efficiency.

Longitudinal submerged arc welded pipe due to the use of different environmental conditions, and the objective conditions of change over time, coupled with the inherent defects in a certain period of time there will be different forms of damage. Such as hydrogen-containing welded steel pipe, in the high enough stress or residual stress cracking occurs, the form of such damage is commonly referred to as hydrogen induced cracking. Hydrogen-induced cracking of welded steel is due to the diffusion of hydrogen in the metal matrix, forming solid solutions in the form of metal hydrides or metal hydrides, resulting in brittle fracture of the pipe. It is a source of potential pipeline damage. Hydrogen induced cracking can occur in a few weeks even at high stresses or pressures when buried underground.

2, the quality of welding directly determines the quality of welded pipe, seamless steel pipe welding the biggest difference is. Longitudinal high-frequency welding, straight seam carbon can not be eliminated, the weld and the parent material just connected together, can not be fully integrated into one - can not stand the test of time and pressure. Hot stretch reducing pipe high-frequency welding heating after the whole, the overall annealing temperature of 800 degrees, and then open the process of change, in this series of processes, the weld and the parent organization has the same performance as the complete melting, good from the joints without Transition.

Drainage Pipeline

Analysis of Steel Tube Bending and Deformation Deformation heat treatment principle shows that the heat processing (welding), due to uneven heating temperature, compression plastic deformation caused by high temperature cooling contraction site can also be through other parts (low temperature cooling zone or the first part) block, resulting in residual stress and each Kind of modification Steel pipe heat treatment (steel or thermal expansion) after the market is mainly used for bending steel.

Advantages and disadvantages of welded steel pipe Wall light table average wall thickness (steel appearance, steel grade resolution, brightness) can be any length. Therefore, it is economically and aesthetically accurate, using low pressure fluids.

Large Diameter Seamless Steel Thermoforming Manufacturing Process

Hot-rolled seamless steel pipe defects Separated Located in the vertical distribution of the steel tube surface, a spiral rise, massive metal separation or fracture-like stripping.

Spiral welding production process is simple, high production efficiency, low cost and rapid development. The strength of spiral welded pipe is generally higher than the vertical, you can narrow-billet production of large-diameter steel pipe, you can also use the same width billet production of different diameter steel pipe. However, the length of the weld is 30 to 100% compared to the length of the straight pipe weld and the productivity is low. Therefore, the smaller diameter pipes are mostly straight seam welded, large diameter spiral welded pipe.

Hot-rolled seamless steel pipe products generally require two heating, which perforated pipe in the heating and rolling of the pipe diameter after a given pre-heating; production of cold rolling (pulling) when the pipe requires an intermediate annealing to eliminate residual stress Use; For some special requirements of the steel, in order to improve the mechanical properties of steel and improve the organization and process performance, and heat treatment. Common tube (tube) heating tube defects uneven heating, oxidation, decarburization, overheating, overheating heating cracks.

Spiral Weld Seam

The advantages of galvanized pipe are as follows: First, the surface of the galvanized tube after hot-dip galvanizing can be protected and difficult to access at the corners of the tube lumen or any other coating. Deeper zinc can easily reach the top, protecting the entire galvanized tube.

Spiral pipe (spiral submerged arc welded steel pipe): By the belt molding machine, folded spiral direction, and then double-sided submerged arc welding is through the capacitor. Spiral welded pipe production process, prone to welding edge leakage and many other conditions. However, chlamydia appears to be the hardest to grasp helical butt weld in these situations.

Cold drawn oil cracking pipe production

At present, carbon steel pipe pickling method is adopted for the construction and management of the two-ring pickling and pickling inner ring.

Butt resistance welding (hereinafter referred to as butt) is the entire end face of a resistance welding method in which two workpieces of a thermal resistance are welded together at the same time. High butt productivity, easy to automate, so widely available.

Steel is the most widely used gas pipeline project. Its main advantages are: high strength, good toughness, large compressive stress, impact resistance, compactness, good plasticity, easy welding and heat treatment, thin wall thickness, saving the metal. But its poor corrosion resistance, the need to take appropriate anti-corrosion measures.

This method of welding has great advantages over other methods. The first advantage is fully automated. The second advantage, which is buried in arc welding, is its heat exchange and relatively strong performance guarantees, high quality The third advantage, due to the submerged arc welding buried in the flux, so it can be used for high current, welding efficiency is relatively high.

Due to the constraints of the production process, the high cost of seamless steel pipe production, resulting in its gradual decline in economic efficiency. As the technology advances, China's metallurgical industry, instead of hot-drawing seamless steel pipe to reduce the beginning of new products appear.

Cold-drawn tubes are generally divided into medium and low pressure boiler tubes, high pressure boiler tubes, steel tubes, stainless steel tubes, petroleum cracking tube, other steel, thin-walled carbon steel, alloy steel thin-walled, thin-walled stainless steel, special steel.

Cold drawn non-uniform thickness of the reasons for the uneven steel: 1) cutting the slope, through the big bend, the center of the hole error easily lead to uneven wall thickness. 2) When the perforation extension coefficient is too large, the roll speed is too high, rolling instability. 3) Puncher throwing steel capillary instability can easily lead to uneven thickness of the tail.