Distinguishing Between Annealed and Non-Annealed Stainless Steel Welded Pipes

How to distinguish between annealed and non-annealed stainless steel welded pipes?

1. The pipe can be judged by echo.

Tap each pipe and listen to the echo at the nozzle. If the echo is higher, it is sharper and has been annealed. Since the internal crystal structure of the annealed part is more uniform and dense, it can produce a higher interval echo without the need for annealing. Due to a large number of organizational defects, it can absorb some sound energy, so the tone at the nozzle is very low and dull. If conditions permit, it can be detected by ultrasound.

2. Use a more precise digital multimeter to measure the resistance per unit length (e.g., 2 meters). The resistance of stainless steel should be measurable. The resistance of annealed steel is less than that of non-annealed steel. Dry before testing, no liquids. These methods can distinguish between annealed and non-annealed stainless steel welded pipes.