4.1 Residual stresses in tubing may be detrimental to the future performance of the tubing. Such stresses may, for example, influence the susceptibility of a tube to stress corrosion cracking when the tube is exposed to certain environments.
4.2 Residual stresses in new thin-walled tubing are very sensitive to the parameters of the fabrication process, and small variations in these parameters can produce significant changes in the residual stresses. See, for example, Table 1, which shows the residual stresses measured by this practice in samples from successive heats of a ferritic Cr-Mo-Ni stainless steel tube and a titanium condenser tube. This practice provides a means for estimating the residual stresses in samples from each and every heat.
| Heat No. | Ferritic Cr-Mo-Ni Stainless Steel | Titanium | ||
| kPa | psi | kPa | psi | |
| 1 | 234000 | 34000 | 37000 | 5400 |
| 2 | 272000 | 39400 | 52000 | 7600 |
| 3 | 217000 | 31500 |
| |