Everything You Need to Know About Seamless Tube Manufacturing, Galvanizing, and Threading

A seamless tube is widely used in construction, oil and gas, water transport, and other industrial applications due to its strength, precision, and durability. To ensure performance and longevity, seamless tubes undergo several post-production treatments such as pickling, galvanizing, and threading. This article provides a complete overview of these processes and helps buyers understand how to choose the right type of seamless tube for their needs.

Galvanizing Methods for Seamless Tubes

After the seamless tube is manufactured, it typically goes through acid pickling to remove surface oxides. Depending on customer requirements, a galvanizing treatment may follow to enhance corrosion resistance. There are three common types of galvanizing for seamless tubes:

1. Dip Galvanizing

· This method ensures the highest zinc coating thickness, reaching up to 500 g/m².

· It provides superior corrosion resistance and is suitable for harsh environments.

2. Blow Galvanizing

· Produces a zinc coating of around 300 g/m².

· Offers good protection while maintaining cost efficiency.

3. Galvanized Strip

· Mostly used for welded pipes rather than seamless tubes.

· Has the lowest zinc coating thickness of 60–150 g/m², making it less durable than the other two methods.

Choosing the right galvanizing method depends on the environment and performance requirements. For high-strength, long-lasting pipelines, dip-galvanized seamless tubes are often the best choice.

Threading Process for Seamless Tubes

Threaded seamless tubes are essential for pipeline connections. Once galvanizing is complete, threading can begin. This is performed on specialized lathes to meet precise standards for taper, pitch, and thread type. Common standards include:

· American Standard (NPT)

· British Standard (BSP)

· National Standard

The process includes:

· Cutting threads at both ends of the seamless tube

· Cleaning and inspecting the threads

· Adding a pipe coupling on one end and a plastic cap to protect the other

Threaded seamless tubes can be categorized by tooth count, such as 1 inch 8 threads or 10 threads per inch, depending on regional specifications.

Importance of Pipe Couplings

The pipe coupling is the most critical part of the entire assembly. It bears high pressure during service, which means its material quality must be equal to or higher than that of the seamless tube itself.

Manufacturing steps for pipe couplings include:

· Cutting raw round steel

· Machining to fixed dimensions on a lathe

· Threading

· Inspecting thread accuracy and size

A well-made coupling ensures safety and reliability in demanding applications.

Identifying Inferior Galvanized Steel Pipes

Low-quality hot-dip galvanized spiral pipes often show surface folds. These folds, caused by improper rolling pressure, lead to cracks during use and reduce overall strength. Choosing a reliable manufacturer ensures that seamless tubes and couplings meet the highest safety and performance standards.

Conclusion

From galvanizing to threading, every step in the manufacturing of a seamless tube affects its durability and performance. Dip-galvanized seamless tubes with precisely machined threads and high-quality couplings are the best choice for industries requiring strength and corrosion resistance. By understanding these processes, buyers can make informed decisions and select the right seamless tube for their applications.