ARMOHIB 28
Armohib 28 Hydrochloric Hydrochloric-Hydrofluoric acid mixtures
Armohib aliphatic nitrogen inhibitors retard the corrosive effect of acids on metals during pickling, process equipment cleaning and oil well acid.
Armohib 28 is a mixture of water soluble amine derivatives.
Armohib® are aliphatic amines that inhibit the corrosive effect of acids on metals during acid cleaning, pickling, and oil well acidizing operations.
Specifications
Typical Data
Typical Data are based on our own measurements or derived from the literature.
They do not constitute part of the delivery specification.
Parameter Limits Method
Performance test (corrison inhibition): Passed PM/4.002
Chemical and Physical Data Typical Value
Appearance: brown liquid at 25°C
Boiling point: 100°C
Cloud Point: -5°C
Density: 1024 kg/m³ at 15°C
Flash point (Pensky Martens Closed Cup): 47°C
Pour point: < -10°C
Viscosity: 116 mPa s at 5°C
Solubility in water: soluble
Packaging / Storage Store Armohib 28 at max 30°C in well-ventilated inside store or shaded external store and not in direct sunlight.
Armohib 28 should always be homogenized before use, unless the entire quantity is used.
ARMOHIB CORROSION INHIBITORS
APPLICATIONS
Armohib aliphatic nitrogen inhibitors retard the corrosive effect of acids on metals during pickling, process equipment cleaning and oil well acidizing operations.
Armohib comes in two versions for use with specific acids:
PRODUCT ACID APPLICATIONS
Armohib CI-28
Hydrochloric
Hydrochloric-Hydrofluoric acid mixtures
Acid inhibitor for hydrochloric acid and hydrofluoric acid to inhibit the acid attack on a variety of metals including ferrous and copper.
Product Description
Armohib 28 is a corrosion inhibitor manufactured by AkzoNobel.
It is essentially comprised of a blend of Hydrochloric-Hydrofluoric acid mixtures.
Its physical state is of a liquid that appears to be amber in color.
Specific gravity (25°C) of Armohib 28 is about 0.925.
Advantages : Low-cost, dependable protection over a wide range of temperature.
Economical and effective: Only a small quantity of Armohib mixed with the acids will deliver the desired cleaning effect while retarding acid attack on metals.
Corrosion performance-tested: 0.25% Armohib 28 in 15% hydrochloric acid at 200°F must show less than 0.022 lb/ft2/day corrosion of mild steel.
There are three major applications for Armohib:
ACID PICKLING PLANT CLEANING OILWELL ACIDIZING
Hydrochloric acid is used for pickling very high carbon and alloy steels and for wire pickling.
Hydrochloric and hydrofluoric acid blends are used to clean ferritic, martensitic and austenitic steels.
Iron oxide scale is soluble in hydrochloric acid, and therefore there is no acid attack on the metal surface.
Hydrogen embrittlement is a major problem during the pickling of mild steel wire.
The addition of Armohib 28 to the hydrochloric acid eliminates or reduces embrittlement.
This embrittlement occurs when atomic hydrogen produced by the introduction of the acids, diffuses into the lattices of the metal and strains it.
This results in brittleness at the molecular level, with no advanced indications such as visible pitting.
The use of Armohib 28 as an inhibitor, in hydrochloric acid pickling of steel, has no adverse effect on the quality of the metal in subsequent hot dip galvanizing.
Tests conducted at an independent laboratory show that the use of Armohib 28 does not have any noticeable influence on the structure of the zinc, or the thickness of the zinc layer.
Armohib CI -28 optimized blend containing amine ethoxylates for acidic preparations especially hydrochloric acid
Armohib CI-31
Armohib 31 is a thiourea corrosion inhibitor that is used on metal equipment and surfaces that are acid cleaned to prevent the formation of rust.
Sulfuric
Sulfamic
Citric
Phosphoric
PHYSICAL PROPERTIES
Product Attributes
· Easy to Use
· Liquid Form
· Soluble in acid
· Non-staining
· Does not precipitate when standing
Advantages
Low-cost, dependable protection over a wide range of temperatures Economical and effective:
Only a small quantity of Armohib mixed with the acids will deliver the desired cleaning effect while retarding acid attack on metals.
Typical Data
Armohib
Corrosion performance-tested:
· 0.25% Armohib CI-28 in 15% hydrochloric acid at 200°F must show less than 0.022 lb/ft2/day corrosion of mild steel.
· 0.06% Armohib CI-31 in 15% sulfuric acid at 200°F must show less than 0.027 lb/ft2/day corrosion of mild steel.
APPLICATIONS
Following is a discussion on the three major application areas for the Armohib products:
· ACID PICKLING
· PLANT CLEANING
· OILWELL ACIDIZING
ACID PICKLING
Pickling is the removal of oxide scales formed during metal working operations by mineral acids.
Hydrochloric, phosphoric and sulfuric acids are commonly used.
These scales must be removed without undue acid attack on the base metal surface.
An inhibitor is therefore used to protect the cleaned surface, reduce acid wastage and metal loss and prevent pitting and discoloration of the metal.
Inhibitors protect weld areas and impede “burning” of the metal, even during a temporary shutdown of pickling operations.
These inhibitors form a foam blanket preventing heat loss and acid spray.
Amohib CI-28 uses: Hydrochloric acid is used for pickling very high carbon and alloy steels and for wire pickling.
Hydrochloric and hydrofluoric acid blends are used to clean ferritic, martensitic and austenitic steels.
Iron oxide scale is soluble in hydrochloric acid, and therefore there is no acid attack on the metal surface.
Hydrogen embrittlement is a major problem during the pickling of mild steel wire.
The addition of Armohib CI-28 to the hydrochloric acid eliminates or reduces embrittlement.
This embrittlement occurs when atomic hydrogen produced by the introduction of the acids, diffuses into the lattices of the metal and strains it.
This results in brittleness at the molecular level, with no advanced indications such as visible pitting.
The use of Armohib CI-28 as an inhibitor, in hydrochloric acid pickling of steel, has no adverse effect on the quality of the metal in subsequent hot dip galvanizing.
Tests conducted at an independent laboratory show that the use of Armohib CI-28 does not have any noticeable influence on the structure of the zinc, or the thickness of the zinc layer.
Armorhib CI-31 uses: Phosphoric acid is used in the surface preparation of structural steel to remove mill scale, rust and contaminants, prior to protective surface coating.
Phosphoric acid is of particular value in pickling operations where the scale film is thin, or if the film is a hydrate oxide of iron.
Sulfuric acid is used extensively in metal cleaning because of its low cost.
In the absence of inhibitor, up to 80% of the acid may be wasted in dissolving metal under the scale
Steels that are heated above 575°C produce a scale that consists of three layers:
magnetite, ferric oxide, and wurstite. This complicates the pickling process because the sulfuric acid solution and the liberated hydrogen gas, produced as a by-product of the interaction, penetrate the cracks in these layers.
The use of Armohib CI-31 as an inhibitor regulates these complex reactions and minimizes the amount of surface material that is dissolved.
Scale produced on steels heated at temperatures below 575°C consist of only two layers, magnetite and ferric oxide.
These oxide scales are normally very brittle, and as the metal cools they crack, due to the difference between their coefficients of expansion and that of the metal.
To increase the degree of cracking, the steel is sometimes flexed.
Again, Armohib CI-31 regulates the scale removal process to minimize brittleness.
PLANT CLEANING
Inhibited acids are used extensively in plant cleaning; both pre-commission and periodic planned service cleaning.
Many plants use acid cleaning, including breweries, dairies and sugar refineries, but the major use of acid cleaning is in power plants.
In all application, the use of a corrosion inhibitor is necessary to maximize the cleaning effect, while minimizing any unwanted corrosion.
Pre-commission cleaning removes welding slag, silica, rust, oil, grease and other matter from new boilers.
It is impossible to mechanically clean many inaccessible boiler parts once the final unit has been manufactured.
Therefore,an acid-flush is necessary to clean the tubes.
Any impurities left in the boiler can cause blockage of strainers and serious damage to turbine blades.
Boilers that have not been cleaned, prior to commissioning, can have up to ten percent loss of generating power.
Hydrochloric acid solutions are used in pre-commission cleaning.
However,citric acid is preferred for austenitic steels (e.g. superheaters), since it is thought that chloride ions might cause stress corrosion.
Where copper or copper alloys are present, citric acid solutions are also preferred.
Service cleaning serves to remove hard scales and deposits formed during steam generation.
These deposits reduce heat transfer from the boiler.
The absolute minimum attack of acid on metal must be ensured, and the type of scale encountered (high in carbonates) does not need attack on the base metal to aid its removal.
The purpose of the inhibitor is, if possible, to prevent any attack at all.
Acid cleaning is followed by neutralization and passivation processes, aimed at producing a thin protective layer of magnetite on the clean metal surfaces.
Hydrochloric acid is the acid most often used for plant cleaning, although sulfamic, sulfuric, citric and phosphoric acids are also used.
The appropriate Armohib CI-28 or CI-31 product will serve the corrosion inhibiting needs of any of the acid applications.
Armohib CI-28 is used to create efficiently inhibited hydrochloric solutions for hydrochloric applications for steels such as admiralty, carbon steels, cast iron, copper and its alloys such as monel, brass, bronze, cupro-nickel and chrome-molybdenum.
Sulfamic acid is often used as an alternative to hydrochloric acid.
While sulfamic is more expensive per pound, the quantity required for a given operation is considerably less, so that overall costs per application are lower.
Sulfamic acid, inhibited with Armohib CI-31, is used to clean deposits from 300 and 400 series stainless steels and occasional cleaning of aluminum and its alloys.
Sulfuric acid is also not as sensitive to contamination as hydrochloric acid.
Inhibited sulfuric acid is used for cleaning 300 and 400 series stainless steels.
OIL WELL ACIDIZING
In the fracturing and acidizing of compact oil formations, dilute hydrochloric acid is used to dissolve the undesirable carbonate deposits or scales, which interfere with the passage of oil, in tubing or in the formation itself.
The lines and tubing must be protected during this operation from corrosive attack by the acid, by the high temperatures and pressures, and by the potential for a “sour” environment resulting from the high hydrogen sulfide and carbon dioxide contents.
Armohib CI-28 used at a concentration of 0.25%,based on the total hydrochloric acid solution, is highly recommended for this purpose.
It provides effective protection at temperatures in excess of 230°F (110°C) for at least 6 hours.
AMOUNT OF INHIBITOR NEEDED TO ACHIEVE USE CONCENTRATIONS
Armohib corrosion inhibitors may be added to either dilute or concentrated acid solutions.
Never dilute the Armohib concentrates with water, as they will separate.
Dilute Acid Solutions: To obtain the inhibitor concentrations listed, add approximately the indicated amounts of inhibitor to each 100 gallons of dilute acid solution.
Concentrated Acid Solutions: Armohib corrosion inhibitors can be used to prepare inhibited concentrates, which may be diluted with water to the desired concentration at the point of use.
The conversion table presented below indicates the amounts of inhibitor to be added to 100 gallons concentrated acid to achieve a final concentration in a specific percent diluted acid solution.
For example: To obtain a 15% acid solution containing 0.03% Armohib CI-31, add 30 fluid ounces of the inhibitor to each 100 gallons of the concentrated acid.
At the time of use, 15 gallons of this inhibited concentrate can be added to 85 gallons of water, to obtain the 15% inhibited acid.