The manufacturing of welded pipes and tubes is a significant part of precision engineering. Immense care is taken to maintain the dimension and strength of the products. The same tolerance is sustained throughout the procedure to provide you quality standards products.
At its premature stage, the metal is obtained in the form of coils of specific thickness. The metal coil is then inspected before processing. The quality requirements of the raw material are governed based on technical parameters and specifications. The metal coil is levelled for deviations, and if any, it is brought to appropriate thickness.
The next operation performed on the coil is slitting. The length of the metal coil is cut in several sections either by carbide cutters or saw blades of superior quality. These strips of the metal coil are tested with ultrasonic to see for any flaws before processing. The ultrasonic waves are set to appropriate frequency, high sensitivity, and high penetrating power that are then transmitted into the coil to detect flaws of all types. With this process, even the miniscule flaws can be identified and removed. The inspection process thereby becomes automated and the results are immediate, making the process smoother and faster.
The condensed strips then undergo preliminary forming. The rollers of specific shapes are placed in alignment to give the metal its tubular shape. The shape of the pipe is obtained along the process line. The pipe is welded along its length under a specific pressure to gain its tubular shape, the welding of the pipe makes it strong and uniform. Therefore, the welding technique is vital for the process.
The integral part used in welding is the Electric resistance welding, (ERW) which operates on electric current, the heat generated from the electric resistance acts as a power source to conduct welding. The required pressure is provided by the electrodes. As the current is passed through the electrodes, resistance by the metal to the current increases the heat and the required butt weld is formed. ERW has high energy efficiency, high productivity, less inconsistencies, easy automation, and no metal filler requirements unlike conventional welding techniques. Welded pipes and tubes are also often called ERW (Electric Resistance Welded) pipes.
The formed pipes are once again checked under Ultrasonic equipment. And to remove internal stresses caused during the welding process the metal pipes are gone through a heat treatment called annealing. This process involves heating the metal above its recrystallization temperature, maintaining it for a suitable period and then cooling it, this will improve the metal’s ductility or toughness. The pipe after getting its strength from annealing and water cooling goes for in-line process of sizing, fly cutting and straightening. A precise dimension is obtained after these processes. Now to finally obtain its accuracy, the pipe is gone through hydrostatic testing and eddy current testing. Hydrostatic testing detects the strength of the metal as well as finds out for any leaks in the pipe whilst Eddy current test detects any surface and subsurface flaws. The thoroughly examined welded pipe and tubes are finally weighed, measured and packed for usage.