Thin-walled Stainless Steel Tube Research Articles

Development, characterization, and applications of a portable analyzer for continuous monitoring of H2S in gas streams

A bench-scale analyzer for continuous monitoring of H2S in gas streams was previously described (2012 Sens. Actuators B 162 377–83). The analyzer was based on the exothermic reaction between the scrubbed H2S, in alkaline solution, with hydrogen peroxide. The analyzer offers several advantages but suffers from a relatively slow response time (i.e. 7 min) and a relatively low sensitivity (limit of detection = 100 ppm). In the present work, a substantially improved detector design and direct mixing of the gas with the liquid reagents are described. The improved detector, in the form of a coiled thin-walled stainless-steel (SS) tube also acts as a compartment for direct gas absorption and reaction with sodium hydroxide and hydrogen peroxide reagents, which eliminates the need for a gas scrubber based on microporous hollow fiber membranes (HFMs). The average temperature of the SS coil was measured by three thermocouples attached to the outer surface of the coil with thermally conductive epoxy. The improved detector design and the simplified scheme proved very successful in achieving six times faster response (i.e. 70 s) and ten times more sensitive response (i.e. 10 ppm) in the gas stream and improved repeatability (coefficient of variation = 0.55%). In addition, the previously reported advantages, such as excellent signal stability, wide dynamic range (up to 5% H2S) and convenient tuning of the sensitivity and linearity by varying the ratio between the gas and reagent flow rates were perfectly retained. The improved detector is utilized to construct a compact portable version of the H2S analyzer (∼6 kg), which provides a stand-alone operation for real-time monitoring of H2S in the gas stream for up to 4 h prior to the need for reagent refill or battery recharge. The applications of the described portable analyzer in monitoring H2S removal from H2S–N2 gas stream using an HFM contactor and absorption solvent, and in the determination of sulfide ions in liquid samples are presented. A comparison between the response of the present portable H2S analyzer and a commercial analyzer is also presented.

The impact of brazing process on mechanical properties of S30408 stainless steel by experimental investigation

The stainless steel core-plate structure is a new prefabricated structure with the stainless steel core-plate as the major component. Studying the material characteristics of the stainless steel core-plate is the premise of structure design. The panels and the core tubes (thin-walled round stainless steel tube) are welded by the copper brazing, and the mechanical properties of material may be changed by this process. The tensile tests at room temperature, elevated temperatures and after fire exposure were carried out in this paper, and the results were compared with other tests. It was found that the yield strength of S30408 Stainless steel decreased to 64% of the raw material at room temperature due to the brazing process, and the ductility was slightly increased. The mechanical properties of the material after brazing process decreased more rapidly than other tests. The improved stress-strain relationship model at room temperature and elevated temperatures of the S30408 stainless steel after brazing process was proposed.

In situ characteristics of bottom sediment in Ichkeul Lake, Tunisia

The supply of sediment to Ichkeul Lake has decreased due to the construction of several reservoirs in the upstream reaches of the rivers that flow into it. Furthermore, it is necessary to control lake sediment outflow in order to preserve the ecological balance of the lake. Soil stabilization methods could be used to prevent the erosion of bottom sediment. Therefore, this study explored the physical and mechanical condition of the lake bed in situ to aid the identification of an effective erosion prevention scheme based on solidification methods. Two locations on the lake bottom were investigated and compared: one where the sediment dried up in summer, and the other where the sediment was saturated with water throughout the year. Undisturbed samples were collected using a thin-walled stainless steel tube sampler. The shear strength and its depth distribution in the lake bed were measured using the vane shear test. The depth distributions of the shear strength at the two sampling locations studied were found to be rather different. The shear strength was highest in the surface layer at the location that was dry in summer, whereas the shear strength was lowest in the surface layer at the location that was always wet. The shear strength of the surface layer (20 mm depth) at the wet/dry location was 3.3 kPa and there was 93.1% moisture, while the shear strength at this depth at the permanently wet location was 1.8 kPa and there was 95.7% moisture. The strength of the wet/dry sediment, which underwent shrinkage when drying, was greater than that of the permanently wet sediment. This finding could facilitate the classification of areas that require soil improvement as well as the rational design of an erosion prevention plan.

Experimental investigation of boiling heat transfer in helically coiled tubes at high pressure

Helically coiled once-through steam generators have been used widely during the past several decades for small nuclear power reactors. The boiling heat transfer characteristics of helically coiled tubes are important to optimal design of helically coiled steam generators. In the present work, various experiments with helically coiled tubes are performed to investigate the boiling heat transfer characteristics at high pressure with water as the working medium. Six test sections are made of thin walled stainless steel tubes having inner diameters of 12.5 mm and 14.5 mm. The system pressure is varying from 2 to 8 MP. The effects of heat flux, mass flux and system pressure on boiling heat transfer behavior are discussed in detail. Increase in heat flux increases the subcooled boiling and saturated nucleate boiling heat transfer coefficient. However, heat flux has no influence on saturated convective boiling heat transfer coefficient. Mass flux increases the saturated convective boiling heat transfer coefficient. Increase in system pressure increases the subcooled boiling and saturated nucleate boiling heat transfer coefficient but decreases the saturated convective boiling heat transfer coefficient. For the investigated experimental conditions, the results show that the Baburajan's correlation gives the best prediction in subcooled boiling region and the Gungor and Winterton's correlation predicts well with the experimental data in saturated boiling region. For the investigated experimental conditions, the results also indicate that the helically coiled tubes have similar performance of heat transfer in boiling regions compared with straight tubes.

An experimental study on terrestrial cryogenic transfer line chilldown I. Effect of mass flux, equilibrium quality, and inlet subcooling

This is the first of a two-part series which presents the experimental results of the chilldown of a thin-walled stainless steel tube with liquid nitrogen under a wide range of pressures and mass fluxes in terrestrial gravity. Data is presented in this paper for a vertically upward (against gravity) flow orientation. The experimental data covers mass fluxes ranging from 6 to 1650kg/m2s (liquid Reynolds numbers ranging from 850 to 231,000), equilibrium two-phase flow qualities from −0.13 to 0.4, inlet subcooling from 0 to 10K and local pressures from 150 to 720kPa. The temperature and pressure measurements were made at two axial distances of 14.9cm and 40.1cm from the inlet. Analysis is presented on the effects of the mass flux, equilibrium quality, inlet subcooling, pressure, and axial distance from the tube inlet on the measured film, transition, and nucleate boiling heat transfer coefficients as well as the critical heat flux.

Some considerations on instability of combined loaded thin-walled tubes with a crack

Instability of a thin-walled stainless steel tube with a crack-shaped defect under combined loading is studied in this paper. Furthermore, the effects of the tube length, crack orientation, and crack length on the buckling behavior of tubes are investigated. The behavior of tubes subjected to combined is analyzed by using the finite element method (by Abaqus software). For cracked tubes with a fixed thickness, the buckling load decreases as the tube length and the ratio of the tube length to its diameter increase. Moreover, the buckling load of cracked tubes under combined loading also decreases with increasing crack length.

Temperature Distribution Analysis of TIG Welding Process of Thin-Walled Stainless Steel and Red Copper

The connecting pipe in solar hot water system is made by TIG welding of thin-walled stainless steel and copper. As the welding of stainless steel and copper belongs to dissimilar metal welding and their physical properties are very different, thus the welding of them is difficult and it is likely to cause a variety of defects in the welding process. In this paper, ANSYS software is used to simulate the welding process of stainless steel and copper, and the temperature distributions in the welding process are obtained. The results show that: as the heat transferring of copper is faster than stainless steel, the temperature field distribution of thin-walled stainless steel and copper tubes in the welding process is extremely uneven. As a result, the melting degrees on both sides in the welding seam are inconsistent, which may cause poor forming of weld seam. The results provide references and theoretical basis for the welding technology of dissimilar materials.

薄壁不锈钢圆管激光切割工艺研究及夹具设计

薄壁不锈钢圆管激光切割工艺研究及夹具设计

Quasi-static and dynamic axial crushing of thin-walled circular stainless steel, mild steel and aluminium alloy tubes

Quasi-static and dynamic axial crushing tests have been performed on circular thin-walled sections made of three materials: 304 stainless steel, aluminium alloy 6063-T6, and mild steel. The tests were arranged to investigate the mode transitions during the impact crushing of thin-walled tubes and the three materials were chosen for their distinctive individual characteristics, such as strain rate sensitive properties, pronounced strain hardening, etc. The stainless steel, aluminium alloy and mild steel shells have moderate diameter-to-thickness ratios, 2R/H, of 22, 33 and 26, respectively, and were examined over a range of different axial lengths that encompassed both classical progressive buckling and the global bending modes of failure. The tests were conducted at a standardised energy of 9 kJ, approximately, with a few tests repeated at a higher energy of 18 kJ. The shells were impacted at velocities up to 13.4 m/s with masses up to 502 kg. Standard collapse modes developed in the tubes and the associated energy absorbing characteristics have been examined and compared with previous studies on mild steel. Quasi-static and dynamic tensile test results on the materials are also reported and the critical slenderness ratios at the transition between the two principal modes of failure are identified. The effects of strain hardening, strain rate as well as inertia effects due to the individual characteristics of the three materials are explored.

ステンレス鋼薄肉パイプ溶接継手部の力学性状に関する研究 : 軽量ステンレス鋼構造に関する研究 その3

In recent years, stainless steel is superior in fire and corrosion resistance to ordinary steel, and is widely used as a thin walled member in the structure. Its material characteristics are considerably clarified, but the structural characteristics such as tube branches are not sufficiently studied. In this paper, the structural behaviors of the thin-walled stainless steel tubes with X branch joints are investigated by both the experiment and the FEM analysis. Expanding the concept of a ring-model, yield strength and ultimate strength of the branch joint are estimated.

A novel hermetic differential scanning calorimeter (DSC) sample crucible

The design of a novel differential scanning calorimeter (DSC) sample crucible that allows for the analysis of liquid and solid materials (the solids can also be wetted with a liquid) at high temperatures is described. The sample to be analyzed is placed within a thin walled stainless steel tube, which is then sealed by tungsten inert gas (TIG) welding. The stainless steel tube is 8.8 mm (0.35 in.) long, has an outer diameter of 3.14 mm (0.125 in.) and a wall thickness of 0.015 mm (0.006 in.). Placing the flattened end of the tube in the jaws of a large copper block (heat sink) allows for the sealing of the tube by TIG welding without heating the sample excessively. The utility of the sample crucible is demonstrated by a study of the kinetics of the thermal decomposition of di- t-butyl peroxide (DTBP), where an activation energy of 140 kJ mol −1 and a frequency factor of 5.30×10 13 s −1 was obtained.

Coupled guided acoustic modes in water-filled thin-walled tubes.

Recent results [J. D. N. Cheeke et al., J. Acoust. Soc. Am. 104, 3678 (1998)] reported a 20% decrease in group velocity for flexural mode circumferential waves propagating around water-filled thin-walled stainless-steel tubes. In the present work, the full theory of such modes is developed to explain the structure modes which originates from the coupling between the water filler and stainless tube. Calculated values of the group velocity for the first two coupled modes are in excellent agreement with experiment. The results are of interest for the physics of acoustic waves in fluid-loaded structures and have potential application for liquid level detection.

Observation of flexural Lamb waves (A mode) on water-filled cylindrical shells

Results are presented for the propagation of circumferential acoustic waves around a thin-walled stainless steel tube. Sol gel lead titanate-zirconate (PZT) films and chirp interdigital transducer (IDT) electrodes were used to generate the A0 mode from 0.8 to 6.0 MHz. Group and phase velocity measurements are in good agreement with the theory for the empty tube. When the tube is filled with water a large decrease of 21% in group velocity is observed. While there is as yet no theoretical explanation for this effect, the results show promise for liquid sensing applications.

Boiling heat transfer in the quenching of a hot tube under microgravity

Quenching of a hot tube by injection of a subcooled liquid was investigated under microgravity conditions. Liquid Freon (R-113) was injected at mass fluxes between 160-850 kg/ms into an initially hot, thin-walled stainless steel tube, 11.3 mm i.d. and 914 mm long. Data collected in microgravity aboard NASA's KC-135 aircraft were compared with quenching tests in a horizontal tube under normal gravity. The re wetting temperatures were found to be 15°-25°C lower in microgravity than those obtained under 1 g, and the film boiling heat transfer coefficients in microgravity were only 20-50% of the values obtained in 1 g. This resulted in much longer precursory cooling periods in microgravity, and hence, the time to totally quench the initially hot tube in microgravity was greatly extended. However, once the tube was cooled sufficiently to allow axial propagation of the quench front, the re wetting velocity was found to be slightly greater in microgravity. The boiling curves showed that the nucleate and transition boiling curves in microgravity were shifted to lower wall superheats as compared to 1 g as a result of the lower re wetting temperature. The heat flux profiles were otherwise quite similar, indicating that these boiling regimes are little affected by reduction in gravity.

Intracoronary Stenting—Hope or Hype?

Intracoronary Stenting—Hope or Hype?

Pulsed eddy-current inspection of thin-walled stainless steel tubing Oak Ridge National Laboratory, Oak Ridge, Tennessee (United States), ORNL-6408, 120 pp. (Sep. 1987)

Pulsed eddy-current inspection of thin-walled stainless steel tubing Oak Ridge National Laboratory, Oak Ridge, Tennessee (United States), ORNL-6408, 120 pp. (Sep. 1987)

Pulsed eddy-current inspection of thin-walled stainless steel tubing : Oak Ridge national laboratory, Oak Ridge, Tennessee (United States), DE88-001492, 118 pp. (Sep. 1987)

A pulsed eddy-current system has been developed for production inspection of small, thin-wall, non-ferromagnetic tubing. To detect and accurately size both outer and bore-side flaws required an operating frequency higher than available from present commercial equipment. A pulsed eddy-current instrument was designed and constructed that used 3.2 MHz square waves, with a bandwidth of 20 MHz. The system is able to reliably detect flaws as small as 0.015 mm (0.6 mils) on either the inner or outer surface of the tube. A computer controls the scanning of the tube, as recording, analyzing, and plotting the data. The computer programs and instrument details are given in the report.

A pulsed eddy current method for examining thin-walled stainless steel tubing : 38826 Pickett, C.A.; Koerner, D.W.; Dodd, C.V.; Deeds, W.E. Oak Ridge Y-12 Plant, Tennessee (United States), Y-DW-721, DE88-002294, 13 pp. (31 Jul. 1987)

A pulsed eddy current method for examining thin-walled stainless steel tubing : 38826 Pickett, C.A.; Koerner, D.W.; Dodd, C.V.; Deeds, W.E. Oak Ridge Y-12 Plant, Tennessee (United States), Y-DW-721, DE88-002294, 13 pp. (31 Jul. 1987)

Pulsed eddy-current inspection of thin-walled stainless steel tubing : Oak Ridge National Laboratory, Oak Ridge, Tennessee (United States), ORNL-6408, 120 pp. (Sep. 1987)

Pulsed eddy-current inspection of thin-walled stainless steel tubing : Oak Ridge National Laboratory, Oak Ridge, Tennessee (United States), ORNL-6408, 120 pp. (Sep. 1987)

Pulsed eddy-current inspection of thin-walled stainless steel tubing Oak Ridge national laboratory, Oak Ridge, Tennessee (United States), DE88-001492, 118 pp. (Sep. 1987)

Pulsed eddy-current inspection of thin-walled stainless steel tubing Oak Ridge national laboratory, Oak Ridge, Tennessee (United States), DE88-001492, 118 pp. (Sep. 1987)