In 2017, the NBIC was restructured into four (4) parts, adding a new Part 4, Pressure Relief Devices. This purpose of this restructuring was to provide one distinct integrated part for pressure relief devices compiled from all PRD information referenced in Part 1, Installation; Part 2, Inspection; and Part 3, Repairs and Alterations. And in this new Part 4, Pressure Relief Devices, the National Board had this to say about “intervening stop valves” either between the pressure vessel and the valve or between the valve and the discharge location. Since this is a “new” part to the NBIC, I thought it might be helpful to remind everyone about the value in having valves in their relief systems as well as the DANGERS of doing so without proper administrative controls in place to manage these catastrophic risks. Here are the NBIC requirements: (emphasis by me)