What Is Black Steel Pipe?

Black steel pipes are made of steel that has not been coated with a substrate such as zinc or paint. Since it has a dark color surface that is forms by iron oxide during the manufacturing process, it is called black steel pipe.

Different Types of Black Steel Pipes

1. ERW black steel pipes

Electric Resistance Welding (ERW) steel pipes are manufactured by rolling steel and then welding it longitudinally across its length. Therefore ERW steel pipes have a welded joint in its cross-section.

2. Seamless black steel pipes

Seamless pipes are manufactured by extruding the metal to the desired length. Thus, they do not have any joint in its cross-section throughout its length.

Black Steel Pipe: Mechanical Properties

Typical tensile strength is 375-500 MPa (Q235 material), yield strength ≥ 235 MPa, and elongation ≥ 25%. Its strength is proportional to its carbon content, but weldability decreases with increasing carbon content.

Black Steel Pipe: Advantages and Disadvantages

1. Advantages

Low price (20%-30% lower than galvanized pipe), good processability, and high-temperature resistance (can withstand temperatures below 400°C).

2. Disadvantages

Susceptible to rust, requiring anti-rust paint or regular maintenance. Its service life in humid environments is only 1/3-1/2 that of galvanized pipe.

Black Steel Pipe: Common Material

Black steel pipe is mostly made of carbon steel or stainless steel. Carbon steel black pipe, due to its excellent strength and rigidity, is a common support material in building structures. Stainless steel black pipe, due to its excellent corrosion resistance, is widely used in corrosive environments such as chemical and marine environments.

1. Carbon steel black pipe

Carbon steel black pipes are primarily produced by applying special surface treatments to the carbon steel pipe, such as spraying black anti-rust paint or hot-dip galvanizing followed by dyeing, to achieve a black appearance. This type of pipe offers high strength and rigidity, making it suitable for structures that bear heavy loads and provide stable support.

2. Stainless steel black pipe

Stainless steel black pipes are made from stainless steel, but with a special surface treatment, such as black oxidation or black PVD coating, to achieve a black appearance. Stainless steel's inherent corrosion resistance and long service life, combined with its aesthetically pleasing black appearance, make stainless steel black pipes highly sought after in high-end architectural decoration and industrial equipment.

Application of Black Steel Pipes

Black steel pipes have a variety of use thanks to their strength and needs for little maintenance. They tend to be used for transporting gas and water to rural areas and urban areas or for conduits that protect electrical wiring and deliver high pressure steam and air. In addition, black steel pipes are also used in oil and petroleum industries for piping large quantities of oil through remote areas.

Other uses of black steel pipes include gas distribution inside and outside homes, water wells and sewage systems. However, black steel pipes are never used for transporting potable water due to the fact that they tend to corrode in water and mineral of the pipe will dissolve into the water and clog the line as well.