W-B75 type Wechsler hardness tester can be used for annealed stainless steel pipes with inner diameter over 6.0 mm and wall thickness under 13 mm. It is very fast and easy to test. It is suitable for rapid and non-destructive inspection of stainless steel pipes. Stainless steel pipes with inner diameter over 30 mm and wall thickness over 1.2 mm are tested by Rockwell hardness tester for HRB and H. RC hardness. Stainless steel pipes with diameter greater than 30 mm and wall thickness less than 1.2 mm are tested by surface Rockwell hardness tester. Stainless steel pipes with inner diameter less than 0 mm and larger than 4.8 mm are tested by special Rockwell hardness tester. When the diameter of stainless steel pipes is greater than 26 mm, Rockwell hardness tester or surface Rockwell hardness tester can also be used. Hardness of the inner wall of the pipe.