Hot-rolled seamless pipes are relative to cold-rolled seamless pipes. Cold rolling is rolling below the crystallization temperature, and hot rolling is rolling above the recrystallization temperature.

High-frequency welding is a new welding process that uses the skin effect and adjacent effect generated by high-frequency current to connect steel pipes and other metal materials. The emergence and maturity of high-frequency welding technology is a key process in the production of longitudinally welded pipes (ERW). The quality of high-frequency welding directly affects the overall strength, quality level and production speed of the welded pipe.

The welded pipe is a steel pipe made of steel plate or strip steel after being crimped and welded, generally with a length of 6 meters. The production process of welded steel pipe is simple, the production efficiency is high, there are many varieties and specifications, and the investment in equipment is small, but the general strength is lower than that of seamless steel pipe.

Spiral steel pipe (SSAW) is a spiral seam steel pipe made of strip steel coil as raw material, extruded at regular temperature, and welded by automatic double-wire double-sided submerged arc welding process.

There are three kinds of steel pipes commonly used in long-distance pipelines

The high-temperature prefabricated direct-buried thermal insulation pipe is a direct-buried prefabricated thermal insulation pipe with good thermal insulation performance, safety and reliability, and low engineering cost. It effectively solves the problems of thermal insulation, sliding lubrication and waterproofing of exposed pipe ends for prefabricated direct-buried thermal insulation pipes for 130°C-600°C high-temperature heat transfer in urban central heating.