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"Chemical cleaning of boilers"


Q. Is there an alternative to Rodine 31A for monophase citrosolve?

Vishal Sareen
- Australia
February 16, 2023

A. Hi Vishal. I don't know anything significant about inhibitors, but Louis Geuskens seems to have suggested Dodicor 25/65 from Clariant (Switzerland), and Mark Newsome did not name his company but claim they make a similar product in Yorkshire, UK.
Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

↓ Closely related postings, oldest first ↓

Q. Dear Sir,

Do you know what kind of Rodine inhibitor, with hydrofluoric acid I can use for chemical cleaning on steam boilers (mainly carbon steel)?

Maciej Filipek
- Opole, Poland

A. When cleaning boilers we use the Rodine 426 or Rodine 213 inhibitor. Depending on the acid utilized (the above is for HCl) we use it at a concentration of 2 gallons per concentrated HCl.

Respectfully yours,

George H. Bodman
chemical cleaning - Kingwood, Texas

A. In the past Rodine 240 was used as corrosion inhibitor for HF solutions, however I believe this chemical is no longer produced.

Rodine 31a can be used for this kind of chemical cleaning solution. There are alternative inhibitors that can be used.

Giuseppe Snichelotto
chemical cleaning services - Portici, Italy

Q. Dear Sir,

Do you know what kind of Rodine inhibitor, with hydrofluoric acid I can use for descaling of highly silica scaled chiller condenser (shell and tube type - copper tubes)? Please also suggest the dosage and time of circulation needed for this.

Thanks a million in advance.


Rajkumar Muthu
- Bangalore, Karnataka, India

A. Inhibitors for HF (Rodine 51) of Henkel can be used

Suresh Venkataraman
- Vadodara, Gujarat, India
October 29, 2011

"Boiler Failure Analysis"
by NALCO Water
from Abe Books

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Q. What kind of Rodine can be used to clean SS-316 with solution of HCl. We are planning to clean a heat exchanger made of SS-316, and I want to know what is the better corrosion inhibitor using mineral acids in combination with Rodine as cleaning solution.
Many thanks for your help.

Jose de Jesus Lopez
- Salamanca, Guanajuato, Mexico

A. To Jose de Jesus Lopez.
Dear Jose, never use HCl on SS.
HCl contains chloride and that is killing for SS.
We are using sulfamic acid for removing scale on SS and inhibited with Rodine 130.

Henk Visscher
- Barendrecht The Netherlands

A. No HCl on SS, To clean heat affected zones can use HF / Nitric formulation for cleaning heat effected zones for SS

Suresh Venkataraman [returning]
- Vadodara, Gujarat, India

Q. Can anybody tell me why during alkali boil of boiler we load the boiler up to half the working pressure?
Can anybody tell me what is the reaction of sodium dihydrogen phosphate and trisodium phosphate [affil link] with grease?

- India

Ed. note: Since 1989 we've strived to build a legacy of aloha & camaraderie incompatible with anonymity; everyone is welcome to read anonymously, but is asked to use their real name & town when posting :-)

A. Na3PO4.12H2O mostly used for new boilers.
At 160 °C pressure will be 7 bars. Circulation time about 48 hours after reaching temperature. Blow down half a gauge glass every 6 hours.In open space by 80 °C same procedure by external circulation pump. The chemical will give a strong emulsion. Rinse with good quality water.
Inhibitor 31A will not be suitable for HF.
Use Dodicor 25/65 from Clariant /Swiss.

Louis Geuskens
- Barendrecht, Holland

Q. A specialist company is cleaning our boiler after start-up. They have problems of precipitation of inhibitor Rodine 31a. They are using a mono-phase process with citric acid and sodium nitrite. Do you know something about similar problems?

Cartechini fabrizio
power generation - termoli, Italy

A. We would like to inform you that Henkel has been supplying a lot of customers from many years with Rodine 31 A for Industrial Cleaning field and this inhibitor never caused any kind of problems.

Piermario Anelli
- Caleppio di Settala, Italy

A. Rodine 31-A may "plate out" or precipitate if too much is used or if the solution is made too alkaline. Precise control is required if neutralizing an acid solution (in situ) containing Rodine 31-A.

Terry Wagner
- Portland, Oregon

A. Concerning the case presented by Mr. Cartechini about the problems involved with the use of Rodine 31 A, during the so called Citrosolv Monophase process the solution after the end of the acid phase is alkalized to proceed to passivation. Thus what most likely occurred is "the precipitation" as Terry Wagner assumed.

Giuseppe Snichelotto
worldwide chemical cleaning services - Portici, Italy

A. Regarding problem of Rodine 31A precipitation in citric acid formulation(s), please follow the instructions below.

The pH of the system must be brought below 5 or 6 prior to the addition of Rodine 85 or 31A to the system or you risk the "tarring" effect. If the inhibitor is added to an acidic pH, it should not tar out (precipitate). If initially added at a higher pH, it has the propensity of tarring out (precipitating).

Dennis Blom
- Manama, Bahrain
August 24, 2011

"Companion Guide to the ASME Boiler & Pressure Vessel Codes"
by K. R. Rao
from Abe Books

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Q. We have carried out cleaning of a titanium plate heat exchanger using a 8% solution of Sulphamic acid. We used Rodine 31a as the inhibitor and found that after a 20 circulation hour period the impeller of our cast iron failed having been heavily corroded. This was a brand new pump. Inspection of the heat exchanger showed no damage at all. The only corrosion was on our pump and pipe work. The inhibitor levels where checked throughout the work and found to be effective (tested with wire wool). Can anyone explain and / or suggest an alternative inhibitor.

Mark McSorley
chemical cleaning - Dammam, Saudi Arabia

A. Dear sirs,
the watering out of CI Pump may because of two reasons, the inhibitor inefficiency and secondly the Type of water used and the respective velocities. If the temperature was ambient then much of it can be from the velocity and the quality of water.
If water used was normal raw water then it would be from two other sources ( 1. velocity and the other Quality of acid where free sulfuric acid may play a role. )
Was any other additive added to this please let me know

Suresh Venkataraman [returning]
- Vadodara, Gujarat , India

A. As long time operator in the chemical cleaning field I always limited the use of sulphamic acid to very specific cases such as sea-water condensers, desalination units or any heat-exchanger heavily fouled by carbonates. As a matter of fact this acid can be considered in the family of mild acids. The kinetic of the attack on deposit is slower respect to other acids suitable for same type of deposits. A slower kinetic avoids uncontrolled and sudden development of CO2 with serious problems for personnel, operation and equipment. With regard to metals constituent the process equipments this acid is considered more friendly to most metals. This "mild behaviour" has gained to sulphamic acid a false reputation of could-be-used-even-without-inhibitor, therefore any kind of inhibitor, has been used to prevent his corrosive action. I personally consider this acid on the border line between the organic (Rodine 31A or similar products) and the inorganic (Rodine 213 or similar products) therefore any of the two products or similar could be used.
However I would advise to use this acid only in the initially mentioned cases, at lower concentration (2 - 3 % max) to maintain control of reaction and gas production, at medium temperature around 50 °C. Make-up of acid as for the analysis when acid concentration drops below 1 %. Duration of chemical cleaning 6 - 8 hours. Continuous monitoring of the chemical parameters and corrosion rate.

Concerning the corrosion of the pump and piping in a 20 hr operation I think it is normal. To my knowledge there is not any inhibitor that guarantees a filming effect at high velocity (normally above 1 m/s), the boundary layer gets thinner and doesn't guarantee protection. I guess in the pump as well as in the connecting piping velocity would have been higher than that.
In your cost estimate you have to consider to replace several parts of the pump every few chemical cleanings. The use of pumps made by better and costlier metals doesn't prevent you from this problem entirely. Good luck.

Giuseppe Snichelotto
chemical cleaning services - Portici, Italy

Q. I am a Chemist and working in a power industry in Pakistan. My understanding for boiler acid cleaning is to remove scales in three steps i.e. acid cleaning by HCl, followed by treatment with ammoniated citric acid (passivation) and then hydrazine boil-out. Keeping in mind steel alloy and not carbon steel I would like to correct the sequence of chemical reactions that would occur during the course of chemical reactions and mentioned below is the first step if you can provide all other reactions.

Thank you

Fe3O4 + 8 HCl = FeCl2 + 2 FeCl3 + 4H2O

Saleem Ahmed
Power Company - Karachi, Pakistan

Q. I would like to know some technical information about Rodine 60 and its chemical specification, also its producers all around the world.
Secondly, is there any more effective inhibitor (Rodine) to protect nickel or cobalt base material against intergranular corrosion during H2SO4 acid stripping.

repair of utility gas turbines - Karaj, Tehran, IRAN

A. In The UK this type of inhibitor is used widely for inhibiting HCl during many de-scaling operations - wire drawing, cleaning of steel prior to galvanising etc.

My company produces such a product which is added to the 28% HCl at a rate of 0.175% or in to 35% HCl at 0.22% irrespective of the dilution afterwards. The inhibitor does not affect the rate of oxide removal but slows considerably the attack on the underlying metal. I have in the past done comparisons of uninhibited and inhibited acid at room temp and at 70 °C with mild steel test coupons. Comparing uninhibited and inhibited acid cases the metal lost per m2 after one hour of exposure is :-

At room temp, 97% less
At 70 °C, 92% less.

I used 15% HCl for the above.

Mark Newsome
- Leeds, Yorkshire, UK

Q. I want to know the permissible limit of metal loss during boiler descaling. What kind of corrosion inhibitor to be used to minimize the chances of metal loss.


Q. How do you clean zinc, platinum and silica and sulphate scale of boiler.
Please answer.

Kerim Derin
chemical engineer - Istanbul, Turkey

Q. Dear sir
I'm using two small boilers (capacity 48 kg/hr and 72 kg/hr pressure 4 kg/cm2 150 c ) which is heated by internally mounted electrical heaters.I want to just clean the inside of the drum. Can anyone please suggest me a simple cleaning method. I know the boiler is too small ... but still can anyone help.

Research Executive - Chennai, India

Q. I want boiler chemical cleaning procedure for new boiler 420 t/h

Lubna Ahmed
employee - Sudan
December 2, 2008


February 20, 2009

A. Dear All Finishers,

For Cleaning a boiler I use Sulphamic acid with Rodine 31; after that we neutralized with TEA-EDTA salt (0,1 - 0,3%)

Best regards,

Nugraha Puspawardhana
- Indonesia

Boiler Descaling with Tetra-Ammonium EDTA

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A. Latest boiler chemical cleaning techniques is the use of inhibited EDTA ammoniated at around 140 °C and at a conc'n of around 4 - 5 % with oxygen scavengers. This has been successfully used in many of the new boilers erected.
We have performed this operation in more than 20 boilers up to 500 MW and have found it effective.

Suresh Venkataraman [returning]
- Baroda, Gujarat, India

Q. Dear Sir,

Do you know what kind of Rodine inhibitor, with Ammoniated EDTA for chemical cleaning on steam boilers (mainly carbon steel)?

Soosai Raj Peter
Chemical Cleaning - Jubail, Saudi Arabia
August 17, 2013

Q. I want to know the concentration of Rodine 213 I can use for acid cleaning MSFPLANT.
Is there any inhibitor better than Rodine 213 (Rodine 214, for example)
When can I use Rodine MT140 (POWDER) is this an inhibitor also or something else?

May 18, 2009

Q. Any idea what is the proper Rodine or equivalent inhibitor for chemical cleaning of boilers with TETRA-AMMONIUM EDTA?

Any information about the source of such inhibitor?

Thanks. Regards.

John Pitsilos
Chemical Cleaning Services - Athens, Greece
November 20, 2009

Q. We've a Steam Generator capacity of 6 ton/hr. Due to malfunctioning our boiler coil temperature got higher so we are thinking of coil inter chemical cleaning. Would you please suggest us about the chemical care and method of cleaning

Muhammad Ihsanul haq
- Hub, Pakistan
March 16, 2010

Q. Dear sir.
What is the relationship between pressure of boiler and deposit on the internal surface of the tube?
Is there any standard for this question?

hasan eghbaly
- tehran
October 19, 2010

Q. Hi everybody,

could you please advice me to clean a external fired boiler of 54 m3 volume,

the contamination details are attached here with.

Boiler (Waterside) Deposit Analysis Elemental analysis by X-ray Fluorescence
Appearance: Solid Color of Solids: Brown
The sample preparation was: Dried at 105 C Condition of Solids: Dry
The results are reported as oxides.
Phosphorus (P2O)
26 wt %
Magnesium (MgO) 19 wt %
Iron (Fe2O3) 17 wt %
Calcium (CaO) 6 wt % 6 wt %
Copper (CuO) 5 wt % 5 wt %
Sodium (Na2O) 5 wt % 5 wt %
Sulfur (SO3) 5 wt % 5 wt %
Nickel (NiO) 1 wt % 1 wt %

Boiler (Waterside) Deposit Analysis
Analysis by X-Ray Diffraction
The XRD was performed on: Dried at 105 C
Major Compounds Amorphous Material
Minor Compounds Iron Oxide (Magnetite) - Fe3O4
Trace Compounds Elemental Iron Fe
Calcium Magnesium Carbonate (Dolomite) - CaMgCO3
Basic Calcium Phosphate (Hydroxylapatite) -
Iron Oxide Hydroxide (Goethite) FeOOH
Iron Oxide (Hematite) - Fe2O3
Sodium Sulfite Hydrate - Na2SO3:7H2O

1 There are bulges in tube metal
2 The deposit (which Is about 200 mg/cm2)
3 Presence of trace substantial concentration of magnesium and calcium besides phosphorus
4 Presence of trace amount of dolomite (CaMgCO3)
5 The presence of sulfur @ 5% (when expressed as SO3)

Well, these are the analytical reports and observations that I made.

and the contamination seems to be very unique.

Could any body help me on this?

Arshad Azad
- jubail, Saudi Arabia
August 14, 2011

Q. How can I come to know that chemical cleaning of boiler is satisfactory completed?
Check by chemical test preferred.

Manoj Paneri
employee - Gujarat, India
October 15, 2011

Q. Ours is a 370 T/Hr 120 MW Power Boiler. During recent RLA studies, heavy oxide scaling up to 1250 Micro s is observed in the Final Super Heater coils. Chief Inspector of Boilers in AP suggested acid cleaning of Boiler inclusive of Super Heaters. Generally SH are not included in the Acid cleaning path. Please advice me accordingly, duly giving information regarding the procedure for acid cleaning of Boilers including Super Heaters.

P.V.V. Muralimohan
March 6, 2012

? Please specify the contents of alloying material of your super heater; the choice of solvent will depend on that. Please indicate the Mo / Cr content, etc.

Suresh Venkataraman [returning]
- Vadodara, Gujarat, India

Q. As part of a boiler retubing, the OEM recommended an acid flush of the supply lines to the boiler to remove any existing impurities. The acid flush consisted of addition of Rodine 31A to demineralized water in the system at 50 °C, then adding TritonX100. Shortly after the addition of these two chemicals, a significant amount of foaming was observed in the system causing significant level deviations in the expansion tank. Sag 10 antifoam was added to the system, which decreased the foaming and a 10% solution of phosphoric acid was added to the system to conduct the cleaning. Following the cleaning, inspection of the system revealed significant amounts of sticky, shellac-like brown and black coating throughout the system. Analysis indicated that this came from the Rodine 31A. The residue seems to clean up with isopropyl alcohol in areas we can reach, and we have been using hydrolazing up to 20 Kpsi to remove it from other areas, but are not able to reach all parts of the boiler. Is there a safe way to remove this residue throughout the system once it has formed, that will not affect tubing, or support systems?

Edward Elliott
Electric Utility - Cheyenne, Wyoming USA
September 27, 2012

thumbsdown In my steam boiler, the water is red in color. There are many suppliers of boiler treatment chemicals but nobody is ready to actually work at the boiler to find out the reason for this problem.

as above - YAMUNANAGR Haryana INDIA
January 24, 2013

Q. Hey.

We are a small cleaning company that will start cleaning the larger boilers, but we have problems with auto circulation how it should be done.

We know that the connections should be fitted to all down comers 1/3rd distance from bottom but which connections? Would be greatly appreciated if I could get a detailed explanation / calculation of execution, pressure and amount of nitrogen circulation of a boiler of 100 m3 at 40 m height. Superheater and Eco pumped forced circulation.

Thanks in advance!

Anders Sundstrom
- Goteborg Sweden
January 28, 2014

Q. My name is Elnazeer Musa, lab supervisor; my background is chemical engineer joined this company in 2011 in above position.

My Question: we have scale in pumps section; 6 units and this scale is CaCO3. After analysis we use HCl, and after one hour circulation use NaOH for alkali for pH stabilization. In addition to that we have boiler that has a cock inside tube we need to clean. Tell me what is the best way for cleaning and what inhibitor we should use in it.

Elnazeer Musa
- Juba - Equatotia state - S.Sudan
July 11, 2015

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