Stefanhg, thanks for your help,
Wayne, we have 50 gages NPT, and I need calibrate it, I never do calibrated NPT, I was searching how calibrate it, due a my short time, I think than only need measure the pitch diameter and the L1, I read than the tolerance for these plug gages is ± half turn, then the pitch diameter should be on this turn, whether I am wrong please help me, thanks.