Thick wall steel pipe

What Is Thick Wall Steel Pipe?

Thick-walled steel pipe, the steel pipe with the ratio of the outer diameter of the steel pipe to the wall thickness is less than 20 is called the thick-walled steel pipe. Mainly used as petroleum geological drill pipe, cracking pipe for petrochemical industry, boiler pipe, bearing pipe and high-precision structural pipe for automobile, tractor, aviation, etc.

The Difference Between Thick-Walled Steel Pipe And Thin-Walled Steel Pipe

The biggest difference between thick-walled steel pipes and thin-walled steel pipes is the thickness of the steel pipe wall. Generally speaking, thin-walled steel pipes are cold-drawn technology, while thick-walled steel pipes and thick-walled steel pipes generally use hot-rolling technology, if they are distinguished by units of measure.

Then, it is generally believed that the wall thickness/pipe diameter equal to 0.02 is the watershed between thick-walled steel pipes and thin-walled steel pipes, those with wall thickness/pipe diameter less than 0.02 are thin-walled steel pipes, and those larger than 0.02 are thick-walled steel pipes.

In terms of use, thin-walled steel pipes Wall steel pipes are mostly used on pipes. Thick-walled steel pipes are mostly used in blanks for hollow parts. Use on pressure-bearing and important pipelines.

Thick-Walled Seamless Pipe

Take thick-walled seamless pipe as an example. Thick-walled seamless pipe refers to seamless steel pipe with a large wall thickness to outer diameter ratio (typically wall thickness ≥ 10mm or outer diameter/wall thickness ratio ≤ 10). Its core features include:

1. Seamless Structure

Formed in a single step through hot rolling or cold drawing, it has no welds, eliminating the weak links of traditional seam pipes.

2. High Strength

The increased wall thickness significantly increases pressure bearing capacity. For example, the tensile strength of thick-walled pipe can reach over 415 MPa under the ASTM A106 standard.

3. Diverse Materials

Common materials include carbon steel (such as 20# and 45#), alloy steel (such as 16Mn), and stainless steel (such as 304 and 316), adapting to different environmental requirements.

Production Process of Thick Wall Seamless Pipe

1. Hot Rolling

The steel billet is heated to above 1200°C and then pierced and rolled. This process is suitable for producing large-diameter (OD ≥ 200mm) and thick-walled (wall thickness 20-100mm) pipes.

2. Cold Drawing

The steel pipe is drawn to the target size at room temperature. This process offers higher precision (tolerance ±0.2mm), but the wall thickness is typically ≤40mm.

Materials for Thick-Walled Seamless Pipes

1. Carbon Structural Steel Thick-Walled Seamless Pipes

Material: Carbon is the primary alloying element. Common grades include 20# and 45#.

Performance: Moderate strength, good ductility and toughness, excellent weldability, and low cost.

Applications: Suitable for low-pressure pipelines, mechanical structural components, and general engineering pipes (such as water and gas pipelines).

2. Alloy Structural Steel Thick-Walled Seamless Pipes

Material: Made from carbon steel with alloying elements such as chromium, molybdenum, nickel, and manganese. Common grades include 16Mn, 40Cr, 15CrMo, and 27SiMn.

Performance: High strength, high wear resistance, and high or low temperature resistance. Mechanical properties can be further enhanced through heat treatment (quenching and tempering).

Applications: High-pressure pipelines, mechanical transmission components (such as drive shafts and hydraulic cylinders), petrochemical equipment, and power plant boiler pipes.

3. Stainless Steel Thick-Wall Seamless Pipe

Material: Chromium content ≥ 10.5%. Common grades include 304, 316, and 321. 316 boasts superior corrosion resistance due to the addition of molybdenum.

Performance: Excellent corrosion resistance (acid, alkali, and oxidation resistance), high-temperature resistance, and a high-quality surface finish.

Applications: Corrosive environments such as the chemical, pharmaceutical, food processing, and seawater treatment industries, or high-temperature piping systems (e.g., boiler superheaters).

4. Specialty Thick-Wall Seamless Pipe

Low-Temperature Steel: such as 16MnDG, suitable for low-temperature environments below -40°C (e.g., LNG pipelines).

High-Pressure Boiler Steel: such as 20G and 12Cr1MoVG, resistant to high temperatures and pressures, used for main steam piping in power plant boilers.

Pipeline Steel: such as X70 and X80, high-strength and fatigue-resistant, used for long-distance oil and natural gas pipelines.

Thick-Wall Seamless Pipe Specifications

Application of Thick Wall Seamless Pipe

Thick-walled steel pipes are mainly used in water engineering, petrochemical industry, chemical industry, electric power industry, agricultural irrigation, and urban construction.

For liquid transportation: water supply, drainage.

For gas transportation: gas, steam, liquefied petroleum gas.

For structural purposes: for piling pipes, for bridges, for wharfs, roads, building structures, etc.

Summary

Thick-walled steel pipes offer high strength and are widely used in various applications. When using them, it's important to select the appropriate specifications and materials, and to adhere to relevant regulations and safety procedures to ensure safety and a long service life.