The reason you need to wait 48 hours after welding is that hydrogen cracking - often called delayed cracking- can take a while to develop. The type of cracking experienced in A514 due to PWHT is reheat cracking. It normally occurs in the HAZ during the heating cycle of the PWHT. No inspection delay is required. Since the code doesn't say that a 48 hour wait after PWHT is required, and the cracking that PWHT causes doesn't have an incubation cycle, the wait is not necessary. However, always think twice before PWHT of A514. Not that it can't ever be done sucessfully, but it can lead to cracking, harm the properties of the weldment, and is hardly ever recommended.