The welding procedure of API 5L X52 straight seam welded pipe mainly includes the following steps:
Material inspection
First, make sure that the parent material of the straight seam welded pipe meets the API 5L X52 standard, check the quality certification documents of the pipe, and check the chemical composition and mechanical properties of the material. At the same time, check the welding materials (welding rods, welding wires, flux, etc.) to ensure that they match the parent material, are of qualified quality, and have complete product certificates.
Groove processing
According to the wall thickness of the pipe and the welding process requirements, process the appropriate groove. Common groove forms include V-type, U-type, etc. Parameters such as groove angle, blunt edge size and root gap should be set strictly in accordance with the welding procedure specification (WPS). For example, for pipes with thicker wall thickness, U-shaped grooves may be used to ensure good fusion of the weld root and reduce the amount of filler metal.
Cleaning work
Thoroughly remove impurities such as oil, rust, and scale from the groove and nearby areas (generally 20-30mm on both sides of the groove). Mechanical grinding (such as using an angle grinder) and chemical cleaning can be used. The cleaned surface should reveal a metallic luster to prevent impurities from mixing into the weld during welding, resulting in defects such as pores and slag inclusions.
Assembly positioning
Assemble the pipes to be welded to ensure that the butt gap is uniform and consistent. Generally, the gap is controlled within an appropriate range (such as 2-4mm). Use a special fixture or perform positioning welding to fix the pipe. The length, spacing and height of the positioning welding should also comply with relevant standards and welding process requirements. The purpose of positioning welding is to prevent the pipe from displacement and deformation during welding.
Welding method selection
For API 5L X52 straight seam welded pipes, commonly used welding methods include submerged arc welding, gas shielded welding (such as carbon dioxide gas shielded welding), etc. Submerged arc welding is suitable for welding thick-walled pipes, and has the advantages of high welding efficiency and good weld quality; gas shielded welding is more commonly used in welding thin-walled pipes or when the requirements for welding deformation control are high, because its heat input is relatively small.
Welding parameter determination
Reasonably determine the welding parameters based on factors such as welding method, pipe wall thickness and welding position. For example, when using submerged arc welding, the welding current is generally selected according to the diameter of the welding wire and the wall thickness of the pipe, usually between several hundred amperes and more than one thousand amperes; the welding voltage is generally between 25-40V; the welding speed is adjusted according to the welding current and voltage to ensure good weld formation. For gas shielded welding, the welding current is generally between 100-300A, the welding voltage is between 15-30V, and the welding speed also needs to be controlled according to the actual situation.
Key points of welding operation
During the welding process, the arc should be kept stable. For submerged arc welding, attention should be paid to the coverage of the flux to ensure that the weld is welded under the good protection of the flux. For gas shielded welding, ensure that the shielding gas flow is appropriate (such as carbon dioxide gas shielded welding, the gas flow is generally 10-20L/min) to prevent air from entering the molten pool and generating pores. The welding direction is generally from the bottom of the pipe upward, and it is necessary to move at a uniform speed along the straight seam direction, observe the shape and size of the molten pool, and adjust the welding parameters in time to keep the molten pool in good fluidity and stability, ensuring that the weld is beautiful and of reliable quality.
X52 Round Steel Tube
