Seamless Steel Pipes for Petroleum Cracking

Seamless steel pipes / tubes for petroleum cracking are special seamless steel pipes designed specifically for the high-temperature, high-pressure, hydrogen-exposed, and corrosive environments of oil refineries. They are critical pressure-bearing components for transporting reaction media during the petroleum refining process.

Using Cr-Mo alloy steel and stainless steel as base materials, through a seamless integral structure, rigorous non-destructive testing, and specific heat treatment processes, they can operate stably for extended periods in the high-temperature, high-pressure, hydrogen-exposed, and corrosive environments of core units such as catalytic cracking and hydrocracking, ensuring the safety and reliability of the equipment.

Standards: 

Seamless steel pipes for petroleum cracking are mainly used in furnace tubes, heat exchanger tubes, and pipelines in oil refineries, suitable for transporting oil products, oil and gas, and corrosive media under high-temperature and high-pressure conditions. In international trade, they often correspond to the following standards:

ASTM A335: Seamless alloy steel tubes for high-temperature applications
ASTM A106: Seamless carbon steel tubes for high-temperature applications
ASTM A213: Seamless alloy steel tubes for boilers, superheaters, and heat exchangers

Which Units are Suitable for Seamless Steel Pipes for Petroleum Cracking? 

Seamless steel pipes for petroleum cracking are mainly used in key units of oil refineries, such as heavy oil catalytic cracking, hydrocracking, delayed coking, and viscosity-reducing cracking.

1. Catalytic Cracking Unit

In catalytic cracking units, seamless steel pipes are used as riser reactors, feed lines to fractionation towers, and high-temperature oil and gas transmission pipelines. They must withstand temperatures above 500℃ and corrosion from sulfur-containing media.

Advantages of seamless steel pipes: The weld-free structure avoids stress corrosion cracking; overall uniformity resists high-temperature creep.

2. Hydrocracking Unit

Hydrocracking units use seamless steel pipes for reactor inlet and outlet pipelines, high-pressure heat exchanger piping, and circulating hydrogen pipelines. These pipes require both high-temperature strength and resistance to hydrogen corrosion, and must withstand high pressures of 10-20 MPa, hydrogen-rich environments, and the risks of hydrogen embrittlement and corrosion.

Advantages of seamless steel pipes: Uses hydrogen-resistant steel (such as 15CrMoR(H)); the absence of welds eliminates the risk of hydrogen-induced cracking.

3. Delayed Coking Unit
Delayed coking units are mainly used in coke tower outlet pipelines, quench oil pipelines, and high-temperature residue oil conveying pipelines. The coke tower outlet and quench oil pipelines face alternating hot and cold shocks from 400-500℃ high-temperature residue oil, and the medium contains sulfur.

Advantages of seamless steel pipes: The seamless integral structure resists thermal fatigue cracking, preventing welds from becoming the failure point.

4. Viscosity Reduction Cracking Unit
Viscosity reduction cracking units are used in reactor inlet and outlet pipelines for conveying high-temperature viscous oils. These pipelines are used for long-term transport of high-temperature heavy oils in environments with high viscosity, sulfur content, and organic acid corrosion.

Advantages of seamless steel pipes: Continuous metal flow lines ensure structural integrity and prevent leakage.

Common Specifications: 

Seamless steel pipes for petroleum cracking cover a wide range of sizes, mainly falling into the following two application categories:

● Furnace tubes and heat exchanger tubes: such as furnace tubes for heating furnaces and various heat exchanger tube bundles.
Common outer diameter: 10 ~ 273mm
Common wall thickness: 1.0 ~ 20mm

●Pressure piping: Such as process piping and connecting lines within an equipment.
Common outer diameter: 6 ~ 630mm
Common wall thickness: 0.25 ~ 75mm

Dimensional tolerances: 

Strict dimensional tolerances are specified in the standard according to different manufacturing processes and size ranges.

Hot-rolled tubes: When the outer diameter is ≤159mm, the allowable deviation is ±1.0%; when the outer diameter is >159mm, the allowable deviation is ±1.25%. When the wall thickness is ≤20mm, the allowable deviation is ±12.5%; the length is usually 4~12 meters.

Cold-drawn tubes: Higher precision, for example, when the outer diameter is ≤30mm, the allowable deviation can reach ±0.20mm; the length is usually 3~10.5 meters.

Performance Characteristics: 

Seamless steel pipes for petroleum cracking are indispensable key materials in high-temperature and high-pressure environments such as petroleum refining and chemical production. Their performance directly affects equipment safety and process stability. This product is suitable for manufacturing seamless steel pipes for equipment such as petroleum refining units, ethylene cracking furnaces, and hydrogenation reactors. It is mainly used in petroleum cracking units, such as cracking furnace tubes, heat exchanger tubes, and reactor tubes. Its operating environment typically involves high-temperature and high-pressure conditions with working temperatures between -20℃ and 600℃, pressure ratings higher than conventional pipelines, and piping systems in contact with corrosive media such as hydrogen sulfide and organic acids. This product is not suitable for low-temperature environments (below -20℃) or special fields such as nuclear power.

Other Technical Details:

1. Common Materials

Seamless steel pipes for petroleum cracking typically use Cr-Mo alloy steel (such as 15CrMo, 1Cr5Mo, 12CrMo) or stainless steel (such as 1Cr19Ni9Nb), meeting the material selection requirements of NACE MR0175/ISO 15156 (resistance to sulfide stress cracking) and Nelson curve (resistance to hydrogen corrosion).

2. Quality Assurance: 

The manufacturing process strictly adheres to international standards, requiring:

100% non-destructive testing: such as ultrasonic testing.
Strict chemical composition control: especially limiting sulfur and phosphorus content.
Specific heat treatment processes: such as normalizing + tempering or quenching + tempering.

3. Design Considerations

This type of pipeline requires stress analysis according to ASME B31.3, with sufficient corrosion allowance (usually ≥3mm).

In conclusion, seamless steel pipes for petroleum cracking can operate stably for a long time in high temperature, high pressure, hydrogen-containing and sulfur-containing environments. They are an indispensable pressure pipeline material in the core processes of petroleum refining, ensuring the safe and efficient operation of the equipment.

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