Q1: What do ERW and LSAW stand for, and what is the fundamental difference in their manufacturing?
A: ERW stands for Electric Resistance Welding. The pipe is formed from a hot-rolled coil, and the seam is welded using electrical resistance without any filler metal. LSAW stands for Longitudinal Submerged Arc Welding. It is manufactured from steel plates, which are bent and then welded along their longitudinal seam using the submerged arc welding process with filler wire-2.
Q2: What are the typical size ranges for ERW and LSAW pipes?
A: ERW pipes are generally produced in smaller diameters, typically from 1/2 inch to 24 inches. LSAW pipes are used for large diameters, often from 16 inches to over 60 inches, making them suitable for major pipeline projects-2.
Q3: How does the welding process affect the internal quality of the weld seam?
A: The ERW process can sometimes leave behind inherent welding defects like "cold welding" if not strictly controlled-5. In contrast, the submerged arc welding used for LSAW pipes produces a thick weld bead with high penetration, resulting in superior mechanical strength and better internal weld quality.
Q4: What are the key raw material challenges in producing high-quality ERW pipes?
A: The quality of ERW pipes is highly dependent on the steel strip. Key issues include unstable mechanical properties (strength that is too high or too low can cause cracking or wrinkling), surface defects (like sickle bend or wavy shape), and geometrical size deviations, which together account for over 30% of quality problems-5.
Q5: What are the main forming processes for LSAW pipes?
A: The two primary processes are UOE (where the plate is U-pressed, O-pressed, and expanded) and JCOE (where the plate is formed step-by-step in a J-C-O shape). UOE generally allows for higher production efficiency and pipe dimensional accuracy
