Welded Pipes & Tubes

Kaizen Steel Industries provides a wide range of welded pipes to clients around the world, including options like super duplex welded piping, nickel alloy, and 6% moly. We ensure that the welded pipes from our trusted mills and manufacturers meet high quality standards and are fully tested to international norms.

Although welded pipes are generally considered weaker than seamless pipes due to their seam, modern manufacturing techniques and quality control procedures have greatly improved. As long as the welded pipe’s temperature and pressure limits are not exceeded, it can perform effectively in many applications.

Welded pipes are a suitable choice for industries such as petrochemical, desalination, oil & gas, and chemical processing.

Welded pipes come in three types: welded on the outside, welded on the inside, or welded on both sides. Regardless of the type, all welded pipes have a seam. As a leading supplier of stainless steel and alloy welded pipes, we offer:

• Welded Duplex Pipe
• Welded Super Duplex Pipe
• Welded Stainless Steel Pipe
• Welded Nickel Alloy Pipe

Manufacturing Welded Pipes

Welded pipe manufacturing has significantly advanced in recent years. The ability to weld different types of steel varies:

• Austenitic Steels: These are generally the easiest to weld.
• Ferritic Steels: These can be welded in thin sections.
• Duplex Steels: These are now considered weldable but require more care than austenitic steels.

The manufacturing process for welded pipes begins with rolling a steel coil to the desired thickness, creating a flat strip or plate. This strip is then rolled into a tube, and the seam is welded. There are two main welding methods:

Electric Resistance Welding (ERW):

In the ERW process, a flat steel sheet is cold-formed into a cylindrical shape. An electrical current is passed through the edges of the cylinder, heating them until they bond together. This method does not require welding filler material.

Submerged Arc Welding (SAW):

The SAW process is used for thicker steel sheets or long welds. It involves creating an arc between a continuously fed electrode and the workpiece. A flux covers the arc, generating protective gases and slag, and adding alloying elements to the weld. The arc is covered by the flux layer, which makes it invisible during welding and minimizes heat loss.

Welded Pipes Finishing

Welded pipes can be finished in various ways based on customer needs and their intended use. Common finishes include:

• Threaded and Coupled Ends: For different diameter lines.
• Threaded End Without Coupling: Suitable for various applications.
• Plain End or Cut Square: For general purposes.
• Pre-Grooved or Bevelled Ends: Ideal for structural applications.

To enhance corrosion protection, metallic coatings like galvanizing, aluminizing, and cladding can be applied. For storage and transport protection, non-metallic coatings such as oil, paint, plastic coating, or coal tar may be used.

Additionally, welded pipes can undergo a process called “pickling and passivation,” where the pipe is dipped in acid to remove the outer layer of metal and then rinsed in water. This process creates a smoother surface that helps reduce corrosion.