Welding inspection

Industri minyak dan gas (migas) merupakan salah satu bidang yang paling besar memberikan dana kontribusi dalam pembangunan suatu Negara. Migas juga merupakan salah satu sector industri vital di Indonesia. Industri migas memproduksi bahan bakar yang membantu untuk kegiatan sehari-hari masyarakat di Indonesia. Tanpa bahan bakar minyak masyarakat Indonesia saat ini akan kesulitan dalam menjalankan aktivitas mereka. Oleh karena itu industry migas di Indonesia memegang peranan pening dalam mendukung dan menjaga ketahanan energi nasional. PT Pertamina (persero) merupakan bahan usaha milik negara (BUMN) yang bergerak di bidang energy yaitu minyak dan gas. PT Pertamina (Persero) memeiliki 6 unit pengolahan (refinery) yang tersebar di berbagai daerah di Indonesia. PT Pertamina (Persero) Refenery Unit IV Cilacap merupakan refinery unit terbesar dari enam unit yang masih beroperasi. Sebagai unit pengolahan terbesar tentunya memiliki sarana dan prasarana yang memadai termasuk kilang dan pipa-pipa yang menyertainya. Sebagai salah satu divisi yang berada di PT Pertamina Refenery Unit IV Cilacap maka stationary and inspection engineering memiliki fungsi untuk melakukan inspeksi terhadap kualitas dari peralatan yang akan dipakai dan melakukan maintenance planning terhadap umur pakai semua perlatan yang ada di lapangan. Welding inspection merupakan salah satu inspeksi yang dilakukan untuk mengetahui hasil dari proses pengelasan yang dilakukan. Hasil dari proses welding merupakan salah satu unsur yang cukup penting dalam berjalannya proses produksi di PT Pertamina karena menentukan umur pakai dari sebuah alat. Hasil dari maintenance yang dilakukan pun menentukan apakah alat tersebut bisa digunakan kembali atau tidak. Welding proses yang biasa dilakukan biasanya diakibatkan dari korosi yang menyebabkan cacat pada alat yang digunakan sehingga alat tersebut tidak berjalan normal. Pada proses pemeriksaan pengelasan, kualitas las

Reliability centered maintenance (RCM) has a key role in the quality system of thermal power plants. Electricity production is definitely not only production of a product, but also becomes a customer service. Reliability is the top quality tier of this service. Incorporation in the Integrated energy system means fast transformations of organization on all levels. The reliability of modern generation components basically influences the efficiency and capacity of a power plant as a whole. This paper presents the results of RCM practice on Unit Two of The Thermal Power Plant ″Nikola Tesla -B″, 2x600 MW, Yugoslavia. RCM implementation on current problems during exploitation emphasized problems with the boiler tubing system. The methodological approach included outages analyses, marking of the most significant ones, determination of main causes of damage (determination of the material exhaustion state based on expert analyses), application of adequate remaining life assessment methodology and finally the recommendations. Based on these analyses, certain technical solutions were performed and as a result, the mean time between failures of the plant increased, as well as its reliability. According to cost efficiency, RCM methodology presented the most effective cost-benefit method for reliability upgrade.

Damage of boiler tubes is a very serious problem in many utilities worldwide, including even in the most advanced countries. Preserve of boiler tube integrity present major part in maintenance programs centered to achievement of high levels of availability and reliability of thermal power plants. This is due to a very specific and complex interconnection of design and operating characteristics of the boiler unit. Based on the results of numerous boiler tube damages investigation performed on domestic thermal power plants it is concluded that the initiation of different damage mechanism was strongly influenced by tube weld geometry defects. In this paper particular attention was dedicated to this not well documented problem. Structural integrity of the boiler tubes are greatly affected by the weld excessive root penetration (melt-through) on the tube inner surface. This type of weld geometry defect, which occurred often on boiler tubing system, present local flow disruptor and also very strong stress riser. In the vicinity and downstream of excessive root penetration type disruptor initiation of different damage mechanisms (erosive and corrosive wear, under-deposit corrosion, stress corrosion, corrosion fatigue) occurred due to working fluid nucleate boiling destabilization (evaporator), or due to turbulent flow (superheater and reheater), followed by intensive suspended solids deposition.

Reliability centered maintenance (RCM) has a key role in the quality system of thermal power plants. Electricity production is definitely not only production of a product, but also becomes a customer service. Reliability is the top quality tier of this service. Incorporation in the Integrated energy system means fast transformations of organization on all levels. The reliability of modern generation components basically influences the efficiency and capacity of a power plant as a whole. This paper presents the results of RCM practice of one 620 MW thermal power plant. RCM implementation on current problems during exploitation emphasized problems with the boiler tubing system. The methodological approach included outages analyses, marking of the most significant ones, determination of main causes of damage (determination of the material exhaustion state based on expert analyses), application of adequate remaining life assessment methodology and finally the recommendations. Based on these analyses, certain technical solutions were performed and as a result, the mean time between failures of the plant increased, as well as its reliability. According to cost efficiency, RCM methodology presented the most effective cost-benefit method for reliability upgrade.

Vertical cylindrical vessel-chambers as a part of coal — drying plants, whose purpose is to collect wastewater, are supported at 3 points in upper dish head area and are made of fine-grained Mn steel plates, joined by welding. Significant thinning and leaking in upper dish head area of the vessel occurred due to original design provoking an intensive abrasion, cracking and rupture. After reconstruction, in the upper zone of cylindrical shell, two new joints were made in sity by manual arc welding, with subsequent, local post-weld heat treatment. However, cracks appeared firstly in new welded zones in radial and axial joints, and then in zones of openings. Later, the similar failure features began to appear in the area of original welded joints. All of these cracks were repaired by properly specified technology. Unfortunately, after some period of exploitation the initiation of new cracks was observed, at first by the visual inspection. This problem was detected in the repaired areas in all (16) vertical cylindrical vessels. Cracks have propagated in different directions with various penetration depths, up to 3 mm. It is interesting to note that crack appeared in the HAZ of vertical joints, while in the area of radial welded joints the cracks were randomly distributed in a larger zone. For cracks up to 3 mm, deep grinding was applied whereas for greater crack depths repair welding with local post-weld heat treatment was used. Since welding with subsequent heat treatment could only be used twice to repair the welded joints [1, 2], it is clear that in the areas repaired several times (up to 7) proper mechanical characteristics of the material is rather difficult to maintain.

Filler material choice for repair welding of stop valve spindle of thermal power plant by-pass pipeline was presented in this paper. Repair welding of the stop valve spindle was necessary because of plant operating problems due to very frequent localized damage appearance in the form of erosive wear on it. For this purpose it was necessary to choice appropriate filler material with high wear resistance characteristic. Experimental investigation and testing (hardness measurement, chemical composition analysis and microstructural investigation) of prepared specimens after welding simulation with different kind of filler material was performed. On the basis of obtained results it was recommended procedure for application of the filler material with generally preferable characteristic.

Convective boiling beyond critical-heat-flux is encountered in a number of applications, one of which is water wall tubing of steam generators. Sometimes, the heat transfer process in particular zones of heated surfaces of boiling tubes system is combined with fluctuation of wall temperature. This phenomena is connected with heat transfer crises during departure from nucleate boiling (DNB) as well as dry out and causes the interruption of water layer along a tube wall provoked the formation of drying areas. This process has a great influence on intensity and localization of hydrogen attack and deposits formation on the waterside of the tube. Standard investigation procedure were applied on specimens taken from furnace walls tubing, made of 0.2C0.5Mn0.25Cr, steel in the purpose of failure analysis..

Welding is an important joining technology but the defects in welds wreck the quality of the product evidently. Due to the variety of weld defects' characteristics, weld defect detection is a complex task in industry. In this paper, we try to explore a possible solution for weld defect detection and a novel image-based approach is proposed using small X-ray image data sets. An image-processing based data augmentation approach and a WGAN based data augmentation approach are applied to deal with imbalanced image sets. Then we train two deep convolutional neural networks (CNNs) on the augmented image sets using feature-extraction based transfer learning techniques. The two trained CNNs are combined to classify defects through a multi-model ensemble framework, aiming at lower false detection rate. Both of the experiments on augmented images and real world defect images achieve satisfying accuracy, which substantiates the possibility that the proposed approach is promising for weld defect detection.

As a solid-state welding process, Friction Stir Welding (FSW) offers a variety of advantages over traditional welding processes . Problems that are typically occurring due to the cooling of the liquid phase, such as solidification cracking and formation of porosity, generally do not occur in FSW. Nevertheless, as a result of suboptimal settings of the welding process parameters and certain uncontrollable conditions, FSWs are still associated with a number of specific flaws, e.g. root flaws and wormholes.

Ultrasonic non-destructive testing and evaluation techniques (NDT&E) can be used for quality
assessment of friction stir welded joints. In this paper, a novel approach for the detection of root flaws is
proposed using an immersion ultrasonic testing method in oblique incidence and backscatter mode. The
backscattered energy C-scan images obtained after an empirical positioning and proper time gating can
be straightforwardly interpreted by direct comparison with typical ‘flaw’ patterns, allowing for identification
and localization of the root flaws in the weld. The method is illustrated for FSW butt joints of the
AlZnMgCu (7XXX series) alloy.


Highlights

•  An empirical positioning and time gating technique is applied for root defect examination of welded butt joints.

•  The backscattered energy of the time gated echo depends on grain morphology and on the presence of micro-defects.

•  Identification and localization of root defects is realized by analyzing their unique backscatter energy C-scan fingerprint.

•  Alternative ultrasonic inspection technique for AL alloys without the habitual need for high frequency analysis.

Filler material choice for repair welding of stop valve spindle of thermal power plant by-pass pipeline was presented in this paper. Repair welding of the stop valve spindle was necessary because of plant operating problems due to very frequent localized damage appearance in the form of erosive wear on it. For this purpose it was necessary to choice appropriate filler material with high wear resistance characteristic. Experimental investigation and testing (hardness measurement, chemical composition analysis and microstructural investigation) of prepared specimens after welding simulation with different kind of filler material was performed. On the basis of obtained results it was recommended procedure for application of the filler material with generally preferable characteristic.

Reliability centered maintenance (RCM) has a key role in the quality system of thermal power plants. Electricity production is definitely not only production of a product, but also becomes a customer service. Reliability is the top quality tier of this service. Incorporation in the Integrated energy system means fast transformations of organization on all levels. The reliability of modern generation components basically influences the efficiency and capacity of a power plant as a whole. This paper presents the results of RCM practice on Unit Two of The Thermal Power Plant ″Nikola Tesla -B″, 2x600 MW, Yugoslavia. RCM implementation on current problems during exploitation emphasized problems with the boiler tubing system. The methodological approach included outages analyses, marking of the most significant ones, determination of main causes of damage (determination of the material exhaustion state based on expert analyses), application of adequate remaining life assessment methodology and finally the recommendations. Based on these analyses, certain technical solutions were performed and as a result, the mean time between failures of the plant increased, as well as its reliability. According to cost efficiency, RCM methodology presented the most effective cost-benefit method for reliability upgrade.

of applications, one of which is water wall tubing of steam generators. Sometimes, the heat transfer process in particular zones of heated surfaces of boiling tubes system is combined with fluctuation of wall temperature. This phenomena is connected with heat transfer crises during departure from nucleate boiling (DNB) as well as dryout and causes the interruption of water layer along a tube wall provoked the formation of drying areas. This process has a great influence on intensity and localization of hydrogen attack and deposits formation on the waterside of the tube. Standard investigation procedure were applied on specimens taken from furnace walls tubing, made of 0.2C0.5Mn0.25Cr, steel in the purpose of failure analysis..

Vertical cylindrical vessel-chambers as a part of coal — drying plants, whose purpose is to collect wastewater, are supported at 3 points in upper dish head area and are made of fine-grained Mn steel plates, joined by welding. Significant thinning and leaking in upper dish head area of the vessel occurred due to original design provoking an intensive abrasion, cracking and rupture. After reconstruction, in the upper zone of cylindrical shell, two new joints were made in sity by manual arc welding, with subsequent, local post-weld heat treatment. However, cracks appeared firstly in new welded zones in radial and axial joints, and then in zones of openings. Later, the similar failure features began to appear in the area of original welded joints. All of these cracks were repaired by properly specified technology. Unfortunately, after some period of exploitation the initiation of new cracks was observed, at first by the visual inspection. This problem was detected in the repaired areas in all (16) vertical cylindrical vessels. Cracks have propagated in different directions with various penetration depths, up to 3 mm. It is interesting to note that crack appeared in the HAZ of vertical joints, while in the area of radial welded joints the cracks were randomly distributed in a larger zone. For cracks up to 3 mm, deep grinding was applied whereas for greater crack depths repair welding with local post-weld heat treatment was used. Since welding with subsequent heat treatment could only be used twice to repair the welded joints [1, 2], it is clear that in the areas repaired several times (up to 7) proper mechanical characteristics of the material is rather difficult to maintain.

Reliability centered maintenance (RCM) has a key role in the quality system of thermal power plants. Electricity production is definitely not only production of a product, but also becomes a customer service. Reliability is the top quality tier of this service. Incorporation in the Integrated energy system means fast transformations of organization on all levels. The reliability of modern generation components basically influences the efficiency and capacity of a power plant as a whole. This paper presents the results of RCM practice on Unit Two of The Thermal Power Plant ″Nikola Tesla -B″, 2x600 MW, Yugoslavia. RCM implementation on current problems during exploitation emphasized problems with the boiler tubing system. The methodological approach included outages analyses, marking of the most significant ones, determination of main causes of damage (determination of the material exhaustion state based on expert analyses), application of adequate remaining life assessment methodolog...

Type 316 stainless steel has excellent corrosion resistance due to it's high molybdenum content. This makes it suitable for a wide range of marine and chemical applications. This report investigates the response of a 185mm×60mm×5.5mm Type 316 plate to welding done with an E2209-16 electrode under direct current electro-positive (DCEP) and direct current electronegative (DCEN) conditions. The open-circuit voltage was 60 V and the preset current was 85 A (limited by the electrode's diameter).

The Friction stir welding process is a new entrant in welding technology. The FSW joints have high strength and helps in weight saving considerably than the other joining process as no filler material is added during welding. The weld quality is affected because of various kinds of defects occurring during the FSW process. Defects like cavity, surface grooves and flash could occur due to inappropriate set of process parameters which results in excessive or insufficient heat input. Defects analysis can be done by several non-destructive methods like immersion ultrasonic techniques, X-ray radiography, thermography, eddy current testing, synchrotron technique etc. In the present work the image processing techniques are applied over the test samples to detect the surface defects like pin holes, surface grooves etc. ARTICLE HISTORY

Convective boiling beyond critical-heat-flux is encountered in a number of applications, one of which is water wall tubing of steam generators. Sometimes, the heat transfer process in particular zones of heated surfaces of boiling tubes system is combined with fluctuation of wall temperature. This phenomena is connected with heat transfer crises during departure from nucleate boiling (DNB) as well as dry out and causes the interruption of water layer along a tube wall provoked the formation of drying areas. This process has a great influence on intensity and localization of hydrogen attack and deposits formation on the waterside of the tube. Standard investigation procedure were applied on specimens taken from furnace walls tubing, made of 0.2C0.5Mn0.25Cr, steel in the purpose of failure analysis..

The successful weld between dissimilar metal is one that is as strong as the weaker of the two metals being joined. Bimetallic combinations of SS 316L and IS 2062 are used widely in the heat exchangers, super heaters employed in the oil gasification plants, chemical processing equipments, and nuclear sector. However effective welding of dissimilar metals has represented a major challenge in thermal and mechanical properties of the material to be joined under a common welding condition. Over the years the lifespan of many machines have been reduced or have not matched its estimated lifespan due to poor joints. The poor joints may be due to the improper welding joints. And variety of problems come up in dissimilar welding like cracking, large weld residual stresses, migration of atoms during welding causing stress concentration, stress corrosion cracking etc. To overcome these problems, it is required to study the effect of welding process parameters. The main purpose of this project is to study the mechanical properties of SS 316L and IS 2062 alloys welded by TIG welding and to achieve the optimized process parameters using Taguchi and ANOVA techniques. And lastly micro structural properties of the jointed materials were investigated. This process provides a purer and cleaner high volume weldment. The effect of different welding Current (110, 120,130Amp), different Voltage (40, 50,60V) and different Gas flow rate (8, 9,10Lit/min) on ultimate tensile strength and Hardness of dissimilar welding, are used to find out the significance of input parameter by DOE.

The paper deals with the development of a system for automatic weld recognition using new information technologies based on cloud computing and single-board computer in the context of Industry 4.0. The proposed system is based on a visual system for weld recognition, and a neural network based on cloud computing for real-time weld evaluation, both implemented on a single-board low-cost computer. The proposed system was successfully verified on welding samples which correspond to a real welding process in the car production process. The system considerably contributes to the welds diagnostics in industrial processes of small-and medium-sized enterprises.

The work is devoted to the problem of weld segmentation in modern methods for evaluating the quality of welds. One of the methods of the weld quality evaluation is visual inspection. This work deals with the possibility of implementing algorithms of recognition and evaluation of welds using visual system in single-board computers. Result of this paper is computing time comparison of chosen embedded single-board computers and weld segmentation results based on entropy.

RESUMEN El desgaste es un fenómeno de degradación de los diferentes materiales por efectos de abrasión, impacto, fatiga, erosión y corrosión entre otros. Este fenómeno acarrea grandes perdidas económicas por deterioro de elementos de máquinas y equipo industrial, asimismo una altísima cuota en impacto ambiental. Para contrarrestar los efectos nocivos generados por desgaste, surge la reconstrucción y mantenimiento de materiales por soldadura. Se tiene un molino vertical ATOX 32.5 para molienda de caliza con un juego de 6 placas borde de mesa, se hicieron aplicaciones de placas con revestimientos de soldadura con carburos de cromo y carburos complejos en las zonas más críticas. ABSTRACT The wearing is a phenomenon of degradation of different materials by abrasion effects, impact, fatigue, erosion and corrosion among others. This phenomenon carries great lost economic by deterioration of machines elements and industrial equipment, also a highest quota in environmental impact. In order to resist the injurious effects generated by wearing, it arises the reconstruction and maintenance from materials by weld. A vertical mill ATOX 32,5 for limestone milling is had with a wild game of 6 plates of table, applications were made more of plates with coatings of weld with complex chromium carbides and carbides in the zones critics.

The paper deals with the development of a system for automatic weld recognition using new information technologies based on cloud computing and single-board computer in the context of Industry 4.0. The proposed system is based on a visual system for weld recognition, and a neural network based on cloud computing for real-time weld evaluation, both implemented on a single-board low-cost computer. The proposed system was successfully verified on welding samples which correspond to a real welding process in the car production process. The system considerably contributes to the welds diagnostics in industrial processes of small-and medium-sized enterprises.

The main aim of the inspections is to ensure that the quality of the welds meets the design requirements and operating conditions, as well as meeting safety and reliability requirements in many industrial sectors. There are many different ways of non-destructive testing NDT are employed for checking welds. The radiographic testing RT is one of the most prevalent and widely used processes in the industry to detect both surface and subsurface defects. In recent years, industrial radiography has been well developed to be used alongside with the combination of techniques of image processing to enhance both the process of inspection and the time of operation. The RT images are often affected by some external surroundings and degraded by noises during the process of acquisition of them. The filtering process is intended to recover the original image from the corrupted one. Median filtering can be considered as an appropriate procedure since it is used by many researchers. In this paper, a comparison among four types of median filter is used to get the best one, to adopting it in welding inspection images. The peak signal to noise ratio (PSNR) and root means square error (RMSE) indexes are used to perform the quality of image filtering techniques. The results shown that the median filter is a good tool for clarification of welding defects and both adaptive median filter (AMF) and decision based median filter (DBMF) gives the best results respectively. The results obtained were consistent with the results of the engineering examination for qualified and certified welding defects inspectors.

The paper deals with the development of a system for automatic weld recognition using new information technologies based on cloud computing and single-board computer in the context of Industry 4.0. The proposed system is based on a visual system for weld recognition, and a neural network based on cloud computing for real-time weld evaluation, both implemented on a single-board low-cost computer. The proposed system was successfully verified on welding samples which correspond to a real welding process in the car production process. The system considerably contributes to the welds diagnostics in industrial processes of small-and medium-sized enterprises.

The paper deals with the development of a system for automatic weld recognition using new information technologies based on cloud computing and single-board computer in the context of Industry 4.0. The proposed system is based on a visual system for weld recognition, and a neural network based on cloud computing for real-time weld evaluation, both implemented on a single-board low-cost computer. The proposed system was successfully verified on welding samples which correspond to a real welding process in the car production process. The system considerably contributes to the welds diagnostics in industrial processes of small-and medium-sized enterprises.

This research evaluates the effect of the variables of Phased Array Ultrasonic Testing (PAUT) on the sectoral angular beam scans "S-Scan" and the geometric morphology of planar discontinuities such as the inclination for the ultrasonic beam and the shape of the extremity on accuracy in measurements. The study was carried out in two stages. During the first stage, eight ASTM A36 steel samples with machined notches by penetration from EDM and a welded sample with lack of penetration in a butt weld were designed and produced. In the second stage, it was measured the size of the discontinuities using ultrasound inspection and different configurations of the phase arrangement. The effect of each variable and inspection setting with errors between 0.2 % and 120 % were determined by statistical analysis.