Water Technologies & Solutions fact sheet

Steamate* PAS6076

condensate corrosion inhibitor

Reduces condensate corrosion due to metal passivation
Reduces maintenance costs
Improves boiler system reliability
Reduces the levels of iron and copper in boiler feedwater
Controls oxygen corrosion, at low temperatures

description and use

Steamate PAS6076 is an aqueous blend of a volatile, organic oxygen scavenger, metal passivator and neutralising amines.

Steamate PAS6076 does not contribute inorganic solids to the boiler feedwater steam and condensate system.

Steamate PAS6076 is designed to control corrosion in condensate systems due to dissolved oxygen, carbonic acid and process contaminants.

problem description

Condensate corrosion is primarily caused by carbonic acid and oxygen. Steam containing carbon dioxide forms a weakly acidic solution “carbonic acid” when condensation occurs.

Feedwater alkalinity is the main source of carbon dioxide as bicarbonate and carbonate alkalinity breakdown at elevated temperatures as follows:

2NaHCO3 + heat  Na2CO3 + CO2 + H2O
Na2CO3 + H2O + heat  2NaOH + CO2

The first decomposition reaction proceeds to 100% completion whereas the second reaction proceeds to about 80% completion.

Oxygen can be present in the steam due to improper deaeration or air leakage into the system.

typical applications

Condensate treatment programmes generally include neutralising and/or filming amines. These programs reduce the amount of corrosion but do not achieve the two necessary effects required for efficient corrosion control that is effective passivation of the system metal and oxygen scavenging.

Steamate PAS6076 is unique since it functions both as an effective oxygen scavenger and metal passivator at temperatures typically encountered in condensate systems.

Since Steamate PAS6076 reacts to control pitting of the system metal, even at low temperatures, it protects condensate systems from oxygen corrosion both during operation and shutdowns. Once a protective iron oxide layer is formed, Steamate PAS6076 maintains it resulting in reduced corrosion. Significant inhibition of both iron and copper oxide corrosion is proven.

Improved condensate corrosion control reduces the quantity of iron and copper in returned condensate and reduces the potential for boiler tube failure and the need to dump condensate.

Steamate PAS6076 has been highly effective in condensate applications for boiler systems operating over a wide pressure range and in many cases with superheaters and turbines.

treatment and feeding requirements

Feed point – Steamate PAS6076 can be fed to the deaerator or boiler feedwater line. If required, it can

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E-FSbSteamatePAS6076_EN.docx Apr-11

also be high pressure dosed to condensate lines or receivers.

Feed rate – Steamate PAS6076 should be fed at a fixed feed rate of between 1 to 5 ppm based on steam flow. During start up the minimum feed rate should applied to minimise sloughage of any metallic oxide corrosion products.

Dilution – Steamate PAS6076 can be fed neat or diluted to any convenient feeding strength. For dilution use good quality condensate, demineralised water or deaerated feedwater to make a convenient feeding strength. Mild agitation should be provided for initial mixing only. Solutions of Steamate PAS6076 should have minimum exposure to atmospheric oxygen.

Equipment – Feed through a 316 stainless steel nozzle directly to the steam header or condensate line. Feed using hot rolled mild steel tanks with iron piping, fittings and shut-off valves. Relief valves, agitator shaft and propeller should be 316 stainless steel.

general properties

The physical properties of Steamate PAS6076 are shown on the Safety Data Sheet, a copy of which is available on request.

packaging information

Steamate PAS6076 is a liquid blend and is available in a wide variety of customised containers and delivery methods. Contact your local VEOLIA representative for details.