Today, we will analyze two fundamental types of pipes used in industrial applications. Carbon steel pipes are robust, long-lasting, and offer high tensile strength. Black steel pipes are rigid, general-purpose steel pipes used in many scenarios. Both pipes have distinct advantages and perform optimally in specific use cases. They are used in several industries, such as construction, oil and gas, sewage, and manufacturing. A comprehensive knowledge of their properties can help you choose according to your requirements.
Definition and Composition
Carbon Steel Pipes
Carbon steel is an alloy of iron and carbon. It comes in 3 categories: high-carbon, medium-carbon, and low-carbon steel. The percentage of carbon by mass can range from 0.05% to 2.5%. Carbon steel pipes are renowned for their hardness and longevity. They can be manufactured by the seamless, spiral-welded, or butt-welded method. Carbon steel pipes can have different physical properties depending on the production technique.
Black Steel Pipes
Mild steel pipes without any coating are called black steel pipes. They are named after the black finish produced on their surface due to the forming of a layer of iron oxide. Manufacturing black steel pipes involves preparing the raw material: mild steel plates. The steel pipe is subjected to rolling, welding, and heat treatment to improve its solidity. Black steel pipes are cheap and versatile. They conduct several materials like oil, gas, waste, and sludge.
Composition Differences
The primary constituents of carbon steel tubes are iron and carbon. It has several other elements in trace amounts: phosphorus, sulfur, silicon, and manganese. Carbon steel pipes come in several grades, like ASTM A53, A106, and A333. Different grades have distinct manufacturing methods and compositions that impart unique characteristics.
In terms of composition, black steel pipes are not that different from carbon steel pipes. In fact, black steel pipes are carbon steel pipes that undergo a unique crafting process. Their primary elements are iron and carbon, with the formation of an iron oxide layer at the surface. This very compound imparts a dark hue, giving it the name black steel pipe.
Manufacturing Process
The manufacturing process differs for many types of carbon steel pipes. The life of a steel pipe generally begins as a billet. The billet is heated in a furnace and transferred to a rotary piercer. The piercer is composed of a strong alloy. It bores a hole through the billet. This process involves cross-action compression forces. Eventually, the hollow shell is heat-treated, cut with a laser, and cooled to form the pipes we see daily.
There are two main variants of black steel pipes: welded and seamless. Seamless black steel pipes begin their journey as steel billets. They are converted into pipes through extrusion, cold drawing, or hot rolling. For welded black steel pipes, flat metal plates are rolled into shape. Thereafter, they are welded together and subjected to heat treatment.
Temperature and Pressure Resistance
Carbon steel pipes are renowned for their versatility. They come in various grades, with properties to match specific temperature and pressure ratings. Generally, the critical factors to consider are steel grades, schedule, and thickness. Carbon steel pipes can handle temperatures up to 650 degrees Celsius. Common standards of mild steel pipes are API 5L, ASTM A53, and A106.
Black steel pipes also have excellent temperature and pressure ratings like their carbon steel counterparts. Their composition allows them to withstand high temperatures. Matching the schedule and thickness according to your needs can ensure immense pressure resistance.
Susceptibility to Corrosion
Carbon steel is susceptible to rusting due to the absence of chromium. Therefore, galvanized pipes are a good option, especially if you plan to deploy the pipes outdoors.
Black steel pipes lack a zinc coating on the outer surface, making them prone to corrosive damage. For optimal use, they should be used indoors. While they are preferred for oil & gas transportation, they are not recommended for household water supply.
Appearance
The surface of a carbon steel pipe will have a rough, matte-like finish. It is dull and luster-less. Upon oxidation, it can form a layer of rust.
As you might have guessed by the name, black steel pipes have a dark finish. They are also coarse to the touch. This is caused by a layer of iron oxide on the surface.
Cost Effectiveness
Due to the availability of several grades, carbon steel pipes can come with varied price tags. While mild steel pipes are cheap, high-carbon pipes can be expensive. For example, ASTM A36 mild steel is significantly cheaper than ASTM AISI 1059 pipes.
Black steel pipes are simple to make and highly affordable. They are perfect for several transportation and structural applications, cost-effective, weldable, and versatile.
Environmental Friendliness
Carbon steel pipes are safe for the environment and local ecology. They are long-lasting and robust, which reduces infrastructure deterioration. This, in turn, leads to less wastage. For a given project, procuring mild steel pipes is generally cheaper than black steel pipes. However, it must be noted that the production of carbon steel pipes generates more CO2 emissions than black steel pipes. Environmental considerations and government regulations may prompt infrastructure developers to consider black steel pipes for structural projects.
Applications
Both carbon and black steel pipes find enormous usage in several industries. Carbon steel pipes are preferred due to their rust resistance in waste management networks like sewage treatment systems. In the transportation of other materials, however, both see frequent use. For example, engineers may favor either type of pipe in a gas pipeline or oil rig. It will depend primarily on the specific application and grading requirements. Both types of pipes are a staple in structural engineering projects. Some other industrial applications of steel pipes are HVAC, energy systems, chemical plants, and automotive factories.
Conclusion
While carbon steel offers immense versatility, black steel displays strength and cost-effectiveness. Carbon and black steel tubes are industry staples. A crucial factor in choosing between them is your requirements. For example, if you are designing an indoor plumbing system, you would prefer mild steel pipes for their corrosion resistance. In structural applications, black steel pipes are deployed as beams and scaffoldings, providing a robust solution. UNIASEN is a professional carbon steel pipe manufacturer. If you have any questions, please contact our pipe experts.