High availability in flat steel production

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4 minutes Reading time
4 minutes Reading time

Many flat steel production plants operate 24/7 to efficiently fulfill customer orders. Salzgitter Flachstahl GmbH uses the Industrial IoT to monitor measurement technology in a continuous pickling line and optimize maintenance processes.

The challenge: Constant availability in 24/7 operation

Salzgitter Flachstahl GmbH products can be found in many households – for example as food cans, table frames, balcony railings, in car bodies or as refrigerator housings. One process step is further processing in cold rolling mills. A crucial step in this process is the removal of the oxide layer (burn-off) from the steel production process. For this purpose, Salzgitter uses a continuous pickling line that performs its task in a continuous flow.

In the continuous pickling line, individual coils are unwound, straightened and then welded to the tail of the previous strip. The resulting endless strip is then passed through an acid bath and then cleaned in a sink. Finally, the strip is trimmed at the edges, oiled and separately rewound into individual coils. The plant operates 24/7 and is only stopped every two weeks for a scheduled maintenance and repair shutdown.

Thus, the continuous pickling line processes an average of around 2,500 tons of steel per shift. If the plant were to fail, there would be a threat of interruption to flat steel production at Salzgitter Flachstahl’s cold rolling mill. The continuous pickling line is thus a core unit in production and is very highly automated. To improve availability, the continuous pickling line started a digitization project together with Endress+Hauser some time ago. Until now, detailed examination of the condition of the measurement technology required reading the information on site in the plant. The central recording and visualization of all condition data in the Netilion is intended to increase the availability of the plant.

The solution: Expanding automation technology with an Industrial IoT solution

During the construction of the continuous pickling line, the approximately 330 meter long line in the chemical area was equipped with more than 100 measuring points. These measuring points, which are networked via a field bus, determine all the measured variables required for automation, such as flow rate, level, temperature, pressure, pH value and conductivity. The automation of the continuous pickling line consists of more than 13 different automation devices (PLC). These systems are fully networked with field buses. Approximately 2,500 nodes are managed in these fieldbuses.

The solution automatically scans the entire metrology fieldbus and registers all devices found, eliminating the need for manual configuration. The Ethernet/PROFIBUS gateway SFG500 routes data out of the fieldbus and sends it to a cloud via an edge device connected to the Internet. There the application creates Netilion Analytics from the Netilion IIoT ecosystem from Endress+Hauser a digital twin of every device. It is a representation of the plant status including all measured values and warning messages. Netilion Health enables employees at Salzgitter Flachstahl GmbH to see the condition of equipment and also provides direct access to maintenance information. 

To feed the data out of the automation infrastructure, Endress+Hauser uses a second fieldbus channel in read-only mode. Thus, there is no interference with the automation technology and data security remains guaranteed. Although the entire system is connected to the Internet via the edge device, no one can interfere with its operation. To prevent eavesdropping, data is transmitted encrypted using the standard TLS(Transport Layer Security) protocol. In addition, the overall system has a security architecture that avoids cyberattacks.

The result: Faster and more precise maintenance processes

The primary task of the Netilion solution is to monitor the condition of the measurement technology, detect malfunctions at an early stage and determine maintenance requirements. This should improve plant availability, ultimately increasing throughput.

In addition, the solution is designed to make the work of maintenance and repair personnel easier. With Netilion, technicians receive all the necessary information – the location of the machine, the type of malfunction, and the necessary tools and spare parts – before they even go out on the job.

Currently, the solution is operating as a pilot project and is being continuously further developed. In the near future, for example, Salzgitter also intends to use predictive maintenance for the measurement technology used in order to optimize maintenance processes.

Once all the requirements of Salzgitter Flachstahl GmbH have been met, the concept can be quickly transferred to other plants and mills. Netilion can be integrated into systems with HART, Profibus DP/PA, Ethernet IP, Modbus TCP and Profinet fieldbuses without major changes to the plant architecture, provided that the sensors and actuators to be monitored are networked via these. The online services are future-proof, as the cloud allows the application to be scaled as required.

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