How to Improve the Stability of Large Diameter Spiral Welded Steel Pipe

Large diameter spiral welded steel pipe is widely used in industries such as oil and gas transportation, water supply projects, and structural applications. Because of its size and complex manufacturing process, ensuring the stability and durability of the pipe is crucial. One of the main challenges during production is preventing cracks that may occur during heat treatment and cooling. Below, we’ll explore key methods to enhance the stability of large diameter spiral welded steel pipe.

1. Timely Tempering After Quenching

Cracks in spiral steel pipes are not always visible immediately after quenching. Many appear later, a phenomenon known as aging cracks. This happens because of high residual stress. To prevent this, large diameter spiral welded steel pipe should undergo tempering immediately after quenching. This process helps release internal stress and avoids delayed cracking.

2. Utilize Self-Tempering with Residual Heat

For steel grades that are highly sensitive to cracking, using the residual heat from quenching for self-tempering is an effective method. This allows the material to slowly adjust, reducing the risk of quenching cracks and improving the overall stability of the steel pipe.

3. Control Quenching Temperature and Preheating

When working with high-alloy steel, it is important to adopt a lower quenching temperature and shorten the holding time. Due to poor thermal conductivity of alloy steel, multiple preheating stages may be necessary. Proper preheating minimizes internal stress and prevents deformation or cracking in the large diameter spiral welded steel pipe.

4. Protect Weak Sections During Heat Treatment

Certain areas, such as threaded holes, sharp corners, and grooves, are more prone to cracking. These parts should be reinforced by plugging with asbestos ropes or wrapping with iron sheets before quenching. Pre-cooling these sections can also help slow down the cooling rate, thus reducing the chances of cracks.

5. Choose Suitable Cooling Media

The choice of cooling medium plays a decisive role. For spiral welded steel pipes, oil cooling is often preferable to water cooling, as it provides a slower cooling rate. In some cases, high-concentration salt solutions can be used to minimize the risk of quenching cracks in complex-shaped pipes. Proper control of cooling duration—such as removing the pipe from the medium at the right moment—also ensures better stability.

Conclusion

Enhancing the stability of large diameter spiral welded steel pipe requires careful control of heat treatment processes, proper preheating, and the use of suitable cooling methods. By implementing these strategies, manufacturers can significantly reduce the risk of cracks, extend the service life of the pipe, and ensure reliable performance in demanding applications.