The only nozzles that require 300# ANSI are the nozzles used for multi-port pressure relief valves. Maufacturers only supply 3" 300# or 4" 300#
Other connections will be for specific instruments such as liquid pumps or etc
Manways will always use 150# c/w blind
Hope that helps
cmsurfsup, would it be that a corrosion allowance wasn't originally considered and you are putting this in to your calculations
In some circumstances especially low pressure vessels, the rules governing nozzle thickness in UG-45 can be avoided
Just a thought....!!!!
