EFW welded pipe refers to welding by melting metal through arc, without pressurization, and the filler metal comes from the electrode. During production, the process can be selected from submerged arc welding, melting gas shielded welding, and spiral welding. If it is a thick-walled pipe, submerged arc welding is selected, and the flux covers the arc. Melting gas shielded welding belongs to inert gas shielded welds, which can reduce oxidation and extend service life. Spiral welding refers to spiral continuous welding to improve production efficiency. The materials are mostly stainless steel and carbon steel. Stainless steel includes 304 and 316L, and carbon steel is low-carbon steel. There are also many sizes. The outer diameter of conventional industrial pipes is 19mm-711mm, and the wall thickness is 1.2mm-75mm. Thick-walled pipes mostly use SAW technology.
EFW welded pipes are essentially different from other welded pipes in terms of welding principles and application fields:
Welding principle: arc heat melts metal, welding materials need to be filled, and submerged arc welding and gas shielded welding are used;
Weld seam morphology: obvious fusion line, weld excess height, wide heat affected zone (HAZ), and coarse grain embrittlement zone is prone to appear;
Process defects: EFW typical defects are pores and slag inclusions, and radiographic detection is required to check internal defects, and the water content of the flux is ≤0.10%;
Application scenarios: thick-walled high-pressure pipelines, requiring EFW wall thickness>40mm, and areas with high corrosion resistance requirements, not only corrosion-resistant, but also long service life.
EFW welded pipes are suitable for high-strength materials, support welding of special materials such as chromium-molybdenum alloy steel and low-temperature carbon steel, and are widely used in the chemical industry because of their corrosion resistance. During use, it shows strong high-pressure and high-temperature adaptability, with a design pressure of more than 10MPa, a temperature range of -46℃-425℃, and CL22 type welded pipes need normalizing treatment to ensure low-temperature impact toughness (-46℃ impact energy ≥27J).
It is precisely because of these characteristics of efw that we must control the quality more accurately from weld inspection to post-weld treatment. 100% radiographic flaw detection (RT) is used to ensure that there are no pores or slag inclusions, and normalizing and tempering are used to eliminate residual stress, and the hardness of the heat-affected zone is ≤248 HV10.
efw welded pipes can be customized according to usage requirements. No matter what kind of welded pipe you need, you can contact our customer service.
