What is submerged arc welding? What are its characteristics and application scope?
Submerged arc welded steel pipe is also a kind of straight welded steel pipe. The pipe body has a longitudinal weld. When the diameter is greater than 914mm, two welds are allowed.
Submerged arc welding technology is characterized by using the electric heating effect of welding wire to fuse with steel plate. The welding technology adopted is submerged arc welding, which uses filler welding and particle protection flux to submerge arc. This is filler welding.
Submerged arc welding process
Submerged arc welding technology is suitable for heavy industry applications, such as pipeline, pressure vessel, locomotive manufacturing and heavy construction. Suitable for industries that need high productivity, especially for welding thick materials, the weld has excellent chemical composition and mechanical properties, minimum arc visibility and lower welding smoke, improved working environment comfort and good weld shape.
Features of submerged arc welded steel pipe: Welded pipes with larger diameter can be produced with narrower billets, and welded pipes with different diameters can also be produced with billets with the same width. The production cost is low, the process is simple, and it is easy to produce large-diameter pipelines.
How to distinguish high frequency straight seam steel pipe from submerged arc welded steel pipe?
The difference between high frequency straight welded steel pipe and submerged arc welded steel pipe is mainly reflected in appearance and weld. From the appearance, the main body of high-frequency steel pipe is smooth, and there is no oxide scale attached. On the weld, the weld of high frequency straight seam steel pipe is extruded, serrated and irregular. The weld was "scraped off" before leaving the factory, leaving a relatively flat weld. Submerged arc welded steel pipes have slight banded bulges in appearance, which are mainly distributed inside the steel pipes, and the neat height of the weld is 1-3mm higher than that of the base metal. Therefore, it can be "polished" as required before leaving the factory.
Factory inspection of submerged arc welded steel pipe
Each batch of submerged arc welded steel pipes will go through a strict inspection system to check the mechanical properties, chemical composition, fusion state and surface quality of steel pipes, and carry out nondestructive inspection to ensure that the steel pipe manufacturing process is qualified before it is officially put into production.
Parts with continuous acoustic flaw detection marks on the weld will be inspected by manual ultrasonic and X-ray. If there are defects, NDT will be carried out again after repair until it is confirmed that the defects have been eliminated.
Submerged arc welding steel pipe has been developed into double-wire submerged arc welding, which further improves the welding efficiency and is widely used in steel structure, piling, fluid transportation, long-distance pipeline and other fields.
