Longitudinal submerged arc welded pipe (LSAW) is generally made of steel plate as raw material. After different forming processes, double-sided submerged arc welding and post-weld diameter expansion are adopted to form a welded pipe.
The main equipment includes a milling machine, pre-bending machine, forming machine, pre-welding machine, expanding machine, etc. At the same time, there are many types of farming methods for LSAW pipes: 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 carried out. After welding, the diameter is usually expanded at the end of the full length (Expanding) is called UOE welded pipe. It UO welds pipe. Roll Bending the steel plate, and then perform internal and external submerged arc welding. After welding, the diameter is extended to RBE welded pipe or not to RB welded pipe. Form the steel plate in the order of J type-C type-O type, and expand the diameter to JCOE welded pipe or not to expand the diameter to JCO welded pipe after welding
UOE LSAW pipe forming process:
The three main forming processes of the UOE LSAW steel pipe forming process include steel plate pre-bending, U forming, and O forming. Each process uses a dedicated forming press to complete the three processes of pre-bending the edge of the steel plate, U forming and O forming in sequence to deform the steel plate into a circular tube. As shown:
JCOE LSAW pipe forming process:
Forming: 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 press from the middle to form An open "0"-shaped tube blank is formed. As showed:
Comparison of JCO and UO molding methods: JCO forming is progressive pressure forming, changing the forming process of steel pipe from two steps of UO forming to multiple steps. During the forming process, the steel plate deforms uniformly, 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. It can produce large quantities of products as well as small batches; it can produce large-diameter high-strength thick-walled steel pipes and can also produce Small diameter and large wall thickness steel pipes; especially in the production of high steel grade thick wall pipes, especially small and medium diameter thick wall pipes, it has an advantage that other processes cannot match. 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 annual output is generally 100,000 to 250,000 tons.
UO molding adopts U and O twice pressure molding. It is characterized by large capacity and high output. Generally, the annual output can reach 300 to 1 million tons, which are suitable for mass production of a single specification. The investment is huge, and it is difficult for developing countries to bear.
