Different series of pipes in HG20553.

Dear teachers, hello: HGT 20553-2011 is a Chinese standard; its full name is \"Series for the Selection of Dimensions of Seamless and Welded Steel Tubes for Chemical Plant Piping.\" This standard specifies the series of outer diameters and wall thicknesses for seamless and welded steel pipes used in chemical piping. In this standard, pipes are classified into IA, IB, and II series, primarily to meet various design and usage requirements as well as to ensure compatibility with domestic and international standards. The IA series generally refers to imperial pipes, that is, a series of steel pipes that use inches as the primary unit of measurement. The outer diameter and wall thickness of the IA series are primarily based on standards originally established by the United Kingdom and the United States, which are widely used in many engineering projects and equipment around the world. The IB series refers to metric pipes, that is, a series of steel pipes that use millimeters as the primary unit of measurement. The dimensions of the IB series are based on metric standards, which are in line with the international ISO standards as well as the metric dimensioning system specified in China’s ** standards. The II series is a type of pipe with a relatively thicker wall thickness, typically used in applications that require higher pressures or meet other special requirements. They may not belong to imperial or metric pipes, but rather to a pipe series designed for specific applications. In general, the IA, IB, and II series are designed to meet various design standards, application requirements, and the need for compatibility with international standards. When selecting pipes, designers and engineers need to choose the appropriate pipe series based on specific project requirements, equipment specifications, and pressure levels. .