Experimental and numerical analyses of an U-bend tube made of an output inter-heater tube after exploitation

One of the important tasks of evaluating the integrity of mechanical process elements and structures is to determine the local mechanical properties. In this paper, experimental and numerical analyses of the mechanical behavior of an output inter-heater tube, made of 12H1MF heat-resistant steel, was performed after 200,000 h of exploitation. During exploitation, the tube was exposed to various mechanisms of damage including gas corrosion. The tube was cut from a pipe system during reparations of a thermal power plant, and then cold-deformed by bending to obtain a U-bend tube, which was then used in the experiment. For this purpose, a specimen holder made of structural steel S235 was specifically designed to test such a sample. The U-bend tube was then exposed to the external compressive load during the experiment. Experimental research was based on the application of the 3D digital image correlation (DIC), while a finite element method (FEM) was applied in numerical simulation performed by using the Abaqus software package. The 3D DIC is an optical and contactless experimental method that allows measurements of displacement fields and deformations of geometrically complex structures. The Aramis system was used for the experimental analysis as well as for verification of the numerical model. During the experiment, the von Mises strain field was measured at the top of the U-bend tube, in the tightening zone, as it represents a critical place for crack initiation and propagation during the work of an inter-heater. Based on the obtained results and a comparative analysis of experimental and numerical values of the von Mises strain field at the U-bend tube, deviation of the model predictions of about 18 % was determined. The FEM predicted smaller values of the von Mises strain field compared to the DIC method. This is the result of an incomplete geometry applied in the model due to deformation that occurred in the bend zone of the U-bend tube, loss of material and the tube surface damage due to the influence of gas corrosion during 200,000 h of exploitation. Experimental analysis has confirmed that the U-bend tube, after 200,000 h of exploitation, can remain in service even if it is damaged due to the effect of gas corrosion.

Leakage Investigation on a Fired Heater Tube of a Petroleum Refinery due to Carburization

The fired heater of a petroleum processing refinery leaks in one of the convection tubes. The tube is made of ASTM A-106 Gr.B. Process fluid in the tube is xylene with a design pressure of 15.8 kg/cm²g and design temperature of 299 °C (at the inlet) and 405 °C (at the outlet). This study aims to determine the type and causes and the mechanism of leakage in the tube. A number of tests have been carried out including visual inspection and macroscopic analysis, chemical analysis, metallographic and hardness testing, and SEM (scanning electron microscopy) analysis which is equipped with EDS (energy dispersive spectroscopy). The results obtained showed that the leak that occurred in the convection tube was caused by carburization and metal dusting. Carburization occurs in the inner walls of the tube that experience some localized overheating due to the formation of coke deposits. AbstrakDapur pemanas pada sebuah kilang pengolahan minyak bumi mengalami kebocoran pada salah satu pipa konveksi. Pipa tersebut terbuat dari baja karbon rendah jenis ASTM A-106 Gr.B. Cairan proses di dalam pipa adalah xylene dengan tekanan desain 15,8 kg/cm²g dan suhu desain yaitu 299 °C (pada saluran masuk) dan 405 °C (pada saluran keluar). Penelitian ini bertujuan untuk menentukan jenis dan faktor penyebab serta mekanisme terjadi kebocoran pada pipa tersebut. Sejumlah pengujian telah dilakukan meliputi pemeriksaan visual dan makroskopik, analisa kimia, pengujian metalografi dan kekerasan, serta analisa SEM (scanning electron microscopy) yang dilengkapi dengan EDS (energy dispersive spectroscopy). Hasil penelitian yang diperoleh menunjukkan bahwa kebocoran yang terjadi pada pipa konveksi disebabkan oleh karburisasi dan pembentukan debu/serbuk logam. Karburisasi terjadi pada dinding bagian dalam pipa yang mengalami panas berlebih secara lokal akibat terbentuknya endapan kokas.

Tissue Processor Based PLC (Programmable Logic Controller)

Tissue Processor Tissue Processor consists of consists of several stages of dehydration, clearing, and paraffin infiltration.Phase dehydration to remove water content in tissues by immersion into alcohol. Clearing stage is the process of pulling out the alcohol content in the network by using a liquid xylol. Paraffin infiltration stages is the stage of filling cavities with liquid paraffin tissue. The purpose of this research is to modify the equipment that had broken before became an useful equipment that use basic controlled PLC. This modification tool-making using the "one-group posttest design" by treatment of the instrument without first measuring the initial state, the results of treatment directly measured without comparison to a control group. Making the modification tool using PLC as the main controller throughout the series. The tool mechanical motion using DC motors and AC motors as well as the use of two sensors limit switch as the controller limits the motor movement. Based on the results obtained temperature measurement error with the largest value of 4.44% in paraffin heater tube 1 and the biggest error of 4.0% in paraffin heater tube 2. While the measurement time of each - each tube obtained the smallest error on the tube-to-one by 0 , 03%, and the biggest error of measurement contained in the tube to the fourth, fifth, sixth, eighth and tenth of 0.16%.