Seamless steel pipes, also known as standard straight seam steel pipes, are used for low-pressure fluid transportation. They are primarily used for conveying water, gas, oil, and heated steam, etc. The wall thickness of steel pipes is divided into ordinary and reinforced types, while the pipe ends are categorized as plain-end and beveled-end pipes. The specifications of steel pipes are indicated by nominal diameter, which is an approximate value of the inner diameter. Welded steel pipes are employed for low-pressure fluid transportation, serving not only as direct fluid conveyance but also as the original pipeline for galvanized welded steel pipes, also used for low-pressure fluid transportation.