Small punch creep (SPC) technique, a non-destructive test method, which is excepted to evaluate residual creep life of field exposed material more precisely compared with microstructure technique was studied. It was found that the load P in small punch creep test can be converted easily to the uniaxial creep stress σ which give the same rupture time as that obtained from the small punch creep test. The correlation is almost independent of welding, aging and deterioration