Morpholine is an organic chemical compound having the chemical formula O(CH2CH2)2 NH. This heterocycle, pictured at right, features both amine and either functional groups. Because of the amine, morpholine is a base; its conjugate acid is called morpholinium. For example, neutralizing morpholine with hydrochloric acid makes the salt morpholinium chloride.
Morpholine is a common additive, in parts per million concentrations, for pH adjustment in both fossil fuel and nuclear power plant steam systems. Morpholine is used because its volatility is about the same as water, so once it is added to the water, its concentration becomes distributed rather evenly in both the water and steam phases. Its pH adjusting qualities then become distributed throughout the steam plant to provide corrosion protection. Morpholine is often used in conjunction with low concentrations of hydrazine or ammonia to provide a comprehensive all-volatile treatment chemistry for corrosion protection for the steam systems of such plants. Morpholine decomposes reasonably slowly in the absence of oxygen at the high temperatures and pressures in these steam systems.

Highly effective
Volatile in nature
Long shelf life