... . Very recently,we signed a contract of double-submerged arc spiral welding pipe mill with domestically leading high iron grade up ... X80,Φ406mm-Φ1422mm ,with Yangzhou Tongya Pipe Co.,Ltd.The Spiral Welding Pipe Mills designed and manufactured by our company have ... mill production process's perspective,they can be divided into: Accumulator Pit Stored Welding Material,or Backward Swing Long Machine Unit ...