I was wondering why there was a nitrogen pipeline at Seal Sands. Then I found this https://www.rigzone.com/training/insight.asp?insight_id=329&c_id= Seal Sands is the heart of petrochemical works and nitrogen is in an inert gas in that it doesn't react at the temperatures and pressures involved. The nitrogen is safe to use because it won't explode so can be used to flush out pipes and pressure check. The article explains how it is made.
