The Use of ERW Steel Pipe

High frequency electric resistance welded pipe, also known as ERW steel pipe. ERW has many advantages, such as high production efficiency, low-cost, saving in material, and easy-to-automation. It is a kind of important welding technology which is widely used in various industrial sectors such as aviation, energy, electricity, automobile, light industry and so on.

ERW steel pipe uses hot rolled coil as raw material, its wall thickness is uniform and is controlled at ± 0.2mm or so, the two ends of the pipe should repair the end, bevel, and cut to length according to the United States APl standard or GB/T.1 standard. Compared with the submerged arc welding process, ERW welding process does not add any welding materials, weld molding has not been hot-melting state, the weld metal goes through the recrystallization process, so the formed weld is completely the same chemistry as the base metal. The steel pipe after welding will be annealing, manufacturing cold forming internal stress, welding internal stress are improved, so ERW steel pipe comprehensive mechanical properties better.

ERW steel pipe is mainly used for conveying oil, gas and other vapor-liquid objects, to meet the high and low pressure requirements. At present, the field of transportation and transportation in the world plays a heavy role. In recent years, the engineering gas has been widely used ERW steel pipe as the main gas pipe network.

About more details about definition, manufacturing process and application of ERW steel pipe, you can click the hyper-link to know. If you have any requirements of carbon steel pipe or steel pipe fittings, Prime Steel Pipe will give you the most complete solution.


The Effect of Input Power on ERW Steel Pipe Production

When using high frequency technology to produce ERW steel pipe, controlling the input power of High-frequency welding is very important. So what effect does it have on ERW steel pipe production? And what should steel pipe factory do for that? Next, ERW steel pipe manufacturer Prime Steel Pipe who has years of experience on manufacturing carbon steel pipe will give your answer.

If the input power is too small, the pipe groove is not heated enough to reach the welding temperature, which can cause the welding failure such as pseudo soldering, unsoldering and slag welding. If the power is too large, it will affect the welding stability. When the heating temperature of the pipe groove surface is much higher than the temperature required for welding, which will result in severe splashing, pinholes, slag and other defects, those defect are known as over burning defects. When manufacturing ERW steel pipe, the input power of high-frequency welding need to adjust and determine according to the thickness of the wall and the molding speed. Different molding methods, different unit equipment, and different material grade of steel all need us to sum up from the production line, and work out high-frequency process that suitable for their own equipment.


The Principle of Submerged Arc Welding

Submerged arc welding (SAW) is a method that burning under flux layer to weld. SAW is one of the most occurring arc welding process. It needs a electrode which may be solid of tubular. The electrode should be used in a continuous approach. It should be fed continuously.Flux refers to a material that can thaw the formed slag and gas when welding, and has the protection and metallurgical treatment to melt metals.The wire is the material that as a filler metal or as a conductive wire for welding.

Submerged arc welding is commonly used to manufacture LSAW steel pipe and SSAW steel pipe, and those two kinds of steel pipe are widely used in various kinds of production and transportation activities. The main feature of submerged arc welding is that the weld and the arc area is protected from environmental contamination by the application of a granular flux which is fusible. The weld pool is protected by a blanket of flux. So that area is actually submerged under that flux. When temperature rises and molten the flux becomes conductive. And thus this creates a path for electron flow between electrode and workpiece. SAW or Submerged Arc welding can be done by manual procedure or automatic process. But it can be done by semi-automatic process where welding gun is hold by hand.


LSAW Steel Pipe Manufacturing Process

LSAW steel pipe manufacturing process is simple, its production efficiency is high and at low cost, the development of straight seam welded pipe is rapid. Therefore, the straight welding is mostly used in smaller diameter of steel pipe. Today, as an excellent steel pipe manufacturer, Prime Steel Pipe will share the LSAW steel pipe manufacturing process in details for all of you.

LSAW steel pipe Manufacturing process:

1.Plate Analyzing:After the steel plate used to manufacture large diameter LSAW steel pipe entering into the production line, steel pipe manufacturer should carry out ultrasonic testing to the whole plate;

2.Edge Milling: Through the milling machine to carry out double-sided milling on both sides of the steel plate, to make it achieve the required plate width, board parallelism and groove shape;

3.Edge Crimping: Using the pre-bending machine to preliminary rolling, so that the board has the required curvature;

4.Molding: In the JCO forming machine At the first, steel pipe manufacturer should do stamping repeatedly for half of the pre-bent steel plate in the JCO forming machine, so that the steel plate is formed "J" shape, and then bending the other half of steel plate to form "C" shape, and finally formed the opening of the "O" shape;

5.Tack Welding: Making the LSAW steel pipe after forming joint colse and using the gas shielded welding (MAG) for continuous welding;

6.Automatic Internal Welding: Using vertical multi-wire submerged arc welding (up to four silk) to weld in the inside of the LSAW steel pipe;

7.Automatic External Welding: Using vertical multi-wire submerged arc welding to weld in the outside of LSAW steel pipe;

8.Automatic UT I: Using Automatic UT to 100% test the inside and outside wleded seam of LSAW steel pipe and the base material on both sides of weld seam;

9.X-Ray Testing I: Carrying out 100% X-ray industrial television inspection on the inside and outside the weld seam, and using image processing system to ensure the sensitivity of testing;

10.Mechanical Expanding: Expanding the full length of LSAW steel pipe to improve the dimensional accuracy of steel pipe and improve the distribution of stress in steel pipe;

11.Hydrostatic Testing: Testing the steel pipe after expanding one bu one in the hydraulic test machine to ensure that the steel pipe to meet the standard requirements of the test pressure, the machine has automatic recording and storage functions;

12.Chamfering: the pipe passed the inspection will be carried out pipe end processing qualified, to achieve the required pipe end groove size;

13.Automatic UTⅡ: Testing pipe one by one again by using root ultrasonic inspection to examine if there is defect on LSAW steel pipe after expanding and hydrostatic testing;

14.X-Ray TestingⅡ: Carrying out X-ray industrial television inspection on the pipe after expanding and hydrostatic testing, and take photos of the weld seam in the end;

15.Pipe End Magnetic Particle Testing(MPT): Carry out this inspection to find pipe end defects;

16.Corrosion protection and coating: Qualified steel pipe will carry out corrosion and coating according to user requirements.