food grade product line by Water Services Ltd

WSB SFA

Use

WSB SFA filming amine is used to control corrosion caused by carbon dioxide and oxygen in the afterboiler section of steam generating systems by forming a non-wettable, monomolecular film on metal surfaces.

Features

WSB SFA is a stable water emulsion of a filming amine.

Appearance : white, homogeneous liquid

Density (kg/m3) : 980

pH (5% solution) : 5.5

Freezing point : 0°C

 hese data are to be seen as typical values and are not to be considered as specifications.

Feeding

As a general rule, a starting dosage of 4 to 8 ppm is applied. Taking into consideration what

is discussed below, the dosage is increased by 2 ppm every two weeks or longer if necessary

until 10 to 15 ppm is applied. The dosage of WSB SFA is adjusted to hold the general corrosion rate and pitting to a minimum.

WSB SFA may loosen old corrosion products which will be transported with the steam and condensate. In these cases, a low starting dosage of WSB SFA is applied and then the dosage is gradually increased in order to slowly remove old corrosion products.

WSB SFA is prepared as a 5% or less dispersion using condensate. WSB SFA should be fed to the main steam header through a stainless steel nozzle or to the feedwater line near the boiler or directly to the boiler.

Handling precautions

Wear suitable protective gloves and safety goggles. In case of contact immediately flush with plenty of water. After eye contact seek medical advice. Small spill can be flushed with water. Large spills should be collected for disposal. Before use review the Material Safety Data Sheet for additional information.

Transport classifications

A.D.R. : not classified

IMDG : not classified

U.N.nr. : not classified

Labeling for handling

Symbol : not regulated

R-phrases : none

S-phrases : none

Packaging

WSB SFA is packed in 25 kg pail. and 200 Kg drum.
 

Hints

Because high velocities result in potential erosion of the film, a continuous feed is required to replenish the material on surfaces where it has been eroded. In addition, deposits destroy the protection afforded by such filming amines, and they do not protect well in areas where pitting has already occurred. The presence of dissolved solids degrades or precipitates traditional filming amines significantly and renders them ineffective in a condensate contaminated by carryover from the boiler or by leakage in the process (e.g., oil in refineries). In addition, use of filming amines should be avoided when organic contamination of the steam is common to prevent stripping of the amine film by solvent-type organics.

Ferric oxide also presents a potential problem because it can cause polymerization of the amine, the results of which, combined with degradation products formed in the condensate, can accelerate corrosion. Over-treatment, whether caused by overfeed, poor distribution, or high recycling with the returned condensate, aggravates these problems.

Because filming amines have an affinity for underlying metal, they may undercut iron oxide deposits causing rapid slough-off, often a deterrent to their use in older plants. Sloughed-off iron oxide deposits mix with the adsorbed amine, causing blockage of traps and valves in the condensate system and in the spray nozzles of the deaerator. Even a gradual increase of amine dosage is often ineffective because pH excursions can break down the films formed by such amines. Filming amines are most effectively used on uncorroded metal in systems where condensate return is not high. They are generally not recommended for use in systems with high condensate return, in which the degraded or polymerized amine that is returned can result in deposit formation.

Because filming amines are most effective when applied to uncorroded metal, their use is most desirable in newer systems. The problems created by applying them to previously corroded metal surfaces can be overcome by the accompanying use of volatile oxygen scavengers. By passivating the metal surface, the scavenger "prepares" it for the filming amine. Filming amine bonds to passivated magnetite surfaces are far more stable and effective than bonds to hematite.