In the modern chemical and petroleum industries, seamless steel pipes, as a key foundational material, undertake the crucial task of transporting high-temperature, high-pressure, and corrosive media. Their performance is directly related to the safe operation and production efficiency of the equipment.
First, the Material Characteristics and Core Advantages of Seamless Steel Pipes
Due to their seamless, integrated structure, seamless steel pipes significantly surpass welded steel pipes in pressure bearing capacity and sealing performance. For example, seamless steel pipes for petroleum cracking plants must withstand temperatures exceeding 450°C and hydrogen sulfide corrosion. They are typically made of Cr-Mo alloy steel (such as 15CrMoG) or austenitic stainless steel (such as 0Cr18Ni9). These pipes must meet the GB5310 “Seamless Steel Pipes for High-Pressure Boilers” standard and possess a tensile strength of at least 415 MPa and a yield strength of at least 205 MPa.
Second, Typical Application Scenarios and Technical Parameters of Seamless Steel Pipes
1. Refining Units: The transfer line of the atmospheric and vacuum distillation unit utilizes large-diameter seamless pipes ranging from 219mm to 813mm, with an operating pressure of up to 4MPa. The regenerator cyclone separators of the catalytic cracking unit require 310S heat-resistant stainless steel pipes to withstand 900°C flue gas erosion.
2. Ethylene Cracking Units: Data indicates that the convection section tubes of cracking furnaces are mostly made of HP40Nb centrifugally cast pipes, which have a chromium-nickel content of 25Cr-35Ni and a creep rupture strength exceeding 30MPa at 1000°C. 3. Coal Chemical Gasifier: The slag conveying pipes for a certain brand of coal gasification unit require both wear resistance and corrosion resistance. Bimetallic composite pipes are often used, with an inner layer of high-chromium cast iron (HRC ≥ 58) and an outer pressure-bearing carbon steel layer.
Third: Comparison of Domestic and International Standard Systems for Seamless Steel Pipes
My country’s petrochemical pipes primarily adhere to standards such as GB/T8163 (fluid transportation) and GB9948 (petroleum cracking), which are aligned with ASTM A335 (American Standard) and EN10216 (European Standard). Taking P91 steel pipe as an example, the impact energy requirements of GB5310 and ASME A335 differ significantly: the national standard requires a transverse impact energy of ≥ 40 J (at 20°C), while the American standard requires a longitudinal impact energy of ≥ 54 J.
Fourth: Key Quality Control Points for Seamless Steel Pipes
1. Manufacturing Process: Hot-rolled steel pipes must maintain a final rolling temperature of 50°C above Ar3 to avoid banding; cold-drawn pipes require intermediate annealing to eliminate work hardening.
2. Inspection Technology: In addition to conventional ultrasonic testing, large-diameter, thick-walled steel pipes should be inspected for delamination defects using TOFD (Time-of-Flight Diffraction). Steel pipes serving high temperatures should undergo intergranular corrosion testing (e.g., GB/T4334E method).
3. On-site Installation: The hydraulic test pressure should be 1.5 times the design pressure, with a holding time of at least 10 minutes. A petrochemical project demonstrated that excessive chloride ion content (>25 ppm) in the test water caused stress corrosion cracking in austenitic steel pipes.
Fifth, Technological Innovation and Development Trends in Seamless Steel Pipes
1. Material Upgrade: An engineering institute is promoting TP347HFG fine-grained stainless steel, which offers 20% higher endurance strength than conventional TP347 and is suitable for ultra-supercritical operating conditions at 700°C.
2. Composite Technology: Titanium/steel composite pipes produced using explosive composite and hot rolling methods offer a 60% lower cost than pure titanium pipes and have been successfully used in acetic acid plants. 3. Intelligent Monitoring: An online corrosion monitoring system based on fiber optic sensors can provide early warnings of wall thickness changes with 0.1mm accuracy. The application at one refinery has extended maintenance cycles from three years to five.
With the advancement of the “dual carbon” goals, steel pipes for green hydrogen plants face new challenges. Existing research indicates that hydrogen-related pipelines require the development of new oxide dispersion-strengthened steels (ODS), which can reduce hydrogen permeability by two orders of magnitude compared to traditional steels. Simultaneously, digital twin technology is being promoted and applied throughout the pipeline lifecycle. Using 3D modeling, it provides real-time predictions of remaining life and data support for preventive maintenance.
Conclusion
The technological evolution of seamless steel pipes for petrochemical applications has consistently resonated with industrial needs. From microstructural control in materials science to macro-performance optimization in engineering applications, every detail embodies the wisdom of modern manufacturing. With breakthroughs in deep processing and the penetration of intelligent technologies, this traditional field will be revitalized, continuing to safeguard the safe and efficient operation of the energy and chemical industry.
Post time: Aug-05-2025