API 5L welded steel pipe

The American Petroleum Institute (API) released the API 5L standard in early 1926, initially covering three steel grades: A25, A, and B. Over time, additional grades were introduced. By the year 2000, the global use of steel grades for pipelines was distributed as follows: X70 accounted for approximately 40%, X65 and X60 for about 30% each, and a significant number of small-diameter product pipelines used X52 steel grade, primarily for resistance-welded straight pipes (ERW steel pipes).

Current Usage in China

In China, petroleum pipelines commonly use spiral welded pipes (SSAW), LSAW pipes (LSAW), and electric resistance welded pipes (ERW). Seamless steel tubes are preferred for diameters less than 152mm. From the late 1960s to the 1970s, the rapid development of spiral pipe plants led to the predominant use of spiral welded steel pipes for crude oil pipelines, including the "West-East" pipeline. However, spiral welded pipes have disadvantages, such as high internal stress, poor dimensional accuracy, and a higher likelihood of defects.

Expert Recommendations

Experts suggest a dual approach, encouraging both technological transformation of existing spiral welded pipe plants and vigorous development of the straight seam submerged arc control tube industry in China. ERW steel pipes, known for their smooth appearance, high dimensional accuracy, and lower cost, are widely used both domestically and internationally.

Advantages of Straight Seam High Frequency Welded Steel Pipes

The straight seam high frequency welded steel pipe (HFW) forming process is advanced and reliable, ensuring stable welding parameters, high welding speed, and high yield. The entire production line and technology are world-class. Specific advantages include:

- Minimal Springback and Residual Stress: The forming process results in minimal springback and residual stress.

- Low Strain Hardening: The process ensures precise geometric dimensions and a full circular shape, aiding in construction and welding quality.

- High-Quality Weld Bead Shape: The weld bead shape is good, reducing the risk of edge biting and internal/external weld misalignment defects.

- Favorable Weld Positioning: The weld is distributed at a single point on the circumference, allowing for welding at favorable positions as needed.

Applications of API 5L Welded Steel Pipes

API 5L welded steel pipes are primarily used for the transportation of onshore and offshore oil and gas, coal slurry, slurry media, and in offshore platforms, power plants, the chemical industry, and urban construction. They are also used for structural tubes in various applications.