What are black steel pipes?
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.
What are black steel pipes used for?
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.
A brief history of black steel pipes
Steel pipes are produced by two distinct methods that would eventually result in either a welded or seamless pipe. In both methods, raw steel is first cast into a more workable starting form. Then it is made into a pipe by stretching the steel out into a seamless tube or forcing the edges together and sealing them with a weld. The first methods for producing steel pipes were introduced in the early 1800s, and they have steadily evolved into the modern processes today.
Each year, millions of tons of steel pipe are produced. Its versatility makes it the most often used products in the steel industry. Steel pipes can be found in a range of places. Since they are strong, they are used underground for transporting water and gas throughout cities and towns. They are also employed in construction to protect electrical wires. What interesting about steel pipes is that they can be both strong and lightweight. This makes them ideal to be used in the bicycle frame manufacture. Steel pipes can also be found in automobiles, refrigeration units, heating and plumbing systems, flagpoles, street lamps, and medicine to name a few. Pipes have been used for thousands of years. The first use was probably by ancient agriculturalists to divert water from rivers and streams into the fields. It is also suggested that the Chinese used reed pipes for transporting water to desired locations as early as 2000 B.C.
Development of the modern day welded steel pipes can be traced back to the early 1800s. In 1815, William Murdock invented a coal burning lamp system. To fit the entire city of London with these lights, Murdock joined together the barrels from discarded muskets and used this continuous pipeline to transport the coal gas. When his lighting system proved successful there was a greater demand for long metal tubes. To produce enough tubes to meet such demand, a range of inventors set to work on developing new pipe-making processes. An early notable method for producing metal tubes quickly and inexpensively was patented by James Russell in 1824. In this method, he created tubes by joining together opposite edges of a flat iron strip. The metal was first heated until malleable. Then its edges are folded together and welded using a drop hammer. The pipe was finished by passing it through a groove and rolling mill. However, Russell’s method was not used for long because in the following year, Comenius Whitehouse developed a better method for making metal tubes. Called the butt-weld process, his process is the basis for the pipe-making procedures today. In this method, thin sheets of iron were heated and drawn through a cone-shaped opening. As the metal went through the opening, its edges curled up and created a pipe shape. The two ends were welded together to finish the pipe.
Welded pipe is formed by rolling steel strips through a series of grooved rollers that mold the material into a circular shape. Next, the unwedded pipe passes by welding electrodes. These devices seal the two ends of the pipe together. This process in the United States was opened in 1832 in Philadelphia. Gradually, there were some improvements made in the Whitehouse method. John Moon introduced one of the most important innovations in 1911. He suggested the continuous process method in which a manufacturing plant could produce pipe in an unending stream. He built machinery for this specific purpose and many pipe manufacturing facilities adopted it. While the welded tube processes were being developed, a need for seamless metal pipes arouses. Seamless pipes are those that do not have a welded seam. They were first made by drilling a hole through the center of a solid cylinder. This method was developed during the late 1800s. These types of pipes were ideal for bicycle frames because they have thin walls, are lightweight but strong. In 1895, the first plant to produce seamless tubes was built. As bicycle manufacturing gave way to auto manufacturing, seamless tubes were still needed for gasoline and oil lines. This demand was made even greater as larger oil deposits were found.
As early as 1840, ironworkers could already produce seamless tubes. In one method, a hole was drilled through a solid metal, round billet. The billet was then heated and drawn through a series of dies which elongated it to form a pipe. This method was inefficient because it was difficult to drill the hole in the center. This resulted in an uneven pipe with one side being thicker than the other. In 1888, an improved method was awarded a patent. In this process, the solid billed was cast around a fireproof brick core. When cooled, the brick was removed leaving a hole in the middle. Since then new roller techniques have replaced these methods.
How are black steel pipes different from other types of steel pipes?
In terms of components: black steel pipes vs. carbon steel pipes
Characteristics of carbon steel pipes
The amount of carbon that steel contains determines its characteristic. Steel is considered as carbon steel when no minimum content is specified or required for chromium, cobalt, niobium, molybdenum, nickel, titanium, tungsten, vanadium or zirconium, or any other elements to be added to obtain a desired alloying effect; when the specified minimum for copper does not exceed 0.4%; or when the maximum content specified for any of the following elements does not exceed the percentages noted: manganese 1.65%, silicon 0.6%, copper 0.6%. The majority of the steel produced globally falls into the category of carbon steel.
Carbon steel pipe can be divided into different categories according to a number of standards:
(1) in terms of end-use, it can be divided into carbon structural steel, carbon tool steel and easy cutting steel; carbon structural steel is divided into the project building structural steel and machinery manufacturing steel;
(2) in terms of smelting method, it can be divided into open-hearth steel and converter steel;
(3) in terms of the deoxidation method, it can be divided into the boiling steel (F), killed steel (Z), semi-killed steel (b), and special killed steel (TZ);
(4) in terms of the carbon content, it is divided into ultra-high carbon steel (1.00 – 2.00%); high carbon steel (0.60 – 0.99%); medium carbon steel (0.30 – 0.59%); low carbon steel (0.16 – 0.29%); mild carbon steel (0.05 – 0.15%);
(5) in terms of the quality of steel, it is divided into ordinary carbon steel (phosphorus, sulfur, higher), high-quality carbon steel (phosphorus, sulfur, low), high quality steel (phosphorus, sulfur, lower ) and super high quality steel.
Applications of carbon steel pipes
Carbon steel pipe is the earliest to use the largest amount of basic material in the modern industry. The world’s industrial countries, in attempts to increase high strength low alloy steel and alloy steel production, which is also very attention to improving the quality of carbon steel pipe and expanding the range of varieties and use. The proportion of carbon steel pipe production in the country’s’ total output of steel, approximately maintained at about 80%, it is not only widely used in buildings, bridges, railways, vehicles, ships and all kinds of machinery manufacturing industry, but also in the modern petrochemical industry, marine development, has also been heavily used.
How are black steel pipes different from carbon steel pipes?
In general, black steel pipes and carbon steel pipes have almost the same procedures for welding. That is in the case of general welding, but not of some specific application like very cold temperatures. Black steel pipe is not really a specification but rather a generic term used primarily by plumbers to distinguish regular steel pipe from galvanized steel pipe.
Black steel pipes are cast from several grades of ductile or malleable iron, whereas carbon steel pipes are generally welded or seamless. Black steel pipes are used for underground or submerged applications as well as for mainstream pipes and branches subjected to acids. It is also common to use cast iron pipes and fittings for municipal cold-water lines 4″ diameter and above. Commercial die casting is unsuitable for lines subjected to expansion strains, contractions, and vibration unless the pipe is very heavy. It is not suitable for superheated steam or for temperatures above 575 degrees F. Cast iron pipes in underground applications (such as sewer lines) usually have bell and spigot ends whereas exposed pipes usually have flanged ends.
In terms of coating: black steel pipes vs. galvanized steel pipes
Characteristics of galvanized steel pipes
Black and galvanized steel pipes are both made of steel, but galvanized pipes have a zinc coating while black pipes do not. Therefore, galvanized pipes are more expensive and more durable.
How does the galvanization protect steel pipes?
The zinc of galvanized steel pipes serves as a sacrificial layer. It will rust before the steel beneath it, allowing the integrity of the pipe to remain intact for much longer time than regular pipes. Moreover, even if the zinc layer is scratched or damaged, it can still protect the steel beneath it.
How long will galvanized steel pipes last?
The thicker your zinc coating, the longer the pipe lasts. The environment also plays a crucial role in determining the pipe’s life span. If the pipes are placed in highly corrosive conditions, they often last from 50 to 100 years.
Applications of black steel pipes and galvanized steel pipes
Black steel pipes and galvanized steel pipes are the two most common types of pipes used for transporting liquid and gas.
Black steel pipes are more likely to erode than galvanized pipes and for this reason, they tend to be used for transporting gas while galvanized pipes for carrying water.
The layer of zinc covering galvanized pipes offers it higher ability of corrosion protection, but as time goes by it can cause the mineral to flake off and block the pipe, which might lead to a burst. Transporting gas by galvanized pipes is therefore dangerous. Instead, it is used for carrying water to supply home and commercial buildings or serves as scaffolding frames thanks to its rust prevention.
In contrast, black steel pipes are uncoated and made without steam. Therefore, it is widely used for transporting gas like propane and natural gas to residential and commercial building. Black steel pipes can also be used for fire sprinkler system since it can prevent fire better than galvanized pipes.
Comparing costs of black steel pipes and galvanized steel pipes
In general, black steel pipes are cheaper than galvanized pipes. It is due to the zinc coating on the galvanized pipes and the manufacturing process. Galvanized fittings also cost more than the fittings used on black steel due to its demand for maintenance.
How to differentiate black steel pipes and galvanized steel pipes?
There are two primary methods to distinguish black steel pipes and galvanized pipes:
First, you can examine the color of the pipe. Black steel pipe is darker than galvanized pipe; it is flat black while galvanized pipe is silver and gray.
And second, galvanized pipes are usually used for water transportation whereas black steel pipe for gas deliver.
Other types of coatings
Depending on the use of the pipe, other types of paints or coatings are used. A range of measures are taken to ensure that the finished steel pipe meets specifications. For instance, X-ray gauges are used to regulate the steel’s thickness. The gauges work by utilizing two X-rays. One ray is directed at a steel of known thickness while the other at the passing steel on the production line. If there is any variance between the two rays, the gauge will automatically trigger a resizing of the rollers to compensate. Pipes are also inspected for defects at the end of the process. One method of testing a pipe is by using a special machine that fills the pipe with water and then increases the pressure to see if it holds.
Different types of black steel pipes
In terms of the welding process: ERW vs. seamless black steel pipes
ERW black steel pipes
What are 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.
Manufacturing process of ERW black steel pipes
Seamless black steel pipes
What are 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.
Manufacturing process of seamless black steel pipes
Comparing ERW and seamless black steel pipes
There are a few aspects of differences between ERW steel pipes and seamless steel pipes. ERW pipes are used in the transportation of liquid, such as fuel, gas and so on, regardless of its pressure, which make it one of the most typical conveying tubes all over the world. Seamless pipes are, on the other hand, a kind of steel pipe in the shape of square or rectangle having no seam around with hollow cross-sections, which is used in conveying liquid as well as making structural and machine parts, thanks to its high anti-bending and anti-torque strength and unbelievable lightness. In general, ERW and seamless steel pipes are quite different in use.
The biggest difference between ERW pipe and seamless steel pipe is that ERW pipe has welding line, which is the same as welded steel pipe, but seamless black steel pipe doesn’t have, either does the welded steel pipe. Furthermore, the welding line of ERW pipe is the key to the quality of ERW steel pipe. The more unrecognizable the welding line of ERW pipe is, the higher quality ERW pipe has.
There are two ways to eliminate the welding line: geometric seamlessly and physical seamlessly. Geometric seamlessly is to eliminate the burr both inside and outside while physical seamlessly is to take steps to make base metal and metallographic structure uniform and consistent, which seems more complicate to achieve, however, a ERW pipe without a welding line can be successfully attained through which.
Compared with processing technique of ERW pipe, the processing technique of seamless steel pipe is much simpler. There are two entirely different types of processing technique: cold-drawing and hot rolling. Compared with hot rolling, the technological process of cold-drawing is more complicated. Moreover, in the appearance, cold-drawn seamless stainless-steel pipe is shorter than hot-rolled one and the wall thickness of cold-drawn seamless stainless-steel pipe is generally smaller than the wall thickness of hot-rolled one. What’s more, the technological process of hot rolling needs high temperature which reduces the resistance of deformation so that a big deflection is achieved. Generally speaking, the technological processing of ERW pipe and seamless steel pipe are quite different, due to the different appearance.
In general, although ERW pipe and seamless steel pipe both play an important role as the welded steel pipe does in the construction of society, ERW pipe and seamless pipe has different use and different making progress thanks to their different appearance.
How to Identify whether a pipe is ERW or seamless?
To identify if a pipe is ERW or seamless, simply read the stencil on the side of the pipe. If it is ASTM A53, Type S means seamless; Type F is furnace but welded; Type E is Electrical resist welded. It is the easiest way to identify whether a pipe is ERW or seamless.
In short, seamless pipes are marketed on an outdated myth that it does not have flaws but that welded has an inherent flaw throughout the length of each tube, as stated above. Intuitively this concept is easily accepted by purchasers and designers with limited experience with the various products. Each product form and manufacturing method has its own inherent problems and potential defects.
Consumers must become familiar with what those problems and defects are, and how they might affect particular applications. Then they can make an informed decision based on facts, rather than myth.
In terms of shape: Black Hollow Structural Section Steel Pipes
A Hollow Structural Section, or HSS, is a type of metal with a hollow tubular section. These sections can be circular (CHS), square (SHS) or rectangular (RHS).
Hollow Structural Sections, especially RHS steel is commonly used in welded steel frames while SHS and CHS are more often used in columns. Hollow Steel Sections are also commonly used as beams. The flat square surfaces of RHS has the ability to ease construction, and they are sometimes preferred for architectural aesthetics in exposed structures, but circular Hollow Structural Sections are becoming more popular in exposed structures for the same reasons.
Black RHS (Rectangular Hollow Section) Pipes: for strength and economy
Following the introduction of CHS, RHS have also become very popular in many forms of construction and other structural & mechanical applications. This has been greatly assisted by the section’s inherent flat surfaces making it more economical for joining and other fabrication processes. In this instance, and unlike CHS, the sections only need to be straight-cut (when joining to other flat surfaces) instead of profile cut (e.g. when preparing a CHS end or when joining to curved surfaces). Minimal edge preparation is required for joining and welding RHS.
Like CHS, RHS can be used for architectural aesthetics, possessing clean lines, it is functional, and interacts less with external environmental effects.
Black SHS (Square Hollow Section) Pipes: for balanced strength, symmetry and aesthetics
In terms of its appearance and structural behaviour, the popular SHS is positioned somewhere between a CHS and RHS. The “equal-sided” symmetry of SHS tends to exhibit some of the aesthetic aspects of CHS yet still possess the inherent flat surfaces of RHS for better connectivity. When a balance is required between strength and functionality, SHS are commonly used in many structural and mechanical applications.
Black CHS (Circular Hollow Section) Pipes: for strength and aesthetics
This was the first and still common form of hollow section. It is used in a multitude of applications including building construction and other structural and mechanical areas. From an architectural perspective the constant clean lines provide a very smooth surface appearance which is often employed in many high-profile applications. The lack of protruding edges on these fully closed sections assists in reducing the effects of exposure to the elements and also in increased cleanliness from dust and other material build-up.
Black steel pipe fittings
Black steel pipes and tubes are cut and threaded to fit the job. Fittings for this type of pipe are of black malleable (soft) cast iron. They connect by screwing onto the threaded pipe, after applying a small amount of pipe joint compound on the threads. Larger diameter pipe is welded rather than threaded. Black steel pipe is cut either with a heavy-duty tube cutter or cutoff saw or by hacksaw.
Standards of black steel pipes
What is ASTM?
ASTM International is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services. Some 12,575 ASTM voluntary consensus standards operate globally.
A group of scientists and engineers, led by Charles Benjamin Dudley formed ASTM in 1898 to address the frequent rail breaks affecting the fast-growing railroad industry. The group developed a standard for the steel used to fabricate rails. Originally called the “American Society for Testing Materials” in 1902, it became the “American Society for Testing and Materials” in 1961 before it changed its name to “ASTM International” in 2001 and added the tagline “Standards Worldwide”. In 2014, it has changed the tagline to “Helping our World Work better”. Now, ASTM International’s headquarters is in West Conshohocken, Pennsylvania, about 5 mi (8.0 km) northwest of Philadelphia, and it has offices in Belgium, Canada, China, Peru, and Washington, D.C.
ASTM’s steel standards
ASTM’s steel standards are instrumental in classifying, evaluating, and specifying the material, chemical, mechanical, and metallurgical properties of the different types of steels, which are primarily used in the production of mechanical components, industrial parts, and construction elements, as well as other accessories related to them. The steels can be of the carbon, structural, stainless, ferritic, austenitic, and alloy types. These steel standards are helpful in guiding metallurgical laboratories and refineries, product manufacturers, and other end-users of steel and its variants in their proper processing and application procedures to ensure quality towards safe use.
ASTM A53 is a carbon steel alloy, used as structural steel or for low-pressure plumbing. The alloy specifications are set by ASTM International, in specification ASTM A53/A53M.
A53 pipe comes in three types and two grades, A53 Type F, which is longitudinally furnace butt welded or continuous welded (Grade A only), A53 Type E, which is longitudinally electric resistance welded (Grades A and B), and A53 Type S, which is seamless pipe, produced by hot working, and possibly cold finishing, the steel (Grades A and B). ASTM A53 pipe is sized according to the nominal pipe size (NPS) system. It is commonly available with national pipe thread ends or with plain cut ends. It can be used for steam, water, and air conveyance. It is also weldable and can be used in structural applications, although ASTM A500 tube, which is available in the same NPS sizes, is sometime preferred.
ASTM A-53 vs. A106
ASTM A-53 vs. A106 : Scope
ASTM A53 is Standard specified for Steel, Welded and Seamless, Black and Hot-Dipped, and Zinc-Coated Pipe.
ASTM A106 is Standard specified for Seamless Carbon Steel Pipe for High-Temperature Service.
A53 Pipe vs. A106 Pipe: Applied Type of Pipe
A53 pipes can be welded or seamless depending on the purpose of purchase.
A106 is a similar pipe in chemical composition but is intended for high temperature service (up to 750 degree F). It is a seamless pipe.
At least in the US, there is usually A53 for welded pipe while A106 is seamless. If you ask for A53 in the US they will quote A106 as an alternate.
A53 Pipe vs A106 Pipe: Chemical Composition
When we compare between A106-B and A53-B seamless in terms of chemical composition, it is found that:
- A106-B contains silicon, min. 0.10% where A53-B has zero%, and silicon is the important element for improving the heat resistance criteria.
- A106-B contains manganese 0.29-1.06%, where A53-B 1.2%.
- A106-B contains low sulfur and phosphorus, max. 0.035% where A53-B contains 0.05 and 0.045% respectively.
Chinh Dai Company’s Black Steel Pipes
Chinh Dai Company’s Black Steel Pipes Products are manufactured based on JIS G3466, ASTM A500, and AS/NZ 1163 in order to make a breakthrough solution of quality, price as well as other economic benefits; therefore, they have high durability, perfect resistance to corrosion and rust, and suitability for sea area’s construction (high oxidation).
Our product was pioneered in industrial-scale manufacturing and became an alternative to a large part of the former Black Steel Pipe use.
Read more about Chinh Dai’s qualifications on: https://www.chinhdaisteel.com/en/quality-certification/
Chinh Dai Black Steel Pipes are widely used in construction works, used as scaffolding, workshop, interior, mechanical manufacturing.
For more information on Chinh Dai Company’s black steel pipes, please visit: https://www.chinhdaisteel.com/en/black-steel-pipes/