In a sense, straight seam steel pipe is a steel pipe welding process that is opposite to spiral steel pipe. The welding of straight seam steel pipes is relatively common in the market because the process is relatively simple and the cost of welding is relatively low. It can achieve high efficiency during production. Moreover, straight seam steel pipe is a widely used product, so what are the practical advantages of straight seam steel pipe? Straight seam steel pipes are welded using a welding method parallel to the longitudinal direction of the steel pipe and are also widely used. For the same diameter and length, the welding length of straight seam steel pipes is much less, while the welding length of spiral steel pipes may increase by more than 30%. Due to process reasons during welding, the efficiency is relatively low and the output is also quite low. But for the same blank, spiral welded pipes can generally be produced in various diameters. In contrast, straight seam steel pipes cannot achieve this welding effect.

Straight seam steel pipes are widely used in the market because of their characteristics. Since the cost of the process used during welding is relatively low, and the manufacturing processes of forged steel, extrusion, rolling, and drawing steel can all be manufactured, and the specifications are also certain, it provides a wide range of applications. possibility. To resolutely implement the battle against air pollution, major steel producers have encountered environmental storms one after another. In this regard, some analysts believe that the environmental governance of the steel industry has entered the implementation stage. In the long term, as various environmental governance initiatives continue to advance, the straight-seam steel pipe industry will be labeled as green and environmentally friendly in the future.

During the steel pipe production process, the core pumping machine encountered some technical problems, such as uneven wall thickness of the products produced, rolling jam, and out-of-tolerance inner straights and outer diameters. How to improve steel pipes and speed up production is an important issue at hand. Laboratory experiments cannot solve production problems. On-site experiments in the workshop are too expensive and not sustainable. The conclusions drawn from experiments once or twice are unreliable. Therefore, it is very important to use numerical simulation methods to study the rolling process of straight seam steel pipes. At present, in our industry, we take the rolling speed and the key factor affecting the 5-stand MPM continuous rolling product roll gap value as the research objectives, use the relative equal load description method to establish a numerical simulation plan, and study the key adjustable parameters (roll gap value and rolling speed) on the continuous rolling force and metal stacking. Through the MARC platform, a finite element model of the straight seam steel pipe rolling process was established to study its influence on the rolling force and wall thickness during the rolling process.

In our country, the petrochemical industry, water supply engineering industry, urban construction, power engineering, etc. all have demand for straight-seam steel pipes. The straight seam welded pipe diameter expansion is a pressure processing technology that uses hydraulic or mechanical means to apply force from the inner wall of the steel pipe to expand the steel pipe outward in the radial direction. The mechanical method is simpler and more efficient than the hydraulic method. The diameter expansion process has been adopted in several large-diameter straight seam welded pipe pipelines in the world. Please see below for a detailed introduction to the process.

The mechanical diameter expansion of straight seam steel pipes uses the segmented fan-shaped block at the end of the diameter expander to expand in the radial direction so that the pipe blank can achieve plastic deformation of the entire pipe length in a step-by-step manner along the length direction. Divided into 5 stages:
1. Preliminary rounding stage. The sector blocks are opened until all the sector blocks are in contact with the inner wall of the steel pipe. At this time, the radius of each point in the inner circular pipe of the steel pipe within the step range is almost the same, and the steel pipe is initially fully rounded.
2. Nominal inner diameter stage. The sector block starts to reduce its movement speed from the front position until it reaches the required position, which is the required inner circumferential position of the finished pipe.
3. Rebound compensation stage. The sector block starts from the second stage position and further reduces the speed until it reaches the required position. This position is the inner circumferential position of the steel pipe before rebound is required by the process design.
4. Pressure stabilization stage. The sector-shaped block remains stationary in the inner circumferential position of the steel pipe for some time before springing back. This is the pressure-maintaining and stable stage required by the equipment and diameter expansion process.
5. Unloading return stage. The sector block rapidly retracts from the inner circumferential position of the steel pipe before rebounding until it reaches the initial diameter expansion position, which is the minimum contraction diameter of the sector block required by the diameter expansion process.