What is a chemical steel pipe
What is a chemical steel pipe?
Steel pipes for petrochemical and chemical industries (including coal chemical industry) are commonly referred to as steel pipes for three chemical industries, which generally refers to petrochemical industry, including steel pipes for petroleum refining, chemical fiber production, coal chemical industry, chemical industry and chemical fertilizer production. According to the production mode of steel pipe, it is divided into seamless steel pipe and welded pipe. According to the steel type, it can be divided into carbon steel pipe, alloy steel pipe and stainless steel pipe, as well as composite steel pipe widely used in recent years. Because the main physical and chemical reactions in the three chemical production process are carried out under specific pressure and temperature. Raw materials, reaction processes and products all have temperature and pressure requirements, and raw materials, reaction processes and products all have certain corrosivity. Therefore, there are certain technical requirements for steel pipes applied to specific three chemical production.
Cracking pipe is a furnace pipe, heat exchanger and connecting pipe used in petroleum refinery. It is one of the earliest varieties of special seamless steel pipe developed in China. See GB9948-2006 for the current technical standard of cracking pipe.
The special pipe for chemical fertilizer is the equipment and pipeline for chemical fertilizer and chemical plant with working temperature of – 40-400 ℃ and working pressure of 10-30mpa. See GB6479-2000 for the current technical standards of chemical pipe.
In addition to the above two special standards, the three chemical industries also use a large number of ordinary steel pipes, steel pipes for liquefied transportation, low and medium pressure boiler pipes, high-pressure boiler pipes, alloy steel pipes, stainless steel pipes, titanium alloy pipes, composite pipes, etc.
Requirements of three chemical pressure devices on steel properties
In the petrochemical industry, most of the operating conditions of vessels are not normal temperature and atmospheric pressure, that is, the operating pressure is higher or lower than atmospheric pressure; The operating temperature is higher or lower than normal temperature; The operating medium of the container is mostly flammable, explosive, and even toxic and corrosive. Moreover, with the increasing depth of petroleum processing and the development of petrochemical industry, the operating conditions of refinery equipment will be more and more harsh, which means that the requirements for pressure vessel and pipeline materials are higher and higher. It mainly includes: high working temperature strength, sufficient creep strength and lasting strength, good toughness, microstructure stability, low notch sensitivity, good macrostructure, good processing properties and welding properties.
Table.1 Common piping materials and service temperature range
| The serial number | Steel pipe Standard Name | Steel tube standard number | The name of the material | Outer diameter or nominal diameter (mm) | Service temperature (℃) | note |
| 1 | Seamless steel tube for conveying fluid | GB/T8163 | 10 | 6-630. | -445 | |
| 2 | Seamless steel tubes for petroleum cracking | GB9948 | 10 \, 20 | 10-273. | -445 | |
| 3 | High pressure seamless steel tubes for fertilizer equipment | GB6479 | 10 | 14-273. | -440 | Working pressure 10-320mpa |
| 4 | Seamless steel tube for conveying fluid | GB/T8163 | 20, 16 mn | 6-630. | -445 | |
| 5 | High pressure seamless steel tubes for fertilizer equipment | GB6479 | 16Mn | 14-273. | -440 | |
| 6 | High pressure seamless steel tubes for fertilizer equipment | 16MnD | -290 | |||
| 7 | High pressure seamless steel tubes for fertilizer equipment | 19Mn2VD | -150 | |||
| 8 | High pressure seamless steel tubes for fertilizer equipment | 19Mn2NiD | -170 | |||
| 9 | Seamless steel tubes for petroleum cracking | GB9948 | 12CrMo | 10-273. | 525 or less | |
| 10 | High pressure seamless steel tubes for fertilizer equipment | GB6479 | 12CrMo | 14-273. | 525 or less | |
| 11 | Seamless steel tubes for petroleum cracking | GB9948 | 15CrMo | 10-273. | 550 or less | |
| 12 | High pressure seamless steel tubes for fertilizer equipment | GB6479 | 15CrMo | 14-273. | 550 or less | |
| 13 | Seamless steel tubes for high pressure boilers | GB5310 | 12Cr1MoVG | 10-530. | 575 or less | |
| 14 | High pressure seamless steel tubes for fertilizer equipment | GB6479 | 12Cr2Mo | 14-273. | 575 or less | |
| 15 | High pressure seamless steel tubes for fertilizer equipment | GB6479 | 1Cr5Mo | 14-273. | 600 or less | |
| 16 | Seamless steel tubes for petroleum cracking | GB9948 | 1Cr5Mo | 10-273. |
Steel pipes and varieties commonly used in the three chemical plants
Cracking pipe is a furnace pipe, heat exchange and connecting pipe used in petroleum refinery. It is one of the earliest varieties of special seamless steel pipe developed in China. See GB9948-2006 for the current technical standard of cracking pipe.
The special pipe for chemical fertilizer is the equipment and pipeline for chemical fertilizer and chemical plant with working temperature of – 40-400 ℃ and working pressure of 10-30mpa. See GB6479-2000 for the current technical standards of chemical pipe.
In addition to the above two special standards, the three chemical industries also use a large number of ordinary steel pipes, steel pipes for liquefied transportation, low and medium pressure boiler pipes, high-pressure boiler pipes, alloy steel pipes, stainless steel pipes, titanium alloy pipes, composite pipes and low-temperature resistant pipes.
Since the 1980s, the development of medium pressure hydrocracking technology with operating pressure of 6-10.0mpa has been very active. With the improvement of environmental protection requirements, there is more and more demand for hydrogenation units in recent years, such as hydrocracking, benzene hydrogenation, kerosene hydrogenation, gasoline, diesel hydrogenation and lubricating oil hydrogenation. Hydrocracking technology plays an increasingly important role in the refining and chemical industry.
China’s energy resources are characterized by rich coal and less oil. Using China’s rich coal resources and adopting coal liquefaction technology, coal can be transformed into high-quality liquid fuel or directly gasified into coal to gas. It is an effective way to utilize power coal, especially high sulfur coal in China. Direct coal liquefaction is a hydrogenation process under high pressure and high temperature, so the process equipment and materials must have the properties of high pressure resistance and hydrogen corrosion resistance under critical hydrogen conditions.
In short, the range of steel pipes used in the three chemical plants is very wide, and the requirements are also very diverse. Therefore, as a steel pipe manufacturer, it should be closer to the market, understand the needs of users, and develop the steel pipe that best meets the needs of users according to the user’s use environment rather than adhering to the requirements of standards.
The types of steel pipes most used in pressure vessels are:
Carbon steel
Carbon structural steel and high-quality carbon steel are often used in pressure vessels. In the national standard gb699-88 technical conditions for high quality carbon structural steel, high quality carbon steel is divided into steel grades according to the content and manganese content. The commonly used pressure vessels are 20R, 16MnR, 10# and 20# seamless steel pipes.
Alloy steel
According to the content of alloying elements, it is divided into low alloy steel, medium alloy steel and high alloy steel.
① Low alloy steel
Low alloy steel is an alloy steel added with a certain amount of alloy elements on the basis of carbon steel. The total content of alloying elements is generally not more than 5%, so as to improve the strength of the steel and ensure a certain plasticity and toughness, or make the steel have some special properties, such as low temperature resistance, high temperature resistance, hydrogen resistance or corrosion resistance.
1) Low temperature steel
Low temperature steel is mainly used for various low-temperature containers such as air separation equipment and liquefied petroleum gas storage and transportation equipment and metal structures in cold areas. Therefore, it has high requirements for low-temperature toughness of steel. Generally, good low-temperature toughness is obtained by solid solution strengthening and grain refinement of alloy elements, grain refinement and homogenization structure through normalizing and tempering treatment. Common low temperature alloy steels for pressure vessels include 16MnDR, 15MnNiDR, 09mn2vdr, 09MnNiDR, etc.
2) Heat resistant steel
Common low alloy heat-resistant steels for pressure vessels include 1cr-0.5mo (15CrMo), 11 / 4cr-0.5mo, 21 / 4cr-1mo, 3cr-1mo, etc. The Cr and Mo alloy elements and carbide forming elements such as vanadium, niobium, titanium, tungsten and boron contained in these alloy steels are also the basic elements to significantly improve the hydrogen resistance of the steel. Therefore, the above low alloy heat-resistant steel can also be used as hydrogen resistant steel.
② Medium alloy steel
Alloy steels with a total alloy element content of 5-12% are collectively referred to as medium alloy steels. Pressure vessels are rarely or basically not used. They are mostly used in piping and heating furnace tubes, mainly Cr5 Mo and CR9 Mo steel.
③ High alloy steel
Alloy steels with a total content of alloying elements higher than 13% are called high alloy steels. It is divided into Ferritic, martensitic, austenitic and austenitic + ferritic dual phase steels according to the structure under the supply state. CR or Cr Ni steel is the most widely used in this kind of steel. Because it contains high Cr or Cr Ni alloy elements, it has corrosion resistance to atmosphere and various corrosive media, so it is also called stainless steel. The commonly used steel grades of pressure vessels and their internals include 0Cr13, 1Cr13, 2Cr13, 0Cr18Ni9, 00Cr19Ni10, 0Cr18Ni10Ti, 0Cr17Ni12Mo2, 00Cr17Ni14Mo2, 0Cr18Ni12Mo2Ti, 0cr19ni13mo3, 00cr19ni13mo3, etc.
Market analysis of large diameter thick wall steel pipe for petrochemical industry
Large diameter thick wall seamless steel pipe for high pressure hydrocracking project
Since the 1980s, the development of medium pressure hydrocracking technology with operating pressure of 6-10.0mpa has been very active. With the improvement of environmental protection requirements, there is more and more demand for hydrocracking units in recent years, such as hydrocracking, kerosene hydrogenation, gasoline, diesel hydrogenation and lubricating oil hydrogenation units. Hydrocracking technology plays an increasingly important role in the oil refining industry.
According to the introduction of Beijing Design and Research Institute, a 1.2 million T/A hydrocracking unit, with a design pressure of 10.0MPa, uses about 600 tons of seamless steel pipes, including about 100 tons of large-diameter thick wall seamless steel pipes, with a maximum wall thickness of 400mm and a maximum diameter of 600mm.
Large diameter thick wall seamless steel pipe for ethylene project.
In the petrochemical industry, the consumption of seamless pipe in ethylene plant is the largest, and the wall thickness can reach 90mm. A typical 900000 ton ethylene plant needs about 40000 tons of ∮ 18-610 steel pipe.
The consumption of seamless pipes in 900000 T/A ethylene plant is about 3000 tons. At present, many ethylene plants in China are being reconstructed and expanded to a scale of 900000 tons. With the increasing development of ultra-high pressure technology, the design scale is becoming larger and larger, especially the development of tubular production of ultra-high pressure ethylene plant, the required inner diameter of ultra-high pressure large-diameter thick wall seamless steel pipe is becoming larger and larger. Therefore, according to the investigation and analysis, in the petrochemical industry, the number of large-diameter thick wall seamless steel pipe to be consumed by ethylene plant in the next few years is about 20000 tons per year.
Large diameter thick wall seamless steel pipe for coal liquefaction
China’s energy resources are characterized by rich oil and less coal. Making use of China’s rich coal resources and adopting coal liquefaction technology to convert coal into high-quality liquid fuel is an effective way for the utilization of power coal, especially high sulfur coal.
Direct coal liquefaction is a hydrogenation process under high pressure and high temperature, so the process equipment and materials must have the properties of high pressure resistance and hydrogen corrosion resistance under critical hydrogen conditions. In addition, the materials for direct liquefaction treatment contain solid particles such as coal and catalyst, so the technical problems such as deposition, wear and sealing caused by the treatment of particles should be solved. The inclined conveying with large-diameter seamless steel pipe can inhibit the phase separation of slurry and liquid and the residue in the conveying pipe in the process. The wall thickness of seamless steel pipe can be as high as 105mm
Source: China Stainless Steel Pipe Manufacturer – Yaang Pipe Industry Co., Limited (www.pipelinedubai.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, 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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