Rough Inner Wall of Seamless Carbon Steel Pipe

Seamless carbon steel pipes are widely used in the petroleum, chemical, and shipbuilding industries. Due to their high strength, excellent pressure resistance, and seamless welds, they are a key foundational material for industrial modernization.

However, during actual use or testing, roughness may sometimes be observed on the inner wall of seamless carbon steel pipes. This not only increases fluid flow resistance but also accelerates corrosion and wear, affecting the pipe's service life and safety.

Causes of Rough Inner Walls on Seamless Carbon Steel Pipes

1. Material Quality Issues

Substandard material quality of seamless carbon steel pipes, such as cracks and pores, can lead to increased inner wall roughness.

Particularly when the surface quality of the pipe is poor, defects such as inner wall pinholes are more noticeable.

2. Production Process Issues

Uneven temperature control during rolling, drawing, or heat treatment can lead to coarse grains and an uneven inner wall.

Insufficient lubrication or inadequate equipment precision can cause scratches, bumps, or depressions on the inner wall. Inadequate pickling and bright annealing after cold drawing can lead to residual oxide scale, which increases surface roughness.

3. Operating Condition Issues

The fluid contains hard particles such as sand, iron oxide scale, and metal debris, and the wear caused by friction can also cause roughness on the pipe's inner wall.

Corrosive media (such as acidic gases and water containing chloride ions) can exacerbate pitting and corrosion pit formation.

Long-term operation without cleaning can lead to deposits that cause secondary wear and scaling.

Hazards of Rough Inner Surfaces on Seamless Carbon Steel Pipes

1. Increased Fluid Resistance

Increasing the roughness of carbon steel pipes increases the friction coefficient and pump energy consumption.

2. Accelerated Corrosion

The rough surface of seamless carbon steel pipes is more susceptible to media retention, forming localized corrosion spots.

3. Shortened Service Life

Long-term wear and corrosion can lead to reduced wall thickness and even perforation and leakage.

4. Reduced System Safety

Under high-pressure transmission or load-bearing conditions, a rough inner surface of carbon steel pipes can become a potential source of failure.

Treatment Methods for Inner Surface Roughness of Seamless Carbon Steel Pipes

1. Select High-Quality Pipes

When selecting pipes, choose seamless carbon steel pipes that comply with international or national standards such as GB, ASTM, and API, with smooth surfaces to minimize defects such as pinholes and pores.

Maintaining the roughness of seamless carbon steel pipes within a certain range significantly impacts the service life and safety of the pipe.

For critical operating conditions (high pressure, high temperature, and corrosive environments), cold-drawn precision seamless steel pipe can be selected, offering a smoother inner surface and better dimensional accuracy.

Perform ultrasonic flaw detection and eddy current testing on processed pipes to screen out defective products.

2. Strengthen Production Management

Rational control of production processes, such as rolling and drawing, and maintaining stable temperature and pressure during production can mitigate inner surface roughness.

For cold-drawn pipes, internal surface polishing and honing techniques should be used to achieve a roughness of less than Ra0.8 μm.

3. Strengthen Pipeline Maintenance

Regularly clean the inner surface of the pipe to prevent damage from particle accumulation and abrasion. For seamless carbon steel pipes conveying particulate media, filters or desanders can be installed to reduce wear.

For corrosive media, it is recommended to use an inner wall anti-corrosion coating (such as epoxy resin coating or plastic-lined pipe), or to choose alloy steel pipe as an alternative.

FAQ

1. Can Seamless Carbon Steel Pipes with Rough Inner Walls Continue To Be Used?

It depends on the situation.

If the roughness is only minor, it can be cleaned or polished before continued use.

However, if the wall thickness is significantly reduced or corrosion pits or cracks appear, it should be replaced promptly.

2. What is The Typical Controllable Inner Wall Roughness of Seamless Carbon Steel Pipes?

Depending on the project requirements, the inner surface roughness Ra of common industrial pipelines is generally between 1.6 and 3.2 μm.

For cold-drawn precision seamless steel pipes used in precision hydraulic or high-pressure systems, the inner wall roughness can be controlled to Ra below 0.8 μm.

Conclusion

Rough inner walls can affect the service life and safety of seamless carbon steel pipes. Selecting high-quality pipes, strengthening production management, and improving pipeline maintenance can effectively prevent these problems and ensure the proper function of the pipes. Furthermore, enhanced maintenance and upkeep during use ensure the safety and reliability of the pipes.