SAWL Steel Pipe

Production Flow of SAWL Steel Pipe

To manufacture the SAWL steel pipe, we first perform rigorous plate inspection, including appearance inspection as well as physical and chemical inspection. Appearance inspection means to check steel plate thickness, width, weight, appearance defects, etc. Physical and chemical inspection mainly covers tensile test, impact test, drop impact test, hardness test, metallographic inspection, etc.

We adopt the HSD automatic ultrasonic testing system to inspect the LSAW steel pipe or steel plate at a speed of 0-3m/min. Inspection coverage rate is 100%.

The imported edge milling machine comes with functions like automatic centering and cutter head floating. Milling speed and amount are automatically set according to steel grade, steel tube wall thickness as well as beveled edge shape and size. Meanwhile, the machine is computer controlled to ensure proper plate width and straightness. Generally, the maximum milling thickness is 60mm. For X80 steel grade, the maximum milling thickness is 40mm. The milling width ranges from 2000mm to 4500mm, and beveled edge is in X, Y or V shape.

The whole process from steel plate feeding to edge crimping is computer controlled. After edge milling, the steel plates are conveyed to the side roller table between two press machines. Then, the lower die jacks up steel plates for repeated edge crimping, and thereby certain curvature can be reached. The maximum press force is 4800 tons, and die length is 3000mm.

Our longitudinal welded pipe adopts step-by-step JCO forming mode. After pre-bending, the half of steel plate is gradually bent according to certain length. Then, the left half is bent in the same way. Finally, O shape steel tube is formed. Workable steel plate length is 11550-12550mm, and pipe diameter is Φ711-Φ1422mm. The maximum wall thickness is 60mm and the maximum steel grade is X120. Nominal pressure is 6500 tons.

2000A digital welding machine of American Lincoln and automatic laser tracking system are used. Pipe feeding and discharging are computer controlled. Gas metal arc welding is performed at the maximum speed of 7m/min. Welding power source is PW AC/DC 1000 SD, and gas type is CO2/CO2 Ar.

The internal welding unit is composed of Lincoln digital welding machine, automatic laser tracking system, monitoring system, welding flux conveying and recycling system as well as control system. Workpieces are transported by jumbo, and welding head is settled. Welding characteristic curve can be adjusted according to actual needs, and welding parameters are automatically recorded, stored and traceable.

The external welding unit incorporates Lincoln digital welding machine, automatic laser tracking system, welding flux recycling system, TV monitoring system and digital control system. This unit is similar to the internal welding machine regarding other features. Welding speed is 0.5-3.0m/min., and power source is PW AC/DC 1000 SD. The maximum welding wire quantity is 4 wires for internal welding and 6 wires for external welding.

This equipment consists of gantry, probe support, control system and instrument. Testing speed is 0-20m/min. Dead zone at steel tube end is ≤100mm, and tracking range of probe is ≥±50mm. There are 28 channels in total.

The 320kV on-line X-ray testing machine is composed of flat imaging system, cantilever, general console, protective device, monitoring system and automatic processing apparatus. This machine makes instant imaging quality judgment available, convenient for quality control. Sensitivity for static imaging is more than 1.5%, and sensitivity for dynamic imaging is more than 3%. Testing speed is 2-6m/min.

The computer controlled pipe expanding machine realizes complete pipe clamping and expanding without interval. After processing, mechanical property and straightness of the welded pipe are more excellent. The maximum pipe expanding force is 1500 tons, and expanding rate is 0.8%-1.5%.

This machine is also computer controlled with maximum bearing capacity of 4000 tons. It adopts compound oil cylinder, which means small cylinder (with diameter of 710mm) suits 980 tons of bearing capacity, and large cylinder (with diameter of 1400mm) is fit for 980-3020 tons of bearing capacity. Both small and large cylinders should be used for 3020-4000 tons of bearing capacity. This method makes for perfect match of pipe diameter and cylinder diameter, and also prevents welded pipe from over bending and seal ring damage.

The maximum testing pressure is 50MPa. Pressure value and time curve in the whole process can be displayed, recorded, saved and printed.

The weld dressing machine is used to grind SAWL steel pipe end within certain length range.
Internal weld seam:
Grinding length: ≥200mm
Weld seam width: ≤40mm
Weld seam height: ≤4mm
Surface roughness of weld seam: ≤3.2μm.

External weld seam:
Grinding length: ≥150mm
Weld seam width: ≤40mm
Weld seam height: ≤4mm
Surface roughness of weld seam: ≤3.2μm.

This machine enables pipe end face cutting and beveling.
Steel pipe diameter: Φ711-1422mm
Maximum wall thickness: 60mm
Pipe length: 8000-12500mm
Maximum steel grade: X120
Beveled edge shape: single-V, double-V, Y, etc.

The HSD-28 automatic ultrasonic testing system adopts impulse-type longitudinal and transverse wave testing principle, and enables to test heat affected zone of steel tube within 25mm.
Testing speed: 0-20m/min.
Dead zone at pipe end: ≤100mm
Tracking range: ≥±50mm
Channel quantity: 28

SMART200 portable X-ray inspection device is incorporated by digital flat imaging system, mechanical device, general console, monitoring system and automatic processing apparatus.
Sensitivity: More than 1.5%
Milliampere stability: ±2%
X-ray tube focus: IEC336 1.5mm, EN12543, 3.0mm

Final inspection contents for the JCOE welded tube cover pipe diameter, wall thickness, ovality, length, straightness, weld seam size and shape, etc.

By using the automatic weighing and length measuring equipment, actual weight and length of steel tube can be obtained. Specially developed software automatically records the testing value which can be saved on computer.
Pipe diameter range: Ф508-Ф1422mm
Wall thickness: 60mm
Measuring range: 8000-12000mm
Weighing range: 0.6-17 tons