Compared with  seamless pipe, erw steel pipe has the following features:

1, High dimensional accuracy, for the diameter and wall thickness deviation, erw steel pipe is much smaller than seamless due to the steel rolling and pipe forming easy to control.

2, Good mechanical properties, easy to implement due to the pipe with a control strip rolling, with the development of welding technology and heat treatment technology, the weld properties can be controlled, so the elongation of erw pipe is higher 8%-10% than seamless, mainly carbon-containing of erw pipe is lower 1/2 than seamless.

3, High concentricity, uniform thickness. Weld heat treatment, the metal structure is uniform, so there is a higher resistance to collapse capability.
 
4, Since the ductility of steel, flattening test of erw pipe is better than seamless.

5, Impact toughness: impact test of erw pipe taken transverse, longitudinal specimens taken seamless, generally longitudinal impact toughness is superior to the transverse impact toughness specimens, but base metal of erw pipe is controlled rolling, so transverse specimens of erw pipe is still higher than the impact toughness of seamless steel pipe.

6, Weld coefficient of erw pipe can be up to 1 due to the rigorous line heat treatment. That is the strength of the weld metal and heat affected zone of the base metal and plastic and the same. From the microstructure before heat treatment and after heat treatment is evident, weld normalizing martensite and Wilcoxon tissue disappear, homogeneous, grain refinement.