Seam and Seamless Pipe

Weld and seamless pipe poor
Concentricity: Manufacturing Process for Seamless Pipe A hole of stainless steel billets are fired at a temperature of 2200 ° F. At this temperature, the tool steel becomes soft and stamped and spirally drawn in Hong Kong. Uneven wall thickness, high eccentricity. As a result, ASTM allows seamless pipe wall thicknesses to differ significantly from those of pipe joints. Steel pipe fittings made of precision cold rolled sheet (4-5 feet per foot width). Cold-rolled sheets typically have a wall thickness of 0.002 inch. The sheet is cut into wide πD, where D is the tube outside diameter. Slit pipe wall thickness tolerance is small, and the entire circumference of the wall thickness is very uniform.


Welding performance: The general chemical composition of seamless steel pipe and pipe joints have some differences. The production of seamless steel parts in full compliance with the basic requirements of ASTM. It produces fittings that contain chemicals suitable for welding. Such as silicon, sulfur, manganese, oxygen and other elements of the triangular ferrite easily produce heat transfer welding process in the welding process, through a certain percentage of mixing, so that the entire weld penetration. Such as steel chemical composition than defects, such as seamless steel pipe, the welding process will have a variety of uncertainties, not easy to weld, not easy to penetrate.


Particle size: In general, the metal grain size and heat treatment temperature are related to the time keeping the same temperature. Therefore, the seamless grain size of the annealed and slitted pipe is the same. If the pipe joint is cold treated to a minimum, the grain size of the weld is smaller than the grain size of the weld metal, otherwise the grain size is the same.


Strength: The strength of the pipe depends on the alloy composition, which contains the same seamless and seamed pipe of substantially uniform strength alloy and its heat treatment. After the tensile test and the three-dimensional vibration test, the tearing of the pipe joint occurred almost completely away from the welding spot or the heating place. This is because the weld less impurities, high nitrogen content, and weld strength is better than other regions. However, the ASME Boiler and Pressure Vessel Association believes that pipe fittings can only withstand 85% of the allowable pressure, mainly because of the data collected from the improved welding equipment used today. ASME regulations 100% ultrasonic flaw detector can withstand the pressure. Similarly, Europe and Asia also ensure quality through slit-tube eddy-current testing, which is required by legal procedures and allows their bodies to be weldable. Eddy Current Testing of the Swedish Ministry of Power. ASME believes the current loss is based on the smaller pipe joint high performance.


Corrosion resistance: good or bad depends on the corrosion resistance of the same alloy composition. The same chemical composition of seamless pipe and heat treatment has been completely pipe, corrosion resistance is consistent. Supplementary Tests ASTM certifies that the weld is corrosion resistant equal to or better than the metal to be welded. In acid chloride environments, incomplete heat treatment accelerates corrosion at the weld, but this only requires a corrosion test, in fact, the environment is not bad. Bending and Tensile Properties: Weld seam extension can be verified by the following tests: ASTM 45 ° bending followed by 90 ° and then flattening along the weld seam; then rewinding the tube joint to the bend inside diameter of the weld Reached 180 °. The welding quality standard is magnified 40 times with tearing or separation allowed. Pipe bending radius controlled by the alloy composition, the general minimum bend radius 2d, weld conditions in the neutral or compressed state is more ideal. In addition, the tube should be annealed to reduce its hardness, thereby improving the bending properties.