Manufacture Of Vessels Research Articles

Metallurgical Failure Investigation of Cracking of a Vent Nozzle on a Pressure Pulsation Dampener of a Natural Gas Compressor

Abstract A leakage occurred in the area of the weld of a vent nozzle in the pressure pulsation dampener of a natural gas compressor. It was caused by a crack adjacent to the weld on the side of the pipe. A metallurgical failure investigation was ordered to identify the mechanism that caused the damage. The defective pressure pulsation dampener was brought back to the welding manufacturer for repair. The crack that caused the leakage was opened and the pipe was detached from the shell by the vessel manufacturer. A sample of the pipe containing the crack edge on the side of the pipe was brought to the laboratory for examination. A fatigue crack which initiated at the outer surface of the pipe was identified as the metallurgical cause of the failure. No indications of weld defects were found. In the damaged area, the microstructure at the outer surface of the vessel's vent nozzle presents a number of damage-promoting features such as small surface ruptures and scale residues (which will lead to an increased notch effect there) as well as decarburization and coarse grain. The design of the vessel's nozzle at the shell of the pressure pulsation dampener does not seam very suitable for dynamic loading. Also taking into account the poor surface quality of the pipes, the vessel's nozzles are insufficiently dimensioned for the present loading condition which clearly comprises dynamic elements. It was recommended to review the design and to apply adapted repair measures.

An evaluation of multipass narrow gap laser welding as a candidate process for the manufacture of nuclear pressure vessels

Nuclear pressure vessels are currently fabricated using arc welding processes. Recently, considerable effort has been directed at the development of electron beam welding as an alternative fabrication technique owing to the substantial productivity gains it would offer. However, little attention has been directed at laser-based techniques. In this work we evaluate the potential for applying multipass narrow-gap laser welding (NGLW) to the fabrication of nuclear pressure vessels, based on the characterization of a 30 mm thick weld in SA508 steel. Although still a multipass process, the number of passes is reduced in comparison to an arc weld of the same thickness, and the deposition of successive passes provides a degree of tempering to previously deposited weld metal in a way that the electron beam welding process does not. Principal engineering challenges for the implementation of multipass NGLW include the achievement of appropriate joint fit-up, and the shielding of a molten pool at the base of a deep and narrow weld groove.

Selection of candidate materials for reactor pressure vessels: Application of irradiation embrittlement prediction models and a stringency level methodology

The selection of materials for the reactor pressure vessel manufacturing is a complex process that involves great responsibility because small differences in chemical composition can adversely affect the manufacturing process and the in-service behavior of the material. Thus, it is recommendable to perform previous materials pre-selection stages based on the state-of-the-art knowledge, integrating research results with standardized requirements and using simplifier materials selection methodologies like the stringency level method. To address this issue, an evaluation of the influence of chemical composition on the shift of the ductile-to-brittle transition temperature has been performed using the most used and consolidated prediction models that are R.G. 1.99 Rev.2, NUREG/CR-6551, and ASTM E 900-02. A proposal of maximum limits for copper, nickel, and phosphorous to avoid irradiation embrittlement has been presented to carry out the process. The results have been analyzed by using the stringency level methodology to support the decision process. To this end, a materials data collection has been carried out to analyze the requirements described by 20 different specifications of materials from first to fourth generation of light water reactors, covering the main designs of pressurized reactors from Western Europe, North America, Japan, and Russia. It can be concluded that more recently developed materials exhibit more stringent requirements than earlier developed materials.

Corrosion of Nickel Alloys in Molten LiCl-KCl Medium Under Cl2 Bubbling

Pyrochemical reprocessing utilizing molten chloride salt medium has been considered as one of the best options for the reprocessing of spent metallic fuels from future fast breeder reactors. Purification of molten salt is an important step where chlorine gas is purged in molten LiCl-KCl eutectic salt at 873 K. Materials for manufacturing of vessels and components for salt purification system should possess high corrosion resistance under such a highly corrosive environment. The present paper discusses the corrosion behavior of INCONEL Alloys 600 (UNS N06600), 625 (UNS N06625), and 690 (UNS N06690) and their welds in molten LiCl-KCl eutectic salt at 873 K under Cl2 bubbling. Characterization of the exposed surfaces was performed by using scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy, and glancing incidence x-ray diffraction. The results of the present study indicated that N06600 and N06690 offered better corrosion resistance compared to N06625. Surface morphology of the exposed base metal and weld metal surfaces exhibited intergranular and interdendritic corrosion, respectively, on N06600 and N06625. SEM micrographs clearly indicated that N06690 exhibited uniform dissolution, while N06600 and N06625 exhibited localized attack. The paper highlights the results of the present investigation.

Establishing Correlation Between Current and Voltage Signatures of the Arc and Weld Defects in GMAW Process

Welding is one of the major metal-joining process employed in fabrication industries, especially in manufacturing of boilers and pressure vessels. Control of weld quality is very important for such industries considering the severe operating conditions. Industries are looking for some kind of real-time process monitoring/control that will ensure the weld quality online and prevent the occurrence of defects. In this paper an attempt is made to establish a correlation between the current and voltage signatures with the good weld and weld with porosity and burn through defect during the welding of carbon steel using gas metal arc welding (GMAW) process. Experimental setup has been established and experiments were conducted using a welding robot integrated with GMAW power source. The experimental setup includes online current and voltage sensors, data loggers, and signal processing hardware and software. Welding conditions are carefully designed to produce good weld and weld with defects such as burn through and porosity. Current and voltage signatures are captured using data acquisition system (DAS). Software has been developed to analyze the data captured by the DAS. Statistical methods are employed to study the transient data. The probability density distributions of the current and voltage signature demonstrates a good correspondence between the current and voltage signatures with the welding defect.

Vibration Characteristics of Axially Moving Titanium- Polymer Nanocomposite Faced Sandwich Plate Under Initial Tension

In the present research, vibration and instability of axially moving sandwich plate made of soft core and composite face sheets under initial tension is investigated. Single-walled carbon nano-tubes (SWCNTs) are selected as a reinforcement of composite face sheets inside Poly methyl methacrylate (PMMA) matrix. Higher order shear deformation theory (HSDT) is utilized due to its accuracy of polynomial functions than other plate theories. Based on extended rule of mixture, the structural properties of composite face sheets are taken into consideration. Motion equations are obtained by means of Hamilton’s principle and solved analytically. Influences of various parameters such as axially moving speed, volume fraction of CNTs, pre-tension, thickness and aspect ratio of sandwich plate on the vibration characteristics of moving system are discussed in details. The results indicated that the critical speed of moving sandwich plate is strongly dependent on the volume fraction of CNTs. Therefore, the critical speed of moving sandwich plate can be improved by adding appropriate values of CNTs. The results of this investigation can be used in design and manufacturing of marine vessels and aircrafts.

Vibration analysis of functionally graded nanocomposite plate moving in two directions

In the present study, vibration analysis of functionally graded carbon nanotube reinforced composite (FGCNTRC) plate moving in two directions is investigated. Various types of shear deformation theories are utilized to obtain more accurate and simplest theory. Single-walled carbon nanotubes (SWCNTs) are selected as a reinforcement of composite face sheets inside Poly methyl methacrylate (PMMA) matrix. Moreover, different kinds of distributions of CNTs are considered. Based on extended rule of mixture, the structural properties of composite face sheets are considered. Motion equations are obtained by Hamilton's principle and solved analytically. Influences of various parameters such as moving speed in x and y directions, volume fraction and distribution of CNTs, orthotropic viscoelastic surrounding medium, thickness and aspect ratio of composite plate on the vibration characteristics of moving system are discussed in details. The results indicated that thenatural frequency or stability of FGCNTRC plate is strongly dependent on axially moving speed. Moreover, a better configuration of the nanotube embedded in plate can be used to increase the critical speed, as a result, the stability is improved. The results of this investigation can be used in design and manufacturing of marine vessels and aircrafts.

Book Review of The Manufacture of Minoan Metal Vessels: Theory and Practice, by Christina F. Clarke

Book Review of The Manufacture of Minoan Metal Vessels: Theory and Practice, by Christina F. Clarke

Evaluation method for pressure vessel manufacturing codes: the influence of ASME unit conversion

This paper presents an assessment of the selection of manufacturing codes for pressure vessels. We focus on one of the most relevant approximation methods used in manufacturing calculations for pressure vessels, i.e., the unit conversions of the ASME boiler and pressure vessels (B&PV) code. To evaluate the influence of its conversions, several errors arising from the manufacturing process and measurement systems have been calculated, estimated and considered. In addition, a decision tool for manufacturing codes of pressure vessels with novel considerations based on stringency levels is presented to improve the current selection process. The general conclusion is that adjusting the pressure units is not recommendable when designing a pressure vessel due to large errors that can accumulate. Furthermore, the length conversion is only suitable for parts manufactured with maximum dimensions of five inches (125 mm).

Evaluation method for pressure vessel manufacturing codes: the influence of ASME unit conversion

This paper presents an assessment of the selection of manufacturing codes for pressure vessels. We focus on one of the most relevant approximation methods used in manufacturing calculations for pressure vessels, i.e., the unit conversions of the ASME boiler and pressure vessels (B&PV) code. To evaluate the influence of its conversions, several errors arising from the manufacturing process and measurement systems have been calculated, estimated and considered. In addition, a decision tool for manufacturing codes of pressure vessels with novel considerations based on stringency levels is presented to improve the current selection process. The general conclusion is that adjusting the pressure units is not recommendable when designing a pressure vessel due to large errors that can accumulate. Furthermore, the length conversion is only suitable for parts manufactured with maximum dimensions of five inches (125 mm).

Forming and Shaping Pottery Boundaries in Contemporary South-Eastern Botswana

In southern African archaeology, the equation of pottery styles with archaeological ‘cultures’ and their attribution to the antecedents of contemporary ethnic groups has been a common practice for a long time. Ethnoarchaeological studies from other parts of Africa and beyond have shown that the matter is complex and that stylistic and technological boundaries in ceramic distributions can reflect different kinds of social boundaries under different circumstances. To expand on these findings and make them locally relevant, a large-scale ethnoarchaeological study of 41 potters in south-eastern Botswana aims for a better understanding of ceramic technological style and boundary relations. Here, we present and explain only the results concerning the boundaries in the forming and shaping stage of ceramic vessel manufacture. We conclude that learning networks explain the visible boundaries in the technological style of forming and shaping pots in south-eastern Botswana today; language and ethnic affiliation do not. Boundaries in the other stages in the operational sequence of pottery manufacture, such as clay sourcing and preparation, vessel surface treatment and decoration, firing and finishing, will be presented in a series of further publications.

Additive manufacturing of micrometric crystallization vessels and single crystals.

We present an all-additive manufacturing method that is performed at mild conditions, for the formation of organic single crystals at specific locations, without any photolithography prefabrication process. The method is composed of two steps; inkjet printing of a confinement frame, composed of a water soluble electrolyte. Then, an organic semiconductor solution is printed within the confinement to form a nucleus at a specific location, followed by additional printing, which led to the growth of a single crystal. The specific geometry of the confinement enables control of the specific locations of the single crystals, while separating the nucleation and crystal growth processes. By this method, we printed single crystals of perylene, which are suitable for the formation of OFETs. Moreover, since this method is based on a simple and controllable wet deposition process, it enables formation of arrays of single crystals at specific locations, which is a prerequisite for mass production of active organic elements on flexible substrates.

Winding angle optimization of filament-wound cylindrical vessel under internal pressure

The maximum strength ratio and more uniform strength for all layers can be achieved by variation of winding angle of filament-wound (FW) vessel. The deformation and stresses of a thick-walled cylinder with multi-angle winding filament under uniform internal pressure are proposed. The stresses of each orthotropic unit of fiber layers, as well as longitudinal stress along the fiber direction, transverse stresses perpendicular to the fiber direction and shear stress in the fiber layer are derived analytically. An optimization model of FW closed ends vessel under uniform internal pressure subjected to Tsai–Wu failure criterion to maximize the lowest strength ratio through thickness with optimal variation of winding angle is built. Two optimization methods are adopted to find the optimized winding angle sequence through different ways, and their combination led to more efficient algorithm is suggested. The research shows that the material utilization and working pressure can be increased by proper winding angle variation, and several optimization winding angle sequence schemes are found for different thickness ratios cylindrical vessels with two typical composite materials E-glass/epoxy and T300/934, which are useful for many applications of FW vessel design and manufacture.

Provenance of Weeden Island “sacred” and “prestige” vessels: implications for specialized ritual craft production

ABSTRACTWeeden Island mortuary ceremonialism united distinct cultures across the Late Woodland social landscape. The Weeden Island pottery series is central to recognizing regional ceremonial parity, with prestige (elite) and sacred (cult) wares showing strong similarities among distant sites. Finely made vessels and their ostensibly shamanistic themes led archaeologists to consider the liturgical and political roles of ritual specialists, whose tasks might have included vessel manufacture in centralized locations. This research evaluates the prospect of craft specialization and centralized production of sacred and prestige wares through comparisons of the provenance of vessels from three Florida localities: Palmetto Mound (8LV2), the mounds at Melton (8AL5, 8AL7), and McKeithen (8CO17). Results of Neutron Activation Analysis and petrographic analysis show that the majority of the sampled vessels were made far from the mounds in which they were deposited, from a variety of locations but especially within the area between Kolomoki and the Tallahassee Hills. We argue that production was not centralized but may have been specialized to the extent that an integrated ritual network was necessary to coordinate rules of manufacture and use that were evidently observed by all participants.

Unmeasured temperature control in the presence of unknown drifting parameters in a cruise ship application

In cruise ship applications several waste heat recovery systems have been developed over the years in order to harvest the excess heat produced by the diesel engine and is stored in the coolant as thermal energy for instance. In this paper, a detailed model of a Fresh-Water-Cooling system is developed based on first principles and a given circuit scheme provided by the vessel manufacturer. The Fresh-Water-Cooling system consists of multiple interconnected subsystems; in this paper the main focus lies on the heat exchanger, where the waste heat recovery process takes place. Due to the presence of unmeasured states and uncertain model parameters the heat exchanger is modelled as partially measured stochastic system. Further the process is proved to be conditionally Gaussian, which makes the use of a conditionally Gaussian filter possible. It produces optimal estimates for the states and the unknown drifting parameters in the mean square sense. The process state is locally stabilized by the estimated process values using stabilizing feedback control.

Estimation of Spring-Back of Single Torus Inner Vessel Sector by Finite Element Analysis

Inner vessel in reactor assembly of sodium cooled fast reactor separates hot and cold pool sodium. The shape of inner vessel is optimized with reduced upper & lower shell diameters and toroidal redan for future Fast Breeder Reactor (FBR). This results in higher buckling strength and reduced thickness and hence reduced weight. To achieve the intricate toroidal shape with specified dimensional tolerances, a comprehensive technology development exercise was carried out successfully for the manufacture of inner vessel 30° sector. The achieved profile of the redan meets the specified dimensions and other design requirements. Spring-back observed in the sector was small. To verify the developmental exercise results, a finite element analysis (FEA) of forming of inner vessel sector was performed on finite element software ABAQUS. In this paper, FEA results and spring back are discussed. Spring back assessed is maximum at the center and relatively lower towards the edges for the redan with the chosen radius of 5980 mm.

Investigating pottery vessel manufacturing techniques using radiographic imaging and computed tomography: Studies from the Late Archaic American Southeast

Advances in image acquisition and processing, including the increasing availability of computed tomography (CT), have expanded the research potential for radiography. This paper employs recent radiographic advancements to investigate how hand-formed pottery was manufactured, with a focus on defining “micro-techniques” that may be isomorphic with past social groups. By creating and imaging experimental vessels, unique structural “fingerprints” are defined for a number of micro-techniques, which are then used to categorize assemblages from two contemporaneous and neighboring archaeological sites. Results suggest that the two sites were occupied by distinct potting communities and that radiographic imaging can be a powerful tool for determining the presence of past social groups.

Application of Halpin-Tsai Method in Modelling and Size-dependent Vibration Analysis of CNTs/fiber/polymer Composite Microplates.

In the present study, modelling and vibration analysis of Carbon nanotubes/ fiber/ polymer composite microplates are investigated. The governing equations of the Carbon nanotubes/ fiber/ polymer composite microplates are derived based on first order shear deformation plate theory, rather than other plate theories, due to accuracy and simplicity of polynomial functions. The modified couple stress theory is employed because of its capability to interpret the size effect. Halpin-Tsai model is utilized to evaluate the material properties of two-phase composite consisted of uniformly distributed and randomly oriented Carbon nanotubes through the epoxy resin matrix. Afterwards, the structural properties of carbon nanotubes reinforced polymer matrix, which is assumed as a new matrix, and then, reinforced with E-Glass fiber, they are calculated by fiber micromechanics approach. Employing Hamilton’s principle, the equations of motion are obtained and solved by Hybrid analytical numerical method. The influences of various parameters such as the weight percentage of single-walled carbon nanotube, aspect ratio, and size effect on the vibration characteristics of microplate are discussed in details. Results indicate that the stability of Carbon nanotubes/fiber/polymer composite microplates can be improved by adding appropriate values of Carbon nanotubes. In addition, increase in the frequencies is more pronounced in the case of microplates reinforced with SWCNT compared with MWCNT. These findings can be used in design and manufacturing of marine vessels and aircrafts.

Nonlocal vibration of axially moving graphene sheet resting on orthotropic visco-Pasternak foundation under longitudinal magnetic field

In the present research, vibration and instability of axially moving single-layered graphene sheet (SLGS) subjected to magnetic field is investigated. Orthotropic visco-Pasternak foundation is developed to consider the influences of orthotropy angle, damping coefficient, normal and shear modulus. Third order shear deformation theory (TSDT) is utilized due to its accuracy of polynomial functions than other plate theories. Motion equations are obtained by means of Hamilton’s principle and solved analytically. Influences of various parameters such as axially moving speed, magnetic field, orthotropic viscoelastic surrounding medium, thickness and aspect ratio of SLGS on the vibration characteristics of moving system are discussed in details. The results indicated that the critical speed of moving SLGS is strongly dependent on the moving speed. Therefore, the critical speed of moving SLGS can be improved by applying magnetic field. The results of this investigation can be used in design and manufacturing of marine vessels in nanoscale.

Obnašanje superzlitine na osnovi niklja pri rekristalizaciji

The thermomechanical processing of a nickel-based superalloy is the way to considerably influence the grain size. A uniform coarse-grain size increases the creep strength and the crack-growth resistance. In this work, the processing for achieving a uniform recrystallized-grain structure with a variation in the thermomechanical parameters is investigated. The MoNiCr alloy is intended for modern designs of nuclear reactors, in which molten fluoride salts are used as the coolants in the primary and/or secondary circuit. It represents a material alternative with a high corrosion resistance in the area of fluoride salts and it has very good creep properties in the temperature range of 650–750 °C as well. The manufacture of vessels and fittings from the MoNiCr alloy requires the mastering of the technology for forming this high-alloyed material. The key step seems to be the transition of the cast state of the material to the state of a cast recrystallized microstructure with homogenous fine grains. A particular stress condition is, besides the temperature, very important during hot forming. Nickel alloys are able to accept a significantly higher deformation level if the compressive stress prevails. A forming process involving the compression state of stress increases the probability that the material will reach, without failure, a level of deformation that allows recovery and recrystallization processes. A particular deformation process was carried out on a physical simulator. The preceding cold deformation essentially accelerates the recrystallization process of a deformed cast structure.