After the heat treatment of the inner cylinder, the hydrostatic test does not pass, then the weld needs to be reworked again for heat treatment (the probability of reworking the weld is very low, basically the hydrostatic test can pass)
Jacket welding, it is best to set up a pad on the cylinder (jacket fillet weld), the pad is welded first, and with the inner cylinder with the heat treatment. Welding jacket, will not be welded directly on the inner tube, so the inner tube can not be heat-treated again.