Diagnostics of Large Non-Conductive Anti-Corrosion Coatings on Steel Structures by Means of Electrochemical Impedance Spectroscopy

This paper proposes a testing methodology for barrier properties of large non-conductive anti-corrosion coatings on steel structures. Electrochemical impedance spectroscopy (EIS) was adapted to in situ testing of steel structures by using a prototypical flexible measuring probe and a gel electrolyte that filled the probe, to take measurements on any surface regardless of its position. The first stage of the testing methodology was to perform time-consuming impedance measurements and quick electromagnetic measurements of coating thickness at selected test points. The results were used to determine correlation relationships between the logarithm of the impedance modulus for the coating at a measuring frequency of 0.1 Hz measured with the EIS method and the average thickness of the coating measured with an electromagnetic thickness gauge. Quick electromagnetic measurements were performed in the second stage to specify thickness of the other surface of the steel structure coating. The barrier properties of this coating were identified on the basis of the determined correlation.

METHODS AND RESULTS OF MICROMETER STUDIES OF HYDRAULIC SYSTEM SEALING UNITS OF AGRICULTURAL MACHINERY

End-type sealing units based on round-section rubber rings are the most common types of seals for volumetric hydraulic drive units of various agricultural machinery. Its service life depends on the correspondence of the geometric dimensions of the elements that make them up, as well as on the combination of limit deviations of the specified elements. (Research purpose) The research purpose is in studying deviations and identifying statistical distribution of the cross-section diameters of new rings and the depth of grooves under them in order to determine the number of connections that meet the requirements of the standard. (Materials and methods) Author examined the sealing joints of the oil pipeline and the valve cover of the hydraulic distributor of the MTZ 80/82 tractor and new rubber rings that are part of repair kits intended for repair. Micrometric studies were performed using the GM-50 micrometer depth gauge and the TN 1060T thickness gauge. (Results and discussion) About 90 percent of the examined compounds do not meet the requirements of the standard, which explains to a large extent the low level of their reliability. At the same time, a significantly higher level of inconsistencies is in the metal parts of these connections. The vast majority of nonconforming joints have a combination of ring and groove sizes, which provides increased initial compression deformation of the ring in the groove. (Conclusions) Inconsistencies in the dimensions of the groove and the cross-section of the ring, which lead to an increase in the initial compression deformation of the seal, and thus the initial contact stresses, cause a certain increase in the theoretical life of the connection. To predict the connection reliability more accurate, it is necessary to study the influence on leaks not only of the geometric dimensions of the mating elements, but also other factors: surface roughness, as well as the actual operating temperature of the node and the aggressiveness of the hydraulic working fluid.

Rancang Bangun Meja Kerja Spraybooth pada Proses Painting Cylinder Block

Rancang bangun meja kerja spraybooth ini bertujuan untuk menghilangkan kesulitan operator pada saat proses pengecatan (painting) pada cylinder block, operator harus membungkuk karena sulitnya mengecat pada bagian bawah dan lekukan pada permukaan drag (depan) dan cop (belakang) dari cylinder block sehingga pada proses ini memiliki poin ergonomi yang rendah (-3). Akibat kondisi kerja yang tidak nyaman sering menghasilkan kualitas produk dibawah standar, untuk mendapatkan poin ergonomi yang lebih tinggi dan kualitas produk yang lebik baik, diperlukan meja kerja yang memudahkan operator pada proses painting. Metode rancangan yang digunakan adalah metode Quality Function Deployment (QFD) meliputi, perencanann produk (HOQ), pengembangan konsep desain, perencanaan proses manufaktur, perencanaan produksi. Meja kerja spraybooth ini memiliki 2 gerakan mekanisme, yaitu gerakan naik – turun dan datar - miring yang masing – masing gerakan membutuhkan 1 sistem pneumatik. Tekanan setiap pergerakan 4 – 6 105 Pa (N/m2) dengan massa cylinder block 50 kg . Pengujian dilakukan adalah tingkat ketebalan permukaan hasil pengecatan cylinder block. Standar ketebalan yaitu 15 – 30 dengan menggunakan thickness gauge sebagai alat ukur.

2D Color-Intensity Representation of Ultrasonic Thickness Gauge Measurements

Ultrasonic thickness gauges are easy to operate and reliable, and can be used to measure a wide range of thicknesses and inspect all engineering materials. Supplementing the simple ultrasonic thickness gauges that present results in either a digital readout or as an A-scan with systems that enable correlating the measured values to their positions on the inspected surface to produce a two-dimensional (2D) thickness representation can extend their benefits and provide a cost-effective alternative to expensive advanced C-scan machines. In previous work, the authors introduced a system for the positioning and mapping of the values measured by the ultrasonic thickness gauges and flaw detectors (Tesfaye et al. 2019). The system is an alternative to the systems that use mechanical scanners, encoders, and sophisticated UT machines. It used a camera to record the probe’s movement and a projected laser grid obtained by a laser pattern generator to locate the probe on the inspected surface. In this paper, a novel system is proposed to be applied to flat surfaces, in addition to overcoming the other limitations posed due to the use of the laser projection. The proposed system uses two video cameras, one to monitor the probe’s movement on the inspected surface and the other to capture the corresponding digital readout of the thickness gauge. The acquired images of the probe’s position and thickness gauge readout are processed to plot the measured data in a 2D color-coded map. The system is meant to be simpler and more effective than the previous development.

A feasibility study on elbow erosion monitoring using active sensing approach and fractional Fourier transform

Elbow erosion monitoring is of great significance to the safety of pipeline systems and maintenance personnel. This paper proposes a new elbow erosion monitoring method, which combines the PZT (lead zirconate titanate) enabled active sensing with the fractional Fourier transform (FrRT), and takes the fractional-order energy peak of the stress wave signal as the damage index. Three 90°-elbows and three 90°-elbow assemblies were used in the experimental studies. Under different erosion degrees, the mass reduction of the three separate elbows was measured by high-precision electronic scale and the residual thickness of the three elbow assemblies was detected by ultrasonic thickness gauge. Two pieces of PZT patches were respectively used to excite and receive the signals in the active sensing. FrFT was used to distinguish the linear sweep signal components of stress wave signals from the energy of other interference or noise signals, and the fractional-order energy peak was used as the damage index. The results show that there is a one-to-one relationship between mass of erosion loss and damage index. Compared with the traditional time domain signal energy method, the new method has the advantage of eliminating the saturation phenomenon. The proposed method and damage index proposed in this paper will be a promising tool for real-time monitoring of elbow erosion.

Effect of Aggregate Shapes on the Properties of Concrete

Aggregates constitute more than 90% of concrete and significantly determine the strength of concrete. In this study, the shape characteristics such as flakiness and elongation were determined using elongation and thickness gauge. The aggregate used for the study is granite. Aggregate crushing value and aggregate impact value tests were performed on the aggregate while slump test, water absorption test, compressive strength test and flexural strength test were carried out on concrete. A total of one hundred and thirty-two concrete cubes were produced using 1:2:4 and 1:3:6 mix each for the compressive strength test and forty-eight reinforced concrete beams were produced for flexural strength test. The slump for all the samples tested was examined to be true. The compressive strength of the concrete cube was greatly affected by the shape of aggregate used and it was noted that; for lower percentage of flaky and elongated aggregate the compressive strength is moderately high compared to when the percentage is high. The highest obtained compressive strength, 15N/mm2 is in compliance with the concrete compressive strength of normal 1:2:4 mix as stipulated in ASTM C109, Also, with 30% of elongated aggregate and 30% of flaky, the flexural strength of 7.03 N/mm2 was obtained. This shows that aggregate shape is a very important property of coarse aggregate that must be put into consideration in production of quality concrete for construction works.

Research on Digital Radiographic Inspection of In-Service Fiber Reinforced Plastic Pipe

With the development of material technology, non-metallic materials are applied to pressure pipes in petrochemical plant. Fiber reinforced plastic (FRP) is widely used because high mechanical strength and corrosion resistance. The non-metallic pipeline has been running for more than 20 years in petrochemical plant of China. Due to the fiber material anisotropy, it is difficult to measure thickness and detect defect by conventional ultrasonic method in FRP inspection. According to Chinese pressure pipeline inspection laws and regulations, the main inspection methods are macroscopic examination and hydraulic pressure test. The inspection of non-metallic pipelines has not been specified in detail. Compared with traditional radiographic detection, digital radiographic detection has better contrast and image processing technology, so digital radiographic detection has more advantages in thickness measurement and corrosion detection. Elbows are most prone to corrosion defects due to fluid erosion. In this paper, fiber reinforced plastic pipe is detected by digital radiographic technology. In digital radiographic detection, appropriate parameters and accurate measurement are proposed. The accurate wall thickness of the pipe is obtained and the internal defects are detected. By comparing the measurement results with the actual wall thickness, the measurement accuracy of digital radiographic detection could meet the requirement of ultrasonic thickness gauge in NB/T47013.3. Digital radiographic technology is strongly recommended for FRP pipeline periodic inspection.