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Spiral forming method
Spiral pipe production is another standard pipe production method in the world.
In this method the sheets passes through a series of rollers with spiral seams to take the pipe form. Unlike straight seam pipe in which the pipe diameter depends on the sheet width, in this method the pipe diameter changes based on the change of angle of the original sheet feeding angle. With the change of feeding angle, pipes with different diameters are produced; whereas in straight-seam method all templates of production line must be replaced. Thus in spiral method it is possible to produce pipes with different diameters with costs less than the straight seam. Spiral pipes are produced with two single-stage and two-stage methods. .
1- Single-stage spiral pipe:
The welding torch is adjusted automatically. After the seam welding, the pipe is cut and transferred to the next stage. The production speed in this method depends on the speed of submerged-arc welding. The speed of submerged-arc welding is around 1 to 2.5 meters per minute and sometimes it even reaches 3 meters per minute. Since the speed of submerged-arc welding is limited the production speed in this method is slow. .
In sheet preparation stage the sheets are welded together and the edge of sheet is chamfered and flattened. If the forming operation is done completely then the edge of previous sheet must be bended so that it prevents from creation of non-compressible bumps. For spiral seam welding firstly the internal seam is welded at 6 o'clock position by the use of submerged-arc welding machine and then the external part is welded at 12 o’clock position..
2- Two-stage spiral pipe:
Production of two-stage spiral pipe is the same as single-stage with this difference that in this method during the sheet formation the seam is welded by the use of GMAW. This type of welding includes the root pass. In the next stages, the seam is filled with submerged-arc welding machine from inside and outside. This process includes 4 main stages: sheet preparation, sheet formation, welding by the use of GMAW and internal/external submerged-arc welding. وجوش زیرپودری داخلی وخارجی
In addition to high production efficiency (due to fast forming), there is another technical advantage in two-stage method due to separation of formation stage from final welding. In formation station, during the forming the root pass is welded by the use of GMAW. The speed of this device with protective gas system of carbon dioxide is around 12 meters per minute and this welding takes place at 6 o’clock position.

Spiral Pipe Production Process:

Two spiral steel pipe productions lines with (automatic) submerged-arc welding process have the ability to produce pipes with diameters ranging from 14 inches (350 millimeters) to 32 inches (810 millimeters), thickness of 4 to 10 millimeters and different grades of steel (according to the customer’s demand); and also regarding having all equipment and facilities needed in quality control process, these two production lines have the ability to produce pipes according to ASTM, AWW, C-200 and DIN standards.
Production Process:
- The roll of sheet is flattened by the use of flattening rollers positioned in specific distances.
- At this stage, edges of both sides of sheet being damaged, crushed or having unwanted cracks are removed from the production line.

Production Lines
Sheet input section
At the beginning of production line this section leads the sheet toward the production line which includes:

• Bringing coil to the machine
• Coil holder
• Sheet trimmer

Section dedicated to cutting and welding the beginning and end of coil:
Cutting and preparing the end of produced coil and beginning of new coil and welding these two edges together by the use of submerged-arc welding (SAW).
Flattener:
The beginning and end of coil is flattened by the use of flattening rollers
Cutting the edge and collecting the waste:
The edge of sheet is cut by the use of spinning discs at the edge cutting section and the waste are collected.
Navigating side pipes:
Holding and adjusting sheet at the center of spiral line
Angle maker of edge of sheet:
Angle making is applied to both sides of the sheet for modifying and reaching the required conditions of the sheet according to the required angle.
Main Engine:
The required forces for opening the coil, moving the sheet in the whole production line and forming the pipe are provided in this section.
Shaping jack:
When the sheets pass through different rollers, they take the form of pipes. These rollers are adjustable for different sizes.
Internal and external welding section:
After taking the form of pipes, the edges are welded by the use of SAW method, and firstly their inside and then their outside are welded.

Ultrasonic Testing Section:
Conducting continuous ultrasonic test on seam welding
Pipe navigator:
One of the forming subsections that hold the pipe in 3 positions and it provides stable conditions for construction and welding.
Cutting the pipe:
Pipes are cut by the use of plasma cutting in different lengths according to the customer’s demand.
Adjusting the edge:
The edge regulatory system is used for adjusting the distance between two edges during the pipe production.

Output section:
After cutting, the pipe exists from the output line.
Pipe numbering:
The pipe number is written at the end of pipe and it includes the following descriptions:

Manufacturer
Size
Steel thickness and grade
Pipe number
Year/week/day of production

Discharging powder from the pipe:
At this stage the powder accumulated inside the pipe during the welding process is discharged.
Chamfering both ends of pipe:
All ends of pipes are chamfered as followed: