Abstract: Addressing the high cost of using conventional instruments for data acquisition, this paper proposes a design method for a deformation detector for subsea pipelines based on the concept of a "virtual instrument." The system mainly comprises three modules: data acquisition, data transmission, and data analysis. The data acquisition module utilizes a USB-1208FS acquisition card, the data transmission module employs RS-232 serial communication, and the data analysis module leverages the powerful analytical capabilities of LabVIEW software. Experimental results validate its feasibility and effectiveness.
Keywords: Virtual instrument; Pipeline deformation; Data acquisition; Detector; Industrial computer; Displacement sensor
Intermediate Classification Number: TP9 Document Identification Code: A
Design of Undersea Pipeline Inside Diameter Deformation Detector Based on LabVIEW
CAI Da-wei
(College of Automatic and electronic engineering Qingdao University of Science&Technology, Qingdao 266042, China)
Abstract: In view of problems that price of data acquisition is very high in use of real instrument , the paper put forward a design scheme of undersea pipeline inside diameter deformation detector based on LabVIEW. The system included the three modules such as data acquisition, data transmission and data analysis. validity.
Key words: Virtual Instrument; pipeline inside diameter deformation; data acquisition; detector; Industrial Personal Computer; displacement sensor
0. Introduction
After offshore oil and gas pipelines are put into operation, due to the harsh environment, high pressure, and corrosion from harmful gases such as water, oil, and hydrogen sulfide, some pipe sections are corroded, the pipe walls become thinner, the strength decreases, and cracks and pipe deformation are easily generated [1]. At present, pipeline defect detection requires very small pipeline deformation. If the deformation inside the pipeline is not detected before pipeline defect detection, it is very easy for the pipeline defect detection instrument to get stuck in the pipe section with large deformation [2].
One of the outstanding features of virtual instruments is that the upgrade of system software largely replaces the replacement of instrument hardware, which will save a lot of money and represents the development direction of instrument technology. At present, virtual instrument technology has made great progress abroad, but in China, the development and application of virtual instrument technology is still in its initial stage [3].
This paper develops a data acquisition system for the deformation, pressure and distance of submarine pipelines based on the virtual instrument LabVIEW[4] and the USB-1208FSP data acquisition card[5] of MCC Company of the United States. It realizes high-speed data acquisition, storage, transmission and analysis of pipeline deformation, pressure and distance parameters, and provides a basis for real-time judgment of the deformation of submarine pipelines.
1. Overall Structure of the Detection Instrument System
The deformation detector for subsea pipelines consists of two parts: hardware and software. The structural block diagram of the detector is shown in Figure 1.
The detector is designed based on the CS-480DX industrial computer. It is propelled forward by high-pressure water or high-pressure gas injected into the pipeline. During the journey, the travel is recorded by the rotation of the odometer wheel sensor. The odometer wheel sensor generates clock pulses during rotation. The number of rotations of the odometer wheel is obtained by recording the rising or falling edge of the pulse, thereby obtaining the travel of the odometer wheel. The pipeline deformation is determined by the angular displacement sensor. When the pipeline reaches the deformation position, the angular displacement sensor will change accordingly, thereby obtaining the deformation at that deformation position. The detector needs to detect 16 pipeline deformation signals, the pressure difference before and after the detector, and the number of rotations of the odometer wheel. The clock on the industrial computer is used to time-mark the collected data. The collected data is first stored in the FLASH memory card of the industrial computer, and then transmitted to the host computer through RS-232 serial communication [6].
2. System Hardware Design
2.1 Deformation Data Acquisition
The detector is divided into 16 points along the circumference, and the angular displacement sensor is installed at each of these points. The angular displacement sensor is model RM22V, and the output signal is a voltage signal of 0~5V. Since the data acquisition card USB-1208FS is a voltage signal input, the magnitude of the deformation can be determined by the magnitude of the input voltage to the data acquisition card.
2.2 Pressure Data Acquisition
One pressure sensor is installed before and after the detector, and another is installed after it to measure the pressure before and after the detector, thus determining whether the detector is stuck. The sensor model is JYB-K0-HAG, and its output signal is a 4~20mA voltage signal. A 250Ω precision resistor is connected in parallel to the analog input terminal of the data acquisition card to convert the current signal into a 1~5V voltage signal. The pressure is then determined by the magnitude of the input voltage to the data acquisition card. This pressure sensor has a linear output and a range of 0~0.5MPa. The voltage input range of the data acquisition card is 1~5V. The scaling conversion formula is as follows:
In the formula: x is the pressure signal containing the pressure information being collected that is input into the computer by the data acquisition card, and y is the original pressure value corresponding to x [7].
2.3 Data Collection from the Mileage Wheel
The travel signal data of the odometer wheel is acquired by mounting odometer wheel sensors (model RM221) on both sides of the detector. When the detector moves, the odometer wheel sensors generate pulse signals, which are then recorded via the USB-1208FS's count port. The detected travel distance is obtained using the following conversion formula:
Where: y1 is the travel distance of the odometer wheel in cm, and x1 is the number of rising or falling edges of the recorded pulse.
3. System Software Design
Both the host computer data analysis software system and the slave computer data acquisition system are developed using LabVIEW software. LabVIEW is a graphical programming language and development environment. Compared with the traditional text programming environment, it can help users design data acquisition and data processing systems in a shorter time. All LabVIEW programs (VIs) include a front panel and a block diagram [8]. The deformation, pressure and distance data acquisition and analysis system in the submarine pipeline also includes a front panel and a block diagram. It mainly completes the real-time acquisition, waveform display, analysis, alarm and real-time storage of pipeline deformation, pressure and distance parameters.
3.1 Front panel of system software
The front panel of the host computer system software consists of three parts: a user login section, a data storage section, and a waveform display section. The user login interface is used to set system permissions. The data storage section stores the collected data; the waveform display section shows real-time curves of the parameters from the 16-angle displacement sensor, pressure parameters, and odometer wheel parameters. The front panel of the slave computer system software primarily handles data acquisition.
3.2 System Software Flowchart
The flowchart of the host computer system software is shown in Figure 2. (a) is the serial port data receiving module, and (b) is the data storage module. The host computer system mainly consists of three parts: waveform display, data storage, and report generation.
1) Waveform Display. The 16-channel displacement sensors use separate and centralized waveform displays. The 2-channel pressure sensors and the 2-channel odometer wheel sensors are also displayed separately. The displayed images facilitate data analysis.
2) Data storage. The collected deformation, pressure and odometer wheel data are stored as text files, which consist of the sampling time and the sampled data[9].
3) Generate reports. The storage of the pipe deformation array is achieved by creating a table.vi file, as shown in Figure 3. This module can convert one or more signals into a data table, listing the amplitude of each signal and the time data for each point in the signal.
The lower-level system software primarily uses the data acquisition module provided by MCC that is compatible with the USB-1208FS. Figure 4 shows the channel creation module, which allows selection of the data acquisition channel on the acquisition card. Figure 5 shows the data reading module, which allows reading data from the acquisition channel. Figure 6 is a flowchart of a data acquisition program for an analog channel and a digital channel.
Data Acquisition. MCC provides a driver for the USB-1208FS data acquisition card in LabVIEW, making data acquisition using the USB-1208FS very convenient in LabVIEW.
4. Conclusion
The subsea pipeline internal deformation detection system designed in this paper was developed using LabVIEW. Utilizing the USB-1208FS data acquisition card from MCC Corporation (USA), it achieves high-speed acquisition, transmission, display, storage, and analysis of pipeline deformation, pressure, and distance data, providing a solid foundation for real-time pipeline deformation detection. Once successfully developed, the subsea pipeline internal deformation detection system can be widely applied to deformation detection of various underwater and onshore pipelines. When used in conjunction with related inspection and maintenance equipment, it can be used for the inspection and maintenance of most subsea pipelines. This system boasts low development costs, a user-friendly interface, simple structure, and convenient operation.
References
[1] Li Jun, Wang Hongbin, Li Yan. Main factors affecting the lifespan of submarine pipelines and prevention suggestions [J]. Petroleum Engineering Construction, 2007, 33(2): 35-38.
[2] Zhou Yilin, Zhan Zhitao. A new type of deformation detector for subsea pipelines [J]. Pipeline Technology and Equipment, 2008, 4: 24-26.
[3] Li Tao, Lei Wanzhong. Research on data acquisition system based on LabVIEW [J]. Industrial and Mining Automation, 2010.11, 11: 121-124.
[4] Li Jiangquan. Typical Examples of Virtual Instrument Design, Measurement and Control Applications [M]. Beijing: Electronic Industry Press, 2010.8
[5] MCC Corporation, USA, USB-1208FS Installation and User Manual [R]. USA: MCC Corporation, 2007.
[6] Hu Qiong, Fan Shidong. Pipeline flow and pressure data acquisition system based on virtual instrument [J]. Traffic Information and Safety, 2009, 5(27): 120-123.
[7] Pan Xia. Development of a comprehensive experimental system for pipeline leakage detection [D]. Wuhan: Wuhan University of Technology, 2006.
[8] Nasser K, Namjin K. Digital signal processing system-level design using LabVIEW [M]. Oxford: Elsevier Inc, 2005.
[9] Lei Zhenshan, Zhao Chenguang. Data storage technology for virtual instrument systems [J]. Microcomputer Information, 2006, 22(8):117-119
