Large-diameter steel pipe refers to pipes with a diameter of DN250 or larger, primarily made of carbon steel, stainless steel, and alloy steel. Common materials include Q235, Q345, 20#, and 16Mn. Different materials are selected for large-diameter pipe fittings based on the operating environment and pipeline pressure and temperature.

Large-diameter pipe fittings primarily include large-diameter elbows, large-diameter flanges, large-diameter reducers, and large-diameter pipe caps. These fittings can be connected to pipelines through welding or flange connections and are widely used in engineering fields such as water supply, natural gas, petroleum, chemicals, pharmaceuticals, telecommunications, power generation, and marine applications.

The production standards for large-diameter pipe fittings include GB12459 (steel butt-weld seamless pipe fittings), GB/T13401 (steel plate butt-weld pipe fittings), and GB/T14383 (forged steel socket-weld pipe fittings). In addition, large-diameter pipe fittings can also be treated with anti-corrosion and heat preservation treatments, such as oiling, galvanizing and 3PE anti-corrosion, as well as polyurethane foam insulation technology, to ensure long-term and stable use in various environments.