CLEANING OF EQUIPMENT FOR OXYGEN SERVICE - AIGA

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AIGA 012/04
4) Due to the harmful effects skin contact must be avoided by using nitrile gloves, apron and safety
glasses with side shields or facemask. Note that polyvinyl chloride (PVC) gloves are only suitable
for short periods of use.
5) Solvents shall only be carried using suitable closed containers.
6) Manufacturers of solvent cleaning plants and associated equipment, including ultrasonic methods,
issue recommendations on safe operation procedures. Operators shall comply with the
manufacturer's advice. Enclosed systems shall always be equipped with pressure relief devices
and a pressure gauge. Heating of solvents shall always be by indirect methods.
7) Aluminium and its alloys without the protective oxide film react vigorously with certain solvents to
produce acid vapour, which is both toxic and corrosive. This particularly occurs on particles of
aluminium such as swarf or grains from machining or cutting processes. When using solvents to
clean aluminium; the following should be observed:
- Use only clean solvent that contains the correct level of inhibitors for aluminium or light alloys.
- Components should be placed gently into the degreasing tank to avoid rupturing the
protective oxide film.
- Newly machined aluminium and aluminium alloy components should be retained in the
normal atmosphere in order to create an oxide film prior to being degreased.
- Ensure that the material being cleaned is free from particles such as swarf or dust.
- Solvents shall not be kept in contact with aluminium for extended periods. Alter cleaning
remove solvents as quickly as possible.
4.2.4 Detergent Cleaning
This method relates to the cleaning of plant components, vessels, piping systems etc., either
externally or internally.
Detergent cleaning is done in water solutions containing chemicals with different functions like dirt
solvency, dispersion, water softening, corrosion inhibition and wetting. It is normally performed in an
alkaline environment, the higher pH value, and the better the degreasing efficiency.
Detergents are supplied in solid or concentrated liquid form. They are prepared for use by mixing with
hot water to form aqueous solutions. Prepared solutions can be pumped, re-circulated or jetted onto
or through the component. They are well suited as cleaning agents in ultrasonic baths.
The degreasing strength of detergents is as good as that of the solvents.
Aqueous systems have few problems with worker safety compared to most other solvents. They are
not flammable or explosive and toxicity is low for most formulations.
The omission to water is the main environmental question to consider in aqueous cleaning.
Dependent on local regulations, type of contaminants and detergent, concentrations, pH etc., the
waste from water based detergent cleaning might be disposed of into the sewer for which a permit or
consent may be required.
4.2.4.1 Notes on Detergent Cleaning
a) Before use, ensure that detergent chemicals used are suitable as some non-metallic materials are
not compatible with the detergent chemicals or may absorb the fluid.
b) Advice should be sought and followed from the detergent manufacturer regarding solution
concentration, the materials it is suitable for, and safety precautions required
c) For details with narrow cavities, the cleaning stage should be of the immersion type, where all
parts of the contaminated details come in contact with the cleaning agent. Spray cleaning
machines like a normal dishwasher is therefore an unsuitable alternative.
d) Aqueous cleaners have higher surface tension compared to organic solvents and therefore
difficulty in penetrating into threads and narrow cavities. To get a good contact between cleaner
and contaminated details, some kind of mechanical energy should therefore be added. This
mechanical energy might be provided by air agitation, jet flushing or ultrasonic. Rotation may be
necessary to ensure elimination of air pockets.
e) Increased temperature improves the cleaning. The cleaning bath should therefore be equipped
with a heating device and temperature control.