make sure you are reading the spec correctly
sometimes it says....fully replace all shell material removed.....this means you can not take credit for excess material in head or shell
In general, it means that area cut out of the shell or head to insert a nozzle is replaced by a similar area as reinforcement. Specifics vary, as noted above.
In some cases, they want nozzles reinforced so that maximum allowable pressure is not limited by nozzles.
I believe there is a code case that allows less than full nozzle area replacement to be used, also.
Some specs call for more than Code req'd reinforcemet. This term may be used to imply that no credit may be taken for the excess area in the shell or nozzle - the reinforcing element and welds must provide 100% of the area required. Depending on who's using the term it may also define area required as either that required by Div. 1 (i.e. treq*dia) or the entire cut out area (tmon*dia).
