Seamless steel pipes for three chemical industries (petroleum cracking, fertilizer, chemical industry pipes) and their use temperature range

Pipes for three chemical industries (petroleum cracking, fertilizer, chemical industry pipes)
Steel pipes for petroleum, petrochemical, and chemical industries (including the coal chemical industry) are commonly referred to as steel pipes for three chemical industries, generally referring to the petrochemical industry, including the general term for steel pipes used in petroleum refining, chemical fiber production, coal chemical industry, chemical industry, and fertilizer production. According to the production method of steel pipes, they are divided into seamless steel pipes and welded pipes. According to the type of steel, they can be divided into carbon steel pipes, alloy steel pipes, and stainless steel pipes, as well as composite steel pipes that have been widely used in recent years. Because the main physical and chemical reactions in the three chemical production processes are carried out under specific pressures and temperatures. Raw materials, reaction processes, and outputs all have temperature and pressure requirements, and raw materials, reaction processes, and outputs are all corrosive. Therefore, there are certain technical requirements for steel pipes used in specific three chemical productions.

1. Requirements for steel performance of three-chemical pressure devices
In the petrochemical industry, the operating conditions of the containers are mostly not normal temperature and pressure, that is, the operating pressure is higher or lower than the atmospheric pressure; the operating temperature is higher or lower than the normal temperature; the operating medium of the container is mostly flammable, explosive, and even toxic and corrosive. Moreover, with the continuous increase in the depth of oil processing and the development of petrochemicals, the operating conditions of refinery equipment will become more and more harsh, which means that the requirements for pressure vessels and pipeline materials are getting higher and higher. Mainly including higher working temperature strength, sufficient creep strength, and endurance strength, good toughness, organizational stability, lower notch sensitivity, good low-multiple organization, good processing technology performance, welding performance, etc.

2. Steel pipes and varieties commonly used in three-chemical devices
- Cracking pipes are furnace pipes, heat exchange, and connecting pipes used in oil refineries. It is one of the earliest varieties of special seamless steel pipes developed in my country. The current technical standards for cracking pipes can be found in GB9948-2006.
- Fertilizer special pipes are used for fertilizers, chemical plant equipment, and pipelines with working temperatures of -40-400℃ and working pressures of 10-30MPa. The current technical standards for chemical pipes are shown in GB6479-2000.
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.
In short, the three chemical devices have a very wide range of steel pipes and very diverse requirements. Therefore, as a steel pipe manufacturer, it should be closer to the market, understand user needs, and develop steel pipes that best meet user needs based on the user's use environment rather than sticking to the requirements of the standards.
The most commonly used steel pipe varieties in pressure vessels are:
2.1 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. Commonly used pressure vessels are 20R, 16MnR, 10, and 20 seamless steel pipes.
2.2 Alloy steel: According to the content of alloy 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 with a certain amount of alloy elements added to carbon steel. The total content of alloy elements generally does not exceed 5% to improve the strength of the steel and ensure certain plasticity and toughness, or to give the steel certain 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, as well as metal structures in cold areas. Therefore, high low-temperature toughness requirements are placed on steel. Generally, good low-temperature toughness is obtained through solid solution strengthening of alloy elements, grain refinement, and grain refinement and homogenization of the structure through normalizing and tempering. 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 basic elements that significantly improve the hydrogen resistance of steel, so the above-mentioned low-alloy heat-resistant steels can also be used as hydrogen-resistant steels.
② Medium alloy steel: Alloy steels with a total alloying element content of 5-12% are collectively referred to as medium alloy steels. They are rarely or even basically not used in pressure vessels, and are only used in piping and heating furnace tubes. They mainly include Cr5-Mo and Cr9-Mo steels.
③ High alloy steel: Alloy steels with a total alloying element content higher than 13% are called high alloy steels. According to the organization in the delivery state, it is divided into ferrite, martensite, austenite, and austenite + ferrite dual-phase steel, etc. The most widely used steel in this type is Cr or Cr-Ni steel. Because it contains a high content of Cr or Cr-Ni alloy elements, it has corrosion resistance to the atmosphere and various corrosive media, so it is also called stainless steel. Commonly used steel grades for pressure vessels and their internal parts are 0Cr13, 1Cr13, 2Cr13, 0Cr18Ni9, 00Cr19Ni10, 0Cr18Ni10Ti, 0Cr17Ni12Mo2, 00Cr17Ni14Mo2, 0Cr18Ni12Mo2 Ti, 0Cr19Ni13Mo3, 00Cr19Ni13Mo3, etc.

3. Market analysis of large-diameter thick-walled steel pipes for petrochemicals
3.1 Large-diameter thick-walled seamless steel pipes for high-pressure hydrocracking projects: Since the 1980s, the development of medium-pressure hydrocracking technology with an operating pressure of 6-10.0Mpa has been very active. With the improvement of environmental protection requirements, the demand for hydrogenation units has increased in recent years, such as hydrocracking, kerosene hydrogenation, gasoline, diesel hydrogenation, and lubricating oil hydrogenation units. The construction of hydrocracking technology has increased, and the position of hydrocracking technology in the oil refining industry has become increasingly important.
3.2 Large-diameter thick-walled seamless steel pipes for ethylene projects: In the petrochemical industry, the consumption of seamless steel pipes for ethylene units is the largest, and the wall thickness can reach 90mm. With the increasing development of ultra-high pressure technology, the design scale is becoming larger and larger, especially the development of ultra-high pressure ethylene units produced by the tubular method, and the inner diameter of ultra-high pressure large-diameter thick-walled seamless steel pipes are required to be larger and larger. Therefore, according to the survey, in the petrochemical industry, the number of large-diameter thick-walled seamless steel pipes that ethylene units need to consume in the next few years will be about 20,000 tons per year.
3.3 Large-diameter thick-walled seamless steel pipes for coal liquefaction: my country's energy resources are characterized by rich oil and little coal. Utilizing my country's abundant coal resources and adopting coal liquefaction technology to convert coal into high-quality liquid fuel is an effective way to utilize my country's thermal 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 properties such as high-pressure resistance and hydrogen corrosion resistance under critical hydrogen conditions. In addition, the materials directly liquefied contain solid particles such as coal and catalysts, so it is necessary to solve technical problems such as deposition, wear, and sealing caused by the treatment of particles. Using large-diameter seamless steel pipes for inclined transportation can inhibit the phase separation of slurry during the process and the residue in the conveying pipe. The wall thickness of the seamless steel pipe can be as high as 105mm.