API steel pipe, often referred to as API line pipe or API pipe, is a type of steel pipe that meets specific standards and requirements set by the American Petroleum Institute (API). These standards are designed to ensure the quality, durability, and safety of steel pipes used in the oil and gas industry. API steel pipes are commonly used for transporting oil, natural gas, and other fluids in the energy sector.

There are several different specifications and grades of API steel pipe, with the most commonly used being API 5L. API 5L sets the standards for the manufacturing and testing of steel pipes used for conveying oil and gas. The different grades within API 5L (e.g., API 5L Grade B, X52, X60, X65, etc.) are designed for specific applications and operating conditions. These grades specify the minimum yield strength, chemical composition, and mechanical properties of the steel pipe.

API steel pipe is typically available in various sizes and wall thicknesses, and it can be seamless or welded, depending on the specific application and requirements. These pipes are used in pipelines, well drilling, and various other oil and gas industry applications.

The use of API steel pipes is crucial for ensuring the safe and efficient transportation of oil and gas resources, as they must withstand high-pressure, corrosive, and harsh environmental conditions.