What are the production methods of large diameter straight seam steel pipes?

Straight seam steel pipe refers to the steel pipe with the weld seam parallel to the longitudinal direction of the steel pipe. Its production process is simple, the production efficiency is high, the cost is low, and the development is fast. Mainly used for large-span grid engineering, building steel structure engineering, electric power and ultra-high voltage transmission and distribution engineering, mechanical engineering, cross-sea bridges, bridges, (steel structure engineering of railway stations, airports, stadiums), municipal pipe networks, foundations Ancillary facilities such as piling, water and gas pipelines and road construction.

Common methods for the production of large-diameter straight seam steel pipes:

1. The pipe blanks (plates, strips) are directly formed and welded into pipes, and the main processes are strip forming, welding, and sizing.

Features: few production processes, simple engineering process, short product production cycle, slightly lower product accuracy.

2. The pipe blanks (plates, strips) are first directly formed and welded into size pipes, and then cold drawn or cold rolled into finished tubes, commonly known as DOM electric welded steel pipes. The main processes are forming, welding, sizing, cold rolling or cold drawing (with mandrel or without mandrel), or continuous cold drawing (ie electric welding-cold drawing combined production line).

Features: dispersed production process, long process flow and production cycle, large area, good dimensional accuracy of products, smooth inner and outer surfaces, good mechanical properties and metallographic structure.

3. The pipe blanks (plates, strips) are directly formed and welded into size pipes, and then enter the continuous reducing machine for cold reduction into finished pipes. The main processes are forming, welding, continuous cooling and reducing diameter.

Features: the production process is compact, the process flow is simple, the unit is produced, the specification range is changed quickly, and it is suitable for the production of small diameter and thin-wall electric welding steel pipes.

How to control the quality of large diameter straight seam steel pipe?

Control the quality of straight seam welded pipes, carry out production operations safely, and ensure the personal safety of operators.

1. Check whether the specifications of welding wire and flux are correct according to the welding procedure specification, and prevent welding quality accidents caused by wrong use of welding wire and flux;

2. Supervise the welding environment. When the welding environment is not good (the temperature is lower than 0 °C and the relative humidity is greater than 90%), corresponding measures should be taken before welding;

3. Before pre-welding, check the groove size, including whether the gap, blunt edge, angle and misalignment meet the process requirements;

4. Whether the welding current, welding voltage, welding speed and other process parameters selected in the automatic submerged arc internal and external welding process are correct;

5. Supervise the welding personnel to make full use of the length of the arc striking plate at the pipe end of the steel pipe during automatic submerged arc internal and external welding, and enhance the use efficiency of the arc striking plate during internal and external welding, which helps to improve the welding quality of the pipe end;

6. Supervise whether the welding personnel clean up the slag before repairing welding, whether the joint has been thoroughly treated, and whether there is oil, rust, slag, water, paint and other dirt on the groove.

Tips: seamless pipes are made of steel ingots or solid billets through perforation to make capillaries, which are then hot-rolled, cold-rolled or cold-drawn. The seamless pipe specification is expressed by outer diameter * wall thickness mm.

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