Research and Development of SEW Oil Casing

SEW oil casings in steel grades of J55, N80Q and P110 are developed by means of employment of such processes as HFW, hot stretch-reducing and pipe over-length heat treatment. The mechanical properties and corrosion resistance of the SEW oil casing are tested. The results show that the data of dimensional accuracy, residual stress and external collapse strength of the SEW casing are much better than the seamless oil casing. Moreover, thanks to the SEW process, the problem of low impact toughness and poor corrosion resistance of weld seam is properly fixed. Based on the above mentioned analysis, it is concluded that in case of the same specific steel grade and size, using the SEW casing can avoid the shortcoming of poor collapse strength as staying with the seamless casing so as to meet the requirements by oilfield end users.