Sunhaji Kiyai Abas

Critical process and performance parameters of thermal arc spray coating

Usage of thermal spray coating for corrosion protection was started since early 1900. Even though it was successful, the application was limited. In recent years, most industries especially oil and gas companies have selected the thermal spray wire arc coating as a corrosion protection for steel structure. Advancement in coating research causes major developments in coating processes, equipments, and raw materials for coating. It leads to further expansion in functional coatings and applications scope from conventional coating to specialised industries. The selection of the thermal arc spray coating is due to its ability to act as an effective corrosion protection, able to withstand high process temperature, and cost saving. Previous research revealed that thermal arc spray coating provides better coating characteristics compared to other method of sprays. This paper reviews some critical part of thermal arc spray coating by discussing the process parameter of thermal arc spray technology and quality control of coating. Comparison between coating material usage was reviewed to determine the best applied material coating in certain critical environment. Coating performance against corrosion, wear and special characteristic of coating are discussed. The field application of arc spray technology is presented.

Thermal Arc Spray Overview

Usage of protective coating for corrosion protection was on highly demand during the past decade; and thermal spray coating played a major part during that time. In recent years, the thermal arc spray coating becomes a popular coating. Many big players in oil and gas such as PETRONAS, EXXON MOBIL and SHELL in Malaysia tend to use the coating on steel structure as a corrosion protection. Further developments in coating processes, the devices, and raw materials have led to expansion of functional coatings and applications scope from conventional coating to specialized industries. It is widely used because of its ability to withstand high process temperature, offer advantages in efficiency, lower cost and acts as a corrosion protection. Previous research also indicated that the thermal arc spray offers better coating properties compared to other methods of spray. This paper reviews some critical area of thermal spray coating by discussing the process/parameter of thermal arc spray technology and quality control of coating. Coating performance against corrosion, wear and special characteristic of coating are also described. The field application of arc spray technology are demonstrated and reviewed.

Predicting Bead Geometry of 2F-Fillet Joint Welded by Small Wire SAW

The cost of development of WPS will be very expensive if the welding parameter is selected based on trial and error. Optimal welding condition cannot be easily guessed unless the operator has records of good welding. If a calculator that can predict the welding parameter for the desired bead geometry accurately, such tool will be extremely useful for any fabrication industry. This paper intends to investigate the correlation between the welding parameter and weld bead geometry of 2F position T-fillet carbon steel, when welded by 1.2 mm diameter wire submerged arc welding. Keeping only one parameter as variable, 2F fillet weld coupons are welded by SAW with a range of welding current, welding voltage and welding speed. Only weld bead geometry that complied with the quality requirement of code of practice AWS D1.1 is considered. The trendline graph is created to fit the correlation between the heat input and the fillet weld geometry. By incorporating the trendline formulas into the calculator, the weld bead geometry can be predicted accurately for any welding parameter. The mean absolute deviation (MAD) between the predicted geometry and the experimental results is less than 0.50mm.

Prediction of Flux Cored Arc Welding (FCAW) Parameters and Bead Geometry in Downhill Position (3F)

The robot can perform Flux Cored Arc Welding (FCAW) at high productivity and consistency in quality. The quality of the welding depend on the selection of welding parameter and deposition geometry. These input has to be known before the start of production, generally the welding operator will obtain the information through experimental trial and error. This project planned to develop a tool that can advise the choice of welding parameter that produce quality weld bead with desired geometry. This research focused on the correlation of heat input on weld bead geometry and the range of welding parameter for fillet design welded in downhill direction (3F). From the correlation trend-line equations and welding parameter population boundary, the weld bead geometry and welding parameter for quality deposit are predicted. Consequently two calculators were developed to display the values digitally. The deviation of predicted bead geometry from actual welding is less than 1mm. Mean Absolute Deviation (MAD) is less than 0.4mm, accuracy is good. A wide range of welding parameters can be generated for quality welding at desired bead geometry.

Correlation between welding parameter and bead geometry of flux cored arc welding (FCAW) in horizontal position (2F)

A robotic system can convert the semi-automatic Flux Cored Arc Welding (FCAW) to an automatic welding system. The critical requirement in automated welding process is that the optimal welding parameter has to be set before welding start. These input welding parameters cannot be easily guessed unless one has the knowledge. Only very specific range of heat input that produces quality weld deposition. The correlation between the heat input and fillet weld bead can be displayed in a unique trend-line graph. Mathematical formulas that match the trend-line profile can be used to create a prediction calculator that displays the digital values of weld bead geometry when welded at a specific range of heat input. Small Mean Absolute Deviation between predicted and measured geometry means good prediction accuracy. With this correlation chart, the welding parameter for quality weld bead can be selected and the geometry of FCAW weld deposition in 2F position can be predicted accurately without trial and error.

Modeling and optimization of weld zone development in resistance seam welding

Resistance Seam Welding (RSEW) is an ideal welding method to produce airtight joints where welding input parameters play a very significant role in determining the quality of weld nugget and heat affected zone (HAZ) formation. This research is aimed to study the nugget and HAZ development of 1 mm low carbon steel using RSEW. Welding parameters such as weld current, weld time, weld speed and pressure were identified and investigated to study their effect on the formation of weld nugget by using 24 factorial designs. The objective of this work is to find the optimum parameter to optimize the width of weld nugget and HAZ in order to obtain a good quality of RSEW. Furthermore the mathematical models were developed to predict the weld zone development. Experimental confirmation test was conducted at an optimal condition for observing accuracy of the developed model. Based on the confirmation test, the proposed method can be effectively used to predict the size of weld zone which can improve the welding quality and performance in RSEW.

Distortion Analysis on Multipassed Butt Weld Using FEM and Experimental Study

This paper investigates the simulation technique for analyzing the distortion behavior induced by welding process on welded plate which was clamped on one side. This clamping method is intended to enable the investigation of the maximum distortion on the other side. FEA software SYSWELD was employed to predict multipassed butt weld distortion of low carbon steel with thicknesses of 6 mm and 9 mm. The simulation begins with the development of model geometry and meshing type followed by suitable selection of heat source model represented by the Goldak’s double ellipsoid model. Other parameters such as travel speed, heat input, clamping method etc. were determined. The model is dedicated for multipass welding techniques using Gas Metal Arc Welding (GMAW). The experimental works were conducted by using Robotic welding process.

Casting Core Using Synthetic Resin Coated Sand: Mechanical Properties and Physical Characteristics

This paper outlines the study on synthetic resin coated sand which is one of the main moulding materials for manufacturing of moulds and cores in the casting process. The physical characteristics of the synthetic resin coated sand were analyzed for microstructure observation, Grain Fineness Number (GFN), Loss on Ignition (LOI) and X-ray Diffraction (XRD). Two sets of sample were cured at temperatures 200°C and 250°C with a curing time variation of 30, 45, 60, 75 and 90 minutes each. All samples will be tested for mechanical testing: transverse strength, impact (Charpy and Izod) and tensile tests. The results of the study showed that the mechanical properties were greatly influenced by the curing temperature and time. Whereas, the physical characteristics such as the sand grain shape, size and distribution as well as the major constituents of the synthetic resin coated sand were discovered. The data gathered proved to be beneficial for the casting production of cores.Copyright