Hydrazine Hydrate (Oilfield Boiler Grade)

Hydrazine hydrate (N2H4·H2O, CAS 7803-57-8) is the oxygen scavenger used in high-pressure boilers, heat-recovery steam generators and closed steam systems where sulphite-based scavengers would add dissolved solids. It reacts with dissolved oxygen to give only nitrogen and water (N2H4 + O2 → N2 + 2 H2O), so nothing accumulates in the boiler water, and its excess also helps keep the protective magnetite layer on steel in its reduced state. Global Chemicals LLC supplies it from Muscat stock in 35%, 55% and 80% concentrations to power plants, refineries, desalination plants and industrial boiler houses across Oman.

Dosing. The reaction consumes about 1 ppm of hydrazine per ppm of dissolved oxygen. Plants typically feed 1–2 ppm per ppm of residual oxygen after mechanical deaeration and keep a small hydrazine residual in the feedwater, measured at the economiser inlet. Reaction speed rises sharply with temperature and pH, so the feed point is normally the deaerator storage section or the boiler feed pump suction, not the cold make-up line. Catalysed grades are used where feedwater temperatures are low.

Properties. Clear, colourless liquid, specific gravity 1.03 at 20°C, boiling point 118°C for the monohydrate. Miscible with water in all proportions and strongly alkaline.

Handling. Hydrazine is acutely toxic, corrosive and a skin sensitiser, and is classified as a presumed human carcinogen (EU CLP Carc. 1B, H350). Plants handle it in closed dosing systems from the original drum or IBC, with chemical-resistant gloves, eye protection and local extraction, and keep it away from oxidisers. The SDS and a site-specific handling procedure are part of every first delivery.

What to specify when you order. Concentration (35%, 55% or 80%), pack (drums or IBCs with safety closures), the dosing point and the oxygen target. Certificates of analysis accompany each lot. For low-pressure boilers where dissolved solids are not a constraint, ask about catalysed sodium sulphite as the lower-hazard alternative.