High-pressure seamless steel pipes for fertilizer equipment conform to GB 6479 standards. They are primarily used in pipeline systems within fertilizer production equipment for transporting high-temperature, high-pressure fluids. The operating temperature range is -40~400℃, and the operating pressure is 10~30MPa. The materials are divided into two categories: high-quality carbon structural steel and alloy structural steel. The former improves performance by controlling sulfur and phosphorus content and includes low-carbon and medium-carbon steel, suitable for general structural components and fluid transport. The latter enhances mechanical properties by adding alloying elements and requires heat treatment for high-pressure environments.
This product is manufactured using a seamless process, featuring high bending and torsional strength and light weight. Specifications include various models such as 406×10mm and 356×12mm, and the core indicators are consistent with GB/T6479. Besides the fertilizer industry, it can also be used in fluid transport systems in petroleum cracking, hydraulic supports, and other fields. The material classification and application scenarios meet the pressure resistance and safety requirements of chemical equipment.
Production Process:
The production process of high-pressure seamless steel pipes for fertilizer equipment is complex and precise, mainly including raw material preparation, billet heating, piercing, rolling, sizing, cooling, straightening, end trimming, inspection, marking, and packaging. Piercing and rolling are crucial steps in forming the shape and dimensions of the seamless steel pipe, requiring extremely high technical levels and equipment precision. Simultaneously, to ensure the quality of the steel pipes, multiple inspections are required during production, including chemical composition analysis, mechanical property testing, metallographic observation, and non-destructive testing (such as ultrasonic testing and X-ray testing), ensuring that each steel pipe meets the standard requirements.
Materials for High-Pressure Seamless Pipes for Fertilizer Equipment:
1. High-Quality Carbon Structural Steel
This steel contains carbon (C) and a certain amount of silicon (Si) (generally not exceeding 0.40%) and manganese (Mn) (generally not exceeding 0.80%, but can reach up to 1.20%) alloying elements for deoxidation, but no other alloying elements (excluding residual elements).
This type of steel must simultaneously guarantee both chemical composition and mechanical properties. The content of sulfur (S) and phosphorus (P) impurities is generally controlled below 0.035%. Steel with sulfur (S) and phosphorus (P) content below 0.030% is called high-grade quality steel, and its grade should be followed by "A", for example, 20A. If P is controlled below 0.025% and S below 0.020%, it is called premium-grade quality steel, and its grade should be followed by "E" to distinguish it. For other residual alloying elements introduced into the steel from the raw materials, such as chromium (Cr), nickel (Ni), and copper (Cu), the content is generally controlled at Cr ≤ 0.25%, Ni ≤ 0.30%, and Cu ≤ 0.25%. Some grades have a manganese (Mn) content of up to 1.40%, and are called manganese steel.
This type of steel improves its mechanical properties by adjusting its carbon (C) content. Therefore, based on carbon content, it can be further divided into:
Low-carbon steel – generally less than 0.25% carbon, such as 10 and 20 steel;
Medium-carbon steel – generally between 0.25% and 0.60% carbon, such as 35 and 45 steel;
High-carbon steel – generally greater than 0.60% carbon. This type of steel is generally not used for manufacturing steel pipes.
In reality, there is no clear boundary between these carbon content levels.
This type of steel is produced in large quantities and has a wide range of applications. It is generally rolled (forged) into round, square, and flat profiles, plates, and seamless steel pipes. It is mainly used to manufacture general structural and mechanical structural parts and components, as well as building structural parts and pipelines for transporting fluids. Depending on the application requirements, it sometimes needs to be heat-treated (normalizing or quenching and tempering) before use.
2. Alloy Structural Steel
This type of steel is made by adding one or more alloying elements to high-quality carbon structural steel to improve its mechanical properties, toughness, and hardenability. Products made from this type of steel typically require heat treatment (normalizing or quenching and tempering); parts and components made from it usually require quenching and tempering or surface chemical treatment (carburizing, nitriding, etc.), surface quenching, or high-frequency quenching before use. Therefore, based on different chemical compositions (mainly carbon content), heat treatment processes, and applications, this type of steel can be broadly classified into carburizing, quenching and tempering, and nitriding steels.
This type of steel is mostly rolled (forged) into round, square, and flat profiles and seamless steel pipes. It is widely used in the manufacture of important and large-sized parts and components in mechanical products, as well as high-pressure pipelines and containers. This high-quality carbon structural steel possesses superior comprehensive mechanical properties.
Seamless steel pipes made from this type of steel are widely used in hydraulic supports, high-pressure gas cylinders, high-pressure boilers, fertilizer equipment, petroleum cracking, automobile axle sleeves, diesel engines,
hydraulic fittings, and other applications.
Application Areas:
Seamless steel pipes for high-pressure fertilizer equipment are widely used in high-pressure fluid transportation systems in industries such as fertilizer, chemical, petroleum, natural gas, power, and metallurgy. In fertilizer production, they are not only an indispensable part of the production equipment for key chemical products such as synthetic ammonia and urea, but also play a crucial role in transporting high-temperature, high-pressure gaseous and liquid media. Furthermore, with increasingly stringent environmental policies and the transformation and upgrading of the chemical industry, seamless steel pipes are also finding increasingly widespread application in environmental protection facilities such as waste gas treatment and wastewater treatment.
Standards:
GB 6479, as a mandatory Chinese national standard, not only specifies the technical requirements, test methods, inspection rules, packaging, marking, and quality certificates for seamless steel pipes used in high-pressure fertilizer equipment, but also ensures the safety, stability, and efficiency of these steel pipes under extreme working conditions.
Seamless steel pipes under the GB 6479 standard are mainly made of high-quality
carbon structural steel and low-alloy high-strength structural steel, such as 20# and 16Mn. These materials possess excellent mechanical properties, including high strength, good toughness, and fatigue resistance, enabling them to maintain stable operation under high pressure, high temperature, and corrosive media. In particular, to meet the stringent corrosion resistance requirements of fertilizer production, some steel pipes require special treatments, such as galvanizing, plastic coating, or alloying, to improve their chemical corrosion resistance.
Weight Calculation Methods:
Carbon steel pipe weight calculation formula: [(outer diameter - wall thickness) * wall thickness] * 0.02466 = kg/meter (weight per meter)
Alloy steel pipe weight calculation formula: (outer diameter - wall thickness) * wall thickness * 0.02486 = kg/meter
Read more: Principles for Selecting Wall Thickness of SMLS Pipe
