Seamless Steel Pipes for Petroleum Cracking are specialized seamless steel tubes used for furnace tubes, heat exchanger tubes and pipelines in petroleum refineries. As critical materials in petrochemical equipment, they are mainly used for the cracking of petroleum at high temperature and high pressure to produce light oil products such as gasoline and diesel. A detailed explanation is provided below:
1. Core Definition and Characteristics
- High heat resistance: This is its most prominent feature. Petroleum cracking is usually carried out at high temperatures ranging from 400°C to 1000°C, so such pipes must have excellent oxidation resistance and high-temperature strength to avoid deformation or fracture under heat.
- High corrosion resistance: Petroleum cracking produces corrosive gases such as hydrogen sulfide (H₂S), so the pipes must resist corrosion from these media.
- High purity and uniformity: To prevent embrittlement or coking caused by impurities at high temperatures, the chemical composition of the steel is strictly controlled. High-quality carbon steel or alloy steel is commonly used.
- Seamless structure: Being seamless, they can withstand higher pressure and temperature fluctuations than welded pipes, avoiding the risk of bursting at welds due to stress concentration.
2. Applicable Standards
In China, such pipes mainly comply with the national standard GB/T 9948.
- GB/T 9948: Standard specifically for seamless steel pipes for petroleum cracking.
- Comparison:
- GB/T 8163 (Seamless steel pipes for fluid service): Mainly used for normal or medium-low temperature transportation, with lower heat and corrosion resistance than cracking pipes.
- GB/T 5310 (Seamless steel pipes for high-pressure boilers): Although also resistant to high temperature and pressure, boiler pipes focus on steam generation, while cracking pipes serve petroleum cracking reactions, with slight differences in material grades and heat treatment processes.
3. Common Materials
Due to harsh service conditions, materials are generally higher-grade than ordinary fluid pipes:
- High-quality carbon structural steel: such as 10#, 20# (mainly for general cracking furnace tubes or low-temperature sections).
- Alloy steel: such as 12CrMo, 15CrMo (Cr-Mo steel with excellent high-temperature creep resistance, used in high-temperature sections).
- Stainless steel: such as 1Cr18Ni9Ti (austenitic stainless steel with outstanding corrosion and heat resistance, used in highly corrosive or ultra-high-temperature environments).
4. Main Applications
They are mainly used in core units of petroleum refineries — cracking furnaces and hydrocracking units:
- Furnace tubes: Petroleum feedstock flows inside and is heated to reaction temperature, the primary application of cracking pipes.
- Heat exchanger tubes: Used to recover heat generated from reactions.
- Reformer tubes: For catalytic reforming reactions.
- Transport pipelines: Convey high-temperature, high-pressure oil and gas media.
5. Differences from Ordinary Fluid Pipes
- Service temperature: Ordinary fluid pipes (GB/T 8163) generally operate below 350°C, while petroleum cracking pipes (GB/T 9948) often require long-term service at 500°C to 1000°C.
- Performance requirements: Cracking pipes require not only pressure resistance but also resistance to high-temperature oxidation and hydrogen corrosion. Using ordinary fluid pipes as a replacement will quickly lead to oxidation ablation or hydrogen-induced fracture at high temperatures, causing serious safety accidents.
- Price: Due to higher requirements for materials and manufacturing processes, petroleum cracking pipes are usually much more expensive than ordinary seamless steel pipes.
Summary
Seamless steel pipes for petroleum cracking act as “high-temperature-resistant specialists” in the petrochemical industry.Made of high-quality alloy steel or stainless steel, they are specially designed to “heat” petroleum under high-temperature, high-pressure and highly corrosive conditions, cracking it into required fuels.
