History and need behind the new NBIC rules on weld repair without PWHT

The purpose of the National Board Inspection Code (NBIC) is to maintain the integrity of pressure retaining items after they have been placed into service by providing rules for inspection, repair and alteration, thereby ensuring that these objects may continue to be safely used. The NBIC was originally published to provide rules for inspection and repairs to boilers and pressure vessels. However, the NBIC Committee in preparing for the 1995 edition decided to expand the scope of the NBIC to include rules for the repair or alteration of piping and other pressure-retaining items. This led to a complete rewrite of the Code. Here, support data from several major research programs resulted in revised NBIC rules permitting additional ferritic materials to be repair welded without PWHT.