Black Steel Pipe VS Carbon Steel Pipe

The carbon content in steel determines its properties. Steel is considered carbon steel when no minimum content of chromium, cobalt, niobium, molybdenum, nickel, titanium, tungsten, vanadium or zirconium or any other element added to obtain the desired alloying effect is specified or required; when the minimum copper specified does not exceed {{0}}.4%; or when the maximum content of any of the following elements does not exceed the percentage noted: manganese 1.65%, silicon 0.6%, copper 0.6%. Most of the steel produced worldwide is carbon steel.

Black steel pipe is cast from various grades of ductile iron or malleable iron. Black steel pipe is not actually a specification, but a general term used primarily by plumbers to distinguish between plain steel pipe and galvanized steel pipe. Most black steel pipe is similar in composition to ASTM A-53 pipe. The difference between A-53 and plain steel pipe such as A-106 is so close that some pipes are actually marked as meeting both specifications. Black pipe and A 53 can be seamless or welded, while A106 is seamless. Black steel pipe is used for underground or underwater applications and for mainstream pipes and branches that withstand acid. Municipal cold water pipes with a diameter of 4 inches and above also commonly use cast iron pipes and fittings. Commercial die casting is not suitable for pipelines that are subject to expansion strain, contraction and vibration unless the pipe is very heavy. It is not suitable for superheated steam or temperatures above 575 degrees Fahrenheit. Cast iron pipes in underground applications (such as sewer lines) usually have bell ends, while exposed pipes usually have flange ends. Generally speaking, the welding procedures for black steel pipes and carbon steel pipes are roughly the same.

Carbon steel pipes are usually welded steel  pipe or seamless steel pipe. The raw material of carbon steel pipe is round tube blanks. The round tube blanks are cut into blanks with a length of about 1 meter by a cutting machine, and then sent to the furnace for heating by a conveyor belt. The blanks are sent to the furnace for heating at a temperature of about 1200 degrees Celsius. The fuel is hydrogen or acetylene. The control of the temperature in the furnace is the key issue. After the round tube comes out of the furnace, it needs to be punched by a pressure puncher. The most common puncher is the tapered roller puncher, which has high production efficiency, good product quality, large expansion of the punching diameter, and can punch a variety of steel types. The punched round tube blank is successively subjected to three-roller oblique rolling, continuous rolling or extrusion, and then the tube is removed and sized after extrusion. The sizing machine uses a tapered drill bit to rotate at high speed to insert the steel billet to punch holes to form a steel pipe. The inner diameter of the steel pipe is determined by the length of the outer diameter of the sizing machine drill bit. After sizing, the steel pipe enters the cooling tower and is sprayed with water for cooling. After cooling, the steel pipe is straightened. The straightened steel pipe is sent to the metal flaw detector (or water pressure test) by the conveyor belt for internal flaw detection. Any cracks or bubbles inside the steel pipe will be detected. After the steel pipe quality inspection, it needs to be strictly hand-selected. After the steel pipe quality inspection, the serial number, specification, production batch number, etc. are painted with paint. It is hoisted into the warehouse by a crane.

In the field of materials science and engineering applications, both black steel pipes and carbon steel pipes have their specific applications and material properties, and the differences between them determine their applicability and comprehensive performance to a certain extent. The following is a detailed description of the difference between the two materials from a professional perspective:

Black steel pipe: Through a special blackening process, the black steel pipe forms a solid black oxide scale on its surface, which not only gives it a unique appearance characteristic, but also plays a protective role to a certain extent.

Carbon steel pipe: Carbon steel pipes usually have an original metal finish, that is, a standard silver-gray color. Depending on the purpose, the surface can be coated with different protective layers, such as galvanizing, to meet the corrosion resistance requirements in specific environments.

Black steel pipe: Although covered with a black oxide layer, the corrosion resistance is relatively limited, especially compared with protective layers such as galvanizing.

Carbon steel pipe: Untreated carbon steel pipes are prone to rust. In applications with special requirements for corrosion resistance, carbon steel pipes are usually surface treated, such as hot-dip galvanizing, to enhance their protective capabilities.

Black Steel Pipe: After the pipe is formed, it can be seamlessly manufactured or welded and blackened as mentioned above.

Carbon Steel Pipe Carbon steel pipe can also be seamless or welded, and the choice is based on specific application requirements and budget considerations.

Black Steel Pipe: It is usually used in environments where corrosion resistance is not required, such as general pipelines, gas distribution systems, and structural supports.

Carbon Steel Pipe: Due to its excellent strength and durability, it is widely used in oil and gas, as well as chemical, power and construction fields, and can transport a variety of highly corrosive media.

Black Steel Pipe: Black steel pipe that has been blackened may cost slightly more due to additional processing steps, and the surface oxide layer may peel off during long-term use, affecting durability and aesthetics.

Carbon Steel Pipe: In the case of ungalvanized carbon steel pipe, the cost is lower; with galvanizing or other corrosion-resistant coatings, the cost is higher, but the corrosion resistance and durability are also greatly enhanced.

There is a clear difference between black steel pipe and carbon steel pipe in appearance, and black steel pipe has a place in the market with its unique deep matte color. Corrosion resistance requirements, budget constraints, and end-use scenarios play an important role in determining the priority between the two. Considering these factors, professional engineers and procurement decision makers can choose the most suitable pipeline products according to the characteristics of the project.