Production process of straight seam submerged arc welded pipe

Seam submerged arc welded pipe (LSAW) generally uses steel plates as raw materials, and undergoes different forming processes to form welded pipes by double-sided submerged arc welding and post-welding diameter expansion.

The main equipment includes edge milling machine, pre-bending machine, forming machine, pre-welding machine, diameter expanding machine, etc. At the same time, the forming methods of LSAW pipes include UO (UOE), RB (RBE), JCO (JCOE), etc. The steel plate is first pressed into a U shape in the forming die, and then pressed into an O shape, and then internal and external submerged arc welding is performed. After welding, the expansion at the end or the full length is usually called UOE welded pipe, and the one without diameter expansion is called UO welded pipe. The steel plate is rolled into shape (Roll Bending), and then internal and external submerged arc welding is carried out. After welding, the diameter is expanded into RBE welded pipe or RBE welded pipe without diameter expansion. The steel plate is formed in the order of J type-C type-O type, and after welding, the diameter is expanded into JCOE welded pipe or JCO welded pipe without diameter expansion.

Forming process of UOE straight seam submerged arc welded pipe

The three main forming processes of UOE LSAW steel pipe forming process include: steel plate pre-bending, U forming and O forming. Each process uses a special forming press to complete the three processes of pre-bending the edge of the steel plate, U forming and O forming in sequence, and deform the steel plate into a circular tube

Forming process of JCOE straight seam submerged arc welded pipe

After several steps of stamping on the JC0 forming machine. First, press half of the steel plate into a "J" shape, then press the other half of the steel plate into a "J" shape to form a C" shape, and finally pressurize from the middle to form an open "0" shaped tube blank.

Comparison of JCO and UO molding methods

JCO forming is progressive pressure forming, which changes the forming process of steel pipe from two steps of UO forming to multi-step. During the forming process, the deformation of the steel plate is uniform, the residual stress is small, and the surface does not produce scratches. The processed steel pipe has greater flexibility in the size and specification range of diameter and wall thickness, and can produce both large-volume products and small-volume products. It can produce not only large-diameter high-strength thick-walled steel pipes, but also small-diameter large-wall-thick steel pipes. Especially in the production of high-grade thick-walled pipes, especially small and medium-diameter thick-walled pipes, it has incomparable advantages over other processes. It can meet more requirements of users in terms of steel pipe specifications. The investment is small, but the production efficiency is low, and the general annual output is 100,000 to 250,000 tons.

UO molding is formed by U and O two times of pressure molding. It is characterized by large capacity and high output. Generally, the annual output can reach 300,000 to 1 million tons, which is suitable for mass production of a single specification. The investment is huge, which is unbearable for most developing countries.

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