Straight seam steel pipe refers to a steel pipe in which the welding seam is parallel to the length direction of the steel pipe. Usually divided into metric electric welded steel pipes, electric welded thin-walled pipes, transformer cooling oil pipes, etc.

Straight seam high-frequency welded steel pipe has the characteristics of relatively simple process and fast continuous production. It has a wide range of uses in civil construction, petrochemical, light industry and other fields.

The diameter of straight seam steel pipes is between 89~1600mm, and can even be larger under special circumstances. The ratio of wall thickness to pipe diameter is about 0.06~0.08. Foreign modern pipe making technology can produce welded pipes with wall thicknesses up to 100mm.

In high-frequency straight seam welded pipes, crack manifestations include long cracks, local periodic cracks and irregular intermittent cracks. There are also some steel pipes with no cracks on the surface after welding, but cracks will appear after flattening, straightening or hydrostatic testing.

Double-sided submerged arc welded spiral steel pipes should undergo mechanical performance tests, flattening tests and expansion tests before leaving the factory, and must meet standard requirements. The quality inspection methods of double-sided submerged arc welded spiral steel pipes are as follows:

Straight seam steel pipe is a welded steel pipe that is transformed into a cylindrical shape after being passed through a forming machine to form a hot-rolled steel coil. High-frequency current skin effect and proximity effect or arc combustion under the flux layer are used for welding, so that the edge of the tube blank is heated, melted and finally cooled and formed under a certain extrusion pressure.

Straight seam steel pipe refers to a steel pipe in which the welding seam is parallel to the length direction of the steel pipe. Usually divided into metric electric welded steel pipes, electric welded thin-walled pipes, transformer cooling oil pipes, etc. The production process of longitudinal welded pipes is simple, with high production efficiency, low cost and rapid development.

Straight seam high-frequency welded steel pipe has the characteristics of relatively simple process and fast continuous production. It has a wide range of uses in civil construction, petrochemical, light industry and other fields. It is mainly used to transport low-pressure fluids or manufacture components and light industrial products for various projects.

High-frequency straight seam steel pipe is based on the principle of electromagnetic induction and the skin effect, proximity effect and eddy current thermal effect of charges, thereby locally heating the steel at the edge of the weld to a molten state, and realizing butt welding through intergranular bonding extrusion, thereby achieving The purpose of seam welding.

The characteristics of submerged arc welded steel pipes are: the production process of straight seam welded steel pipes is simple, high production efficiency, low cost, and fast development speed. The strength of spiral welded pipes is generally higher than that of straight seam welded pipes. Welded pipes with larger diameters can use narrower billets.