It seems these days that having a relief valve header is the way to go; but why is that? Why are so many businesses deciding an “RV header” is the way to go with their RV Design Basis? In the process safety world, a facility is required to have a “relief design basis” and the use of a header should be documented as to why a header is needed, not just wanted. So where did the use of an RV header come from and why?