Bimetallic Pipe Research Articles

Design of welded double layer pipelines

The methods of producing two-layer pipelines of different design, including bimetallic pipes, consisting of carbon and high-alloyed stainless steels, are investigated. It is shown that at optimum design, the welded joints in the pipes should be distributed in a zigzag order so that the welded joints on the external and internal pipes are away from each other.

Performance Analysis on CRA-Clad Pipes Extruded from Bimetallic Centrifugal Castings

Recently a new method for manufacturing bimetal clad pipes is introduced, which can integrate centrifugal casting with extrusion technology organically. Through experimental study on microstructure and properties of bimetallic clad pipes manufactured by centrifugal casting and extruding, the results indicates that bimetal clad pipes with intact metallurgical interface have good bonding properties. Meanwhile wider interfacial zone will be favorable for reducing deformation stress. However there are still a few technical difficulties about the bimetallic clad pipe. Due to chemical composition and properties difference between backing materials and CRA layer, chemical elements will spread and microstructure will change during the process of production and even mechanical behavior of backing metal pipe and corrosion resistance of CRA layer will decline. To meet application requirements, appropriate heat treatment with bimetal clad pipes seems vita.

Research on Hydroforming of Bimetallic Lined Pipe

A new kind of hydraulic expansion device for bimetallic CRA-lined pipe has been researched and developed, as well as its operational principal and technical characteristic were introduced. The stress and strain in the liner and outer pipe during the hydroforming process have been analyzed theoretically and the mechanism of hydraulic expansion method is studied, and the final forming pressure formula has been obtained. The theoretical analysis is verified by experimental investigation, the results indicate that the new technology is feasible and can be applied in industrial production.

Analysis of the thermal efficiency, volume, and weight characteristics of heat exchange sections of air cooling equipment

Comparisons and analysis are carried out for the thermal efficiency, volume, and weight characteristics of clusters used in ndustry, and new types of bimetallic finned pipes (BFP). It is established that in a collection of properties a cluster of pipes made of BFP with wound KLM-fins is the optimum. The results obtained make it possible to make a substantiated choice of BFP sizes with modifications and the construction of heat exchange sections for air cooling equipment.

Fabrication of composite pipes by multi-billet extrusion technique

A processing technique named multi-billet extrusion (MBE) has been developed to fabricate clad composites. The MBE process is characterized by co-extruding several solid billets made of the same materials or of different ones, joining them in welding chambers and finally obtaining a desired extrudate by means of a die. It is capable of fabricating bimetallic, metal–ceramic, and ceramic–ceramic composite pipes. An extruded Al alloy/pure Al bimetallic pipe is bonded metallurgically due to the diffusion of Cu atoms across the interface during hot extrusion. In order to fabricate metal–ceramic composite pipes, a powder MBE method based on the plastic flow forming of pastes was used. It is shown that sound extrudates can be obtained no matter what mixing ratios of zirconia and stainless steel powders are used. It is possible to join inner and outer layers well after sintering, as long as the combinations of powder composition and binder content are adequate in the inner and outer layers. Moreover, the preparation of metal–ceramic three-layer pipes and ceramic–ceramic two-layer pipes by a similar powder MBE process is established as feasible.

Some experiences on electricity production at low powers with DSG using parabolic troughs

The following aspects have been carried out in order to implement the direct steam generation (DSG) which works with 4 parabolic troughs modules: 1) Control with computer has been adapted to this system, mainly to study transient states. 2) Some first surface aluminium mirrors have been installed in some regions of the parabolic troughs. During two years their reflectance have not changed. 3) A commercial generator with an efficiency of about 90% has been installed, so solar-electricity efficiency has increased to about 8%. 4) A bimetallic compound pipe absorber (bushing) of copper and steel is proposed to be installed in the future.

Thermal contact resistance of a bimetallic finned pipe and a method of calculating interference between contacting surfaces

Bimetallic pipes, consisting of a smooth steel pipe with spiral fins rolled on to the pipe are used widely in air cooling systems, heaters, condensers of refrigeration equipment, and air and gas coolers. The authors have examined the effect of the change of the height of the fin of thermal contact resistance (TCR) and the contact pressure between the steel surface and the surface of an aluminium shell and developed an approximate method of determining TCR and contact pressure which satisfies the requirements of engineering calculations

Measurement of gripping stress in mechanically bonded bimetallic pipe by AE techniques

Measurement of gripping stress in mechanically bonded bimetallic pipe by AE techniques

Effects of Laser Surface Melting on Corrosion Resistance of Stainless Steel and Nickel-base Alloy Clad Layers in Cast Bi-metallic Pipes.

Laser surface melting for the inner layers of cast bi-metallic pipes has been investigated. Three kinds of centrifugally cast bi-metallic pipes of which inner layers are made of the stainless steel 904L, the nickel-base alloys 825 and 625, respectively were used. Laser surface melting was performed using a 2.5 kW CO2 laser unit with the beam traveling velocity being varied in order to achieve different cooling rates. Corrosion resistance was evaluated by the critical current density for passivation, the pitting potential and the density of pits after the FeCl3 solution immersion test. Corrosion test results indicate that laser surface remelting has a remarkable effect to improve pitting corrosion resistance in the alloy clad layers. EPMA analysis has revealed that element distributions across the solidification cell in the laser-treated alloys become more homogeneous than those in the as-cast alloys. Consequently, the concentrations of molybdenum and chromium at the dendrite cores which decrease in the as-cast alloys, enhance with laser surface melting, which results in the improvement of corrosion resistance in the laser treated alloy layers of the bi-metallic pipes. The theoretical calculation using the Kurz-Giovanola-Trivedi model has demonstrated that the change in element distributions in the laser treated alloys can be attributed to the increased solidification rate by laser surface melting.

Analysis of Bimetallic Pipe for Sour Service

Summary This paper presents the results of laboratory investigations conducted to better our definition of the serviceability of bimetallic pipe manufactured by the thermohydraulic (tight-fit) method for Mobile Bay service. Both Alloy 625/API X-65 and Alloy 825/API X-65 tight-fit pipe (TFP) were evaluated under conditions of (1) standard corrosion test environments to evaluate the metallurgical conditions of the corrosion-resistant-alloy (CRA) liner tubes, (2) long-term, full-scale TFP exposure under a simulated Mobile Bay production environment containing high levels of H2S and CO2, and (3) hydrogen-permeation experiments designed to examine potential effects of CRA liner collapse from hydrogen produced by corrosion on the ID and/or cathodic protection on the OD. Results indicate that bimetallic TFP exhibited an acceptable metallurgical condition of the CRA liner materials. Under the simulated Mobile Bay production environment, TFP exhibited good resistance to general corrosion, stress-corrosion cracking (SCC), and liner collapse. Hydrogen-permeation tests indicate that very conservative estimates of service-life liner collapse from interfacial hydrogen pressure range from 150 to more than 800 years, depending on conditions. For all practical purposes, liner collapse from hydrogen is not a limiting factor for TFP flowline applications.

Corrosion resistant bimetallic pipe manufactured by HIP and hot extrusion(HHE) process.

Corrosion resistant bimetallic pipe manufactured by HIP and hot extrusion(HHE) process.

Special features of crack propagation in the material of bimetallic pipes manufactured by various methods

I. V.M. Leshchenko, B. D. Kosov, and I. A. Kozlov, "Stress-strain and limiting states of flywheels made of composite materials with spokes, report I. Calculation dependences," Probl. Prochn., No. 8, 98-102 (1985). 2. B.D. Kosov, A. P. Pokhil'ko, I. A. Kozlov, and V. M. Leshchenko, "Stress-strain and limiting states of flywheels made of composite materials with spokes, report 2. Optimization of the design in respect of energy capacity," Probl. Prochn., No. 12, 81-86 (1985). 3. B.D. Kosov, I. A. Kozlov, V. M. Leshchenko, and A. P. Pokhil'ko, "Stress-strain and limiting states of flywheels made of composite materials with spokes, report 3. Selection of materials for components of an energy storing device," Probl. Prochn., No. 12, 86-89 (1985). 4. E.K. Ashkenazi, N. B. Gol'fan, L. P. Rozhkov, and N. P. Sidorov, Components Made of Glass-Reinforced Plastic in Ship Engineering [in Russian], Sudostroenie, Leningrad (1974).

液相拡散接合法による金属二重管製造技術の開発

液相拡散接合法による金属二重管製造技術の開発

Elastic Thermal Stresses in Bimetallic Pipe Welds

The elastic thermal stresses in a welded transition between two pipes of the same size but different alloys are explored. A stress-free temperature is postulated and the stress due to a uniform change in temperature is characterized by the maximum stress intensity in the weld. A simple expression for predicting this maximum stress intensity is developed based on the results of finite element analysis.

Manufacture of bimetallic pipes

Manufacture of bimetallic pipes