Large-diameter straight seam welded pipe is a general name, produced with steel strips, and pipes straight seam welded by high-frequency welding equipment are called straight seam welded pipes. (It is named because the welding joint of the steel pipe forms a straight line). Among them, there are different back-end production processes according to different uses. (It can be roughly divided into scaffolding tubes, fluid tubes, wire casings, bracket tubes, guardrail tubes, etc.)
Generally, straight seam steel pipes with diameters above 325 are called large-diameter steel pipes. The welding process used for large-diameter thick-walled straight seam steel pipes is double-sided submerged arc welding technology. Manual welding can also be performed after the steel pipe is formed. The generally used detection method is flaw detection. After passing the flaw detection, it can be shipped from the factory. Unqualified products need to be re-welded. Large-diameter thick-walled straight seam steel pipes are generally suitable for the transportation of fluids and liquids, the support of steel structures, and piling. They are widely used in the petrochemical industry, construction, water supply projects, power industry, agricultural irrigation, urban construction, etc. The steel pipe should be able to withstand the internal pressure of 2.5Mpa and maintain no leakage for one minute. It is allowed to use the eddy current flaw detection method instead of the hydrostatic test. The main molding methods include UOE, RBE, JCOE, etc., among which JCOE has the highest usage rate. The pipe end can also be threaded according to the customer’s requirements, also called threaded or unthreaded.
Introduction to rust removal methods for large diameter straight seam steel pipes:
1. Cleaning: Use solvents and emulsions to clean the surface of large-diameter straight-seam steel pipes to remove oil, grease, dust, lubricants, and similar organic matter. However, it cannot remove rust, oxide scale, welding flux, etc. on the surface of large-diameter straight-seam steel pipes. Therefore, it is only used as an auxiliary means in anti-corrosion production.
2. Tool rust removal: Mainly use tools such as wire brushes to polish the surface of large-diameter straight seam steel pipes to remove loose or lifted oxide scales, rust, welding slag, etc. The rust removal of hand tools can reach the Sa2 level, and the rust removal of power tools can reach the Sa3 level. If the surface of large-diameter straight seam steel pipe is firmly adhered to the oxide scale, the rust removal effect of the tool will not be ideal and the anchor pattern depth required for anti-corrosion construction will not be achieved.
3. Pickling: Generally, chemical and electrolytic methods are used for pickling treatment. Only chemical pickling is used for pipeline anti-corrosion, which can remove scale, rust, and old coatings. Sometimes it can be used as a reprocessing after sandblasting and rust removal. Although chemical cleaning can achieve a high level of cleanliness and roughness on the surface, its anchor lines are shallow and it can easily pollute the environment.
4. Spray (throw) rust removal: Spray (throw) rust removal uses a high-power motor to drive the spray (throw) blade to rotate at high speed, so that steel sand, steel shots, wire segments, minerals, and other abrasives are removed under the action of centrifugal force. Spraying (throwing) the surface of the steel pipe can not only remove rust, oxides, and dirt but also the large-diameter straight seam steel pipe can achieve the required uniform roughness under the action of the violent impact and friction of abrasives.
The production process of large-diameter straight-seam steel pipes: The production process of large-diameter straight-seam steel pipes generally includes hot rolling, hot coiling, casting, and other production methods. The double-sided submerged arc welding production process is generally used when processing large-diameter thick-walled steel pipes. The products are bent. , jointing, internal welding, external welding, straightening, flat head, and other multiple processes to meet the requirements of petrochemical standards.
Large-diameter straight seam steel pipes are mainly used for body support parts, such as bridge piling, submarine piling, and high-rise building piling.
The materials used for large-diameter straight seam steel pipes are generally Q345B and Q345C. Q345D is also used in areas with lower temperatures. Q345E large-diameter straight seam steel pipes are mostly used in large-scale steel structure construction.
Post time: Jan-15-2024