Production site Photo: Courtesy of Taiyuan Heavy Machinery Group Co

The world's largest φ530mm in diameter Assel skew-rolling pipe production line, designed and manufactured by Taiyuan Heavy Machinery Group Co has been successfully put into production, a major step toward self-sufficiency in high-end manufacturing equipment, the Science and Technology Daily reported on Saturday. 

The operation of the production line marks a major breakthrough in the country's large-diameter, medium-thickness seamless steel pipe equipment capabilities and closes a gap in the international market, said the report.

Cross rolling is a rolling method between longitudinal and transverse rolling. It is mainly used for the piercing and rolling of pipes. Large seamless steel forgings are in high demand in China's hydro-power, wind-power and nuclear-power generation industries, Xinhua News Agency reported.

Previously, the giant steel structure used to be forged by segmented welding assembly. However, the welding joints were vulnerable to high pressure, posing safety concerns in nuclear power generation, said the Xinhua report.

The newly commissioned production line is the first in China to employ a "double closed loop + double circuit hydraulic" collaborative control system. According to the company, this architecture delivers precise and stable full process control from roll positioning to rolling force. In particular, the pressure closed loop subsystem features a millisecond level rapid response, which the company says eliminates end of pipe deformation problems and ensures consistent quality from each pipe's head to tail.

In addition, the production line's motor system uses a grouped, centralized-control layout, reducing both capital outlay and power demand. Rolling time per pipe has been cut from three minutes to 1.5 minutes, effectively doubling capacity while also reducing natural-gas consumption. This is expected to lower the user's annual production costs by nearly 10 million yuan ($1.4 million), according to the company.

Notably, the production line employs online automatic replacement technology for the piercing head, reducing changeover time from five minutes to just six seconds and greatly improving production efficiency, said the company.

Global Times