I'm going to assume you're using Sulfite for oxygen scavenging. Where are you injecting it, how much, and are you able to achieve adequate levels? What happens to the pH if you were to decrease / turn off the sulfite feed? I wouldn't expect this ...
Casey, Several questions: Does this system have a standard DA or just a feedwater heater? If a DA - does the system have a vent condenser? What is the final process the steam is being supplied to? (food heat exchangers or other systems that ...
I have seen this with un-neutralized sulfite feed and a sampling point relative to it.