Design and Development of Steel Pipe Measurement Weighing and Marking System

Literature Overview

The paper by Li Zhinong, Li Ningning, Tang Gaosong, Yue Xiuting, and Liu Benxue, published in Manufacturing Automation in 2011, presents the design and development of an integrated system for steel pipe length measurement, weighing, and marking. The system was developed in collaboration between the Key Laboratory of Non-Destructive Testing Technology at Nanchang Hangkong University and the School of Mechanical Engineering at Zhengzhou University, supported by the National Natural Science Foundation of China and other funding agencies. The system uses a Programmable Logic Controller (PLC) for control logic and Kingview (GroupWang) software for human-machine interface programming, achieving real-time communication between the PLC and weighing instruments.

System Architecture and Design Principles

The core design principle of this system is the integration of three functions—length measurement, weight measurement, and marking—into a single workstation. Traditional systems perform these functions sequentially at separate stations, which leads to long cycle times and increases the probability of missed or erroneous markings due to pipe movement between stations. By combining all three functions in one location, the system reduces the cycle time and eliminates the risk of misidentification caused by pipe displacement.

The PLC serves as the central controller, receiving input signals from the weighing instrument and length sensor, processing the data according to predefined logic, and sending control signals to the marking device. The Kingview software provides a graphical interface for operators to monitor the system status, configure parameters, and review measurement data. The communication between the PLC and the weighing instrument is established through a standard industrial protocol, ensuring reliable data transmission.

Operational Workflow and Process Integration

The operational workflow of the system follows a sequential process for each pipe passing through the workstation. First, the pipe enters the weighing platform, and the load cell measures its weight. Simultaneously, the length sensor measures the pipe length as it passes through the measurement zone. The PLC processes both measurements in real time and compares them with the expected values based on the production batch information. If the measurements are within acceptable tolerances, the PLC triggers the marking device to apply the required identification marks on the pipe surface. If the measurements deviate from the expected values, the system flags the pipe for manual inspection.

The integration of all three functions at a single workstation is achieved through precise synchronization of the pipe movement with the measurement and marking operations. The PLC controls the conveyor speed to ensure that the pipe moves at a constant velocity during measurement, which is essential for accurate length measurement. The marking operation is triggered at a specific position along the pipe, determined by the length measurement data, ensuring that the mark is placed at the correct location.

Performance Evaluation and Field Results

The field trial results demonstrate that the system performs reliably under production conditions. The key performance indicators include measurement accuracy, marking accuracy, cycle time, and system availability. The weighing accuracy meets the requirements of the applicable product standards, and the length measurement accuracy is sufficient for quality control purposes. The marking accuracy is significantly improved compared to the previous multi-station system, with virtually no missed or erroneous marks reported during the trial period.

The cycle time reduction is a significant practical benefit. By eliminating the need to transfer pipes between separate measurement, weighing, and marking stations, the system reduces the total processing time per pipe and increases the throughput of the production line. The operator workload is also reduced because the system automates the data recording and comparison process, requiring only supervision and intervention in case of anomalies.

Quality Control Integration and Traceability

From a quality control perspective, the integrated system enables comprehensive traceability of each pipe. The weight and length data are recorded along with the marking information, creating a complete quality record for each individual pipe. This data can be linked to the production batch, heat number, and test results, providing a full traceability chain from raw material to finished product. In the event of a quality issue in the field, the traceability data allows for rapid identification of affected pipes and targeted corrective actions.

The system also supports statistical process control by accumulating measurement data over time. Trends in weight and length variations can be monitored to detect process drifts early, allowing for preventive maintenance of the production equipment before quality issues arise. This proactive approach to quality management is consistent with modern manufacturing philosophies such as Total Quality Management and Six Sigma.

Study Insights and Recommendations for Pipe Manufacturing

The development of this integrated measurement, weighing, and marking system represents a practical application of industrial automation to improve the efficiency and quality of steel pipe production. For pipe manufacturers, the key insight is that integrating multiple quality control functions into a single automated workstation not only improves accuracy and consistency but also reduces labor costs and increases throughput. The system design should be tailored to the specific pipe dimensions and production speeds of each facility, and the PLC logic should be programmed to handle edge cases such as overlapping pipes, stuck pipes, or sensor failures.

From a standards compliance perspective, the system should be designed to meet the measurement accuracy requirements specified in the applicable product standards, such as API 5L, EN 10216, or GB/T standards. The weighing system should be calibrated regularly, and the length measurement sensors should be verified against reference standards to ensure ongoing accuracy. The marking system should be designed to produce marks that are legible and durable under the expected service conditions of the pipes.