Preheating process of LSAW steel pipe

The preheating process is a crucial step in the external coating of LSAW (Longitudinal Submerged Arc Welding) steel pipes. Proper preheating ensures better adhesion of the coating and overall quality of the pipe. There are two primary methods of preheating: gas heating and frequency heating.

Surface Treatment of Pipes

- Gas Heating:

Combustible Gas Preheating Furnace: This method uses a gas furnace to burn the outer surface of the pipe. This process can effectively remove small amounts of contaminants and prepare the surface for coating application. The heat from the gas flame ensures that the surface is adequately cleaned and ready for the next steps.

- Frequency Heating:

Intermediate Frequency Coil: This method employs the skin effect, where an intermediate frequency coil heats the scrap steel. The steel surface coating can be quickly softened, making it easier to apply the subsequent coating. This method is efficient and provides uniform heating.

Equipment Costs

Comparative Costs: While the initial equipment costs for gas heating and frequency heating are comparable, the overall operational cost of frequency heating tends to be higher. This is due to the higher energy consumption and maintenance requirements of intermediate frequency furnaces compared to gas furnaces.

Environmental Considerations

- Gas Heating:

Green Fuel Usage: Gas heating generally uses environmentally friendly fuel gases, which produce fewer emissions compared to other heating methods. This makes it a more sustainable option.

- Frequency Heating:

Electricity Usage: Frequency heating uses electricity, which can generate harsh noise during operation. Additionally, if the frequency power supply is not properly pretreated, it can cause odd harmonics pollution in the power grid. This can have adverse effects on the surrounding environment and equipment.

Conclusion

In summary, both gas heating and frequency heating have their own advantages and disadvantages when it comes to the preheating process of LSAW steel pipes.

- Gas Heating:

Offers a cleaner and more environmentally friendly option, with fewer emissions and lower operational costs. However, it may leave some contaminants on the surface that need to be addressed.

- Frequency Heating:

Provides efficient and uniform heating, making it easier to soften and apply coatings. This method, however, comes with higher operational costs and potential environmental issues related to noise and power grid pollution.

Choosing the right preheating method depends on the specific requirements of the coating process, environmental regulations, and cost considerations. Implementing the appropriate preheating technique ensures better adhesion of the coating, resulting in higher quality and longer-lasting LSAW steel pipes.

Learn more, pelase click here:The purpose of SSAW steel pipe preheating