Pickling & Passivation

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GBH Enterprises, Ltd.
Ammonia Plant Technology
Pre-Commissioning Best Practices
GBHE-APT-0102
PICKLING & PASSIVATION
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Information contained in this publication or as otherwise supplied to Users is
believed to be accurate and correct at time of going to press, and is given in
good faith, but it is for the User to satisfy itself of the suitability of the information
for its own particular purpose. GBHE gives no warranty as to the fitness of this
information for any particular purpose and any implied warranty or condition
(statutory or otherwise) is excluded except to the extent that exclusion is
prevented by law. GBHE accepts no liability resulting from reliance on this
information. Freedom under Patent, Copyright and Designs cannot be assumed.

Ammonia Plant Technology
Pre-Commissioning Best Practices: PICKLING & PASSIVATION
CONTENTS
1 PURPOSE OF THE WORK
2 CHEMICAL CONCEPT
3 TECHNICAL CONCEPT
4 WASTES & SAFETY CONCEPT
5 TARGET RESULTS
6 THE GENERAL CLEANING SEQUENCE MANAGEMENT
6.6.1 Pre-cleaning or “Physical Cleaning
6.6.2 Pre-rinsing
6.6.3 Chemical Cleaning
6.6.4 Critical Factors in Cleaning Success
6.6.5 Rinsing
6.6.6 Inspection and Re-Cleaning, if Necessary
7 Systems to be treated by Pickling/Passivation

0 INTRODUCTION
This Process Engineering guide covers Best Practices in Ammonia Plant -
Pre-commissioning; PICKLING & PASSIVATION and shall apply to all GBH
Enterprises (GBHE) process engineers worldwide.
1.0 PURPOSE OF THE WORK
o To remove scale, iron oxides and deposits.
o To manage a passivation of all tubes and metallic surfaces.
Pickling/passivation procedures which are incorporated in welding procedures
are not part of this subject.
2.0 CHEMICAL CONCEPT
The chemical cleaning should include the following steps:
• Degreasing by circulating a fresh water solution of about 0.1% wetting
agent, 1.5% sodium carbonate, 1.5% sodium metasilicate and 1.5%
trisodium phosphate for about 4 hours under temperature up to 60
degrees Celsius or at about 12 hours at ambient temperature, subject
of the deposits’ chemical analysis results.
• Draining & Forwarding the wastes into a specified slops tank.
• Acid Cleaning by circulating a fresh water solution of about 3% citric
acid , about 0.5% ammonium bifluoride and 0.15% proper inhibitor at
about 12 hours under temperature up to 60 degrees Celsius or of a
10% stronger solution at about 24 hours at ambient temperature,
subject of the deposits’ chemical analysis results.
• Neutralization & Passivation by circulating a fresh water solution of 0.5-
1.0% ammonia, followed by circulating of a 0.5% sodium nitrite water
solution for about 2-8 hours, subject of the deposits’ chemical analysis
results.

3.0 TECHNICAL CONCEPT
The cleaning fluids should be forced in circulation preferable for safety
reasons with plastic, air driven, chemical resistant pumps, reinforced
polyester tanks and proper plastic hoses. For Boilers two separate
cleaning circuits and solutions (1 for the main boiler and 1 for the
superheater ) should be applied in order to avoid the transportation of
sludges from the main boiler into the superheater.
4 WASTES & SAFETY CONCEPT
• Transportation of all cleaning wastes to a specified slops tank should
be effected by pumping the wastes through the chemical tank and the
chemical resistant pump.
• The pumping out facilities should be fixed before starting the cleaning
process in order to be stand by in case of emergency.
• During the cleaning process a specialized in the field qualified
Chemical Engineer should be present in order to monitor the whole
process and to ensure the safe application of the chemicals and the
safe forwarding of the produced wastes.
5.0 TARGET RESULTS
On completion of the chemical cleaning process, all the surfaces of tubes,
drums and headers should be in a 100% clean process, free of sludges,
foreign materials, scale, grease and oxides deposits.
Under the washed surfaces a grey up to black magnetite color should be
appeared.
6.0 THE GENERAL CLEANING SEQUENCE MANAGEMENT
a. Preparing the Area, Equipment and Personnel for Cleaning
b. Pre-cleaning or “physical cleaning”
c. Pre-rinsing
d. Chemical cleaning. Critical Factors in Cleaning Success
f. Rinsing

g. Inspection and re-cleaning, if necessary Preparing the Area,
Equipment and Personnel for Cleaning
Proper preparation is necessary to ensure the safety of your employees
and the effectiveness of the cleaning. To ensure safety, all electric
equipment to be manually cleaned should be disconnected from the power
source. Some equipment may be rinsed and spray-cleaned when it is
running. In this case, workers should be trained to keep their hands away
from moving parts that may cause injury. Motors, switches, and other
electrical components may require covering; consult the equipment
manual or manufacturer if unsure.
A piece of equipment may require disassembly for safety reasons before
cleaning. Disassembly also enables cleaning to be more effective by
improving accessibility and the employee’s ability to see the surface to be
cleaned. It is a common practice to put disassembled equipment parts on
a table or rack, or in a tub, for cleaning.
The plant environment during cleaning can be hazardous to employees
unless proper precautions are taken. Slippery floors, high pressure hot
water hoses, and cleaning chemicals can all be dangerous. Workers
should dress appropriately for the task of cleaning. Boots with non-skid
soles, waterproof aprons and gloves are commonly worn. Ideally, pants
should not be tucked into boots because doing so makes it much easier to
accidentally pour hot water or a chemical solution into the boot. The label
on each container of cleaning chemical should list any special precautions
that should be taken when using that chemical. In addition, there should
be a Material Safety Data Sheet (MSDS) available for each chemical in
use. By law, signs must be posted that inform employees of the MSDS
location.
6.6.1 Pre-cleaning or “Physical Cleaning:
The purpose of this step is to remove large pieces of debris so that later
use of water and chemicals is more efficient. Pre-cleaning may involve
picking up packaging debris, scraping equipment surfaces, and sweeping
or squeegeeing the floor. The importance of this step is sometimes
overlooked. If done properly, it will save you money by reducing water and
chemical costs. Some processors combine pre-cleaning with the next
step, pre- rinsing.

6.6.2 Pre-rinsing:
In this step, the surfaces to be cleaned are rinsed with water. Just as in
physical cleaning, pre-rinsing removes some debris and reduces the need
for chemicals. Generally speaking, the pre-rinse will be more effective if
warm or hot water is used because the solubility of many components of
the debris is greater at higher temperatures. If excessively hot water is
used, there is a risk of “cooking on” the small amounts of protein.
Experience and monitoring will guide your choice of water temperature.
Once the best temperature is determined, monitoring should be done to
ensure that this temperature is actually used. However, microbial biofilms
and/or mineral deposits may remain on equipment. The later step of
chemical cleaning should not be skipped without conclusive supporting
evidence that it is unnecessary.
6.6.3 Chemical Cleaning:
Cleaning chemicals are intended to lift debris from the equipment surface
and keep it suspended in water so that it can be rinsed away. No single
cleaning chemical does this effectively under 0 conditions. Instead, we use
mixtures that may contain several different chemicals to ensure that the
job is done well under normal plant conditions.
1) Water – The cornerstone of chemical cleaning is water. Water used
in cleaning should be potable, and low in suspended matter and
impurities that might affect odor and taste. Ideally, the water should
be low in hardness minerals. Hard water inhibits the ability of some
cleaning compounds to suspend debris and can result in mineral
deposits on equipment surfaces.
2) Surface Active Agent (Surfactant) – The major ingredient in most
mixtures is a surfactant. Its function is to suspend debris
components that normally do not stay suspended in water. Of the
three types of surfactants, anionic, non-ionic, and cationic, the
anionic surfactants are most commonly used.

3) Acid or Alkali – One or more compounds will be included to adjust
the pH (degree of acidity or alkalinity) of the cleaning solution.
Alkaline cleaners are recommended for high- fat debris, particularly
when this debris has been heated. Chlorinated alkaline cleaners
are used for removing many different types of debris and work
especially well against high- protein debris. Acidic cleaners are very
useful for removing mineral deposits. In the apple from the apples
and soil can support microbial growth over time cider processing
plant, a chlorinated alkaline cleaner is commonly used. An acidic
cleaner may be periodically useful if mineral deposits develop.
Phosphoric acid and gluconic acid are two acids commonly used
for this purpose.
4) Chlorine Compounds – Chlorine-containing compounds are
sometimes included in an alkaline cleaning mixture. In this
application, the chlorine is intended to react with protein in the
residue, with little chlorine remaining to kill micro-organisms.
5) Water Softeners – Some cleaning mixtures will contain
components, called either water softeners or chelators, that
chemically bind water hardness minerals. Examples of chelators
include certain polyphosphates, gluconates, and EDTA
(ethylenediamine tetra- acetic acid).
6.6.4 Critical Factors in Cleaning Success
a. Temperature of cleaning mixture
In general, warmer temperatures result in more effective cleaning. Avoid
excessively high temperatures that cook debris onto the surface. Regular
monitoring of the cleaning mixture temperature and adjusting it as
necessary will help you clean more consistently and effectively.
b. Concentration of cleaning mixture
When adding cleaning mixtures to water for use, always follow the
manufacturer’s directions. Increasing the concentration will usually not
proportionally increase the effectiveness of cleaning. The directions are
written so that typical amounts of debris can be easily removed. Amateur
chemistry experiments with cleaning chemicals are absolutely prohibited.

Combining mixtures can result in neutralization of components and loss of
cleaning ability, e.g. adding an acid mix to an alkaline mix. Mixing
chemicals can also create toxic compounds, e.g. mixing acid and sodium
hypochlorite resulting in the release of chlorine gas
c. Force associated with application
The force is in the turbulent flow of the cleaning mixture resulting from the
pump force or acceleration due to gravity as the liquid runs down
equipment sides.
d. Contact Time
Generally speaking, a longer contact time is needed if little force is used in
applying the cleaning chemical mixture. For example, foam and gel
cleaning applications require a longer contact time than a high pressure
spray application.
6.6.5 Rinsing
Once chemical cleaning is done, the cleaning mixture and suspended
debris are removed by rinsing. Rinsing should be thorough and is typically
done with warm water to prevent debris from being re-deposited. As with
the pre-rinse step, this rinse should be done from the top to the bottom of
a given piece of equipment. An easy and rapid way to check if your rinsing
is thorough is to touch a piece of pH paper to a freshly rinsed surface. If
the color of the pH paper indicates that the pH is dramatically different
from the pH of the rinse water, then there are either residues or cleaning
chemicals remaining on the surface.
6.6.6 Inspection and Re-Cleaning, if Necessary
This step is sometimes forgotten as employees look forward to the end of
the working day. All cleaned surfaces should be visually inspected to be
sure that proper cleaning took place. If residues are still visible, then
cleaning must be re-done. Off-odors indicate a serious cleaning problem,
because odors only become detectable when very large numbers of
microbes are present.

7.0 Systems to be treated by Pickling/Passivation.
1. Steam Boilers
2. All Steam Systems used as live steam or induction steam for
turbines as
 (SLL 1) Induction Steam for CO2 compressor turbine
 (SL 22) Induction Steam for Process Air Compressor turbine
 (SM 21) Live Steam for turbines of the following equipment.
• Sea Water Pumps
• Sea Water Circ. Pumps
• CO2 Compressor
• Process Air Compressor
• Natural Gas Compressor
• HP-Boiler Feed Water Pumps
• Semi Solution Pump
• Semi Lean Solution Pump
• Combustion Air Fan
• Flue Gas Fan
• Closed Loop Circ. Pump
• Critical Loop Circ. Pump
 (SSH 21) Live Steam for Syngas Compressor and Refrigeration
Compressor Turbines
SM 21 and SSH 21 pipe work have to treated completely. Branch lines as
connections to steam traps or users others than turbines are not part of the
pickling and passivation circuits.
All pipe sections to be treated in the SL 22 and SLL 1 steam systems have to be
selected in accordance with the Turbine Manufacturer.
Pickling/Passivation of the steam systems do not eliminate further cleaning
by steam blowing.

Pickling & Passivation

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