We are Manufacturer, Supplier, Exporter, Service provider of Passivation Chemicals, Algae Preventing Chemicals, Heat Exchangers, Oil Coolers, Nashik, Maharashtra, India.

What Is Scale

Technical Data

This is news to you, isn't it?

And all this while you have been sitting & burning the 'midnight oil' trying to figure out from all your financial statements and balance sheets, 'what is really eating into my profits ? The answer to your question is 'scales'. A hard water formation or incrustation that chokes plant and equipment, restraining them from functioning normally.

Fine, but you haven't heard of Scaleflow, Scaleclean - A, and Neutraflow.

about us

Scaleflow, Scaleclean - A, and Neutraflow is a revolutionary descaling agent. In other words, it is inhibited hydrochloric acid for general use in all types of chemical descaling operations. It removes water hardness scales, deposits from steam and hot water, mill scales, weld scales, moulding, foundry deposits and many other types of foreign residues on metals

Scaleflow, Scaleclean - A, and Neutraflow in addition to inhibitors, also incorporates wetting agents to assist the solvent action of the acids on the deposits to reduce 'drag out' losses, absorption of inhibitors by scale, rust and helps the solution to penetrate into inaccessible regions.

A scale is a hard water soluble substance formation or incrustation resulting from the general deposition of dissolved solids in water, over heat transferring metal surfaces.

The principal scale forming material, coolant water is calcium carbonate (CaCO3), a hard tenacious adherent baked scale. Other scale forming constituents are magnesium hydroxide, calcium sulphate and silica. Other types of scales which are formed on hot or cold worked metals consist of metallic oxides, sulphide and other components.

When heat is applied to water containing bicarbonate, the CO2 is expelled from Calcium compound. Since the relatively high solubility of Calcium bicarbonate is due to this gas, CaCO3 is precipitated rapidly as soon as the gas is removed. Removal of CO2 by chemical means the same results should be obtained & the precipitation of non-carbonate of calcium follows. As a result of this phenomenon calcium carbonate is precipitated within the boiler/equipment, forming a scale.

Also calcium sulphate, owing to its insolubility at high temperature, is precipitated rapidly. Unless it is converted into some other form by chemical treatment or removed from water as it is formed, it causes a hard, dense scale which adheres tenaciously to the internal metal surfaces of the boiler/equipment.

The problem of deposition of boiler / equipment scale is primarily one of the solubility at elevated temperature i.e. certain slightly soluble substances become less soluble with increase in temperature. The whole body of a boiler solution constantly tends towards a state of super saturation as steam is removed.

In addition, since scale forming substances decreases in solubility with increase in temperature, the film of boiler water adjacent to a heating surface may be relieved by spontaneous crystallization, possibly promoted by irregularities in the surfaces even when vaporisation is taking place.

The growth of deposits is accelerated by the effect of skin friction at the internal surface of the tubes, since the velocities along the tube wall are much smaller than those near the centre of the tube. Deposition of silicate scale might not otherwise develop in the presence of the minimal amount of siliceous materials in feed water.

The solubility of different salts in water is given below :

Salts Solubility as CaCO3 (ppm) At 320F At 2120F
CaCO3 (Water free from CO2) 15 13
Ca(HOC3)2 (Water saturated with CO2) 1620 Decomposes
CaSO4 1293 1246
CaCl2 366000 3430000
MgCO3 101 75
MgSO4 170000 356000
MgCl2 362000 Very Soluble
Na2CO3 62600 289000

Various types of deposits which are found in Boilers, Auxiliaries & miscellaneous plant equipments are given in table 1, Tables 2 & 3 provide analysis of typical scales. (These tables will be found at the back.)

"SCALECLEAN - A" is a liquid preparation with Hydrochloric Acid base, designed to dissolved industrial deposits without affecting metals. "Scaleclean - A" is supplied in fully inhibited and concentrated form and is to be diluted with water for use. In general, any type of equipment on which scale has been deposited, can be cleaned by using "Scaleclean - A".

"SCALFLOW" is specially developed for removal of hard scale like silicate of calcium, magnesium, sulphates, carbonates etc. "Scaleflow" is supplied in fully inhibited and concentrated form and is to be diluted with water for use.

"NEUTRAFLOW" is a liquid preparation with an alkaline base. The "Neutraflow" treatment has the effect of swelling up the scales through hydrolysis of the scale components. The result is that the subsequent "Scaleclean - A" of "Scaleflow" treatment becomes faster and proper.

Some of the operational difficulties caused by scale deposits are :
1. Obstruction of fluid flow
2. Impedance of heat transfer
3. Wear & tear of metal parts
4. Localization of corrosion attack
5. METAL failure at hot spots under scale deposits (plate)

Metal oxide scales (Mill scale, rust etc.) must be removed from metal surfaces before painting, galvanizing, tinplating and other principal metal-finishing processes.

Scaleflow, Scaleclean - A and Neutraflow uses HCL as principal agent.

Although many acids namely Sulphuric, Sulfamic, Citric, Hydrochloric can be used to remove scale, Hydrochloric Acid offers the following definite advantages over others :

•  Calcium Chloride, Iron Chloride etc. which are formed by reaction of scale are highly soluble with HCL in water.
•  The time taken for the solution of rust or scale is minimum, in HCL as compared to that required other acids.
•  The solution rate of mill scale is 10% to 27% higher in 10% & 5% HCL respectively than in similar solutions of H2SO4.
•  A dark slime or "smut" left on metal surface pickled in other acids is not present when HCL is used.
•  During pickling in HCL the scale is directly dissolved by the acid and the "mechanical effect" of removal of scale by hydrogen bubbles (formed by reaction    between metal and acid), is not required. Accordingly HCL can be inhibited with the strength inhibitors.
•  The degree of Hydrogenation and consequently Hydrogen embrittlement are absent when HCL is used.
•  No heating is required during cleaning with HCL as the acid dissolves the scale at normal temperature
•  The tolerated iron contents in pickling solution are higher when HCL is used.
•  The corrosive action of HCL on clothing and skin milder.

What Equipments Must Be Treated With Scaleflow, Scaleclean-A And Neutraflow ?

In general any type of metallic equipment on which scale has been deposited can be cleaned by Scaleflow, Scaleclean-A and Neutraflow. Typical examples of equipments are Boilers, Economizers, Super Heaters, De-aerators, Vents, Condensors, Stage Heaters, Heat Exchangers, Surface Condensors, Feed water treating equipments, valves, and miscellaneous equipments, piping, water mains, oil wells, equipment used for acidizing of oil wells (to improve yields of oil from oil bearing lime stone formations), air-conditioning equipment, canteen equipment, stabilizers, electric boilers, kettles, surgical instruments, immersion heaters, heating coils, sugar and caustic evaporators, black liquor evaporators in the pump industry, railway carriages and bus bodies, brewery equipments, steel strips and sections requiring pickling, cold drawings etc.

1st Stage : Take "NEUTRAFLOW" and mix with water in the ratio of 1:6 (One litre of NF and six litres of water). Circulate the solution or immerse the equipment in this solution for 2 hrs. This will be helpful in loosening the rock hard scale. This will also help to remove oil & grease from the surface.

2nd Stage : Flush the entire system with ample fresh water, at least for 15 to 20 minutes.

3rd Stage : "SCALEFLOW" and mix with water in the ratio of 1:6 (One litre of SF and six litres of water). Circulate the solution or immerse the equipment in this solution for 6-8 hrs.

4th Stage : Flush the entire system with ample fresh water, at least for 15 to 20 minutes.

5th Stage : Take "NEUTRAFLOW" and mix with water in the ratio of 1:6 (One litre of NF and six litres of water). Circulate the solution or immerse the equipment in this solution for 2 hrs.

6th Stage : Flush the entire system with ample fresh water, till the ph of inlet & outlet of fresh water matches.

The information contained in this technical bulletin is adequate for common descaling problems but in case further information is required please write to us giving details of equipments to be de - scaled and type of scale encountered.

Scaleflow, Scaleclean - A and Neutraflow is Marketed in 30 Ltrs. Contaliners


Principal Ion Common Name Mineralogical Name Formulae Determined by X - ray analysis
Calcium Calcium Magnesium Carbonate Dolomite CaCO3 MgCO3
- Calcium Carbonate Aragonite CaCO3
- Calcium Carbonate Calcite B CaCO3
- Calcium Sulphate Gypsum CaSO4 2 H2O
- Calcium Sulphate Anhydrite CaSO4
- Calcium Sulphate Hemi - hydrate CaSO4 5 H2O
- Calcium Hydroxide - CA(OH)2
- Calcium Phosphate Hydroxyapatit Ca 10 (OH)2 (PO4)3
- Calcium phosphate Whitlockite B Ca3P2O3
- Calcium Fluoride Fluorite CaF2
Magnesium Magnesium Hydroxide Brucite Mg (OH)2
- Magnesium Silicate Forsterite Mg2SiO4
Silicate Silicon Oxide opal SiO2nH2O
- Silicon Oxide Quartz SiO2
- Silicon Oxide Cristobalite SiO2
- Sodium-Iron-Silicate Acmite Na2Ofe2O3 4SiO2
- Sodium-Alumina-Silicate Analcite NaA1(SiO2)2 H2O
- Sodium-Alumina-Silicate Natrolite Na2A1 2 Si3 O10 2H2o
- Sodium-Alumina-Silicate Noselite Na4 A13 Si3 O12 SO4
- Sodium-Alumina-Silicate Pectolite Na2O.4CaO.6SiO2 H2O
- Sodium-Alumina-Silicate Wollastonite B-CaSiO3
- Calcium Silicate Xonotlite 5CaO SiO2 H2O
- Calcium-Alumina-Silicate Cancrinite 4 Na2O.CaO.4A1 2 O3
- - - 2 CO2.2SiO2.3H2O
- Magnesium Silicate Serpentine 3MgO.2SiO2.2H2O
- Iron Carbonate Siderite FeCO3
- Iron Oxide Ferrous oxide FeO
- Iron Oxide Hematite Fe2O3
- Iron Sulfided Triolite Fes
- Iron Oxide Magnetite Fe3O4
- Iron Oxide Geothite Fe2O3.H2O
- Copper Sulphide - CuS
- Copper Sulphite Chalcocite Cu2S
- Copper Carbonate Malachite CuCO3.Cu(OH)2
- Copper Iron Sulfide Cu FeS
- Copper Oxide Cuprite Cu2O
Sodium Sodium Sulfate Thenardite Na2SO4(V)
- Sodium – Carbonate-Sulfate Burkeite Na2CO3.2Na2SO4
- Sodium Chloride Halite NaCl
Ammonia Ammonium Bicarbonate Teschemacherite NH4HCO3
Barium Barium Carbonate Witherite BaCO3
- Barium Sulfate Barite BaSO4


Constituent Scale from Boiler 1 Scale from Boiler 2
Silica (SiO2) 2.12 3.24
Iron & aluminium oxide (Fe2O3AL2O3) 0.11 1.21
Calcium carbonate (CaCO3) 85.31 68.00
Calcium Hydroxide Ca (OH)2 1.26 0.98
Calcium Sulphate (CaSO4) 9.86 25.20
Magnesium Hydroxide (Mg (OH)2) 0.15 0.90
Undetermined 1.19 0.47
Total Total 100.00 100.00


Constituent Scale from front of boiler Scale from back of boiler
Silica (SiO2) 2.28 7.08
Iron & aluminium oxide (Fe2O3AL2O3) 2.00 5.52
Calcium Sulphate (CaSO4) 75.38 30.63
Calcium Carbonate (CaCO3) 13.28 41.55
Magnesium Hydroxide (Mg (OH)2) 6.09 10.64
Organic matter, etc. 0.97 4.58
Total 100.00 100.00