Currently, the commonly used methods for steel pipe welding include shielded metal arc welding, submerged arc welding, gas tungsten inert gas welding, gas metal arc welding, flux-cored wire arc welding (FMCW), and downhill welding.
1. SMAW for steel pipe welding:
(1) The advantages of SMAW for steel pipe welding are simple and lightweight equipment, flexible operation, and suitability for welding short seams in maintenance and assembly, especially for welding hard-to-reach areas.
(2) The disadvantages of SMAW for steel pipe welding are high requirements for welder skills, high welder training costs, poor working conditions, low production efficiency, and unsuitability for welding special metals and thin plates.
(3) SMAW for steel pipe welding is commonly used in: SMAW with appropriate electrodes is suitable for welding most industrial carbon steel, stainless steel, cast iron, copper, aluminum, nickel, and their alloys.
2. Submerged Arc Welding of Steel Pipes
Submerged arc welding can use a larger current. Under the heat of the arc, part of the flux melts into slag and undergoes a liquid metallurgical reaction with the molten metal. The remaining slag floats on the surface of the molten metal pool, protecting the weld metal from air pollution and reacting with the molten metal to improve its composition and properties. It also allows the weld metal to cool slowly, preventing defects such as cracks and porosity.
(1) Compared with shielded metal arc welding (SMAW), submerged arc welding of steel pipes offers advantages such as higher weld quality, faster welding speed, and better working conditions. Therefore, it is particularly suitable for welding straight and circumferential seams of large workpieces, and often employs mechanized welding.
(2) Disadvantages of submerged arc welding for steel pipes: It is generally only suitable for welding flat seams and corner seams. Welding in other positions requires special equipment to ensure flux coverage of the weld zone and prevent leakage of molten pool metal; the relative position of the arc and bevel cannot be directly observed during welding, requiring an automatic weld tracking system to ensure the welding torch is aligned with the weld and does not deviate; the current used is relatively large, and the electric field strength of the arc is high. When the current is less than 100A, the arc stability is poor, making it unsuitable for welding thin parts with a thickness of less than 1mm.
(3) Applications of submerged arc welding for steel pipes: Submerged arc welding is widely used for welding carbon steel, low alloy structural steel, and stainless steel. Because the slag can reduce the cooling rate of the weld joint, some high-strength structural steels and high-carbon steels can also be welded using submerged arc welding.
3. Tungsten Inert Gas Welding for Steel Pipes.
Tungsten inert gas welding is an excellent method for joining thin sheet metals and for root pass welding because it can effectively control heat input. This method can be used for welding almost all metals, especially suitable for dry welding of metals that can form refractory oxides, such as aluminum and magnesium, as well as reactive metals like titanium and beryllium. This welding method produces high weld quality, but compared to other arc welding methods, it has a slower welding speed, higher production costs, and is more susceptible to the influence of ambient airflow, making it unsuitable for outdoor operation.
4. Gas Metal Arc Welding for Steel Pipes.
Gas metal arc welding typically uses argon, helium, carbon dioxide, or mixtures of these gases. When argon or nitrogen is used as the shielding gas, it is called gas metal arc inert welding; when a mixture of inert and oxidizing gases, or a mixture of CO2 and CO2+O2, is used as the shielding gas, it is collectively called gas metal arc active welding. The main advantage of gas metal arc welding for steel pipes is that it allows for convenient welding in various positions, and also has advantages such as faster welding speed and higher deposition rate. Gas metal arc active welding is applicable to the welding of most major metals, including carbon steel and alloy steel. Gas metal arc welding (GMAW) is suitable for stainless steel, aluminum, magnesium, copper, titanium, zirconium, and nickel alloys. This method can also be used for spot welding.
5. Flux-cored wire arc welding for steel pipes.
Flux-cored wire arc welding can be considered a type of GMAW. It uses flux-cored wire, with the core containing various components of flux powder. During welding, an external shielding gas, primarily CO2, is applied. The flux powder decomposes or melts upon heating, acting as a gas generator and slag generator to protect the molten pool, alloy infiltration, and stabilize the arc. When flux-cored wire arc welding is performed without an additional shielding gas, it is called self-shielded flux-cored wire arc welding. It uses the gas generated by the decomposition of the flux powder as the shielding gas. In this welding method, changes in the wire extension length do not affect the shielding effect, and the range of variation can be relatively large. Flux-cored wire arc welding has the following advantages: good welding process performance and aesthetically pleasing weld bead formation; fast deposition speed and high productivity, enabling continuous automatic and semi-automatic welding; convenient alloy system adjustment, allowing for adjustment of the chemical composition of the deposited metal through both the metal sheath and the flux core; low energy consumption; and low overall cost. Disadvantages include complex manufacturing equipment, high technical requirements for manufacturing processes, stringent storage requirements for the flux-cored wire, and the wire’s susceptibility to moisture. Flux-cored wire arc welding can be applied to welding most ferrous metals of various thicknesses and joint types.
6. Downward Welding of Steel Pipes
Downward welding is a process method introduced from abroad, suitable for circumferential welding of pipes. It refers to a process where the arc is struck at the top of the pipe weld and welding proceeds downwards. Downward welding has the advantages of high production efficiency and good weld quality.
Post time: Jan-30-2026