How to avoid cs seamless steel pipe bubbles

Posted by chase Liu on February 24th, 2023

CS seamless pipe is a long strip of steel with a hollow section. A large number of pipelines are used to transport fluids, such as pipelines for transporting oil, natural gas, gas, water and certain solid materials. Compared with welded steel tubes, steel pipes have the same flexural and torsional strength, but are lighter in weight, and are economical section steels.

When welding cs seamless steel pipe, among many common welding problems, the most common is the presence of air bubbles in the weld. In particular, the weld seam pores of large-diameter seamless steel pipes not only affect the tightness of the pipe weld seam and cause pipe leakage, but also become the induction point of corrosion, which seriously reduces the strength and toughness of the weld seam.

Cause

1) The molten gas is supersaturated;

2) The sum of various gas pressure dividers in the bubble exceeds the external pressure acting on the bubble;

3) Bubble nuclei exceeding the critical value.

Under specific forging conditions, because there are always many non-metallic inclusions, aggregates and bubbles that have not escaped during scouring, non-spontaneous bubble nuclei in the melt are very easy to produce. In addition, although the amount of peroxide in the melt after refining is less than the equilibrium concentration, the gas concentration in the condensation process is initially distributed, which makes the liquid at the forefront of the crystal form a partial saturation of hydrogen content. Therefore, the generation of air bubbles for seamless steel pipes creates a resource advantage. When the hydrogen partial pressure circuit in the liquid state at the forefront of the crystal expands to exceed the external pressure, bubbles are likely to occur. However, if the buoyancy of the generated air bubbles is lower than the adhesion of the solid surface to the air bubbles, or the upward adjustment rate of the air bubbles is lower than the crystallization rate of the ingot, the air bubbles will remain in the casting and become air holes.

Approach

1) The air content inside the cs seamless pipe should be minimized

2) The surface of the cs seamless pipe is required to be clean and free from oil stains

3) Clean the extrusion barrel

4) The temperature of cs seamless pipe should not be too high

5) Control the amount of lubricating oil applied to avoid excessive lubrication