Diameter Expansion and Rust Removal of Straight Seam Steel Pipe

In addition to the direct use of straight seam steel pipes, it will also be processed according to the purpose of construction. Related processing methods include forging steel, extrusion, rolling, and drawing steel. Forged steel is extruded into the shape and specifications we need. Extrusion is mainly used for In the production of non-ferrous metal steel, the steel is generally placed in an extrusion cylinder, extruded on one side by pressure, and then extruded through a die hole.

Diameter expansion of straight seam steel pipe(LSAW Steel Pipe) is a pressure treatment technology. The force from the inner wall of the steel pipe is increased by hydraulic or mechanical means to expand the steel pipe radially. The mechanical method is simpler and more effective than the hydraulic method. The seam steel controlled pipeline expansion process is adopted. The process is as follows: the mechanical diameter expansion uses the segmented sector block at the end of the expander to expand in the radial direction, so that the tube blank gradually realizes the entire tube length and plastic deformation along the length direction.

(1) Steps to enlarge the diameter of straight seam steel pipe

1. At the initial round stage, the sectors are opened until all sectors are in contact with the inner wall of the steel pipe. At this time, the radius of the round pipe in the steel pipe is almost the same within the step length, and the steel pipe reaches the initial circle.

2. At the nominal inner diameter stage, the sector block decelerates from the front until it reaches the desired position, which is the circumferential position of the finished pipe required by the quality, and the sector block position will further decrease until it reaches the desired position.

3. The pressure maintaining and stabilizing stage. During a period of time before the rebound, the sector block at the circumferential position of the steel pipe remains unchanged. This is the pressure maintaining and stabilizing stage required by the equipment and the diameter expansion process.

4. During the unloading and returning stage, the sector block is rapidly retracted from the circumferential position of the steel pipe before the elastic recovery, until it reaches the initial diameter position of the minimum contraction diameter of the sector block required for the expansion process.

(2) Rust removal of straight seam steel pipe

First, use solvents and emulsions to clean the steel surface to remove grease, dust, lubricants and similar organic matter, but it cannot remove the rust, oxide scale and flux on the steel surface, and can only be used as an auxiliary means of anti-corrosion.

Rust removal is the high-speed rotation of the jet blade driven by a high-power motor. It is made of steel balls, ore and other abrasives under the action of strong centrifugal force on the surface of the motor, and sandblasted on the straight seam steel pipe to remove oxides and rust. And dirt, it can also impact and rub the straight seam steel pipe under the action of abrasive to achieve the required uniform roughness.

Straight seam steel pipe is a steel pipe whose weld seam is parallel to the longitudinal direction of the steel pipe. Straight seam steel pipes can be divided into high-frequency straight seam steel pipes (ERW Pipe) and submerged arc welded straight seam steel pipes (LSAW) according to the production process. Straight seam welded pipe has simple production process, high production efficiency, low cost and rapid development.

ASTM A53 Grade B in ERW (electric resistance welded) pipe, the weld seam of A53 erw pipe shall be done the heat treatment with a minimum 1000°F [540°C]. In this way the no untempered martensite remains.
In case ASTM A53 B pipe in cold expanded, then expansion should not exceed 1.5% of the required OD.