Hydraulic systems for steel works in India

Hydraulic systems for steel works in India
Marginal Column

July 2016


In hardly any other industry are conditions as extreme as those faced in metallurgy. Bosch Rexroth supplied unprecedented numbers of hydraulic parts for one steel works in India. Thanks to customized solutions, they are also doing their job reliably even in harsh environments.

India produced 90 million metric tons of steel last year, thereby making it the fourth largest steel-producing nation in the world. Yet the demand for this versatile material is far from being satisfied. The auditing and consulting company PricewaterhouseCoopers (PwC) is forecasting a roughly 3 percent annual rise in the global demand for steel by 2025. Production will thereby increase from the current level of 1,623 million metric tons to 2,351 million metric tons. PwC is attesting to the fact that India especially will see above-average growth over the next few years. The National Mineral Development Corporation (NMDC), a state-controlled Indian mining company, is bracing itself for this. In Nagarnar, a small location in the central Indian federal state of Chhattisgarh, the country's largest iron ore mining company is currently building a steel works which is expected to produce three million metric tons of steel annually from mid-2017 onwards. Rexroth's technology is supporting the path taken by iron ore en route to becoming finished sheet steel at various key stages.

The valve stands (l.) and the reservoir stands are part of a gigantic contract with more than 550 hydraulic units for a steel plant in India.

The valve stands (l.) and the reservoir stands are part of a gigantic contract with more than 550 hydraulic units for a steel plant in India.


From coke to sheet metal

For Sumit Patel and Daxesh Patel, project managers at Bosch Rexroth in India, collaboration on this large-scale project was something quite special: “Never before have we produced and supplied such a comprehensive hydraulics system in India – in excess of 550 hydraulic units are used in the plant as a whole,” says Sumit Patel, explaining the dimensions. In this regard, the coke oven represents the first stage in Rexroth's technology doing its job. Here, coke is produced from coal, which is necessary for pig iron production in the blast furnace. The Bhilai Engineering Corporation, an expert in heavy machine construction, was responsible for this plant component. “We have already been collaborating with Bosch Rexroth in India over a number of years. We therefore knew that we could depend on the company's know-how,” emphasizes B G. Muralidhar from Bhilai Engineering Corporation. “The hydraulics system in the coke oven alone uses more than 500 cylinders,” reports the responsible project manager, Daxesh Patel.

The lion's share of Rexroth technology is, however, to be found in the subsequent production process. After the pig iron has been converted into steel, the hot molten metal reaches the continuous casting line where the thin slabs are produced. A hot strip mill then processes these slabs into sheets, which is wound into coils. For the continuous casting line and the hot strip mill, the NMDC commissioned the Indian subsidiary of Danieli & C. Officine Meccaniche S.p.A.. The Italian group is a leading plant manufacturer for the metallurgical industry. “We were seeking a complete solution for driving and controlling these plants. Moreover, the services offered during and after purchasing were also very important to us,” explains Punya Kumar Chandeliya of Danieli India. Acceptance followed after a delegation from the Italian parent company had inspected Bosch Rexroth's plant in Sanand. The list of components used in itself reveals the size of the order: 48 groups of motor pumps, 58 storage modules, 308 control blocks, 103 valve stands, 24 sets of oil reservoir units, 13 sets of recirculation units and 178 servo valves and valves for closed-loop control assist in fashioning thin sheets out of molten steel. Added to this are numerous servicing facilities and monitoring systems, including portable fill units and contamination monitoring units or Electrostatic liquid cleaners.

Numerous customized solutions

“The order was highly complex on account of the many components. In addition, we have fulfilled a number of customer-specific parameters,” explains Sumit Patel. For example, in order for the control blocks to be able to defy the extreme operating conditions, the engineers used special steel with a hard-wearing coating. The nameplates themselves were riveted and not bonded in some other way. Furthermore, numerous specific safety regulations had to be observed. These included special protection for the pressure tubes but also the servo valves and valves for closed-loop control with fail-safe position. “We have developed extra special electrical interfaces for these valves,” says Sumit Patel.

The many customized solutions were also possible because Bosch Rexroth was able to draw on a global network in India. “Already at the inquiry stage, we developed the technical solutions in close coordination with the colleagues of the sector in Germany. In addition, Bosch Rexroth in Italy provided us with support when coordinating with Danieli.”