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.

Avoiding Cold Drawn Seamless Steel Tube Uneven Wall Thickness

Seamless steel pipe classification and characteristics

3PE corrosion-resistant steel pipe buried pipe life is crucial, the same material, pipe buried in the ground for decades and some non-corrosive, leaks in a few years. Because they use different outer coating.

When hardness of steel pipe is below 500HB, which is proportional to the tensile strength and hardness. Hardness with tempering temperature decreases, but in the state as well as the quenching and tempering below 300 ℃, the hardness and tensile strength of the relationship is difficult established. When the tempering temperature at around 300 ℃, kg / m ㎡ with HRC is a correlation between that high hardness, tensile strength is high; low hardness, tensile strength is low.

Effect of remanence on welding quality and its influence Gas pipeline construction and repair welding operations, sometimes appear blowing phenomenon, affecting the welding process. The formation of a magnetic strike is due to the presence of metal residual magnetism in the pipe. Usually, the magnetic induction and remanence are divided into two processes. Magnetically-induced plants tend to produce tube links such as metal smelting, handling using electromagnetic cranes, tube parking in a strong magnetic field, non-destructive testing after magnetization, and placing the tube close to the power cord and so strongly. Magneto-electric welding often occurs during the process. When assembling and using the magnetic retainer, the fixture and the DC welding pipe are connected to each other. For example, a long contact is connected to a DC power cable, a bare wire section or a short-circuit pipe welding fixture.