How are seamless boiler steel pipes made?

Seamless boiler steel pipes are a specialized type of seamless tube composed of carbon steel or alloy steel, with strict requirements for the type of steel used in their production. These pipes are designed to withstand high temperature and high pressure conditions. Due to exposure to high-temperature flue gas and water vapor, the pipes must have high durability, excellent resistance to oxidation and corrosion, and good structural stability.

Seamless boiler steel pipes are primarily used for manufacturing superheater tubes, reheater tubes, air guide tubes, and main steam tubes for medium-pressure, high-pressure, and ultra-high-pressure boilers. They are commonly found in steam boilers, power generation, fossil fuel plants, and industrial processing plants.

How Seamless Boiler Steel Pipes Are Made

- Initial Manufacturing Process:

Both medium-pressure and high-pressure boiler tubes undergo similar initial manufacturing steps, including fine drawing, surface brightening, hot rolling, cold drawing, and thermal expansion. However, additional steps can enhance the strength and durability of high-pressure pipes.

- Heat Treatment:

This process involves heating and cooling the high-pressure boiler tubes to improve toughness, hardness, and wear resistance. Key steps in heat treatment include quenching, tempering, and annealing.

Quenching: This step increases the hardness of high-pressure boiler tubes. The tube is evenly heated to the appropriate temperature, then quickly immersed in water or oil to cool rapidly, and finally cooled in air or in a freezer.

Tempering: This step reduces the brittleness caused by quenching, which can lead to threads or cracks in the pipe.

Annealing: This process eliminates internal stress within the tube. The seamless pipe is heated to a critical temperature and then slowly cooled in ash or lime.