasonable overhaul cycle of in-service pressure vessels.

Staged Construction Modeling of Steel Pipes Buried in Controlled Low-Strength Material Using 3D Nonlinear Finite-Element Analysis

AbstractSeveral complexities are inherent in numerical simulation of staged construction modeling of large-diameter steel pressure pipes. A comprehensive robust three-dimensional (3D) nonlinear finite-element analysis model was developed and verified using three experimental field tests conducted at the Rolling Hills Booster Pump Station, Fort Worth, Texas, to simulate the behavior of buried steel pipes during staged construction installation. Controlled low-strength material (CLSM) was used as the embedment material, and the depth of the CLSM embedment and the trench width varied. The developed numerical model includes three possible nonlinearities, including geometric, material, and contact nonlinear algorithms. A large deformation algorithm was considered in the finite-element model and its associated analysis using a total Lagrangian formulation. The contact between each soil layer, soil-to-trench wall, and soil to pipe was carefully implemented. The lateral effect of compaction was identified in prev...

Corrosion Performance of High Strength 15Cr Martensitic Stainless Steel in Severe Environments

High pressure and high temperature corrosion performance of high strength 15Cr martensitic stainless steel was studied in different severe environments—live acid (10% HCl + 1. 5% HF + 3% HAc + 5.1% corrosion inhibitor), spent acid and formation water containing CO2. The results show that the corrosion of high strength 15Cr martensitic stainless steel in live acid is most serious, and the uniform corrosion rate is far greater than those in spent acid and formation water containing CO2 corrosion environments, but all of them can be acceptable for oilfield. Acidizing corrosion inhibitor displays a good matching ability with the high strength 15Cr martensitic stainless steel in terms of decreasing the uniform corrosion rate, which changes mainly the anodic process of high strength 15Cr martensitic stainless steel. The corrosion potential moves to the positive direction, thus the corrosion current density decreases significantly. There arc some different degrees of pitting of high strength 15Cr martensitic stainless steel after corrosion tests in live acid, spent acid and formation water containing CO2, and the pitting density aggravates significantly and the maximum pit depth decreases in the corrosion sequence.

Finite Element Simulation of Deformation of Steel Belt of Overwind Protection for Vertical Shaft Lifting

Steel belt of buffer structure with plastic deformation, employed in vertical shaft lifting as a overwind protection device, is simple and of convenient maintenance. Steel strip bends large deformation and wear when passing through buffer structure, which will damage the buffer strip, and reduce its initial strength as well. This paper focuses on the influence of steel strip thickness and pressure roller diameter on the deformation of steel belt by applying the finite element simulation, to provide theoretical basis for reliability design of the steel strip.

Design and test of a flexible electrochemical setup for measurements in aqueous electrolyte solutions at elevated temperature and pressure.

We present a detailed description of the construction and testing of an electrochemical cell allowing measurements at elevated temperature and pressure. The cell consists of a stainless steel pressure vessel containing the electrochemical glass cell exhibiting a three electrode configuration. The design of the working electrode is inspired by conventional rotating disk electrode setups. As demonstrated, the setup can be used to investigate temperature dependent electrochemical processes on polycrystalline platinum and also high surface area type electrocatalysts.

Design and Implementation of Diamond Press'S Pressure Hammer Protection Based on Voiceprint Recognition

In the manufacturing process of artificial diamond micro powder, if tungsten steel pressure hammer of diamond press makes a tungsten steel hammer pressure crack due to fatigue of workpiece, it is always leading to significant economic losses. The pressure hammer detection and protection device of the diamond press introduced in this paper takes advantage of the voiceprint recognition technology. Firstly, it extracts the characteristic parameters of pressure hammer breaking voice and establishes a sound pressure hammer breaking template library. And then, the paper compares the work field sound characteristic parameters of diamond press and pressure hammer breaking template library. If they are consistent with each other, the work power of diamond press will be cut down. Thus, it implements protection for the rest good pressure hammers.

Coupled Nonlinear Finite-Element Analysis of Soil–Steel Pipe Structure Interaction

Numerical simulation of staged-construction modeling of large-diameter steel pressure pipes is accompanied by several complexities. Finite-element (FE) analysis was performed to simulate the behavior of buried steel pipes during staged-construction installation. The model deflections during the staged-construction process were verified with four different experimental soil box test results. The FE model and its associated analysis algorithm considered large deformation using total Lagrangian formulation. The material and contact nonlinear algorithms were also included in the analysis for both soil and steel pipe materials. The contact between each soil layer and soil-to-pipe was carefully implemented. Uniform thermal loading was applied to simulate the stresses induced by compaction forces on the pipe and trench walls. Finally, the vertical and lateral load-deformation plots obtained from the FE analysis results were compared with the full-scale experimental test results during the staged construction process and after the application of surcharge load. The results of FE analysis are shown to accurately model and simulate the test results.

Evaluation of an energy-based fatigue approach considering mean stress effects

In this paper, an attempt is made to extend the total strain energy approach for predicting the fatigue life subjected to mean stress under uniaxial state. The effects of means stress on the fatigue failure of a ferritic stainless steel and high pressure tube steel are studied under strain-controlled low cycle fatigue condition. Based on the fatigue results from different strain ratios, modified total strain energy density approach is proposed to account for the mean stress effects. The proposed damage parameter provides convenient means of evaluating fatigue life with mean stress effects considering the fact that the definitions used for measuring strain energies are the same as in the fully-reversed cycling (R = −1). A good agreement is observed between experimental life and predicted life using proposed approach. Two other mean stress models (Smith-Watson-Topper model and Morrow model) are also used to evaluate the low cycle fatigue data. Based on a simple statistical estimator, the proposed approach is compared with these models and is found realistic.

Silicon strain gages bonded on stainless steel using glass frit for strain sensor applications

In this paper, a steel pressure sensor using strain gages bonded on a 17–4 PH stainless steel (SS) diaphragm based on glass frit technology is proposed. The strain gages with uniform resistance are obtained by growing an epi-silicon layer on a single crystal silicon wafer using epitaxial deposition technique. The inorganic glass frits are used as the bonding material between the strain gages and the 17–4 PH SS diaphragm. Our results show that the output performances of sensors at a high temperature of 125 °C are almost equal those at room temperature, which indicates that the glass frit bonding is a good method and may lead to a significant advance in the high temperature applicability of silicon strain gage sensors. Finally, the microstructure of the cured organic adhesive and the fired glass frit are compared. It may be concluded that the defects of the cured organic adhesive deteriorate the hysteresis and repeatability errors of the sensors.

Effects of hydrazine addition and N2 atmosphere on the corrosion of reactor vessel steels in diluted seawater under gamma-rays irradiation

Seawater was injected into the reactor cores in the Fukushima Daiichi Nuclear Power Station. Corrosion of primary containment vessel (PCV) steel and reactor pressure vessel (RPV) steel is considered to progress until the molten fuel debris is removed. To evaluate durability of the PCV and RPV steels, corrosion tests were conducted in diluted seawater at 50 °C under gamma-rays irradiation of dose rates of 4.4 and 0.2 kGy/h. To evaluate the effect of hydrazine (N2H4) as an oxygen scavenger under gamma-rays irradiation, 10 and 100 mg/L N2H4 were added to the diluted seawater. Without addition of N2H4, weight loss in the PCV and RPV steels irradiated with the 0.2 kGy/h dose rate was comparable with those without irradiation and weight loss in the vessel steels irradiated with the 4.4 kGy/h dose rate was higher than those without irradiation. Under irradiation, weight loss in the PCV and RPV steels in diluted seawater containing N2H4 was comparable with that in diluted seawater without N2H4. When gas phase in the flask was replaced with N2, weight loss in the PCV and RPV steels, and O2 and H2O2 concentrations in the diluted seawater decreased.

Failure Analysis of Weld Cracking in a Thick-Walled 2.25Cr-1Mo Steel Pressure Vessel

A crack in thick-walled 2.25Cr-1Mo steel pressure vessel girth weld was found during manufacturing. To investigate the cause of failure, optical microscopy, scanning electron microscopy, energy dispersive spectrometer, transmission electron microscopy, and microhardness tester were used in this study. According to test results, the fracture is classified as reheat cracking with multiple origins. The cracking occurred during surfacing or final post-weld heat treatment process. Coarse-grains in the weld and bulk-carbides precipitated along grain boundaries induced by multiple heating are main causes of the fracture from material aspect, while high level of the hoop stress component and excess localized deformation in stress relief procedure are mechanical aspect causes of the cracking. The fracture surfaces present major intergranular feature with a small fraction of transgranular morphologies. Large numbers of M3C and M23C6 carbides particles were found on the fracture surface, these carbides mainly precipitated on prior austenite-grain boundaries, columnar-grain boundaries, and sub-grain boundaries. Additionally, several proposals were also offered to reduce weld cracking of 2.25Cr-1Mo steel pressure vessels.

Effect of Angle of V-Type Steel Belt on Performance of Spiral Wound Gasket

The performance of spiral wound gasket with different angle of V-type steel belt is researched, which includes effect of angle of V-type steel belt and pressure on compression rate and rebound rate. The results indicate that, when the pressure is same, the compression rate of spiral wound gasket decreases and rebound rate of spiral wound gasket increases with the angle of V-type steel belt increasing. When the angle of V-type steel belt is different, the optimum preloading need adjust in order to spiral wound gasket work well. For spiral wound gasket DN80, the optimum pre-pressure should be controlled within 45~55 MPa when angle of V-type steel belt is 80-degree, and the optimum pre-pressure should increase with angle of V-type steel belt increasing.

Forming of Ellipse Heads of Large-scale Austenitic Stainless Steel Pressure Vessel

Aiming at reducing the drawbacks of traditional forming process of large-scale austenitic stainless steel ellipse heads, the draw-bead was introduced to the forming process in this article. Three types draw-bead were considered in this paper: the round draw-bead, the rectangular draw-bead and edge-bead. Accordingly, a finite element model was built to simulate the forming process of ellipse heads. Meanwhile, the geometrical parameters were optimized in terms of the forming quality, the maximum thinning ratio and the maximum punch force by using the finite element analysis and design of experiment. The single-factor experiment was adopted to find out the possible significant factors and the reasonable range of these factors. The influencing factors, such as the type of draw-bead, the distance between the center of the draw-bead and inside of die, the height of the draw-bead, and the roundness radius of die, were researched. By means of orthogonal test and multi-objective experiment, the optimum parameter combination of draw-bead was found.

Steel pressure shaft linings for hydropower plants – developments in recent VERBUND projects in Austria

Steel pressure shaft linings for hydropower plants – developments in recent VERBUND projects in Austria

Investigation of Residual Stress/Strain and Texture in a Large Dissimilar Metal Weld Using Synchrotron Radiation and Neutrons

Bi-metallic piping welds are frequently used in light water nuclear reactors to connect ferritic steel pressure vessel nozzles to austenitic stainless steel primary cooling piping systems. An important aspect for the integrity of such welds is the presence of residual stresses. Measurement of these residual stresses presents a considerable challenge because of the component size and because of the material heterogeneity in the weld regions. The specimen investigated here was a thin slice cut from a full-scale bi-metallic piping weld mock-up. A similar mock-up had previously been investigated by neutron diffraction within a European research project called ADIMEW. However, at that time, due to the wall thickness of the pipe, stress and spatial resolution of the measurements were severely restricted. One aim of the present investigations by high energy synchrotron radiation and neutrons used on this thin slice was to determine whether such measurements would render a valid representation of the axial strains and stresses in the uncut large-scale structure. The advantage of the small specimen was, apart from the easier manipulation, the fact that measurement times facilitated a high density of measurements across large parts of the test piece in a reasonable time. Furthermore, the recording of complete diffraction patterns within the accessible diffraction angle range by synchrotron X-ray diffraction permitted mapping the texture variations. The strain and stress results obtained are presented and compared for the neutron and synchrotron X-ray diffraction measurements. A strong variation of the texture pole orientations is observed in the weld regions which could be attributed to individual weld torch passes. The effect of specimen rocking on the scatter of the diffraction data in the butt weld region is assessed during the neutron diffraction measurements.