How to choose steel pipes manufacturers
Table of Contents
- What are steel pipes?
- How do I choose the right steel pipes?
- Consider selecting appropriate steel pipes materials.
- Material Standards for Pipe Materials
- Types of steel pipes
- Types of Steel Grades
- Chemical Composition of Stainless Steel Grades
- Chemical Composition of Hastelloy Alloy Grades
- Chemical Composition of Monel Nickel Alloy Grades
- Chemical Composition of Brass Alloy Grades
- Chemical Composition of Cast Iron Grades
- Chemical Composition of Titanium and Titanium Base Alloy Grades
- Chemical Composition of Carbon Steel Grades
- Chemical Composition of Inconel Alloy Grades
- Mechanical properties of steel materials
- Mechanical Properties of Stainless Steel
- Mechanical Properties of Magnesium Alloys
- Mechanical Properties of Copper Based Alloys
- Mechanical Properties of Aluminum Alloys
- Mechanical Properties of Gray Cast Iron
- How do I choose piping material?
- Manufacturing methods of steel pipes
- Quality requirements and inspection methods for steel pipes
- Why is steel pipe quality important?
- You should consider the type of coating you need for your steel pipe.
- You must consider the diameter of the steel pipe.
- You should also look at wall thickness of steel pipe.
- It is important to look at the length of steel pipes when ordering.
- How do you identify steel pipes?
- How to choose right steel pipes manufacturers?
Steel pipes are long, hollow pipes that are used for a variety of purposes. They’re made from steel and can be found in everything from water and gas lines to construction projects.
Steel pipes differ from other types of pipe because they’re stronger than most other materials, so they don’t need to be enclosed in concrete or plastic. These strong properties also make them popular choices for oil transportation, which is why steel pipelines were used extensively during the first oil boom in North America in the early 20th century.
Steel pipes are commonly used to transport liquids and gases, but can also be used in construction and manufacturing. They come in a variety of sizes and thicknesses, so there is a pipe that suits your needs. There are many specifications of steel pipes, and different specifications have different uses. The selection should be based on the actual situation. What are the specifications and models of steel pipes? What aspects should be considered when purchasing steel pipes? Now let’s get to know.
This guide will help you choose the right type of steel pipe for your needs.
There are a number of factors that you should consider when choosing the right steel pipes for your needs. First, consider the material of your pipe as it will affect its strength and corrosion resistance. Then, determine the diameter that is right for you based on your requirements, followed by determining which wall thickness would be best suited to your application. Finally, decide how long of a piece you want and ensure that it has been properly coated if necessary!
Before selecting steel pipes, you must know the classifications, types of steel pipes.
Pipes and tubes are used in a variety of applications, including the transport of fluids, gases and heat. We will discuss the classification of steel pipes according to their size, wall thickness and method of manufacture.
Classification of steel pipes
The classification of steel pipes is mainly based on their manufacturing process, and it is also different from how to classify other metals. Generally speaking, the steel pipe can be divided into two categories: seamless steel pipes and welded steel pipes. The seamless steel pipe refers to the production process in which no welding is involved; it has a continuous wall thickness and does not have seams or joints between various sections during processing. Welding refers to the use of mechanical or thermal energy to melt metal powders at high temperature levels so that they adhere together under pressure before cooling down.”
Seamless steel pipes are classified as hollow sections. They are made by continuous casting, which involves passing the steel through a series of rollers at high speed and pressure. The process results in a pipe with no defects that can compromise its integrity.
Seamless steel pipes are used for transportation of liquids and gases because they have excellent resistance to corrosion, fatigue, abrasion and impact, as well as low weight compared to other types of pipe materials (such as cast iron). They’re also resistant to many chemicals found in industrial facilities.
Seamless steel pipes are used for domestic purposes such as transporting water from a central reservoir or well pump; heating systems; air conditioning units; plumbing fixtures; fire sprinkler systems; hot water heating systems etc.,
Welded steel pipes are also called seaml steel pipes. They can be classified as ERW, SSAW and LSAW.
ERW welded steel pipes are widely used in oil and gas industry because they have good mechanical properties and good corrosion resistance.
ERW pipes are conveniently made by extrusion. This means that the pipe is formed by forcing a long rod through a die, resulting in a hollow cylindrical shape with smooth interior walls.
Because of their low strength and high cost, ERW steel pipes are used almost exclusively in low pressure or low temperature applications. These pipes can be found in use in the oil and gas industries, as well as chemical plants and food production facilities around the world.
Steel pipe is a vital part of many industries. The most common type of steel pipe, SSAW (short for spiral welded steel pipe), is used in oil and gas pipelines, power plants, and more.
A SSAW steel pipe is made when two lengths of steel are welded together by a continuous winding process. Most commonly the seams are welded with electric resistance welding (ERW). The seam may also be butt-welded if necessary.
The first step in producing a spiral welded pipe is cutting the raw material into sheets before it’s rolled into coils that resemble springs or scrolls. Next comes an automated process where these coils get inserted into either side of an extrusion machine at both ends while they’re still hot from being formed into circles on rollers earlier in production; after cooling down from their initial heating cycle they become solidified slabs instead but still retain their circular shape as well as some flexibility thanks to residual heat within each individual piece that allows them bend slightly without breaking apart completely yet; finally this whole system will spin around slowly while gradually raising its temperature until reaching approximately 120 degrees Celsius at which point welder robots come along again so that now all four sides are tack-welded together using electrodes positioned along each circumference edge – this forms four separate seams around edges facing outward toward each other forming two sets (front&back/left&right) spaced apart evenly across center axis located between them; then finally once cooled down sufficiently again due to extreme temperatures involved during welding process
LSAW steel pipe is a kind of steel pipe that is produced by LSAW process. It has a long weld seam and high quality. LSAW steel pipe can be used for oil and gas, power, aviation, nuclear energy and other industries.
Depending on the manufacturing method, pipes are divided into two categories: seamless and seamed pipes. Seamless pipes are formed in one stage of the rolling process, but seamed pipes need to be welded after rolling. Seamed pipes can be divided into two categories due to the weld geometry of spiral and straight seam welds. Although there is debate as to whether seamless pipe is superior to seamed pipe, both seamless and welded pipe manufacturers can produce high-quality, reliable and corrosion-resistant pipe. When determining the type of pipe, the main focus should be on application and cost specifications.
Seamless pipe is usually manufactured in complex steps, starting with billet drilling, through cold drawing and cold rolling processes. In order to control the outside diameter and wall thickness, the seamless type dimensions are difficult to control compared to welded pipe, and the cold working improves mechanical properties and tolerances. The most significant advantage of seamless tubes is the ability to produce thick-walled tubes. Since they do not have welded seams, they are considered to have better mechanical properties and corrosion resistance than seamed pipes. In addition, seamless pipes will have better ovalness or roundness. They are usually preferred for use in extreme environmental conditions such as high loads, high pressures and high corrosiveness.
Welded steel pipe is made from welded or spiral welded steel plates rolled into a tube shape. There are different methods of manufacturing welded pipe depending on the form factor, wall thickness and application. Each method involves heating a billet or strip of steel, then making the pipe by stretching the billet and pressing the edges together and sealing them with a weld. Seamed pipes have tighter tolerances but thinner wall thicknesses than seamless pipes. Shorter lead times and lower costs may also be reasons why seamed pipe is preferable to seamless pipe. However, because welds may constitute sensitive areas suitable for crack expansion and lead to pipe fracture, surface finish inside and outside the pipe should be controlled during production.
The first choice for the user when selecting a steel is whether a seamless or a welded process should be used. Traditionally, seamless products have the reputation of being of higher quality. Seamless pipe manufacturing involves a process of pressing a hole into a billet. This is accomplished by a high temperature shear operation, extrusion; or an internal tearing operation, rotary piercing. Both of these operations have the potential to produce smaller ID surface defects. For projects requiring thick walls, seamless tubing is usually preferred because it can withstand high pressure environments.
Welded tubing is made from strips that are roll formed and welded into tubes. The weld is then typically cold worked to create a uniform wall. Over the past 75 years, many advances have been made in welded and drawn tube manufacturing, creating technical and commercial advantages for welded and drawn tube that are superior to seamless products. In addition, it is typically cheaper and has a shorter delivery cycle.
1. Metallographic method
Metallographic method is the main method to distinguish welded steel pipe and seamless steel pipe. There is no welding material added to the high-frequency resistance welded steel pipe, so the weld in the welded steel pipe is very narrow. If the method of rough grinding and re corrosion is adopted, the weld cannot be clearly seen. Once the high-frequency resistance welded steel pipe is welded without heat treatment, the weld structure will be essentially different from the steel pipe parent material. At this time, the metallographic method can be used to distinguish the welded steel pipe from the seamless steel pipe. In the process of distinguishing the two steel pipes, it is necessary to cut a small sample with a length and width of 40mm at the welding point, carry out rough grinding, fine grinding and polishing, and then put it under the metallographic microscope to observe the structure. When ferrite and widmanstatten, parent metal and weld zone are observed, welded steel pipes and seamless steel pipes can be accurately distinguished
2. Corrosion method
In the process of distinguishing welded steel pipe and seamless steel pipe by corrosion method, the weld seam of the processed welded steel pipe shall be polished. After polishing, the polished trace shall be visible. Then, the end face shall be polished with sandpaper at the weld seam, and the end face shall be treated with 5% nitric acid alcohol solution. If there is an obvious weld, it can be proved that the steel pipe is a welded steel pipe. The end faces of seamless steel pipes have no obvious difference after corrosion.
Properties of welded steel pipes
The welded steel pipe has the following properties because it is processed by high-frequency welding, cold rolling and other processes.
First, the thermal insulation function is good. The heat loss of welded steel pipe is relatively small, only 25%, which is not only conducive to transportation, but also reduces the cost.
Second, it is waterproof and corrosion-resistant. In the process of project construction, it is not necessary to set pipe ditches separately, but to directly bury steel pipes underground or underwater, thus reducing the construction difficulty of the project.
Third, it has impact resistance. Even in the low temperature environment, the steel pipe will not be damaged, so its performance has certain advantages.
Properties of Seamless Steel Pipe
Because the tensile strength of the metal material of seamless steel pipe is relatively high, its anti destruction ability is stronger, and it has a hollow channel, so it can effectively transport fluid. It is precisely because of its strong transmission capacity. Therefore, the corrosion resistance of seamless steel pipe is higher than that of welded steel pipe, and its stiffness is relatively large. Therefore, seamless steel pipes can be widely used in projects with high construction requirements due to the more loads they carry.
3. Distinguish welded steel pipe and seamless steel pipe according to process
In the process of distinguishing welded steel pipes and seamless steel pipes according to the process, welded steel pipes are welded according to cold rolling, extrusion and other processes. In addition, spiral pipe welding and straight seam pipe welding will be formed when steel pipes are welded by high-frequency, low-frequency arc welding and resistance welding processes, and circular steel pipes, square steel pipes, elliptical steel pipes, triangular steel pipes, hexagonal steel pipes, rhombic steel pipes, octagonal steel pipes will be formed, Even more complex steel pipes. In a word, different processes will form different shapes of steel pipes, so that welded steel pipes and seamless steel pipes can be clearly distinguished. However, in the process of identifying seamless steel pipes according to the process, it is mainly based on the hot rolling and cold rolling treatment methods. There are also two main types of seamless steel pipes, namely, hot rolling seamless steel pipes and cold rolling seamless steel pipes. Hot rolled seamless steel tubes are formed by piercing, rolling and other processes, especially for large diameter and thick seamless steel tubes; Cold drawn tubes are formed by cold drawing with tube blanks. The strength of the material is lower, but the surface and internal control surface are smooth.
4. Distinguish between welded steel pipes and seamless steel pipes according to their uses
Welded steel pipes have higher bending and torsional strength and more sufficient bearing capacity, so they are generally widely used in the manufacturing of mechanical parts. For example, oil drill pipe, automobile transmission shaft, bicycle frame and steel scaffolding used in construction are all made of welded steel pipes. However, the seamless steel pipe can be used as a pipeline to transport fluid because of its hollow section and long steel bars without joints around it. For example, it can be used as a pipeline to transport oil, natural gas, gas, water, etc. In addition, the bending strength of seamless steel pipes is relatively small, so they are generally used for superheated steam pipes of low and medium pressure boilers, boiling water pipes and superheated steam pipes for locomotive boilers. In a word, welded steel pipes and seamless steel pipes can be clearly distinguished by the classification of their uses.
In order to ensure higher engineering construction quality in China, it is necessary to distinguish between welded steel pipes and seamless steel pipes, and then use appropriate steel pipes for construction. In the process of identifying welded steel pipe and seamless steel pipe, metallographic method and corrosion method can be used to inspect the weld by observing the structure and weld, and finally identify them accurately. At the same time, the two types of steel pipes can also be distinguished according to their properties and uses, and then reasonable steel pipes can be selected for construction.
Consider selecting appropriate steel pipes materials.
Steel pipes are made of steel, which is a durable and strong material. Steel pipe is also an affordable option for your project, making it a great choice if you’re on a budget. It’s flexible and lightweight, allowing for easy transportation and installation.
Material Standards for Pipe Materials
- A53/A53M-02. Standard specification for pipe—steel, black and hot-dipped, zinc-coated, welded, and seamless.
- A105/A105M-02. Standard specification for carbon steel forgings for piping applications.
- A106-02a. Standard specification for seamless carbon steel pipe for high-temperature service.
- A134-96(2001). Standard specification for pipe—steel, electric-fusion (arc)- welded (sizes NPS 16 and over).
- A135-01. Standard specification for electric-resistance-welded steel pipe.
- A139-00. Standard specification for electric-fusion (arc)-welded steel pipe (NPS 4 and over).
- A179/A179M-90a(2001). Standard specification for seamless cold-drawn low-carbon steel heat-exchanger and condenser tubes.
- A181/A181M-01. Standard specification for carbon steel forgings, for general-purpose piping.
- A182/A182M-02. Standard specification for forged or rolled alloy-steel pipe flanges, forged fittings, and valves and parts for high-temperature service.
- A193/A193M-03. Standard specification for alloy-steel and stainless steel bolting materials for high-temperature service.
- A194/A194M-03b. Standard specification for carbon and alloy steel nuts for bolts for high-pressure or high-temperature service or both.
- A210/A210M-02. Standard specification for seamless medium-carbon steel boiler and superheater tubes.
- A234/A234M-03. Standard specification for piping fittings of wrought carbon steel and alloy steel for moderate- and high-temperature service.
- A268/A268M-03. Standard specification for seamless and welded ferritic and martensitic stainless steel tubing for general service.
- A269-02a. Standard specification for seamless and welded austenitic stainless steel tubing for general service.
- A312/A312M-03. Standard specification for seamless and welded austenitic stainless steel pipes.
- A320/A320M-03. Standard specification for alloy-steel bolting materials for low-temperature service.
- A333/A333M-99. Standard specification for seamless and welded steel pipe for low-temperature service.
- A334/A334M-99. Standard specification for seamless and welded carbon and alloy-steel tubes for low-temperature service.
- A335/A335M-03. Standard specification for seamless ferritic alloy-steel pipe for high-temperature service.
- A350/A350M-02b. Standard specification for carbon and low-alloy steel forgings, requiring notch toughness testing for piping components.
- A358/A358M-01. Standard specification for electric-fusion-welded austenitic chromium-nickel alloy steel pipe for high-temperature service.
- A369/A369M-02. Standard specification for carbon and ferritic alloy steel forged and bored pipe for high-temperature service.
- A376/A376M-02a. Standard specification for seamless austenitic steel pipe for high-temperature central-station service.
- A381-96(2001). Standard specification for metal-arc-welded steel pipe for use with high-pressure transmission systems.
- A403/A403M-03a. Standard specification for wrought austenitic stainless steel piping fittings.
- A409/A409M-01. Standard specification for welded large-diameter austenitic steel pipe for corrosive or high-temperature service.
- A420/A420M-02. Standard specification for piping fittings of wrought carbon steel and alloy steel for low-temperature service.
- A437/A437M-01a. Standard specification for alloy-steel turbine-type bolting material specially heat treated for high-temperature service.
- A453/A453M-02. Standard specification for high-temperature bolting materials, with expansion coefficients comparable to austenitic stainless steels.
- A524-96(2001). Standard specification for seamless carbon steel pipe for atmospheric and lower temperatures.
- A530/A530M-03. Standard specification for general requirements for specialized carbon and alloy steel pipe.
- A587-96(2001). Standard specification for electric-resistance-welded lowcarbon steel pipe for the chemical industry.
- A671-96(2001). Standard specification for electric-fusion-welded steel pipe for atmospheric and lower temperatures.
- A672-96(2001). Standard specification for electric-fusion-welded steel pipe for high-pressure service at moderate temperatures.
- A691-98(2002). Standard specification for carbon and alloy steel pipe, electric-fusion-welded for high-pressure service at high temperatures.
- A789/A789M-02a. Standard specification for seamless and welded ferritic/austenitic stainless steel tubing for general service.
- A790/A790M-03. Standard specification for seamless and welded ferritic/austenitic stainless steel pipe.
- A815/A815M-01a. Standard specification for wrought ferritic, ferritic/austenitic, and martensitic stainless steel piping fittings.
Types of steel pipes
There are many types of steel pipes available in the market. The main purpose of these pipes is to transfer liquids and gases from one place to another. Depending on their material, they can be divided into Carbon Steel Pipe, Stainless Pipes, Alloy Steel Pipe, Nickel and Nickel Alloys, Titanium Pipes and Chrome Moly Pipe.
Carbon steel pipe is one of the most common types of steel pipe. It is made from iron and carbon, two metals that are naturally abundant on our planet. Carbon steel pipe can be used for water, gas, oil, and steam transportation because it has excellent corrosion resistance to a wide range of chemicals and can withstand high temperatures without breaking down easily.
Stainless steel pipes are corrosion resistant and used in virtually every industry. They are able to withstand extreme temperatures, pressures and corrosive chemicals which makes them ideal for the food service industry, chemical manufacturing and petroleum refining industries.
Stainless steel pipes come in many different grades ranging from 300 series stainless steel (which is non-magnetic) to 900 series stainless steel (which is magnetic). The most commonly used grades of stainless steels are 300 Series Stainless Steel Pipes & Tubes (also known as Alloy 304), 316L Stainless Steel Pipes & Tubes (also known as Alloy 316L) and Duplex 2205 Pipes & Tubes.
Alloy steel pipes are alloys of iron, carbon and other elements. Alloy steels are more expensive than the more common carbon steels, but they have superior mechanical properties. Alloy steel pipes are used in high temperature applications because they can handle temperatures up to 2200 degrees Fahrenheit (1200 degrees Celsius). The main alloying component in these materials is chromium. The most common types of alloy steel pipe include:
- ASTM A333 Grade B Pipe
- ASTM A333 Grade C Pipe
- ASTM A333 Grades D & E Pipe
Nickel and Nickel Alloys Steel Pipe
Nickel and nickel alloys are non-ferrous metals that have a wide range of applications in the aerospace industry. Nickel alloys are used to make stainless steel, which is used in a variety of industries and products. Some of the most common examples include machine parts and tools, kitchen utensils and cookware, jewelry, coins, pipes and plumbing systems.
Titanium alloy pipes are a popular choice for use in machinery and equipment, as titanium is a light, strong and corrosion resistant metal. While the cost of titanium may be high, it is still an affordable pipe choice for many applications.
Chrome Moly Pipes
Chrome-Moly pipes are also known as chromium molybdenum steel pipes. They are used in high-temperature applications and are capable of resisting corrosion from chemicals and high pressure, making them ideal for cryogenic applications as well as aircraft engines and turbines.
Black steel pipe is the most stable structural steel pipe in sales due to its convenience and high stability. Black steel pipe, also known as raw steel pipe or bare steel pipe, is made of steel without any coating. The “black” in the name comes from the dark iron oxide coating formed on its surface during manufacturing.
Black steel pipes are also used in the transportation of water, oil and construction industries, especially in the production of fences and scaffolding.
Galvanized steel pipe
Galvanized steel pipes are made of steel coated with several layers of molten zinc protection to prevent pipe rust and corrosion. Galvanizing process was invented in the 1950s, and then galvanized steel pipes replaced lead based pipes.
Galvanized steel pipes are mainly used as water conveyance and building materials, and are widely used in many industries, such as automation and general engineering industries, bus body and railway bogie manufacturers.
Types of steel pipes are based on their material.
Types of Steel Grades
The three most common types of steel pipes are carbon steel, stainless steel and alloy steel. Carbon steels are made from iron and carbon. Stainless steels contain chromium and nickel (or other metals) in addition to iron. Alloy steels have several alloying elements added to them during the manufacturing process such as molybdenum and manganese for corrosion resistance or nickel for strength.
A fourth type of pipe that is often used for structural applications is nickel-alloy tubing which is made by adding nickel to an alloy steel pipe to increase its strength at high temperatures as well as provide resistance against corrosion when exposed to certain chemicals such as sulfuric acid or salt water.
Chemical Composition of Stainless Steel Grades
|Austenitic Stainless Steel|
|TP 304||S30400||1.4301||SUS 304||0.08||18||8|
|TP 304 L||S30403||1.4307||SUS 304L||0.035||18||8|
|TP 304H||S30403||1.4948||SUS 304H||0.04-0.1||18||8|
|TP 321||S32100||1.4541||SUS 321||0.08||17||9||5(C+N)<Ti< 0.7|
|TP 321H||S32100||1.4878||SUS 321||0.04-0.1||17||9||4(C+N)<Ti< 0.7|
|TP 347||S3470||1.455||SUS 347||0.08||17||9||10×C<Nb<1|
|TP 347H||S34709||SUS 347||0.04-0.1||17||9||8×C<Nb<1.10|
|TP 316||S31600||1.4401||SUS 316||0.06||16||10||2|
|TP 316L||S31603||1.4404||SUS 316L||0.03||16||10||2|
|TP 316H||S31609||SUS 316H||0.04-0.1||16||10||2|
|TP 316 Ti||S31635||1.4571||SUS 316Ti||0.03||16||10||2||N0.015(C+N)<Ti< 0.7|
|TP 317||S31700||1.4438||SUS 317L||0.08||18||11||3|
|TP 317L||31703||1.4438||SUS 317L||0.03||18||11||3|
|TP 309S||S30908||1.4833||SUS 309S||0.8||22||12|
|TP 310||S31000||1.4841||SUS 310||0.08||24||19|
|TP 310S||S31008||1.4845||SUS 310S||0.1||24||19|
|TP 310H||S31009||1.4845||SUS 310H||0.08||24||19|
|TP 904L||N08904||1.4539||SUS 904L||0.02||19.0>||23||4||1.0-2.0|
|High Temperature Stainless Steel/Heat Resistant Stainless Steel|
|TP 304H||S30403||1.4948||SUS 304H||0.04-0.1||18||8|
|TP 321H||S32100||1.4878||SUS 321||0.04-0.1||17||9||4(C+N)<Ti< 0.7|
|TP 347H||S34709||SUS 347||0.04-0.1||17||9||8×C<Nb<1.10|
|TP 309S||S30908||1.4833||SUS 310S||0.08||22||12|
|TP 310S||S31008||1.4845||SUS 310S||0.08||24||19|
|TP 310H||S31009||1.4845||SUS 310H||0.08||24||19|
|*All figures in weight percentage. In case of order, the limits of the order specification will apply.|
|Duplex Stainless Steel Grade|
|*All figures in weight percentage. In case of order, the limits of the order specification will apply.|
|Stainless Steel Chemical Composition|
|Grade||C (Max)||Mn (Max)||P (Max)||S (Max)||Si (Max)||Cr||Ni||Mo||Azoto (Max)||Cu/Outro|
|301||0.15||2||0.045||0.03||1||16.00 – 18.00||6.00 – 8.00||–||0.1||–|
|304||0.08||2||0.045||0.03||0.75||18.00 – 20.00||8.00- 10.50||–||0.1||–|
|304L||0.03||2||0.045||0.03||0.75||18.00 – 20.00||8.00- 12.00||–||0.1||–|
|310S||0.08||2||0.045||0.03||1.5||24.00- 26.00||19.00 – 22.00||–||–||–|
|316||0.08||2||0.045||0.03||0.75||16.00 – 18.00||10.00 – 14.00||2.00 – 3.00||0.1||–|
|316L||0.03||2||0.045||0.03||0.75||16.00 – 18.00||10.00 – 14.00||2.00 – 3.00||0.1||–|
|317||0.08||2||0.045||0.03||0.75||18.00 – 20.00||11.00 – 14.00||3.00 – 4.00||0.1||–|
|317L||0.03||2||0.045||0.03||0.75||18.00 – 20.00||11.00 – 15.00||3.00 – 4.00||0.1||–|
|321||0.08||2||0.045||0.03||0.75||17.00 – 19.00||9.00 – 12.00||–||0.1||Ti5 ( C + N ) Min or 0.70 max|
|347||0.08||2||0.045||0.03||0.75||17.00 – 19.00||9.00 – 13.00||–||–||Cb= 10x ( C Min ) or 1.00 Max|
|409||0.08||1||0.04||0.01||1||10.50 – 11.75||0.5||–||–||Ti= 6x (C+ N ) Min or 0.70 Max|
|409M||0.03||0.81.2||0.03||0.03||0.40.75||11.00- 12.00||1.5 max.||–||–||Ti= 6x (C) Min or 0.70 Max|
|420||0.35||0.5||0.035||0.015||0.5||12.00 – 13.00||0.20.3||–||–||–|
|430||0.12||1||0.04||0.03||1||16.00 – 18.00||0.75||–||–||–|
|JSL AUS||0.08||7.08.0||0.07||0.03||0.75||15.50 – 16.50||4.25 – 4.75||–||–||0.9 – 1.10|
|JS- 203||0.08||9.2510.25||0.07||0.03||0.75||14.25 – 15.25||2.25 – 2.75||–||–||1.60- 2.0|
|301M||0.1||4.55.5||0.06||0.03||0.75||14.50 – 15.50||6.0 – 7.0||–||–||1.70- 1.90|
Chemical Composition of Hastelloy Alloy Grades
|Hastelloy B||0.1||1.25||0.6||28||0.3||–||–||–||–||–||5.5||rest/bal||Mn 0.80; Si 0.70|
|Hastelloy B2 / Hastelloy B-2||0.02||1||1||26.0-30.0||–||–||–||–||–||–||2||rest/bal||Mn 1.0, Si 0.10|
|Hastelloy C||0.07||1.25||16||17||0.3||40||–||–||–||–||5.75||rest/bal||Mn 1.0; Si 0.70|
|Hastelloy C4 / Hastelloy C-4||0.015||2||14.0-18.0||14.0-17.0||–||–||–||–||–||0..70||3||rest/bal||Mn 1.0 ; Si 0.08|
|Hastelloy C276 / Hastelloy C-276||0.02||2.5||14.0-16.5||15.0-17.0||0.35||3.0-4.5||–||–||–||–||4.0-7.0||rest/bal||Mn 1.0; Si 0.05|
|Hastelloy F||0.02||1.25||22||6.5||–||0.5||–||–||2.1||–||21||rest/bal||Mn 1.50; Si 0.50|
|Hastelloy G||0.05||2.5||21.0-23.5||5.5-7.5||–||1||–||1.5-2.5||1.7-2.5||–||18.0-21.0||rest/bal||Mn 1.0-2.0; P0.04; Si 1.0;|
|Hastelloy G2 / Hastelloy G-2||0.03||–||23.0-26.0||5.0-7.0||–||–||–||0.70-1.20||–||0.70-1.50||rest/bal||47.0-52.0||Mn 1.0; Si 1.0|
|Hastelloy N||0.06||0.25||7||16.5||–||0.2||–||0.1||–||–||3||rest/bal||Mn 0.40; Si 0.25; B 0.01|
|Hastelloy S||0.02||2||15.5||14.5||0.6||1||0.2||–||–||–||3||rest/bal||Mn 0.50; Si 0.40; B0.0009; La 0.02|
|Hastelloy W||0.06||1.25||5||24.5||–||–||–||–||–||–||5.5||rest/bal||Mn 0.050; Si 0.50|
|Hastelloy X||0.1||1.5||22||9||–||0.6||–||–||–||18.5||–||rest/bal||Mn 0.6; Si 0.60|
Chemical Composition of Monel Nickel Alloy Grades
|Designation||C%||Co%||Cr%||Mo%||Ni%||V%||W%||Ai%||Cu%||Nb/Cb Ta%||Ti%||Fe%||Sonstige Autres-Other %|
|Monel 400||0.12||–||–||–||65||–||–||–||32||–||–||1.5||Mn 1.0|
|Monel 401||0.1||–||–||–||43||–||–||–||53||–||–||0.75||Si 0.25; Mn 2.25|
|Monel 404||0.15||–||52.0-57.0||–||–||0.05||rest/bal||–||–||0.5||Mn 0.10; Si 0.10;S o.024|
|Monel 502||0.1||–||–||–||63.0-17.0||–||–||2.5-3.5||rest/bal||–||0.5||2||Mn 1.5;Si 0.5; S 0.010|
|Monel K 500||0.13||–||–||–||64||–||–||2.8||30||–||0.6||1||Mn 0.8|
|Monel R 405||0.15||–||–||–||66||–||–||–||31||–||–||1.2||Mn 1.0; S 0.04|
Chemical Composition of Brass Alloy Grades
|UNS No||AS No||Common Name||BSI No||ISO No||JIS No||Copper %||Zinc %||Led %||Others %|
|C21000||210||95/5 Gilding metal||–||CuZn5||C2100||94.0-96.0||~ 5||< 0.03|
|C22000||220||90/10 Gilding metal||CZ101||CuZn10||C2200||89.0-91.0||~ 10||< 0.05|
|C23000||230||85/15 Gilding metal||Cz102||Cuzn15||C2300||84.0-86.0||~ 15||< 0.05|
|C24000||240||80/20 Gilding metal||Cz103||Cuzn20||C2400||78.5-81.5||~ 20||< 0.05|
|C26130||259||70/30 Arsenical brass||Cz126||Cuzn30as||~C4430||69.0-71.0||~ 30||< 0.07||Arsenic 0.02-0.06 ^M|
|C26000||260||70/30 brass||Cz106||Cuzn30||C2600||68.5-71.5||~ 30||< 0.05|
|C26800||268||Yellow brass (65/35)||Cz107||Cuzn33||C2680||64.0-68.5||~ 33||< 0.15|
|C27000||270||65/35 wire brass||Cz107||Cuzn35||–||63.0-68.5||~ 35||< 0.10|
|C27200||272||63/37 Common brass||Cz108||CuZn37||C2720||62.0-65.0||~ 37||< 0.07|
|C35600||356||Engraving brass, 2% lead||–||CuZn39Pb2||C3560||59.0-64.5||~ 39||2.0-3.0|
|C37000||370||Engraving brass, 1% lead||–||CuZn39Pb1||~C3710||59.0-62.0||~ 39||0.9-1.4|
|C38000||380||Section brass||Cz121||CuZn43Pb3||–||55.0-60.0||~ 43||1.5-3.0||Aluminium 0.10-0.6|
|C38500||385||Free cutting brass||Cz121||CuZn39Pb3||–||56.0-60.0||~ 39||2.5-4.5|
Chemical Composition of Cast Iron Grades
|Range of Chemical Composition for Typical Unalloyed Cast Irons (Values in Percent (%)|
|Type of Iron||Carbon||Silicon||Manganese||Sulfur||Phosphorus|
|Gray Iron||2.5 – 4.0||1.0 – 3.0||0.2 – 1.0||0.02 – 0.25||0.02 – 1.0|
|Ductile Iron||3.0 – 4.0||1.8 – 2.8||0.1 – 1.0||0.01 – 0.03||0.01 – 0.1|
|Compacted Graphite Iron||2.5 – 4.0||1.0 – 3.0||0.2 – 1.0||0.01 – 0.03||0.01 – 0.1|
|Malleable Iron (Cast White)||2.0 – 2.9||0.9 – 1.9||0.15 – 1.2||0.02 – 0.2||0.02 – 0.2|
|White Iron||1.8 – 3.6||0.5 – 1.9||0.25 – 0.8||0.06 – 0.2||0.06 – 0.2|
Chemical Composition of Titanium and Titanium Base Alloy Grades
|R50250||Titanium Gr 1||–||0.1||0.2||0.0125||0.05||0.18||–||–||–||–||–||–||–||–||0.1||0.4|
|R50400||Titanium Gr 2||–||0.1||0.3||0.0125||0.05||0.25||–||–||–||–||–||–||–||–||0.1||0.4|
|R50700||Titanium Gr 4||–||0.1||0.5||0.0125||0.07||0.4||–||–||–||–||–||–||–||–||0.1||0.4|
|R56400||Titanium Gr 5 c||5.5-6.75||0.1||0.4||0.0125||0.05||0.2||–||3.5-4.5||–||–||–||–||–||–||0.1||0.4|
|R56401||Titanium Ti-6Al-4V ELI||5.5-6.5||0.08||0.25||0.0125||0.05||0.13||–||3.5-4.5||–||–||–||–||–||–||0.1||0.4|
|R52400||Titanium Gr 7||–||0.1||0.3||0.0125||0.05||0.25||0.12-0.25||–||–||–||–||–||–||–||0.1||0.4|
Chemical Composition of Carbon Steel Grades
|1008||.10 Max.||.25 – .50||0.04||0.05||1008|
|1010||.08 – .13||.30 – .60||0.04||0.05||1010|
|1012||.10 – .15||.30 – .60||0.04||0.05||1012|
|1015||.12 – .18||.30 – .60||0.04||0.05||1015|
|1016||.12 – .18||.60 – .90||0.04||0.05||1016|
|1017||.14 – .20||.30 – .60||0.04||0.05||1017|
|1018||.14 – .20||.60 – .90||0.04||0.05||1018|
|1019||.14 – .20||.70 – 1.00||0.04||0.05||1019|
|1020||.17 – .23||.30 – .60||0.04||0.05||1020|
|1022||.17 – .23||.70 – 1.00||0.04||0.05||1022|
|1023||.19 – .25||.30 – .06||0.04||0.05||–|
|1025||.22 – .28||.30 – .60||0.04||0.05||1025|
|1030||.27 – .34||.60 – .90||0.04||0.05||1030|
|1035||.31 – .38||.60 – .90||0.04||0.05||1035|
|1040||.36 – .44||.60 – .90||0.04||0.05||1040|
|1043||.39 – .47||.70 – 1.00||0.04||0.05||1043|
|1045||.42 – .50||.60 – .90||0.04||0.05||1045|
|1050||.47 – .55||.60 – .90||0.04||0.05||1050|
|1055||.52 – .60||.60 – .90||0.04||0.05||1055|
|1060||.55 – .66||.60 – .90||0.04||0.05||1060|
|1065||.59 – .70||.60 – .90||0.04||0.05||1065|
|1070||.65 – .76||.60 – .90||0.04||0.05||1070|
|1074||.69 – .80||.50 – .80||0.04||0.05||1074|
|1080||.74 – .88||.60 – .90||0.04||0.05||1080|
|1085||.80 – .94||.70 – 1.00||0.04||0.05||1085|
|1095||.90 – 1.04||.30 – .50||0.04||0.05||1095|
Chemical Composition of Inconel Alloy Grades
Mechanical properties of steel materials
Steel mechanical properties are important indicators to ensure the end-use properties (mechanical properties) of steel, which depends on the chemical composition of steel and heat treatment system. In the steel pipe standard, according to the different use requirements, specify the tensile properties (tensile strength, yield strength or yield point, elongation) and hardness, toughness indicators, and user requirements of high and low temperature properties.
① Tensile strength (σb)
The maximum force (Fb) that a specimen undergoes in tension when it is pulled, divided by the stress (σ) obtained from the original cross-sectional area (So) of the specimen, is called tensile strength (σb), in N/mm (MPa). It indicates the maximum capacity of a metal material to resist damage under tension.
② Yield point (σs)
The metal material with yield phenomenon, the stress when the specimen can continue to elongate without an increase in force (remain constant) during the stretching process, called the yield point. If the force decreases, the upper and lower yield points should be distinguished. The unit of yield point is N/mm (MPa).
Upper yield point (σsu): the maximum stress before the specimen yields and the force first decreases; lower yield point (σsl): the minimum stress in the yielding phase when the initial instantaneous effect is not accounted for.
③ Elongation after break (σ)
In the tensile test, the percentage of the increase in the length of the specimen after the specimen is pulled from its mark to the length of the original mark is called elongation. It is expressed as σ in %. The formula is: σ = (Lh – Lo) / L0 * 100%
In the formula: Lh – the specimen’s specimen length after pulling off, mm; L0 – the specimen’s original specimen length, mm.
④ Fractional shrinkage rate (ψ)
In the tensile test, the percentage of the maximum shrinkage of the cross-sectional area at its shrinkage after the specimen is pulled off and the original cross-sectional area is called the fractional shrinkage rate. It is expressed as ψ in %.
⑤ Hardness index
The ability of a metal material to resist the indentation of a hard object into a surface is called hardness. Depending on the test method and the scope of application, hardness can be divided into Brinell hardness, Rockwell hardness, Vickers hardness, Shore hardness, microhardness and high temperature hardness. For the pipe is generally used in Brinell, Rockwell, Vickers hardness.
A. Brinell hardness (HB)
Using a certain diameter steel ball or carbide ball, press into the surface of the sample with the specified test force (F), remove the test force after the specified holding time, and measure the indentation diameter (L) on the surface of the sample. The Brinell hardness value is the quotient obtained by dividing the test force by the spherical surface area of the indentation. It is expressed in HBS (steel ball) in N/mm (MPa).
Determination of Brinell hardness is more accurate and reliable, but generally HBS is only applicable to metal materials below 450N/mm (MPa), and is not applicable to harder steel or thinner plates. Among steel pipe standards, Brinell hardness is the most widely used, and often the indentation diameter d is used to indicate the hardness of the material, which is both intuitive and convenient.
Example: 120HBS10/1000/30: indicates the Brinell hardness value of 120N/ mm (MPa) measured with a 10mm diameter steel ball held for 30s (s) under a test force of 1000Kgf (9.807KN).
Mechanical Properties of Stainless Steel
|Grade||Tensile Strength min./ksi [MPa]||Yield Strength min./ksi [MPa]||Elongation in 2in or 50mm length % (min)||Hardness (Max) ASTM E18 Brinell||Hardness (Max) ASTM E18 Rockwell|
|201||95 ||38 ||35||219 HBW||95 HRB|
|304||75 ||30 ||35||192 HBW||90 HRB|
|304L||70 ||25 ||35||192 HBW||90 HRB|
|304H||75 ||30 ||35||192 HBW||90 HRB|
|304N||80 ||35 ||35||192 HBW||90 HRB|
|309S||75 ||30 ||35||192 HBW||90 HRB|
|309H||75 ||30 ||35||192 HBW||90 HRB|
|310S||75 ||30 ||35||192 HBW||90 HRB|
|310H||75 ||30 ||35||192 HBW||90 HRB|
|316||75 ||30 ||35||192 HBW||90 HRB|
|316L||70 ||25 ||35||192 HBW||90 HRB|
|316H||75 ||30 ||35||192 HBW||90 HRB|
|316Ti||75 ||30 ||35||192 HBW||90 HRB|
|317||75 ||30 ||34||192 HBW||90 HRB|
|317L||75 ||30 ||35||192 HBW||90 HRB|
|321||75 ||30 ||35||192 HBW||90 HRB|
|321H||75 ||30 ||35||192 HBW||90 HRB|
|347||75 ||30 ||35||192 HBW||90 HRB|
|TP347H||75 ||30 ||35||192 HBW||90 HRB|
|N08904||71 ||31 ||35||192 HBW||90 HRB|
|N08020||80 ||35 ||30||217 HBW||95 HRB|
|800||75 ||30 ||30||192 HBW||90 HRB|
|800H||65 ||25 ||30||192 HBW||90 HRB|
|800HT||65 ||25 ||30||192 HBW||90 HRB|
|N10276||100 ||41 ||40|
|N06022||100 ||45 ||45|
|S31803||90 ||65 ||25||290 HBW||30 HRC|
|S31803||90 ||65 ||25||290 HBW||30 HRC|
|S32101||101 ||77 ||30||290 HBW||30 HRC|
|Wall≤0.187 in. [5.00 mm]||Wall≤0.187 in. [5.00 mm]|
|S32205||95 ||70 ||25||290 HBW||30 HRC|
|S32550||110 ||80 ||15||297 HBW||31 HRC|
|S32304||100 ||65 |
|OD 1 in. [25 mm] and Under||OD 1 in. [25 mm] and Under||25||…||…|
|87 ||58 |
|OD over 1 in. [25 mm]||OD over 1 in. [25 mm]|
|25||290 HBW||30 HRC|
|S32750||116 ||80 ||15||300 HBW||32 HRC|
|S32760||109 ||80 ||25||300 HBW||…|
Mechanical Properties of Magnesium Alloys
|Alloy Designation||Yield Strength (kpsi)||
in 2 in.
|Cast AM 265C||11||27||6||11||48||11|
|Cast AM 240-T4||12||35||9||12||52||20||11|
|Cast AM 260-T6||20||38||3||20||78||22||11.5|
|Die-cast AM 263||22||34||3||14|
|Wrought AM 3S||30||40||7||11||40-52||16.7||11|
|Wrought AM C52S||30||40||17||20||50-71||19||15|
|Wrought AM C52S||32||44||14||20||55-74||20.5||17|
|Wrought AM 59S||38||51||9||27||70||22||18|
Mechanical Properties of Copper Based Alloys
|UNS||Alloy Name||Form||Temper||Yield Strength (Mpa)||Tensile Strength (Mpa)||Elongation in 2 in. (%)||
Mechanical Properties of Aluminum Alloys
|UNS Alloy Number||Temper||Yield Strength (kpsi)||Tensile Strength (kpsi)||Shear Modulus of Rupture (kpsi)||Fatigue Strength (kpsi)||Elongation||
|in 2 in., %|
Mechanical Properties of Gray Cast Iron
|ASTM Number||Tensile Strength (Kpsi)||Compressive Strength||Shear Modulus of Rupture (Kpsi)||Modulus of Elasticity (Mpsi)||Endurance Limit||
(1) The importance of the structure
For important structures such as heavy industrial building structures, large span structures, high-rise or super high-rise civil building structures or structures, the use of high-quality steel pipes should be considered. For general industrial and civil building structures, steel pipes of ordinary quality can be selected according to the nature of the project.
(2) Load situation
For structures directly subjected to dynamic loads and structures in strong earthquake areas, carbon steel steel pipes with good overall performance should be used; for structures usually subjected to static loads, steel pipes with lower prices can be used.
(3) Connection method
The welding process can produce welding defects such as welding deformation and welding stress, and there is a risk of cracking or brittle fracture of the structure. Therefore, the material requirements for welded structures should be more stringent.
(4) The temperature and environment where the structure is located
Steel tubes are susceptible to cooling and embrittlement at low temperatures. Therefore, structures working under low temperature conditions, especially welded structures, should use calming steel with good low temperature brittle fracture resistance. In addition, taiyuan seamless steel tubes for open-air structures are prone to aging, and seamless steel tubes containing harmful media are prone to corrosion, fatigue and fracture. Different materials should also be selected differently.
(5) Steel pipe thickness
Thin-walled steel pipe rolling frequency is higher, rolling compression is relatively large, while the compression of thick steel pipe is relatively small. Therefore, the large thickness of precision steel pipe is not only lower strength, but also plasticity, impact toughness and welding performance is poor. Therefore, for the larger thickness of the welded structure, should use the material better steel pipe.
Steel pipe is a long hollow strip of steel used in large quantities as a pipeline for transporting fluids such as oil, natural gas, natural gas and water as well as certain solid materials. Compared to solid steel such as round steel, steel pipe has the same bending and torsional strength and is lighter in weight. It is an economical cross-sectional steel and is widely used in the manufacture of structural and mechanical parts such as oil drilling rods, automobile drive shafts, bicycle frames and steel scaffolding for building construction.
In both the manufacturing methods, raw steel is first cast into a more workable starting form (hot billet or flat strip). It is then made into a pipe by stretching the hot steel billet out into a seamless pipe or forcing the edges of the flat steel strip together and sealing them with a weld.
Seamless Pipe Manufacturing
Mandrel Mill Process
In the Mandrel Mill Process, a solid round steel billet is used. The billet is charged into a rotary hearth furnace. After the billet is discharged from the rotary hearth furnace, a small hole is punched into its end. This indentation acts as a starting point to aid in the rotary piercing. Rotary piercing is a very fast and dynamic rolling process that cross rolls the preheated billet between two barrel-shaped rolls at a high speed. The design of the piercer rolls causes the metal to flow along with the roll and over a piercer point as it exits the process. The piercer point is a high-temperature, water-cooled alloy tool designed to allow the metal to flow over it as a pipe shell forms from the rotary process. Once the pierced pipe shell is produced, it is immediately transferred to the floating mandrel mill. The floating Mandel mill comprises eight rolling stands using 16 rolls and a set of mandrel bars. These bars are inserted into the pierced pipe shell and then conveyed into the mandrel mill, and rolled into a pipe shell. Then the mandrel mill is re-heated in order to complete the final rolling stage and to gain final dimensions. While the mill is leaving the furnace, the iron-oxide scale is removed from the surface via high-pressure water descale. The pipe shell is further reduced to specified dimensions by the stretch mill.
Mannesmann Plug Mill Process
Mannesmann plug mill process differs from mandrel milling with a great difference of rolling plug usage instead of a mandrel mill. In the Mannesmann process, a pair of conical rolls are arranged on top of each other and operate in the opposite direction to material flow. A hollow pipe shell having thick walls is guided towards the plug mill rolls. As soon as it is gripped by the tapered portion of the work pass, a small material wave is sheared off the hollow pipe shell. This wave is forged to the desired wall thickness on the mandrel by the smoothing portion of the work pass, with the hollow pipe shell plus mandrel moving backward in the same direction as the rolls are rotating until they reach the idler pass of the rolls and are released. As the hollow pipe shell is rotated it is once again pushed forward between the rolls, and a new rolling cycle begins.
Extrusion is a metal forming process in which a workpiece is forced into a die of the smaller cross-section. The length of the extruded part will vary, dependent upon the amount of material in the workpiece and the profile extruded. Numerous cross-sections are manufactured by this method. Steel pipes can be directly produced by extrusion with the usage of a mandrel attached to the dummy block. A hole is created through the workpiece parallel to the axis over which the ram applies the force to form the extrusion. When the operation begins, the ram is forced forward. The extruded metal flows between the mandrel and the die surfaces, forming the part. The interior profile of the metal extrusion is formed by the mandrel, while the exterior profile is formed by the extruding die.
Seamed Pipe Manufacturing
Seamed pipes are manufactured from plate or continuous coil or strips. To manufacture a seamed pipe, the first plate or coil is rolled in the circular section with the help of a plate bending machine or by a roller in the case of a continuous process. When the circular section is rolled from the plate, the pipe can be welded with or without filler material. There are different welding methods used to weld the pipe.
Electric Resistance Welding Process (ERW)
In the electric resistance welding process, the pipe is produced by cold-forming a flat sheet of steel into ay cylindrical geometry. Then the current is passed through the edges of the steel cylinder to heat up the steel and form a bond between the edges at a point that they are forced to meet. During ERW processes filler materials may also be utilized. There are two types of electric resistance welding as high-frequency welding and rotary contact wheel welding.
The requirement for high-frequency welding has arisen from the tendency of low-frequency welding products to undergo selective seam corrosion, hook cracks, and inadequate bonding of seams. So, low-frequency ERW is no longer used to manufacture pipes. The high-frequency ERW process is still being used in pipe manufacturing. There are two types of high-frequency ERW processes. High-frequency induction welding and high-frequency contact welding are types of high-frequency welding. In high-frequency induction welding, the weld current is transmitted to the material through a coil. The coil does not contact the pipe. The electrical current is induced into the pipe material through magnetic fields that surround the pipe. In high-frequency contact welding, the current is transmitted to the material through contacts that ride on the strip. The welding power is applied directly to the pipe, which makes this process more effective. This method is generally preferred for large diameter and high wall thickness pipe production.
Another type of electric resistance welding is the rotary contact wheel welding process. During this process, electrical current is transmitted through a contact wheel at the weld point. The contact wheel also applies the pressure necessary for welding. Rotary contact welding is generally utilized for applications that cannot accommodate an impeder inside the pipe.
Electric Fusion Welding Process (EFW)
The electric fusion welding process refers to an electron beam welding of a steel plate by the use of the high-speed movement of the electron beam. High impact kinetic energy of the electron beam is converted into heat to heat the workpiece so that the weld seam is produced. The welding zone can also be heat treatment so that the weld is not visible. Welded tubes generally have tighter dimensional tolerances than seamless tubes, and if made in the same amount, the cost is lower. Mainly used for dissimilar steel welding sheet or high power density welding, metal welding parts can be quickly heated to high temperatures, melting any refractory metals and alloys.
Submerged Arc Welding Process (SAW)
Submerged arc welding involves arc formation between a wire electrode and the workpiece. A flux is used to generate protective gases and slag. As the arc moves along the joint line, excess flux is removed via a hopper. As the arc is completely covered by the flux layer, it is not normally visible during welding, and heat loss is also extremely low. There are two types of submerged arc welding processes as longitudinal submerged arc welding and spiral submerged arc welding processes.
In longitudinal submerged arc welding, longitudinal edges of steel plates are first beveled by milling to form a U shape. Edges of the U shaped-plates are then welded. Pipes manufactured by this process are subjected to expanding operation in order to relieve internal stresses and obtain a perfect dimensional tolerance.
In spiral submerged arc welding, weld seams are like a helix around the pipe. In both of the longitudinal and spiral welding methods the same technology is utilized, the only difference is the spiral shape of seams in spiral welding. The manufacturing process is rolling the steel strip, to make the rolling direction have an angle with the direction of the pipe center, forming and welding, so the welding seam is in a spiral line. The major disadvantage of this process is bad physical dimension of pipes and higher seam length which can easily lead into a defect or crack formation.
Quality requirements and inspection methods for steel pipes
Why is steel pipe quality important?
The quality of steel pipe is very important because it will affect the performance of the pipe. If the quality of steel pipe is poor, its performance will be affected and even become unsafe. High quality steel pipes are stronger, more durable and have a longer service life than cheap steel pipes. They are also easier to weld together and can be bent into different shapes without breaking. Steel pipes made of high-quality materials are also more corrosion resistant; This means they can be used for a longer time without rusting or cracking.
(A) Quality requirements of steel pipe
① Chemical composition of steel: the chemical composition of steel is one of the most important factors affecting the performance of seamless steel pipe, and is also the main basis for developing the parameters of pipe rolling process and steel pipe heat treatment process parameters.
- a. Alloying elements: intentionally added, according to the use;
- b. Residual elements: steelmaking brought in, appropriate control;
- c. Harmful elements: strictly controlled (As, Sn, Sb, Bi, Pb), gas (N, H, O).
Off-furnace refining or electroslag remelting: improve the uniformity of the chemical composition of steel and the purity of steel, reduce the non-metallic inclusions in the pipe billet and improve its distribution pattern.
② Steel pipe geometric accuracy and shape
a. Steel pipe outside diameter accuracy: depends on the sizing (reducing) diameter method, equipment operation, process system, etc.
Allowable deviation of the outer diameter δ = (D-Di) / Di × 100%.
- D: the maximum or minimum outside diameter mm;
- Di: nominal outside diameter mm.
b. Pipe wall thickness accuracy: with the heating quality of the billet, the process design parameters and adjustment parameters of the deformation process, the quality of the tool and its lubrication quality, etc.
Allowable wall thickness deviation: ρ=(S-Si)/Si×100%.
- S: maximum or minimum wall thickness in cross section;
- Si: nominal wall thickness mm.
c. Steel pipe ellipticity: indicates the degree of non-circularity of the steel pipe.
d. Steel pipe length: normal length, fixed (times) length, length allowable deviation.
e. Steel pipe curvature: the curvature of the steel pipe: the curvature of each meter of steel pipe length, the curvature of the full length of the steel pipe.
f. Steel pipe end tangency: the steel pipe end and the inclination of the steel pipe cross-section.
g. Steel pipe end bevel angle and blunt edge.
(B) The quality of steel pipe inspection methods.
1. Chemical composition analysis: chemical analysis method, instrumental analysis (infrared C-S instrument, direct reading spectrometer, zcP, etc.)
- ① Infrared C-S instrument: analysis of iron alloys, steelmaking raw materials, C, S elements in steel.
- ② Direct reading spectrometer: C, Si, Mn, P, S, Cr, Mo, Ni, Cn, A1, W, V, Ti, B, Nb, As, Sn, Sb, Pb, Bi in block specimens.
- ③ N-0 instrument: gas content analysis N, O.
2. Steel pipe geometry and shape inspection.
- ① Steel pipe wall thickness inspection: micrometer, ultrasonic thickness gauge, not less than 8 points at both ends and record.
- ② Steel pipe outside diameter, ellipticity check: calipers, vernier calipers, ring gauge, measuring the maximum point, the minimum point.
- ③ Steel pipe length check: steel tape measure, manual, automatic length measurement.
- ④ Steel pipe curvature check: straightedge, horizontal ruler (1m), stopper, fine line to measure the curvature of each meter, full-length curvature.
- ⑤ Steel pipe end bevel angle and blunt edge inspection: angle ruler, cardboard.
3. Steel pipe surface quality inspection: 100%
- ① Manual visual inspection: lighting conditions, standards, experience, logo, steel pipe rotation.
- ② Nondestructive inspection: ① Non-destructive inspection.
a. Ultrasonic flaw detection UT.
For a variety of material uniformity of the material surface and internal crack defects are more sensitive.
- Standard: GB / T 5777-1996
- Level: C5
b. Eddy current flaw detection ET: (electromagnetic induction)
Mainly sensitive to point-like (hole-shaped) defects.
- Standard: GB/T 7735-2004
- Grade: B grade
c. Magnetic particle MT and leakage magnetic flaw detection.
Magnetic flaw detection, applicable to the detection of surface and near-surface defects of ferromagnetic materials.
- Standard: GB / T 12606-1999
- Level: C4 level
d. Electromagnetic ultrasonic flaw detection.
Does not require coupling medium, can be applied to high temperature and high speed, coarse and dry steel pipe surface flaw detection.
e. Penetrant flaw detection.
Fluorescence, coloring, detection of steel pipe surface defects.
4. Physical and chemical properties of steel pipe inspection.
① tensile test: measure stress and deformation, determine the strength of the material (YS, TS) and plasticity indicators (A, Z).
Longitudinal, transverse specimens pipe section, arc, round specimens (￠10, ￠12.5).
Small-diameter, thin-walled large-diameter, thick-walled fixed scale distance.
Note: Specimen elongation after fracture and specimen size GB / T 1760.
② Impact test: CVN, notch C-type, V-type, work J value J / cm.
Standard specimen 10 × 10 × 55 (mm) non-standard specimens 5 × 10 × 55 (mm).
③ Hardness test: Brinell hardness HB, Rockwell hardness HRC, Vickers hardness HV, etc.
④ Hydraulic test: test pressure, pressure stabilization time, p = 2Sδ / D.
5. Steel pipe process performance inspection process.
- ① Flattening test: round specimen C-shaped specimen (S/D>0.15) H = (1 + 2) S / (∝ + S/D) L = 40-100mm unit length deformation coefficient = 0.07-0.08.
- ② Ring pull test: L = 15mm no cracks for qualified.
- ③ Flare and rolled edge test: top center taper 30 °, 40 °, 60 °.
- ④ Bending test: can replace the flattening test (for large diameter pipe).
6. Steel pipe metallographic analysis.
① High power test (microscopic analysis): non-metallic inclusions 100x GB / T 10561 grain size: level, grade.
Organization: M, B, S, T, P, F, A-S
Decarburization layer: internal, external.
A method of grading: Class A – sulfides Class B – oxides Class C – silicates Class D – spherical oxidation DS.
② Low magnification test (macroscopic analysis): naked eye, magnifying glass 10x or less.
- a. Acid etching test method.
- b. Sulfur seal inspection method (billet inspection, showing the low peel tissue and defects, such as loosening, segregation, subcutaneous bubbles, flip skin, white spots, inclusions, etc.)
- c. Tower hairline inspection method: test the number, length and distribution of hairline.
You should consider the type of coating you need for your steel pipe.
If you’re buying steel pipes for underground use, a coating is important. It protects the pipe from corrosion, abrasion and impact damage and prevents rusting.
Coatings are usually applied to the outside of the pipe (or inside if it’s an inner tube) to form a protective layer against outside elements. Coatings can be inorganic or organic and they come in many different types:
Bitumen – bituminous coatings are used on oil pipelines such as those found in Canada. They have low friction resistance but are cost effective on large diameter pipelines since they’re easy to apply without removing existing liners before installation;
Epoxy – epoxy coatings have high levels of abrasion resistance but aren’t as strong as other types;
Polyethylene (PE)- PE has good flexibility properties which means it can withstand vibration while also protecting against corrosion;
You must consider the diameter of the steel pipe.
You must consider the diameter of the steel pipe. The diameter of a steel pipe is important because it determines how much fluid can flow through it at any given time. To understand how this works, imagine that you have a garden hose connected to your faucet and your neighbor has a fire hydrant. If both hoses are open and full, you will be able to fill up more water from his hydrant than from yours because he has more pressure. In other words, there is more force pushing against each cubic inch of water in his system than yours.
The same principle applies to steel pipes: the larger their diameters, the higher their flow rates will be (and vice versa). While smaller diameters mean lower pressures within their walls and less risk for bursting or leaking if damaged; they also mean lower flow rates due to friction losses involved with moving fluids through densely packed tubes instead of open channels with larger openings between them like those found on fire hydrants or kitchen sinks where large amounts of water need moving quickly without causing clogs or stoppages which might cause flooding damage inside one’s home.”
You should also look at wall thickness of steel pipe.
When you’re choosing steel pipes, you should also look at wall thickness. The wall thickness of a pipe refers to the thickness of its walls. Thicker pipes are stronger and more durable than thinner ones because there is less room for corrosion to affect them. However, thicker pipes are also more expensive than their thinner counterparts.
It is important to look at the length of steel pipes when ordering.
The length of steel pipes is an important consideration when you are ordering. The longer the pipe is, the more expensive it will be. It is also important to consider how much you will need before ordering a certain length; shorter lengths can be cut to size if needed. In some cases, shorter lengths may end up being cheaper than longer ones because they are not as heavy or require as much material.
However, if you need a higher quality product that will last longer and withstand more pressure than other materials would allow, then it might be better for your application to choose a slightly longer length steel pipe (such as 16 ft).
1. Inferior quality steel pipes are prone to folding
Folding is formed on the surface of the pipe, and this defect often runs through the entire length of the product. The cause of folding is due to the pursuit of high efficiency, poor quality manufacturers to significantly reduce production, in the next rolling, folding will occur, folding products will crack after bending, the strength of the steel will be reduced.
2. Inferior quality steel pipe with pitting
Pitting is caused by irregular and uneven steel surface defects caused by worn bevels. Due to the pursuit of profit, poor quality steel pipe manufacturers often have over-rolled grooves.
3. Inferior steel pipe surface scarring easily
There are two reasons: (1) poor quality steel pipe material is not uniform, inclusions of impurities. (2). Inferior material manufacturer equipment is simple and easy to stick steel, these impurities are easy to scar after the roll bite.
4. The surface of inferior material is easy to crack because it is billet and cracked during the cooling process due to thermal stress and cracks after rolling.
5. Inferior quality steel pipe is easy to scratch because the equipment of inferior steel pipe mill is simple and easy to produce burrs and scratch the surface of steel. Deep scratches will reduce the strength of the steel.
6. Poor quality steel pipe without metallic luster, the raw material is adobe, a slight red or similar to the color of pig iron. The characteristics of the steel pipe does not meet the required standard.
7. Poor quality steel pipe with thin and low crossbars often appears unsatisfactory because the manufacturer wants to achieve large negative tolerances and the quality of the finished product does not meet the standard.
8. The cross section of poor quality steel pipe is oval because the factory is trying to save material, the finished rolls are very large, the strength of the reinforcement is greatly reduced, but also does not meet the standard of the shape and size of the reinforcement.
9. High-quality steel composition is uniform, cold shear tonnage, cutting head end smooth and neat, poor quality manufacturers poor material, cutting head end is not smooth or uneven, but also no metallic luster.
10, poor quality steel pipe impurities are very large, but the steel density is small, the size of the super poor serious, so in the absence of vernier calipers, you can check the weighing.
11. Poor quality steel pipe with large fluctuations in internal diameter due to: 1. unstable steel temperature; 2. uneven steel composition; 3. due to poor equipment and low base strength, there will be large changes in the same week, caused by uneven fracture of steel.
12. High-quality pipe markings and printing is the norm.
13. Steel pipe diameter greater than 16, the spacing between the two trademarks are greater than IM.
14. Inferior quality steel longitudinal bars often heave.
15. Poor quality steel pipe manufacturer, no traffic, loose packaging.
Steel pipe is a common construction material in our daily life, such as welded steel pipe. Therefore, manufacturers specializing in the production of steel pipes vary. In these factories, they have different production capacity, so the quality of steel pipes is also very uneven. It is shameful but unavoidable that some inferior manufacturers who produce inferior steel pipes can mislead customers’ decisions. So, how to distinguish the quality of steel pipes and square tubes? How to choose the right product with reasonable price? We should learn some basic knowledge about these issues.
High quality steel pipe has very even distribution of pipe composition and smooth and neat surface, such as cold rolled steel pipe. However, poor quality steel pipes have obvious creases on the surface, which can form a variety of creases. The creases can seriously affect the strength of the steel pipe; this will become a potential safety issue. For poor quality steel pipe, the composition contains a large number of impurities, resulting in impure raw materials, which can easily cause uneven materials. This poor quality steel pipe cannot be used in actual construction projects.
High quality steel pipes, such as hot dipped galvanized steel pipes, have many excellent properties. For example, quality steel pipes have high strength, are not easily scratched, and minor scratches are not obvious. However, poor quality steel pipes produced by a simple set of equipment can easily produce burrs, which reduce the strength of the pipe. Steel pipes with metallic luster top the steel pipe market, but poor quality steel pipes have more or less uneven spots, which are caused by simple and rough production equipment. We should choose the steel pipe with smooth surface and no obvious burrs.
The above basic points can generally be used to judge the quality of steel pipes. For all steel pipe manufacturers, each manufacturer has its own steel pipe price according to its type or specification. In the fluctuating steel pipe market, choosing the ideal product with high value is not an easy task. It is a commitment of time and effort. In addition, we need to have some relevant information in advance. Therefore, it is very important to learn some methods of judging your choice. If you have other questions about the chosen method, please leave a comment below.
How to choose right steel pipes manufacturers?
When you need to buy steel pipe, it is important to choose an experienced and professional steel pipe manufacturer. Here is a list of factors that can help you make the right decision.
Reputation is one of the most important factors to consider when choosing a steel pipe manufacturer. You want to make sure they are reliable, trustworthy, and have good customer service. This is why it is so important to research each manufacturer before making your final decision.
2. The level of quality of the steel pipe
For example, you can choose a manufacturer with a high-quality product and a good reputation to ensure that the steel pipe you buy not only meets your needs, but is also reliable. A reputable steel pipe manufacturer is more likely to produce a quality product that meets the customer’s standards.
Customers must remember that the level of quality of steel pipe directly affects its use and operation. The higher the quality of these products, the better they will perform in a variety of applications such as construction materials or underground water systems.
3. Price of steel pipes
The price of steel pipe is one of the most important factors for buyers. However, it does not guarantee that a low price means a high quality pipe and vice versa. If you want to get the best deal, you need to know what you are buying and be able to compare prices effectively.
The daily price of steel pipe exhibits constant changes. Therefore, when some customers buy in bulk, they should follow market price trends in real time in order to find a more cost effective phase of purchase. Generally, seamless steel pipe manufacturers follow a number of websites on a daily basis and perform relevant analyses of the steel pipe offers on them. To be able to analyze the market price for the next week with relevant forecasts and to know the future price trends based on the forecasted and analyzed prices. For customers who know the prices of seamless steel pipes in the market, they can choose the right time to buy pipes at low prices, which can really save a lot of money in new projects.
There are two ways to ensure that a pipe manufacturer is financially strong.
Compare what different manufacturers charge for similar output. For example, if one manufacturer can produce 50 tons per month while another can only produce 25 tons per month, it is clear that the industrial output of the second manufacturer will be more expensive than that of the first.
How do they compare costs to the competition?
Pricing is another important factor when it comes to pipe production. Now, if you have never worked with the same pipe manufacturer before, you may not be aware of the fair and competitive pricing that other companies must offer. If that’s the case, go out and check it out, ask for quotes, and stay clear with the manufacturers around you. Ultimately, you can get better overall pricing.
Pipe manufacturers are happy to discuss their pricing and quotes (if they don’t, this can be a red flag). However, keep in mind that simply asking for a quote doesn’t mean you’ve started any contacts, and it’s certainly not uncommon for customers to compare and contrast cost projections with multiple companies. In fact, we hope you do.
After talking to three or four manufacturers, you should have a fairly stable price framework. Remember to never settle for the cheapest price because it is the cheapest. While a much higher estimate than other options may indicate that the company is trying to benefit from it, it may also reflect their knowledge and ability to provide a quality product.
4. Whether the steel pipe manufacturer has experience.
- Experienced manufacturers have a better chance of producing a quality product.
- Experienced manufacturers have more opportunities to provide better service.
- Experienced manufacturers have a better chance of offering better prices.
- Experienced manufacturers have a better chance of providing a better level of quality.
5. Steel pipe manufacturing technology
The manufacturer should have a good knowledge of the product so that you can fully understand the product and compare it with other manufacturers. The manufacturer should have a good reputation, which means that you can buy from them without having to worry about the quality of their products or services. The manufacturer must also be able to provide a high quality product so that even if one pipe is defective, it will not affect other pipes.
It is important for the buyer to choose a professional pipe manufacturer to ensure that good quality pipes are provided.
We must be confident that the information they provide and their products are reliable.
6. Supply capacity comparison
Generally the supply capacity of large manufacturers is very good, in addition to the ability to provide a wide range of steel pipe types, there are many manufacturers who can provide bulk custom processing services. Manufacturers are capable of providing large quantities of steel pipes with quality assurance, then such manufacturers are also worthy of our cooperation.
7. Punctuality of delivery
On-time delivery is also to be the focus, after all, each project has a completion period, too long in all aspects of human, material and financial resources will increase the cost, that the pursuit of a project for the profit and risk ratio changes greatly, when signing the contract must be good delivery period to talk with manufacturers about the importance of the delivery period.
For the buyer, it is very important to select a professional steel pipe manufacturer to ensure the supply of steel pipes with good quality. If you choose a non professional steel pipe manufacturer, many problems may occur during production and transportation. For example: poor surface treatment or no surface treatment at all; Poor welding quality; Cracking between two pipes; Rust caused by poor coating, etc.
The selection of a reliable steel pipe manufacturer is critical to the success of the project. It is difficult to determine which companies are trustworthy, so it is important to make a survey before making a decision. We hope this article will give you some insight into how to find a company to work with you on the next project!
Source: China Steel Pipes Manufacturer – Yaang Pipe Industry Co., Limited (www.epowermetals.com)
(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, and Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels, and other industries.)
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