What is the seamless black steel pipe used for?

Seamless black steel pipe refers to seamless steel pipes that have not undergone galvanizing or anti-corrosion coating treatment. They are called "black steel pipes" because of their dark oxide film on the surface. Compared to welded steel pipes, seamless black steel pipes have no weld defects and have significant advantages in pressure resistance, structural uniformity, and safety reliability. Therefore, they are widely used in industrial fields with high strength and stability requirements.

Seamless black steel pipes have a wide range of applications due to their high strength and low maintenance costs. They are commonly used to transport natural gas and water to urban and rural areas, or to protect power transmission lines and pipelines transporting high-pressure steam and air. In addition, black steel pipes are also used in the petroleum industry to transport large quantities of oil to remote areas.

Types of black steel pipes

There are two methods for producing steel pipes, ultimately resulting in either welded steel pipes or seamless steel pipes. Both methods involve first casting crude steel into an initial shape that is easier to process, then stretching the steel to form a seamless steel pipe, or pressing the edges together and sealing them with welding to finally produce the steel pipe.

1. Welded Black Steel Pipe

The forming process of welded steel pipe involves passing a steel strip through a series of grooved rollers to form a circular shape. Then, the unwelded steel pipe is passed through welding rods. These devices weld the two ends of the steel pipe together.

Welded black steel pipe has thin walls, is lightweight, and has high strength, making it ideal for bicycle frames.

2. Seamless Black Steel Pipe

As early as 1840, steelworkers were able to produce seamless steel pipe. One method involved drilling a hole in a solid metal billet. The billet was then heated and stretched through a series of dies to form a tube. This method was inefficient because it was difficult to drill a hole in the center. This resulted in uneven pipe thickness, with one side thicker than the other. In 1888, an improved method was patented. In this process, solid bricks were cast around a refractory brick core. After cooling, the bricks were removed, leaving a hole in the center. Subsequently, new rolling techniques replaced these methods.

Modern seamless black steel pipe production has achieved uniform wall thickness, high dimensional accuracy, and stable and reliable pressure resistance, making it the preferred material for the oil, gas, power, boiler, and pressure vessel industries.

What are seamless black steel pipes used for?

1. Energy and Oil & Gas Industry

Seamless black steel pipes can be used in crude oil pipelines, natural gas gathering and transmission systems, and refinery process pipelines.

Common Standards: ASTM A106/A53, API 5L, EN 10216

2. Construction Industry

Seamless black steel pipes are widely used in scaffolding columns, steel structure supports, and underground pipe galleries. According to data from the China Iron and Steel Association, the construction sector accounts for approximately 40%–45% of the total demand for black steel pipes.

Common Standards: GB/T 8162, EN 10210, EN 10219, DIN 1629, ASTM A500

3. Machinery Manufacturing

Seamless black steel pipes are also used in the machinery manufacturing industry, such as mechanical structural pipes, equipment frames, drive shafts, and hydraulic lines. Its high rigidity and fatigue resistance make it a preferred choice in heavy equipment manufacturing.

Common standards: EN 10297-1, DIN 2391, ASTM A106, ASTM A519, GB/T 8162

4. Industrial Piping

Seamless black steel pipes are commonly used in high-pressure steam systems, compressed air pipelines, and industrial cooling water and drainage systems.

Common standards: ASTM A106, ASTM A53, API 5L, EN 10216, GB/T 8163

5. Other Applications

Seamless black steel pipes can also be used in other fields, such as automotive manufacturing, HVAC, refrigeration equipment, pharmaceutical and chemical plants, etc.

Is seamless black steel pipe suitable for drinking water?

Seamless black steel pipes are generally not used in drinking water delivery systems.

Reasons include:

Black steel pipes do not have internal anti-corrosion treatment, and long-term contact with water can easily lead to oxidation and corrosion; Rust and mineral deposits may cause:

Water pollution;

Pipe scaling and blockage;

Shortened service life.

Therefore, drinking water systems more commonly use galvanized steel pipes, stainless steel pipes, plastic-lined steel pipes, and ductile iron pipes, while seamless black steel pipes are mainly used in non-drinking industrial fluid systems.

FAQ

1. Are seamless black steel pipes suitable for high-temperature or high-pressure environments?

Yes.

Due to their weld-free structure, seamless black steel pipes exhibit greater stability under high-temperature, high-pressure, and alternating load environments. They are commonly used in boiler piping, steam systems, and high-pressure fluid transportation, applications that welded steel pipes cannot replace.

2. Do seamless black steel pipes require additional anti-corrosion treatment?

It depends on the environment:

Indoor or dry environments: Generally, no treatment is required;

Damp or underground environments: Painting, rust-preventive oil, or external anti-corrosion treatment is recommended;

Corrosive media: Epoxy coating, 3PE, or internal lining are optional.

3. Why do engineering projects prefer seamless black steel pipes?

Because seamless black steel pipes have a higher safety factor, are less prone to leakage, are easier to pass third-party testing, better comply with European and American engineering standards, and have lower overall costs in the long run.

Summary

Seamless black steel pipes, with their seamless structure, high pressure resistance, and wide adaptability, have become a key material in global energy, construction, machinery, and industrial piping systems.

Read more: What should you know about black steel pipes? or Black steel pipe vs carbon steel pipe