The manufacturing processes of Longitudinal Submerged Arc Welded (LSAW) steel pipes and Spiral Submerged Arc Welded (SSAW) steel pipes differ significantly. Here is a detailed breakdown of the manufacturing processes for LSAW and SSAW Steel Pipes:

Longitudinal Submerged Arc Welded (LSAW) Steel Pipe Manufacturing Process

1. Plate Preparation:

High-quality steel plates are cut to the required size and shape based on the pipe dimensions.

2. Edge Milling:

The edges of the steel plates are milled to achieve a precise angle for welding.

3. Pre-Bending:

The plates are pre-bent to the desired curvature before being formed into a cylindrical shape.

4. Forming:

The pre-bent plates are formed into a cylindrical shape using a U-press or O-press.

5. Pre-Welding:

The edges of the formed pipe are pre-welded using a submerged arc welding process.

6. Internal and External Welding:

The internal and external welds are completed using the submerged arc welding process, ensuring a high-quality and strong weld.

7. Ultrasonic Inspection:

Ultrasonic testing is conducted to check the weld integrity and detect any defects.

8. X-ray Inspection:

X-ray inspection is performed to further assess the quality of the weld.

9. Hydrostatic Testing:

The pipe undergoes hydrostatic testing to verify its strength and leak-tightness.

10. End Beveling and Dimensional Inspection:

The pipe ends are beveled, and final dimensional inspections are carried out to ensure compliance with specifications.

Spiral Submerged Arc Welded (SSAW) Steel Pipe Manufacturing Process

1. Uncoiling:

Steel coils are uncoiled and fed into the forming machine.

2. Forming:

The steel strip is formed into a spiral shape using a series of rollers in the forming machine.

3. Submerged Arc Welding:

The edges of the spiral seam are welded using the submerged arc welding process as the pipe moves through the welding station.

4. Internal Welding:

Internal welding is performed to join the spiral seam together.

5. External Welding:

External welding is carried out to complete the welding process along the outer surface of the pipe.

6. Ultrasonic Testing:

Ultrasonic testing is conducted to inspect the weld quality and detect any imperfections.

7. X-ray Inspection:

X-ray inspection is used to further assess the integrity of the weld.

8. Hydrostatic Testing:

The pipe undergoes hydrostatic testing to verify its strength and integrity.

9. End Beveling and Coating:

The pipe ends are beveled, and coating or lining may be applied as per requirements.

In summary, LSAW Steel Pipes are manufactured by longitudinally welding steel plates, while SSAW steel pipes are produced by forming a spiral shape from steel coils and welding the spiral seam. Each process has its advantages and is suited to different applications based on factors such as pipe diameter, wall thickness, and specific project requirements.