To meet the need for the Project of Jining Branch Natural Gas Pipe Line under the "West-to-East Natural Gas Transmission Pipe Line Project", The R & D of X80 straight SAW pipe ( Ф 1016 mm × 18.

It briefly introduces the importance of pre-bending process for production of longitudinal submerged arc welding pipe,function of pre-bending and pre-bending procedure,and analyzes main pre-bending process parameter,such as radius of curvature of upper mould,pre-bending length and pre-bending coiling angle and pre-bending force,etc.

The purpose of prebending process of longitudinal submerged arc welding pipe production line is introduced;character of roller prebending and mould press type prebending is analyzed.

It shows that China has basically been provided with the capacity to supply longitudinal submerged arc welded pipe which can meet the requirements of API Spec.

With regard to transverse cracks during LSAW pipe production,this article analyzed generating reasons from two aspects of stress status and production technology,put forward preventing transverse cracks through improving welding materials and conductive electricity nib,reducing low melting point impurity copper,as well as longitudinal drawing stress.