Learn About Black Steel Pipe And Things You Probably Don't Know

Black steel is a type of steel that plays an important role in many projects as well as applications related to life. So what is black steel pipe and its advantages to make it is used in so many projects like that, today let's learn about black steel pipe with MRS Steel with the most detail in the article below!

1. Definition about black steel pie and the important specifications

Black steel pipe is a product created on the hot rolling process of black steel sheet material, it can be said that this pipe is a form of steel that has not been galvanized. Instead of going through a galvanizing process like many other steels, this steel just undergoes a chemical conversion to create a black or magnetic iron oxide layer. Therefore, the surface this steel is often dark blue and rough based on the dark iron oxide shell on its surface.

Black steel pipe is produced based on certain standards and parameters, usually there are 2 standards most commonly applied today to evaluate black steel pipes including ASTM A53 and ASTM A106.

Accordingly, the ASTM A53 standard will include the required metal components such as Carbon, Manganese, Phosphorus, Nickel, Chromium, Molybdenum and Vanadium in small proportions, the composition is mainly Iron. In which the sum of 5 elements Copper, Chromium, Molybdenum, Nickel and Vanadium must be less than 1%.

ASTM A106 standard is a seamless black steel pipe, meaning that they will not have the joints as basic steel pipe and they are commonly used in high temperature environments. The composition of ASTM A106 type will be similar to that of standard A53, there are only minor differences as the total composition of this standard is now supplemented with Silicon.

2. History of formation and manufacturing processes of black steel pipe

Methods of producing pipe steel appeared as early as more than 200 years ago and they have been gradually researched and developed to this day. The origin of steel pipes appeared in the 1800s when a British inventor created a system of coal-fired lamps to light up the street, from which the need to use steel pipes has paid attention day by day.

In the early stages in the 1820s, researchers at that time created metal pipes by using fire to soften the metal sheet and proceed to join the metal edges and weld them together with a hammer. However, this method was replaced by a more advanced method and it is considered the premise for today's method of forming steel pipes. Basically, the metal sheets will be heated until a certain ductility is reached, then the manufacturer will pull them through a conical groove. As the metal passes through the groove, the edges of the metal will gradually roll and contract to form a long, round tubular shape.

2.1. Manufacturing processes of welded steel pipe

Nowadays, the production methods of black steel pipe have been gradually automated by equipment, so the completion time is greatly accelerated while ensuring the technical uniformity. Black steel pipe is divided into 2 common types, namely welded steel pipe and seamless pipe steel, specifically, the production process of welded pipe steel takes place as follows:

• Slitting line stage: The manufacturer will put hot rolled steel coils into the slitting machine to cut the steel sheets into small widths.

• Rolling: Then the slitting steel will be moved through the clusters and cages to flatten and chamfer on both sides, making the steel surface uniform in size.

• Shaping: Next is the shaping stage, the steel strip then goes through a series of grooved rollers arranged parallel to both sides, as the steel moves towards the end, their shape will gradually be rolled to form a cylindrical shape.

• Welding black steel pipes: This is the step that requires the most technical machines because the joint line will greatly determine the durability of the black steel pipe in the future. The steel pipe will pass through a roller arranged above to create extremely strong friction on the groove. At the same time, both the inside and outside of the pipe are also sprayed with hot zinc to avoid the risk of rusting the joints.

• Quality check: Once the steel pipes have been successfully shaped, they will now go through the cutting machines to complete the final stage. Black steel pipes go through modern gauges to compare technical information as required to ensure the stability and quality of the finished product before being put on the market.

2.2. Manufacturing processes of seamless steel pipe

In contrast to welded steel pipe, seamless steel pipe is derived from a billet, which is then heated and cast to form a hollow section steel. Seamless steel pipe production processes began to appear in the late 19th century and it gradually replaced welded steel pipe because the manufacturing process usually took place quickly in a relatively short period of time. Therefore, during World War II, seamless black steel pipes completely took advantage of applying in life and making weaponry at that time.

Currently, manufacturers usually apply one of two main manufacturing processes to create seamless steel pipe including the Mandrel Mill process and the Mannesmann Plug Mill process. Both processes serve different purposes as Mandrel Mill is used to produce small diameter steel tubes from 25 - 150mm. Whereas the Mannesmann Plug Mill process produces seamless steel tubes with large diameters from 150 to 400 mm.

The process begins with a billet bar heated to 1300 degrees Celsius and then the manufacturer will use a long piercing to drill into the top of the billet bar to create a small hole and this gap is the starting point for radius expansion taking place afterwards. The piercing tool will rotate continuously into the center of the steel pipe and this rotation speed is enough to cause the steel core to gradually melt through its path.

After the steel pipe is successfully penetrated, it will move to the mandrel mill installed on the pipe. The series of rolls here are arranged in the direction of 90 degrees to continuously roll the surface of the steel pipe to reduce the outside diameter and control the thickness. When leaving the furnace and meeting the standard outside diameter, the steel pipe will now undergo a cleaning step with high-pressure water descale to remove excess oxide deposits formed during heating. They are finally moved to the cutoff mechanism to be cut to the prescribed length, then they will be bundled and checked again before implementing shipment.

Mannesmann plug mill process

The process begins with a billet that has just been heated from the furnace and then the manufacturer will use a Mannesmann drill with the head is designed in a conical shape and the size is almost equal to the diameter of the pipe. This drill will rotate continuously into the center of the steel pipe diameter to create a large enough hollow.

During the steel hollow drilling process, on the production line, two rollers will be installed in the opposite direction of the steel to reduce the steel diameter thickness. In order to ensure the quality of the hollow inside, the manufacturer will use a cylindrical mandrel with a size close to the hollow diameter inside it to rotate, the purposing of this stage is control the roundness inside the pipe. Then, the steel pipe is put into the decontaminating stage and be cutted to the required length, finally the product will go through heat treatment and cooling.

3. The characteristics and role of black steel pipe in the current context

A great advantage that black steel pipe brings to the project is its affordable price. Thanks to the quick and simple production process without too much technical technology, the market price of black steel pipe is always reasonable, the level price is always in the low range. Cheap input materials will help managers be more proactive in investing in other areas of the project, thereby helping the plan become stable and reduce the risk of capital shortage. 

Although the price is cheap, this does not affect the quality of the steel, specifically the black steel pipes have high homogeneity thanks to the production process on the same line, so the durability as well as the mechanical properties are not compromised and they obtain consistency from beginning stage to the end stage. In addition, black steel pipe will not shrink when exposed to high temperatures, the nature of black pipe steel is formed from billet with a temperature of up to 1500 degrees Celsius, so it can keep the original shape even after being heated.

However, the black steel pipe is considered for environmental problems in its production process because the production requires the factory to burn fossil fuels and this leads to the large amount of smoke emitted into the atmosphere, polluting water and soil. In terms of long-term economic impacts, this steel pipe is still an ideal choice as the steel's durability has kept it existing for decades, this steel pipe is possible to become an optimal economical solution for the facility infrastructure as well as other manufacturing applications.

Green steel production projects have been gradually popularized to many places of the world, green steel technology completely eliminates the use of fossil fuels from the process, helping the mills cut down on up to 90% the amount of carbon emissions. The importance of scrap steel is also being concerned by many manufacturers when it helps businesses save energy resources and be more proactive in finding input raw materials without having to invest in eloring natural mining sites.

4. Applications of black steel pipe in the fields

Possessing a variety of diameters from 12x12 mm to 100x100 mm and even up to 250x250mm, black steel pipe is now an important factor in the construction field and many industries.

4.1. Pipeline system

One of the most common applications of pipe steel is taking advantage of making water, vapor and natural gas pipelines. Black steel pipe possesses good bearing capacity without distorting, so it will be suitable as a conduit at high pressure places. In addition, these pipes also appear in oil and gas pipelines because they are manufactured according to standard specifications so they can adapt well to corrosion and high temperature environments. 

Various lengths and sizes of steel pipes have made it easier for businesses to install at the locations, specifically in the installation of water and gas pipelines in urban and rural areas. Moreover, black steel pipes usually require less frequent maintenance, so they can be installed underground, which helps to increase the urban beauty with less obstruction to the surrounding ground.

4.2. Building structure

In construction, black steel pipe is used as the foundation of the building as well as appearing in load-bearing scaffolding. Steel pipe has a chemical composition including chromium, silicon to increase the strength and toughness of steel pipes, so it has the function of balancing and distributing the load evenly for the foundation with the scaffolding.

Black steel pipe also appears in the ultrasonic pile system in the foundation structure of the building and it is the main raw material of pre-engineered steel buildings, the light weight of this pipe will help the construction process become more convenient and easier.

5. The difference between black steel pipe compared to other steels

Besides black steel pipe, there are many other types of steel pipe that are the same size and shape as black  pipe, moreover, they are very popular in construction and industrial applications. Some typical steel pipe products placed on the balance sheet compared with black steel pipes can be mentioned as carbon steel pipes and galvanized steel pipes.

5.1 Black steel pipe and carbon steel pipe

Black steel pipe and carbon steel pipe basically still have the basic thing in common, which is an iron alloy with added carbon to create strength. Both types have the similar advantage of being extremely sturdy and durable, so they are very popularly used in the fields of construction and manufacturing engineering. However, if you examine closely each type of steel, you will see that they have significant differences.

Structural composition

In terms of composition, the amount of carbon in steel is also divided into different abundance levels from 0.05% to 2%. Meanwhile, black steel pipe has regulations on the amount of carbon content not exceeding 0.35%. Although the black pipe has a much smaller amount of carbon, they contain elements that carbon steel pipe does not possess such as chromium, silicon and manganese, which are extremely valuable in resisting corrosion and maintaining durability for steel.

Carbon steels are composed mainly of iron and carbon, they have the least chromium content compared to other steels. The element chromium gives effective corrosion resistance to steel, so the absence of chromium will make the steel very susceptible to oxidation and rust surfaces.

Strength and endurance

Evaluation of strength criteria, black steel pipe is more durable and harder than carbon steel pipe because the black iron oxide coating helps increase the hardness of the material, has the effect of protecting the surface of the steel pipe and effectively resisting corrosion. Meanwhile, because carbon steel pipe does not have additional anti-corrosion elements, its durability will be worse than black pipe steel, even when the atmospheric humidity increases to 70%, it can also cause carbon steel to oxidize.

Black steel pipes on the market today are not usually required to be galvanized because they are equipped with a protective layer against corrosion that is formed through the manufacturing process, while carbon steel will require the manufacturer to proceed galvanizing steps to ensure they do not corrode. Especially in gas transportation or plumbing applications, carbon steel is not an appropriate choice.

Eco-friendly in manufacturing

The use of black pipes for construction and industrial applications is considered more eco-friendly than carbon steel pipes. The reason is that the emissions from the production of carbon steel pipes are more than the leaking smoke in the production of black steel pipe. The reason why is that the carbon component accounts for the largest proportion of carbon steel pipe while black steel pipe may not need or will exist very little carbon components. Therefore, many people predict that in the future, it is likely that this black steel will gradually replace carbon steel in many fields before the trend of green economic development globally.

5.2 Black steel pipe and galvanized steel pipe

Black steel pipe and galvanized steel pipe are the two most widely used steels in the transportation of oil, gas, water and other liquids. Both are tubular steels and have the same application, but if you put them on the scale, you will see that these two steels are significantly different.

Corrosion resistance

Although black steel pipe coated with iron oxide has a significant effect on oxidation resistance, this steel is not superior to galvanized steel pipe. Galvanized pipes are coated with a layer of zinc and zinc is one of the leading elements for effective anti-corrosion, in addition, the zinc layer also helps prevent steel from being scratched and helps the steel surface to be maintained in the best condition.

Pipeline system applications

The thicker the zinc layer, the longer the life of the steel, but some studies on air pipeline systems have shown that this zinc coating can peel off and clog pipes, leading to damage for pipe. Therefore, although galvanized steel pipe is very popular in liquid transmission systems, it is not suitable for gas transmission systems.

In contrast, black steel pipe is proven to be a good air transportation product as well as used for fire protection systems because black steel pipe can withstand higher temperatures than galvanized steel pipe. However, black steel pipe is not a good choice for use as a pipeline for compounds with high concentrations of corrosive because this compound will dissolve into black steel pipe and cause pipeline blockage.

Production cost and price

Black steel pipe and galvanized steel pipe have a clear difference in cost because in the production process, manufacturers have to perform additional galvanizing steps for steel, so the cost to sell to the market will be higher than that of black steel pipe. In addition, during time for implementing the construction or commercial buildings, galvanized steel pipes will never be connected to black steel pipes.

6. Looking for a reputable black steel pipe supplier in Vietnam

Thanks to its outstanding properties and affordable price, black steel pipe is always present in most construction projects as well as water and gas transmission systems. Choosing quality black steel pipe products directly sourced from large factories in Vietnam will bring a lot of sustainable value to your project.

Currently, the price of black pipe steel is constantly changing because the Vietnamese steel market in particular and the global steel market are still in a difficult period. The price list of black pipe steel is not only constantly changed from manufacturers, but also from imported sources, which will make it difficult for many customers and especially importers, who want to buy black steel pipe in bulk.

Understanding the needs and difficulties that customers are facing, MRS Steel as an expert in providing steel solutions will help you get a reputable source of goods from large factories in Vietnam such as Hoa Phat, Hoa Sen,... Possessing many years of experience in the steel industry in Vietnam, we are currently establishing many relationships at large factories, so we ensure that the source of black steel pipe always meets quality standards with full C/O and C/Q certifications. The comprehensiveness of MRS Steel is also proven through the team of experts with many years experience who always clearly and promptly grasp the changing policies in market prices, thereby being able to give the best advice for customers. 

If you need advice on a detailed list of black steel pipe sizes in the Vietnam market as well as a detailed price list for each size, please contact via Whatsapp:+84 76 911 2358 or via email vanloc@mrssteel.com.vn.