RESEARCH ARTICLE
Heat Transfer Modeling of an Annular OnLine Spray Water Cooling Process for ElectricResistance-Welded Steel Pipe Zejun Chen1*, Huiquan Han2, Wei Ren1, Guangjie Huang1 1 State Key Laboratory of Mechanical Transmission, College of Materials Science and Engineering, Chongqing University, Chongqing, 400044, China, 2 CISDI Engineering Co., Ltd., Chongqing, 400013, China * [email protected]
Abstract
OPEN ACCESS Citation: Chen Z, Han H, Ren W, Huang G (2015) Heat Transfer Modeling of an Annular On-Line Spray Water Cooling Process for Electric-ResistanceWelded Steel Pipe. PLoS ONE 10(7): e0131574. doi:10.1371/journal.pone.0131574 Editor: Amitava Mukherjee, VIT University, INDIA Received: November 26, 2014 Accepted: June 3, 2015 Published: July 22, 2015 Copyright: © 2015 Chen et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
On-line spray water cooling (OSWC) of electric-resistance-welded (ERW) steel pipes can replace the conventional off-line heat treatment process and become an important and critical procedure. The OSWC process improves production efficiency, decreases costs, and enhances the mechanical properties of ERW steel pipe, especially the impact properties of the weld joint. In this paper, an annular OSWC process is investigated based on an experimental simulation platform that can obtain precise real-time measurements of the temperature of the pipe, the water pressure and flux, etc. The effects of the modes of annular spray water cooling and related cooling parameters on the mechanical properties of the pipe are investigated. The temperature evolutions of the inner and outer walls of the pipe are measured during the spray water cooling process, and the uniformity of mechanical properties along the circumferential and longitudinal directions is investigated. A heat transfer coefficient model of spray water cooling is developed based on measured temperature data in conjunction with simulation using the finite element method. Industrial tests prove the validity of the heat transfer model of a steel pipe undergoing spray water cooling. The research results can provide a basis for the industrial application of the OSWC process in the production of ERW steel pipes.
Data Availability Statement: All relevant data are within the paper and its Supporting Information files. Funding: The authors would like to acknowledge the project is supported by the Fundamental Research Funds for the Central Universities (No. CDJZR14135504), and supported by National Natural Science Foundation of China (No. 51421001). Coauthor Huiquan Han is employed by CISDI Engineering Co., Ltd. CISDI Engineering Co., Ltd. provided support in the form of salary for author HH, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific
Introduction Steel pipes for oil and gas have to serve in harsh environments and need to withstand high temperatures and pressures and corrosive conditions. Therefore, the American Petroleum Institute (API) has drawn up a standard to strictly regulate the manufacture and application of steel pipes as casing or tubing for wells [1]. Improvement of the mechanical properties and performance of steel has become an important topic of research and application for scientists and engineers. The use of stronger steel allows the thickness of pipeline walls to be significantly reduced, with consequent reductions in weight and cost. High strength in combination with high toughness and formability are important requirements for the pipeline industry [2].
PLOS ONE | DOI:10.1371/journal.pone.0131574 July 22, 2015
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Heat Transfer Modeling of Spray Water Cooling for ERW Steel Pipe
role of this author is articulated in the ‘author contributions’ section. Competing Interests: The authors have the following interests: Co-author Huiquan Han is employed by CISDI Engineering Co., Ltd. There are no patents, products in development or marketed products to declare. This does not alter our adherence to all the PLOS ONE policies on sharing data and materials.
The production of electric-resistance-welded (ERW) pipe begins with a coiled plate of steel of appropriate thickness and width depending on the required specification. The ribbon is pulled through a series of rollers that gradually form it into a cylindrical pipe. As the edges of the cylindrical plate come together, an electric charge is applied at appropriate points to heat the edges so that they can be welded together [3]. The production of ERW steel pipe is a highspeed and comparatively economical procedure, because most of the processes involved can be automated. Pipes of uniform wall thicknesses and outside dimensions can be made, with a wide range of other specifications. Because of these advantages, the application of ERW steel pipes has risen steadily in recent years. However, conventional ERW steel pipes do not have sufficiently high strength and formability for some applications. The reason is that such steel pipes are manufactured by cold roll forming of steel bands, and work hardening reduces the ductility of the pipe compared with that of the band from which it is formed. In addition, the rapid cooling process after welding gives rise to quench hardening at the welding joint [4]. To enhance the mechanical properties and performance of ERW steel pipes, especially with regard to the weld joint, attention must be paid to the heat treatment process, which is an essential and indeed critical procedure [5]. In general, this process is performed off-line by electric induction heating. The off-line heat treatment process reduces productivity and increases energy consumption and costs. To overcome the disadvantages of conventional off-line heat treatment, new manufacturing procedures for ERW steel pipes are presented here, based on an on-line spray water cooling system. A schematic diagram of these procedures is shown in Fig 1. The detailed manufacturing route can be described as follows: steel strip ! slitting strip ! cold roll forming ! high-frequency welding ! induction heating ! reducing and sizing ! on-line spray water cooling (OSWC) process ! finishing ! ultrasonic test ! cutting. The OSWC process is a necessary and critical procedure for the on-line heat treatment of ERW steel pipes. It can enhance productivity, decrease energy consumption and costs, and improve the mechanical properties of ERW steel pipe, especially the impact performance of the weld joint. Rapid OSWC of hot steel pipe is performed immediately after hot deformation or welding. The spray water cooling reduces the temperature of the surface, leading to efficient grain refinement [6]. The thermomechanical treatment is performed to realize on-line control of the microstructure and mechanical properties of the steel pipe [7]. During the on-line heat treatment process, the microstructure of the steel will be transformed again into austenite owing to the electric induction heating. It is easy for this to result in coarsening of the microstructure, thus leading to a deterioration in mechanical properties, if the phase transformation is not effectively controlled. Therefore, the rapid OSWC process is critical for improving mechanical properties. If on-line thermomechanical treatment can be carried out satisfactorily, this will lead to refinement of the microstructure of the steel pipe, thus allowing high strength and excellent formability to be achieved simultaneously. Although some temperature models and predictions of heat transfer in spray cooling have been published, they have generally been limited to flat-plate, full-cone sprays [8]. It is very
Fig 1. Schematic diagram of new ERW manufacturing procedure for steel pipe. doi:10.1371/journal.pone.0131574.g001
PLOS ONE | DOI:10.1371/journal.pone.0131574 July 22, 2015
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Heat Transfer Modeling of Spray Water Cooling for ERW Steel Pipe
difficult to apply these approaches to the annular spray water cooling process for steel pipes. In this paper, the annular spray water cooling process is investigated based on an experimental simulation platform, which makes precise real-time measurements of the temperature of the steel pipe and the water pressure and flux. The effects of the spray water cooling process on temperature evolution and mechanical properties of steel pipe, and the uniformity of mechanical properties along the circumferential and longitudinal directions were investigated and validated by the experiment of laboratory and industrial tests. A convective heat transfer coefficient model for annular spray water cooling is developed based on the measured temperature data in conjunction with a simulation using the finite element method (FEM). The ultimate aim is to obtain excellent mechanical properties and performance of steel pipes by implementing an appropriate on-line heat treatment process based on the heat transfer model of the annular OSWC process.
Annular Spray Water Cooling Experiment Materials and specification J55 grade steel pipes were used to investigate the temperature model of the OSWC process. In API SPECT 5CT [1], the composition of steel pipes for J55 grade is specified only in terms of the maximum contents of sulfur and phosphorus. The content of carbon can vary over a large range. The chemical composition of the J55 ERW steel pipe used in this study is shown in Table 1, and its dimensions were outside diameter 139.7mm, wall thickness 7.72mm, and length 600mm.
Cooling experimental platform In the new manufacturing process, the ERW steel pipe was heated to above the austenitizing temperature by electric induction heating, and then its diameter was reduced and sized to various specifications. To refine the microstructure and improve strength and formability, annular OSWC was carried out for the thermomechanically processed pipe. The cooling equipment and cooling process for steel pipe are different from those for steel plate because of their different shapes and heat dissipation properties. The cooling process and effect are influenced by many factors and parameters, such as the cooling technique, the number and arrangement of nozzles, and the flux and pressure of the cooling water. An annular spray water cooling experimental platform was constructed to help in confirming and investigating the roles of cooling parameters (the flux and pressure of the cooling water) and in designing the cooling technique. It consisted of a water tank, pumps and pipelines, a spraying system, a resistance furnace, and a test data acquisition system (Fig 2). The ERW steel pipe was heated by the resistance furnace, and temperatures were measured by waterproof thermocouples [9,10]. The water flux and pressure could be adjusted according to the specified experimental schemes. All data on the water flux and pressure and the temperature of the steel pipe were collected automatically in real time by the test data acquisition system. In the spray water cooling system, the arrangement of nozzles is very important for the effect and uniformity of cooling. Fig 3 shows the internal structure of the spray water cooling box. Two typical nozzle arrangements were evaluated by laboratory simulation experiments, as Table 1. Chemical compositions of J55 ERW steel pipe (%). C
Si
Mn
P
S
V+Nb+Ti
0.21
0.30
1.40
0.025
0.015
0.15
doi:10.1371/journal.pone.0131574.t001
PLOS ONE | DOI:10.1371/journal.pone.0131574 July 22, 2015
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Heat Transfer Modeling of Spray Water Cooling for ERW Steel Pipe
Fig 2. Schematic diagram of cooling experimental platform for steel pipe. doi:10.1371/journal.pone.0131574.g002
shown in Fig 4. In one, the spray direction of the nozzles was centripetal along the circumference. In the other arrangement, the spray directions were tangent to a certain concentric circle of radius r. The centripetal nozzle arrangement will result in severe lateral spatter of water. Large quantities of cooling water then flow into the pipe and lead to a rapid temperature drop at the bottom of the inner wall. The non-uniform temperature distribution results in non-
Fig 3. Internal structure of cooling box. doi:10.1371/journal.pone.0131574.g003
PLOS ONE | DOI:10.1371/journal.pone.0131574 July 22, 2015
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Heat Transfer Modeling of Spray Water Cooling for ERW Steel Pipe
Fig 4. Arrangement of nozzles for spray water cooling system. (A) Centripetal. (B) Tangential to a circle of radius r. doi:10.1371/journal.pone.0131574.g004
uniformity of the microstructure and the mechanical properties around the circumference of the pipe. The tangential arrangement of the nozzles can greatly reduce the lateral spatter of cooling water and improve the uniformity of the temperature of the pipe around its circumference. Furthermore, the radius of the circle tangent to the spray direction is less than the radius of the pipe (r
Heat Transfer Modeling of an Annular OnLine Spray Water Cooling Process for ElectricResistance-Welded Steel Pipe Zejun Chen1*, Huiquan Han2, Wei Ren1, Guangjie Huang1 1 State Key Laboratory of Mechanical Transmission, College of Materials Science and Engineering, Chongqing University, Chongqing, 400044, China, 2 CISDI Engineering Co., Ltd., Chongqing, 400013, China * [email protected]
Abstract
OPEN ACCESS Citation: Chen Z, Han H, Ren W, Huang G (2015) Heat Transfer Modeling of an Annular On-Line Spray Water Cooling Process for Electric-ResistanceWelded Steel Pipe. PLoS ONE 10(7): e0131574. doi:10.1371/journal.pone.0131574 Editor: Amitava Mukherjee, VIT University, INDIA Received: November 26, 2014 Accepted: June 3, 2015 Published: July 22, 2015 Copyright: © 2015 Chen et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
On-line spray water cooling (OSWC) of electric-resistance-welded (ERW) steel pipes can replace the conventional off-line heat treatment process and become an important and critical procedure. The OSWC process improves production efficiency, decreases costs, and enhances the mechanical properties of ERW steel pipe, especially the impact properties of the weld joint. In this paper, an annular OSWC process is investigated based on an experimental simulation platform that can obtain precise real-time measurements of the temperature of the pipe, the water pressure and flux, etc. The effects of the modes of annular spray water cooling and related cooling parameters on the mechanical properties of the pipe are investigated. The temperature evolutions of the inner and outer walls of the pipe are measured during the spray water cooling process, and the uniformity of mechanical properties along the circumferential and longitudinal directions is investigated. A heat transfer coefficient model of spray water cooling is developed based on measured temperature data in conjunction with simulation using the finite element method. Industrial tests prove the validity of the heat transfer model of a steel pipe undergoing spray water cooling. The research results can provide a basis for the industrial application of the OSWC process in the production of ERW steel pipes.
Data Availability Statement: All relevant data are within the paper and its Supporting Information files. Funding: The authors would like to acknowledge the project is supported by the Fundamental Research Funds for the Central Universities (No. CDJZR14135504), and supported by National Natural Science Foundation of China (No. 51421001). Coauthor Huiquan Han is employed by CISDI Engineering Co., Ltd. CISDI Engineering Co., Ltd. provided support in the form of salary for author HH, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific
Introduction Steel pipes for oil and gas have to serve in harsh environments and need to withstand high temperatures and pressures and corrosive conditions. Therefore, the American Petroleum Institute (API) has drawn up a standard to strictly regulate the manufacture and application of steel pipes as casing or tubing for wells [1]. Improvement of the mechanical properties and performance of steel has become an important topic of research and application for scientists and engineers. The use of stronger steel allows the thickness of pipeline walls to be significantly reduced, with consequent reductions in weight and cost. High strength in combination with high toughness and formability are important requirements for the pipeline industry [2].
PLOS ONE | DOI:10.1371/journal.pone.0131574 July 22, 2015
1 / 19
Heat Transfer Modeling of Spray Water Cooling for ERW Steel Pipe
role of this author is articulated in the ‘author contributions’ section. Competing Interests: The authors have the following interests: Co-author Huiquan Han is employed by CISDI Engineering Co., Ltd. There are no patents, products in development or marketed products to declare. This does not alter our adherence to all the PLOS ONE policies on sharing data and materials.
The production of electric-resistance-welded (ERW) pipe begins with a coiled plate of steel of appropriate thickness and width depending on the required specification. The ribbon is pulled through a series of rollers that gradually form it into a cylindrical pipe. As the edges of the cylindrical plate come together, an electric charge is applied at appropriate points to heat the edges so that they can be welded together [3]. The production of ERW steel pipe is a highspeed and comparatively economical procedure, because most of the processes involved can be automated. Pipes of uniform wall thicknesses and outside dimensions can be made, with a wide range of other specifications. Because of these advantages, the application of ERW steel pipes has risen steadily in recent years. However, conventional ERW steel pipes do not have sufficiently high strength and formability for some applications. The reason is that such steel pipes are manufactured by cold roll forming of steel bands, and work hardening reduces the ductility of the pipe compared with that of the band from which it is formed. In addition, the rapid cooling process after welding gives rise to quench hardening at the welding joint [4]. To enhance the mechanical properties and performance of ERW steel pipes, especially with regard to the weld joint, attention must be paid to the heat treatment process, which is an essential and indeed critical procedure [5]. In general, this process is performed off-line by electric induction heating. The off-line heat treatment process reduces productivity and increases energy consumption and costs. To overcome the disadvantages of conventional off-line heat treatment, new manufacturing procedures for ERW steel pipes are presented here, based on an on-line spray water cooling system. A schematic diagram of these procedures is shown in Fig 1. The detailed manufacturing route can be described as follows: steel strip ! slitting strip ! cold roll forming ! high-frequency welding ! induction heating ! reducing and sizing ! on-line spray water cooling (OSWC) process ! finishing ! ultrasonic test ! cutting. The OSWC process is a necessary and critical procedure for the on-line heat treatment of ERW steel pipes. It can enhance productivity, decrease energy consumption and costs, and improve the mechanical properties of ERW steel pipe, especially the impact performance of the weld joint. Rapid OSWC of hot steel pipe is performed immediately after hot deformation or welding. The spray water cooling reduces the temperature of the surface, leading to efficient grain refinement [6]. The thermomechanical treatment is performed to realize on-line control of the microstructure and mechanical properties of the steel pipe [7]. During the on-line heat treatment process, the microstructure of the steel will be transformed again into austenite owing to the electric induction heating. It is easy for this to result in coarsening of the microstructure, thus leading to a deterioration in mechanical properties, if the phase transformation is not effectively controlled. Therefore, the rapid OSWC process is critical for improving mechanical properties. If on-line thermomechanical treatment can be carried out satisfactorily, this will lead to refinement of the microstructure of the steel pipe, thus allowing high strength and excellent formability to be achieved simultaneously. Although some temperature models and predictions of heat transfer in spray cooling have been published, they have generally been limited to flat-plate, full-cone sprays [8]. It is very
Fig 1. Schematic diagram of new ERW manufacturing procedure for steel pipe. doi:10.1371/journal.pone.0131574.g001
PLOS ONE | DOI:10.1371/journal.pone.0131574 July 22, 2015
2 / 19
Heat Transfer Modeling of Spray Water Cooling for ERW Steel Pipe
difficult to apply these approaches to the annular spray water cooling process for steel pipes. In this paper, the annular spray water cooling process is investigated based on an experimental simulation platform, which makes precise real-time measurements of the temperature of the steel pipe and the water pressure and flux. The effects of the spray water cooling process on temperature evolution and mechanical properties of steel pipe, and the uniformity of mechanical properties along the circumferential and longitudinal directions were investigated and validated by the experiment of laboratory and industrial tests. A convective heat transfer coefficient model for annular spray water cooling is developed based on the measured temperature data in conjunction with a simulation using the finite element method (FEM). The ultimate aim is to obtain excellent mechanical properties and performance of steel pipes by implementing an appropriate on-line heat treatment process based on the heat transfer model of the annular OSWC process.
Annular Spray Water Cooling Experiment Materials and specification J55 grade steel pipes were used to investigate the temperature model of the OSWC process. In API SPECT 5CT [1], the composition of steel pipes for J55 grade is specified only in terms of the maximum contents of sulfur and phosphorus. The content of carbon can vary over a large range. The chemical composition of the J55 ERW steel pipe used in this study is shown in Table 1, and its dimensions were outside diameter 139.7mm, wall thickness 7.72mm, and length 600mm.
Cooling experimental platform In the new manufacturing process, the ERW steel pipe was heated to above the austenitizing temperature by electric induction heating, and then its diameter was reduced and sized to various specifications. To refine the microstructure and improve strength and formability, annular OSWC was carried out for the thermomechanically processed pipe. The cooling equipment and cooling process for steel pipe are different from those for steel plate because of their different shapes and heat dissipation properties. The cooling process and effect are influenced by many factors and parameters, such as the cooling technique, the number and arrangement of nozzles, and the flux and pressure of the cooling water. An annular spray water cooling experimental platform was constructed to help in confirming and investigating the roles of cooling parameters (the flux and pressure of the cooling water) and in designing the cooling technique. It consisted of a water tank, pumps and pipelines, a spraying system, a resistance furnace, and a test data acquisition system (Fig 2). The ERW steel pipe was heated by the resistance furnace, and temperatures were measured by waterproof thermocouples [9,10]. The water flux and pressure could be adjusted according to the specified experimental schemes. All data on the water flux and pressure and the temperature of the steel pipe were collected automatically in real time by the test data acquisition system. In the spray water cooling system, the arrangement of nozzles is very important for the effect and uniformity of cooling. Fig 3 shows the internal structure of the spray water cooling box. Two typical nozzle arrangements were evaluated by laboratory simulation experiments, as Table 1. Chemical compositions of J55 ERW steel pipe (%). C
Si
Mn
P
S
V+Nb+Ti
0.21
0.30
1.40
0.025
0.015
0.15
doi:10.1371/journal.pone.0131574.t001
PLOS ONE | DOI:10.1371/journal.pone.0131574 July 22, 2015
3 / 19
Heat Transfer Modeling of Spray Water Cooling for ERW Steel Pipe
Fig 2. Schematic diagram of cooling experimental platform for steel pipe. doi:10.1371/journal.pone.0131574.g002
shown in Fig 4. In one, the spray direction of the nozzles was centripetal along the circumference. In the other arrangement, the spray directions were tangent to a certain concentric circle of radius r. The centripetal nozzle arrangement will result in severe lateral spatter of water. Large quantities of cooling water then flow into the pipe and lead to a rapid temperature drop at the bottom of the inner wall. The non-uniform temperature distribution results in non-
Fig 3. Internal structure of cooling box. doi:10.1371/journal.pone.0131574.g003
PLOS ONE | DOI:10.1371/journal.pone.0131574 July 22, 2015
4 / 19
Heat Transfer Modeling of Spray Water Cooling for ERW Steel Pipe
Fig 4. Arrangement of nozzles for spray water cooling system. (A) Centripetal. (B) Tangential to a circle of radius r. doi:10.1371/journal.pone.0131574.g004
uniformity of the microstructure and the mechanical properties around the circumference of the pipe. The tangential arrangement of the nozzles can greatly reduce the lateral spatter of cooling water and improve the uniformity of the temperature of the pipe around its circumference. Furthermore, the radius of the circle tangent to the spray direction is less than the radius of the pipe (r
