Material grades of carbon steel welded pipe

Carbon steel welded pipe is extensively used across various industries such as petrochemicals, power generation, construction, and manufacturing. Due to its widespread application, the standardization of carbon steel welded pipe is of significant importance. Below is an overview of the major standards and material grades associated with carbon steel welded pipes.

1. International Standards

International standards for steel pipes include ISO, ASTM, DIN, and others. Among them, ISO standards are the most widely adopted globally. These standards define specific requirements for the dimensions, shapes, quality, and performance of carbon steel welded pipes, alloy welded pipes, and more. They serve as a crucial reference for international trade and technical communication.

2. American Standards

In the United States, standards for carbon steel welded pipes are primarily governed by ASTM and API:

ASTM standards offer a comprehensive set of specifications for various grades and types of steel pipe materials.

API standards focus on the oil and gas sector, including widely used specifications such as API 5L for line pipe and API 5CT for casing and tubing.

3. Chinese Standards

China’s national standards combine international practices with localized technical requirements to form a refined system. Key standards for carbon steel welded pipes in China include:

GB/T – the most extensively applied national standard.

JB/T, SY/T, and DL/T – used across specific industries such as machinery, petroleum, and electric power.

Material Grades of Carbon Steel Welded Pipe

Carbon steel exhibits varying mechanical and chemical properties under different working conditions such as pressure and temperature. Therefore, the material grades of carbon steel welded pipes are classified according to mechanical strength, chemical composition, and application scope. The main grading systems come from the United States (ASTM), Europe (EN), and China (GB/T).

1. ASTM Grade Classification

ASTM divides carbon steel welded pipe materials into four primary grades: A, B, C, and D. As the grade increases, so do the strength and corrosion resistance. Lower-grade ASTM pipes are commonly used in fluid transportation, structural components, and hydraulic systems.

2. EN Standard Grade Classification

Under the EN standard, carbon steel grades for welded pipes include P195TR1, P195TR2, P235TR1, P235TR2, P265TR1, and P265TR2. As with ASTM, higher grades offer improved mechanical performance and resistance to corrosion.

3. GB/T Standard Grade Classification

China's GB/T standard classifies carbon steel materials into ten common grades:
Q195, Q215A, Q215B, Q235A, Q235B, Q235C, Q235D, Q275, Q345, and L245.
Each ascending grade represents enhanced strength, toughness, and durability under demanding conditions.

Importance of Carbon Steel Welded Pipe Grades

The material grade of a carbon steel welded pipe directly influences its applicability to specific environments and media, whether gas or liquid. Selecting the appropriate grade ensures the pipe can withstand the expected mechanical load, resist corrosion, and provide a long service life under designated service conditions.

Specification Parameter Table for Carbon Steel Welded Pipe

Below is a specification parameter table summarizing commonly used grades of carbon steel welded pipes along with their mechanical properties, chemical composition, and dimensional specifications.

Summary
This article provides an overview of the material grades and relevant specification parameters of carbon steel welded pipes. It is intended to assist users in better understanding the classification and standards associated with these widely used materials. When selecting carbon steel welded pipe materials, it is essential to choose the appropriate grade based on the specific application environment and the nature of the transported medium—whether liquid or gas—to ensure optimal performance and service life.