ERW straight seam pipe surface quenching and tempering heat treatment is usually carried out by induction heating or flame heating. The main technical parameters are surface hardness, local hardness and effective hardened layer depth. Hardness testing can use Vickers hardness tester, Rockwell can also be used. When the thickness of the heat-treated hardened layer is 0.4-0.8mm, use HRA ruler, and when the thickness of the hardened layer exceeds 0.8mm, use HRC ruler.

If the hardness of parts is required to be high, induction quenching and other methods can be used for local quenching heat treatment. Such a ERW straight seam pipe is usually marked with the location of local quenching heat treatment and local hardness value on the drawing. ERW straight seam pipe hardness testing should be carried out in the designated area. The hardness testing instrument can use Rockwell hardness tester to test HRC hardness value. If the heat treatment hardened layer is shallow, surface Rockwell hardness tester can be used to test HRN hardness value.

Vickers, Rockwell and Surface Rockwell can be converted to each other and converted into standards, drawings or hardness values required by users. Corresponding conversion tables are given in the international standard ISO, American standard ASTM and Chinese standard GB/T.