Compressed Gas Association, Inc. CGA G-4.1 2004 "Cleaning Equipment for Oxygen Service" Fifth Edition.
The parts shall be inspected for foreign particles and cleaned accordingly. Harmful contaminates include both organic and inorganic materials such as oils, greases, paper, fiber, rags, wood, coal dust, solvents, weld slag, rust, sand and dirt. All parts shall be cleaned using the following procedures.
Small parts shall be cleaned in an ultra-sonic cleaner when possible for 20-30 minutes using hot water, approximately 120 degrees to 140 degrees F, and an approved caustic detergent. Parts shall then be rinsed with hot water 120 degrees to 140 degrees F. Final rinse shall be made with de-ionized water.
Larger parts, piping, tubing and large fittings will be pressure washed using hot water 120 degrees to 140 degrees F, and an approved caustic detergent. The parts shall then be pressure rinsed with hot water, 120 degrees to 140 degrees F. Final rinse shall be made with de-ionized water.
Allow parts to air dry in a clean environment or Laminar Flow Station whenever possible. Parts may also be dried using heat or filtered Nitrogen as needed.
Small parts shall be immersed in perchloroethylene (PERC) and allowed to vapor dry. If a scrub or a wipe is used, use only a clean, lint free cloth.
Piping and tubing may be solvent cleaned by either wet swabbing with a clean, lint free cloth saturated with "PERC", followed with a dry swab to check for cleanliness, or pressure washing with "PERC" and drying with filtered Nitrogen or allowing part to vapor dry. A clean lint free swab may be used for inspection.
Large parts may be submerged in "PERC" or using a saturated clean, lint free cloth, wipe the total surface of the part.
The following procedure shall be used to determine cleanliness of the components.
Observe the part under intense white light. Most contaminates can be observed by this method, detecting larger particles of 50 microns or larger. For internal inspection, a clean, lint free swab may be used to wipe the surface. Any particle or smudge constitutes a re-work of the contaminated surface.
Observe the part under a black light (ultra - violet). The UV inspection lamp should be of adequate power (minimum of 50 watt), which causes most common hydrocarbon or organic oils to fluoresce. All oils do not fluoresce under UV light so a secondary inspection procedure may be used. If the part has been wiped with a cotton cloth, some fluoresce may be seen, it is advisable to remove this by using a filtered Nitrogen blow off.
This test is used to detect contaminants on visually inaccessible areas as an aid in the above visual inspections. The surface is rubbed lightly with a clean white paper or lint free cloth that is then examined under white and UV light. The area shall not be confused with actual surface contamination. The item being inspected shall be re-cleaned if an unacceptable amount of contaminants are found to be present.
This test may be used to detect oily residues not found by other means. The surface is sprayed with a fine mist of potable of water, which should form a thin layer and remain unbroken for at least 5 seconds. Beading of the water indicates contaminates and that re-cleaning is necessary.
Hydrocarbon or particulate matter determined by the tests above shall not exceed the amount specified by CGA G-4.1, or the purchaser. If the cleanliness requirements are specified by other means such as a specification supplied by a customer, then the inspection and test results shall not exceed the limits of the specification provided.
The following packaging process shall be used as follows:
Small parts shall be placed in a 4 mil or greater plastic bags and heat sealed, the parts shall then be placed inside another 4 mil or greater plastic bag and heat sealed to assure protection from outside sources.
Small parts may be bulk packaged at customer request. The required lot amount shall be placed inside a 4 mil or greater plastic and heat sealed, the parts shall then be placed inside another 4 mil or greater bag and heat sealed to assure protection from outside sources. Small parts shall be capped if required by customer.
Large parts shall have openings sealed with caps, plugs, or blind flanges where appropriate. Openings shall then be further protected by an appropriate 2nd seal to assure protection from outside sources.
All parts shall be labeled with the following information presented.
A Statement this equipment is "Cleaned for Oxygen Service Per CGA G-4.1.2004".
Date of inspection and the inspector's stamp or marking.
Description of the part, including part number if available.
A Statement "Do not open until ready to use. Do not store near oil, lubricants or other hydrocarbon material".
Warning of asphyxiation hazard if large vessel is purged with Nitrogen.
All cleaning operations for oxygen service equipment shall be carried out in a manner, which provides for the safety of all personnel performing the cleaning and the surrounding personnel shall conform to local, federal and state ordinances.
All personnel shall be trained and instructed in the safe use of the cleaning procedures and materials used in the cleaning process including the hazards associated with these materials.
No highly toxic chemicals shall be used. Carbon tetrachloride shall not be used in any cleaning operation.
Breathing of solvent fumes and liquid contact with the skin should be avoided. Material Safety Data Sheets (MSDS) for solvents shall be obtained from the manufacturer.
Therefore purging with air is not recommended, all purging shall be made with inert gas.
Special consideration should be given to the safe disposal of waste cleaning solutions and materials.
Face shields and/or goggles shall be used for face or eye protection from cleaning solutions. Protective clothing shall be worn for cleanliness and protection from chemicals.
All areas were cleaned operations are performed shall be adequately ventilated. If the operations are performed in an area where air flow is a factor the work will be performed on the positive side of the flow so the vapors are ventilated away from the operation.