Seamless Casing Pipe 1.Grade: J55,K55,N80,L80,P110 2.Thread:BTC, LTC,STC 3.Standard: API 5CT, ISO 4. ... Ltd. in April 2011. (Formerly known as YingKou OuYang Steel Tube Co., Ltd.) YingKou OuYang Metal Manufacturing Co., Ltd. ... very near to two Chinese famous steel plants one is Anshan Iron and steel plant ,the other one is Benxi ... Iron and Steel plant. Due to this reason, we have ...