When it comes to the efficient operation and safety of low and medium pressure boilers, the choice of materials is crucial. This article delves into the primary materials used for low and medium pressure boiler tubes to ensure optimal performance and durability.

1. Low Carbon Steel (10# Steel)

One of the most commonly used materials for low and medium pressure boiler tubes is 10# steel. The chemical composition of 10# steel includes carbon content ranging from 0.07% to 0.14%, silicon content between 0.17% to 0.37%, and manganese content at 0.35% to 0.65%. Phosphorus and sulfur contents are kept low, not exceeding 0.035%. 

The mechanical properties of 10# steel showcase a yield strength of no less than 205MPa, while its tensile strength falls between 335MPa and 475MPa, with an elongation of at least 24%. With its excellent toughness and welding performance, 10# steel is ideal for the stable operation of low and medium pressure boilers.

2. Medium Carbon Steel (20# Steel)

Another important material is 20# steel. Its chemical composition features a carbon content ranging from 0.17% to 0.24%, with silicon content at 0.17% to 0.37%, and manganese content consistent with that of 10# steel. The limits for phosphorus and sulfur remain the same as those for 10# steel.

20# steel exhibits superior mechanical properties, with a yield strength of at least 245MPa and a tensile strength ranging from 410MPa to 550MPa, along with an elongation of no less than 20%. This material is particularly suited for high-temperature regions of low and medium pressure boilers, such as the heated surfaces near the furnace, where it can effectively withstand higher temperatures and pressures.

3. Alloy Steel Materials

12CrMoG

For components that operate at slightly elevated temperatures, 12CrMoG alloy steel is an excellent choice. The chemical composition of this alloy includes carbon content between 0.08% and 0.15%, silicon content at 0.17% to 0.37%, manganese ranging from 0.40% to 0.70%, chromium content from 0.40% to 0.70%, and molybdenum between 0.40% and 0.55%. 

With a yield strength of no less than 205MPa and a tensile strength varying from 410MPa to 560MPa, along with an elongation rate of at least 21%, 12CrMoG is ideal for applications such as superheater tubes in low and medium pressure boilers. Its ability to resist steam corrosion and pressure in high-temperature environments makes it highly valuable in boiler construction.

15CrMoG

Finally, 15CrMoG is a choice alloy steel used for pipe systems in low and medium pressure boilers that require a higher tolerance for temperature and pressure. This material has a carbon content between 0.12% and 0.18%, silicon content of 0.17% to 0.37%, and manganese from 0.40% to 0.70%. Notably, it boasts chromium content ranging from 0.80% to 1.10%, along with a molybdenum content of 0.40% to 0.55%.

The mechanical properties of 15CrMoG demonstrate a yield strength of at least 235MPa and a tensile strength range from 440MPa to 640MPa, with an elongation rate of no less than 21%. This makes it particularly suited for systems like reheater pipes in low and medium pressure boilers, where it can confidently handle high thermal stresses.

The selection of materials for low and medium pressure boiler tubes directly impacts the operational efficiency and safety of boiler systems. From the ductile properties of low carbon steels like 10# and 20# steel to the enhanced temperature and pressure resistance in alloy steels like 12CrMoG and 15CrMoG, understanding these materials ensures reliable performance under various working conditions. Choosing the right material not only enhances the durability of boiler tubes but also contributes to effective boiler operation in the long run.