A piping plan depends on inspection history or inspection data in order to extract propensity of damage mechanism. The inspection data are ①Periodic maintenance inspection record (SDI), ②On-stream inspection data (OSI), ③Unplanned stop or extraordinary inspection records and ④corrosion-loop database visualized by evaluating corrosion rate as a corrosion system. Each of injury site of corrosion thinning with an organic acid as a specific injury mechanism, operating temperature conditions as a condition for extracting parts, fluid corrosion factor, structure factor, and material is quantified qualitatively or semi-qualitatively. It states that priority order by data visualization of damage propensity (Bayesian theorem) is required.
Maintenance planning of stationary equipment in the petroleum plant is based on information of maintenance inspection history, daily routine inspection history and operation monitoring trend recording, and level evaluation of likelihood of damage and degrees of influence of damage when damage occurs is performed using failure mode and effects analysis (FMEA) worksheet. Risk controls such as avoidance and removal, reduction, dispersion and tolerance are taken in accordance with the degrees of influence. While Electro-Dynamic Desalter (EDD) which is important to corrosion reduction of the atmospheric distillation unit is a pressure vessel, EDD is treated as electrical equipment since the internal structure in which 124 or more electrode plates are set has a function of agglomerating and removing fine water droplets which are impurities in crude oil by applied voltage 20-40kV.References concerning risk-based maintenance (RBM) for a large number of running EDD all over the world cannot be found. Damaged parts of EDD internals both in and outside Japan were sampled, and analysis in the viewpoint of failure physics, remaining life evaluation technology for non-metallic materials by a simple non-destructive testing method and knowledge of setting optimum maintenance period are obtained. The details are therefore described in this paper.
To elucidate effects of vision, visual bias, on tactile roughness of wood surfaces, 12 kinds of fancy veneer (Quercus alba) overlaid plywood were prepared. Forty subjects rubbed the surfaces and evaluated their roughness subjectively without vision (unimodal condition), and another 35 subjects robbed and evaluated with vision (multimodal condition). Evaluation scores concerning the tactile roughness of both conditions were compared. The tactile roughness in the multimodal condition was affected by the vision. Especially, edge grain specimens with film-forming finish by acrylic urethane paint were evaluated as rougher surfaces than evaluated in the unimodal condition, when the surfaces were robbed perpendicular to the grain. This result suggests that the visual bias exactly affected the tactile roughness of the coated surfaces.
Mechanical properties in the radial direction of wood with different swelling ratio swollen in different organic liquids diluted with benzene were studied and compared with those swollen by moisture or water. Additionally, modulus of elasticity in bending of untreated or lignin extracted specimens were measured in the condition swollen by water or dimethyl sulfoxide. And, it was considered how the liquids were present in wood and affect mechanical properties. The modulus of elasticity and rupture in bending of specimens swollen by organic liquids diluted with benzene were decreased with increase in cross sectional relative swelling, and those values were larger than those of specimens swollen by moisture and water in similar degree of cross sectional swelling. This is attributed to the difference in the number of several hydrogen bonds between molecules of wood constituents, and the number is affected by the molecular size of the liquid. The degree of decrease in modulus of elasticity was smaller in the lignin extracted specimen due to change of liquids from water to dimethyl sulfoxide. This is because the lignin extracted specimen has few lignin, therefore, the specimen was not much swollen by dimethyl sulfoxide and mechanical property was also not largely decreased. From the results, it is clarified that dimethyl sulfoxide is adsorbed in lignin, and decrease in mechanical property is caused by swelling of lignin due to adsorption of dimethyl sulfoxide.
Stage I fatigue crack propagation along crystallographic slip planes in a Ni-base single crystal superalloy, NKH-304, was investigated. At first, crack propagation tests at room temperature were carried out using four types CT specimens with different combinations of primary and secondary orientations. A series of experiments revealed the Stage I cracks in the single crystal superalloy were mixed mode containing mode I, II and III components, and the <100> primary orientation or the <110> secondary orientation resulted in higher crack propagation rate. In order to interpret such effect of crystal orientations on the Stage I cracking, elastic-plastic FEM model was developed taking account the 3-D geometry of the mixed mode crack plane and elastic anisotropy in the CT specimen. It was found from fracture mechanics analysis that the stress intensity factor derived from the shear stress components on the co-planar slip plane provided a reasonable explanation on the effects of crystal orientation on the Stage I crack propagation rate.
Creep damage assessment of high temperature components in aged thermal power plants is necessary to maintain reliable operation. Although an accurate creep damage assessment result is obtained by a destructive assessment method in which creep tests are performed, it is difficult to cut a standard size specimen from actual components. Therefore, development of testing and damage assessment methods by using a miniature specimen are expected. In this study, creep tests of a CrMoV forging steel were conducted by using a solid bar tensile type miniature creep specimen with 1mm diameter at 600℃. It was demonstrated that equivalent creep deformation and rupture properties to those obtained from the standard size specimen are obtained by the miniature specimen under stress level below 200MPa. Creep damage materials were produced by interrupting creep tests performed by using a standard sized smooth bar specimen and two types of round notch bar specimen with radiuses at notch root of 0.5mm(R0.5) and 2.0mm(R2.0). Uniaxial tensile creep tests were performed by using the miniature creep specimens taken from the plain specimens and the notch roots of the notch specimens. Although accurate creep damage assessment results were obtained from the creep tests with the miniature creep specimens taken from the plain specimens, it should be noted that the results may give under estimation for higher creep damaged condition. Creep damage assessment results based on the creep tests with miniature specimens also gave under estimation for the creep damaged material of R0.5 due to lower axial creep strain accumulation under multiaxial stress states before interrupting the creep tests. On the other hand, accurate creep damage assessment results were obtained for the creep damage materials of R2.0 indicating that creep tests with the miniature specimens may be applicable to creep damage assessment of components under certain range of stress multiaxiality.
To enhance the application of Carbon Fiber Reinforced Thermoplastics (CFRTP) for automobile, it is important to understand the mechanical properties of CFRTP under service environmental conditions. Since the vehicle roof surface is exposed to high temperature, to clarify mechanical properties of CFRTP under high temperature environment is important for reliability assessment. Since the mechanical properties of CFRTP under high temperature environment depend on matrix resin, the highly heat resistant resin is preferred for the matrix of CFRTP. Among highly heat resistant resin, polynonamethyleneterephthalamide (PA9T) is expected to be used for the matrix of CFRTP due to its properties such as high heat-moisture resistance. Although the mechanical properties of neat PA9T resin at high temperature were evaluated and showing better heat resistance property than PA46 and PA6T, the potential of PA9T as the matrix of CFRTP have not been clarified yet. Since the mechanical properties of CFRTP are affected by not only the properties of reinforcing fibers and the matrix resin but also the properties of fiber/matrix interface, it is important to evaluate the effects of temperature on the fiber/matrix interfacial properties of CF/PA9T. In this study, single fiber pull-out tests at R.T., 40 °C and 80 °C, measurement of specific volume and softening point of the resin were conducted to evaluate the fiber/matrix interfacial properties of CF/PA9T model composites and the results were compared with these of CF/PA6 and CF/PA12 model composites. The resin expanded and interfacial shear strength of the CF/PA9T model composites decreased as temperature rose, and the decrease rate of interfacial shear strength of the CF/PA9T model composites was smaller than these of CF/PA6 and CF/PA12 model composites. Instead of chemical deterioration and softening of the resin, the reduction of residual stress at high temperature under 80 °C decreases the fiber matrix interfacial shear strength.
The investigation on application availability of sewage sludge burned ash as concrete admixture was done with mortal. The influence of phosphorus in sewage sludge burned ash was evaluated in setting of cement. The result of experiment showed delay of up to about 1 hour in setting of cement. In the case of fresh mortal before setting, increase of additive amount decreases flowability. To keep flowability of same level, appropriate selection of additive amount and kinds of water-reducing agent is necessary. In case of hardened mortar, compressive strength after 65℃ steam curing was increased, according to increase of additive amount. The increase of compressive strength in fly ash, by-product of pulverizing coal combustion, was not observed under the same condition. In water curing, both early strength and long-term strength increased, not showing big difference. So, steam curing at 65℃ is effective curing method for sewage sludge burnt ash. The strength obtained by steam curing corresponds to water curing for 14 days. It was concluded that the generation of C-S-H contributes improvement of compressive strength, due to the fact that good correlation between the compressive strength and gel pore volume was confirmed. Although mechanism of compressive strength increase has not been explained, Anorthite in sewage sludge burned ash is estimated to be involved in the reaction.
The factors which affect drying shrinkage of concrete are material properties and environmental conditions, and so on. It is said that the type of coarse aggregate is one of the most dominant factors which affect concrete drying shrinkage. It has also been pointed out that the pore structure of coarse aggregate affects drying shrinkage strain of concrete. From the above backgrounds, in this research, we focused on the pore structure of pore radius of 1 µm or less for coarse aggregate and investigated the relationship between the coarse aggregate pore characteristics obtained by using mercury porosimetry and the drying shrinkage strain of coarse aggregate and concrete. For this study we used 10 types of crushed stone from different regions and of different qualities. As a result, we indicated a mutual relationship could be identified between the pore characteristics of coarse aggregate and the drying shrinkage strain of coarse aggregate or concrete when categorization by rock type was used. We also demonstrated that the average pore size of coarse aggregate, calculated from the pore characteristics obtained by using mercury porosimetry, was related to the drying shrinkage strain of coarse aggregate and concrete, and that it is possible that this relationship could be uniformly expressed by a power function.
In ferrite-austenitic duplex stainless steels, due to different coefficients of thermal expansion and elastic moduli between the two phases, phase stresses will evolve during a thermal history of material processing such as casting, forging and annealing. Because residual stress possibly affects the material properties such as fatigue strength, welding stability and so on, residual stress measurement is considered necessary for the application of these multipahse materials. In this study, residual stress distribution along thickness direction of duplex stainless steel hollow cylinders fabricated by centrifugal casting was measured by pulsed neutron diffraction using time-of-flight (TOF) method at Japan Proton Accelerator Research Complex (J-PARC). In order to conduct triaxial stress analysis, strain-free lattice constants of both phases were measured from electropolished thin plates with thickness of lower than 90 micrometer, nearly equal to the grain size of austenitic phase. Based on the measurement results, the mechanism of stress development during centrifugal casting and effect of stress relief heat treatment (SRHT) was discussed.