• Journal of Advanced Marine Engineering and Technology
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• v.37 no.5
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• pp.548-556
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• 2013

A tapered production tubing with two different inner diameters has been suggested to increase production rates. In this research, various tapered tubing combinations are taken into account and possible tubing combinations are proposed to satisfy each objective. In previous studies, production enhancement was the main goal. However, this research also considers flow stability by analyzing tubing pressure traverse, liquid holdup, and operating conditions. For a reservoir assumed in this research, a tapered tubing of, 4.5 inch inner diameter(ID) and 2000 ft in length in the lower part and 5.5 inch ID and 8000 ft in the upper part, shows the highest net present value. Compared to a mono tubing, tapered tubings enable various tubing designs because they have smaller differences in frictional pressure loss. It is important to maintain low liquid holdup to prevent liquid loading. Smaller ID of tapered tubing in the lower part enables to achieve the object. In conclusion, it is identified that various tubing designs are achievable from the analyses of overall production operations depending on purposes specified.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.3
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• pp.212-219
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• 2014

As subsea production has been revived up, the demand of subsea equipment has also been increased. Among the equipment, subsea tree plays a major role in safety. The tubing hanger is one of the most important components in subsea tree. In this study structural reliability analysis on dual bore tubing hanger of subsea tree is performed. The target reliability which is introduced in ISO regulation is used for judging whether tubing hanger is safe or not. The considered loads are working pressure, working temperature and suspended tubing weight. Thermal-stress analysis on tubing hanger is performed and kriging model is created based on the results of FEM analysis. According to von Mises criterion, limit state equation can be estimated. Reliability analysis is performed by using level 2 method and the result is verified by that of Monte Carlo Simulation. For finding most probable failure point, enhanced HL-RF method is adopted. Because the reliability of model doesn't reach target reliability, an improvement measure should be considered. Thus, it is suggested to change the material of tubing hanger main body to AISI 4140.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.3
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• pp.749-761
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• 2014

Tubing adapter is a key connection device in Gas-Tight Deep-Sea Water Sampler (GTWS). The sealing performance of the tubing adapter directly affects the GTWS's overall gas tightness. Tubing adapters with good sealing performance can ensure the transmission of seawater samples without gas leakage and can be repeatedly used. However, the sealing performance of tubing adapters made of different materials was not studied sufficiently. With the research discussed in this paper, the materials match schemes of the tubing adapters were proposed. With non-linear finite element contact analysis and sea trials in the South China Sea, it is expected that the recommended materials match schemes not only meet the requirements of tubing adapters' sealing performance but also provide the feasible options for the following research on tubing adapters in GTWS.

• Nuclear Engineering and Technology
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• v.54 no.9
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• pp.3225-3234
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• 2022

Alloy 690 tubing has been shown to be highly resistant to primary water stress corrosion cracking (PWSCC). Nevertheless, predicting the failure by PWSCC in Alloy 690 SG tubes is indispensable. In this work, a Bayesian-based statistical approach is proposed to predict the occurrence of failure by PWSCC in Alloy 690 SG tubing. The prior distributions of the model parameters are developed based on the prior knowledge or information regarding the parameters. Since Alloy 690 is a replacement for Alloy 600, the parameter distributions of Alloy 600 tubing are used to gain prior information about the parameters of Alloy 690 tubing. In addition to estimating the model parameters, analysis of tubing reliability is also performed. Since no PWSCC has been observed in Alloy 690 tubing, only right-censored free-failure life of the tubing are available. Apparently the inference is sensitive to the choice of prior distribution when only right-censored data exist. Thus, one must be careful in choosing the prior distributions for the model parameters. It is found that the use of non-informative prior distribution yields unsatisfactory results, and strongly informative prior distribution will greatly influence the inference, especially when it is considerably optimistic relative to the observed data.

• Journal of Aerospace System Engineering
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• v.12 no.1
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• pp.47-56
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• 2018

In this paper, the structural analysis of the Geostationary Korea Multi-Purpose Satellite-2 (GEO-KOMPSAT-2) tubing system is discussed, and the structural integrity of the tubing system is assessed by comparative analysis with the results of overseas partner AIRBUS. Securing structural reliability of the tubing system is a very important key element of the propulsion system of the GEO-KOMPSAT-2 satellite. Therefore, FE modeling of the propulsion tubing was carried out directly using the CAE program, and structural analysis was performed to evaluate the stress state under launch conditions. Hoop stress, axial stress, bending stress, and torsion stress were calculated according to diverse load conditions by using pressure stress analysis, thruster alignment analysis, sine qualification load analysis, and random qualification load analysis. From the results, the Margin of Safety (MoS) of the tubing system is evaluated, and we can verify the structural integrity of the tubing system when subjected to various launch loads.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.4
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• pp.258-267
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• 2015

Eddy current testing is widely used for inspecting steam generator tubing in nuclear power plants (NPPs). The inspection technique for steam generator tubing in NPPs should be qualified in accordance with examination guidelines. When the components of a qualified system such as eddy current tester, probe, and data analysis program, are changed, the equivalency of the modified system to the originally qualified system must be verified. The eddy current tester is the most important part of an eddy current testing system because it excites and transmits alternating currents to the probe, receives coil impedance of the probe and generates signals for anomalies. The Korea Hydro & Nuclear Power Co., Ltd. (KHNP) developed an eddy current testing system with an eddy current tester and data acquisition-analysis program for inspecting the steam generator tubing in NPPs; this system can be used for an array probe and as a bobbin and rotating probes. The equivalency assessment for the currently developed system was carried out, and we describe the results in this paper.

• Journal of the Korean Chemical Society
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• v.39 no.11
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• pp.863-868
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• 1995

We have prepared microcolumns made of stainless steel tubing, glass-lined stainless steel tubing, and silica-lined stainless steel tubing and examined their performances comparatively. The length of columns was fixed as 30 cm, and the I.D.'s, either 1 mm or 0.5 mm. Octadecyl bonded silica paticles $(5\mu)$ were used as the stationary phases. p-Nitroaniline, N,N-dimethyl-o-nitro-p-toluidine,and ethylbenzene were used as the test solutes. The glass-lined or silica-lined stainless steel columns showed better performances than the plain stainless steel column did. The number of theoretical plates over 10,000 were obtained even for the 0.5 mm I.D. (30 cm long) column as long as the glass-lined stainless steel tubing was used.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.5 no.1
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• pp.20-24
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• 2009

There is extensive tubing pipe in the nuclear power plant under high temperature and pressure. Erosion and corrosion defects are expected on this tubing pipe due to environmental and mechanical factors. In this study, Guided Ultrasonic Wave technique was applied to detect defects. The technique explores the advantages of the Guided Ultrasonic Wave method that inspects along the wall of the pipe and can travel long distances, providing rapid collection of data. This paper presents a case study of the Guided Ultrasonic Wave testing of 3/8" tubing pipe. This study offers to understand detected signals through correlation between amplitude and depth of defects.

• Journal of the Korean Society of Safety
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• v.23 no.5
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• pp.79-83
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• 2008

The corrugated stainless steel tubing(CSST) for the fuel gas piping system can be installed easily and quickly. It is often constructed under the ceiling and the wall which has a good flexibility and installation in comparison with iron pipe. However, the quality of the CSST is determined to depend upon the welding skill of stainless steel tubing. In this study, it is tested by controlling jet point of Ar as inert and cooling gas, and also compared with the bead state of welding point and the performance. As a result, it has the best condition when the jet point of Ar is located behind $5{\sim}10mm$ of the welding point.

• Polymer(Korea)
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• v.32 no.5
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• pp.440-445
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• 2008

The failure mechanism and failure morphology of linear low density polyethylene (LLDPE) tubing under hydrostatic pressure were investigated. Microscopic observations using video microscope and scanning electron microscope indicate that the failure mode is a brittle fracture including cracks propagated from inner wall to outer wall. In addition, oxidation induction time and Fourier transform infrared spectroscopy results show the presence of exothermic peak and the increase in carbonyl index on the surface of fractured LLDPE tubing, due to thermal-degradation. An accelerated life test methodology and testing system for LLDPE tubing are developed using the relationship between stresses and life characteristics by means of thermal acceleration. Statistical approaches using the Arrhenius model and Weibull distribution are implemented to estimate the long-term life time of LLDPE tubing under hydrostatic pressure. Consequently, the long-term life time of LLDPE tubing at the operating temperature of $25^{\circ}C$ could be predicted and also be analyzed.