CLEANING PROCEDURE FOR OXYGEN SERVICE COMPONENTS ACCORDING TO THE ASTM G93 NORM.
1. - Goal:
1.1. - This specification sets the sequence to follow in order to guarantee the cleanliness level of the valve components to be used in oxygen service as well as their preparation for packing and shipment.
2. - References:
2.1. - Engineering specification .
2.2. - Cleaning Methods and cleanliness level for material and equipment used in oxygen-enriched environments. ASTM G 93 -03.
3. – Definitions:
3.1. - Cleanliness. - The degree in which an oxygen service system is free of contaminant agents.
3.2. - Contaminant. - Unwanted particulate or molecular that may negatively affect the operation, reliability o service life of the systems and equipments in which it resides.
3.3. - Contamination. - The amount of molecular or particulate matter present in the system and/or the process of getting contaminated.
3.4. - Oxygen service. - Service in contact with an oxygen enriched atmosphere during normal operation.
3.5. - Qualified technical personnel .- Individuals such as technicians, engineers and chemist that by jeans of experience, training or formation know how to apply physical and chemical phenomenon involved in the reactions between oxidants and metals.
3.6. - Brushing cleaning.- As used in this document is the action of cleaning metallic surfaces by mechanical action using brushes of the same kina of metal of the surfaces to be cleaned.
3.7. - Cleaning by discharge of abrasive materials (sandblast). - As used in this document is the action of propelling abrasive particles using compressed air in the direction of the surfaces to be cleaned.
3.8. - Abrasive. - High quality sand or aluminium dioxide meant to be used in sandblasting cleaning.
3.9. - Cleaning Method. – Series of steps put in motion in order to set a surface to be cleaned in contact with cleaning agents aiming to remove contaminants.
4. – Equipments:
4.1. - Sandblasting cleaning equipment with compressor, moisture separator and suction container.
4.2. - Standard air gun
4.3. - Compressor with 70 to 100 psi air discharge
4.4. - Metallic Brush.
4.5. - High pressure hydro cleaning machine.
4.6. - UV light Lamp.
5. – Application Conditions:
5.1. – The cleaning process can’t take place in environments with presence of organic contaminants.
5.2. – Personnel must wear protective equipment that also guarantees a contamination free environment at all time.
6. - Procedure.
6.1. – The valve components machining follows the common set of steps.
6.1.1. – Prior to assembly every casting component (body, cover, bonnet, wedge, etc.) must pass a sandblasting stage; machined surfaces must be covered with gray tape or another suitable material in order to protect the finish.
6.1.2. – Personnel involved in the sandblasting cleaning process must wear protective equipment such as boots, gloves, breathing equipment unless the cleaning takes place within a container.
6.1.3. – The immediate health hazard is the free abrasive particles indenting or incrustation, the long term hazard may appear as breathing disorders due to the inhaling of fine particles. Wearing the above mentioned equipment rules out the possibility.
6.1.4. – Prior to assembling, wash the valve components once again using common water. From this point on the use of cloth or organic material near to the parts is prohibited.
6.2. – First cleaning process (common cleaning).-
6.2.1. – Cleaning procedure before assembling is the company’s standard one antes with the following modifications:
a) Water using in testing must be clean, mud and oil free (it may be tap water).
b) For valves with extension piping for oxygen intake the flanges must be protected with covers.
c) The pallets where the valves are being handled should be made of aluminium or have an aluminium or clean neoprene cover previously washed to avoid contamination by grease, oil or organic materials such as Wood, cotton, etc.
d) Test should always take place in the lab if possible.
e) The air to be used should have a filter in the outlet to prevent the interior of the valve getting contaminated.
f) The usage of cloth to dry the valves is prohibited. If possible dry air at a pressure between 80 and 90 psi should be used.
6.2.2. – Effectuate hydrostatic test as specified in
6.2.3. – Once the valve has satisfactorily passed the tests, it will be submitted to the oxygen cleaning service process.
6.3. - Oxygen service cleaning.-
6.3.1. – The cleaning for material to be used in oxygen service will start by disassembling to component level (ASTM G 93 6.2.1. and 6.2.2. NORM)
6.3.2. – Equipment meant to be used in oxygen service must be handled with care during every stage of the cleaning procedure; the environment must be clean and dust free. Grinding, welding and finishing operations in the vicinity of the process must be halted. Once cleaned the parts must not be exposed to an environment with the presence of organic contaminants. Care must be taken to avoid the contamination caused by oil deposits of rotating machinery or aerosol oils in the air. The surfaces that are going to be in direct contact with the oxygen must not be touched unless gloves or handling devices are.
6.3.3. – The personnel involved in the cleaning process must wear special suits, latex gloves, boots and plastic caps at all times to avoid contaminating the components.
6.3.4. – The valve should be disassembled taking care to avoid damaging the components. All the equipment used in this stage such as test caps, hand tools, etc, must also be cleaned.
6.3.5.-The main components (the ones with enough weight to stand the water leaning without suffering damage or properties lost will be submitted to a process of hydro-cleaning with high pressure hot water, using the Karcher HDS 690 machine for this.
6.3.6. – Personnel must no aim the water discharge at other members of the team and must wear protective equipment during the process.
6.3.7. - During the cleaning process using water diluted BG industrial cleaner will be usedin order to obliterate the remaining traces of grease, oil or organic components. The higher the pressure the water stream has the lower the concentration levels of the BG industrial cleaner should be. Next examples of the water pressure dilution ratio:
Pressure Water Temperature Dilution
150 – 300 psi Cold
38ºC – 55ºC 1 – 100
500 – 800 psi Cold 1 – 100
38ºC – 55ºC 1 – 250
1000 psi Cold 1 – 200
38ºC – 55ºC 1 – 400
6.3.7. - The pallets or surfaces where the valves are being handled should be made of aluminium or have an aluminum or clean neoprene cover previously washed with the BG industrial cleaner
6.3.8. - Once the cleaning of the main components of the valve using the high pressure washer is finished, these pieces will be submitted to a final rinsing process, using a water tank (a plastic one) placed in the vicinity of the lab (a 500 litter deposit cut in half is suggested) at a 10% dilution level with water (10 % BG cleaner; 90 % Clean water), If the size makes impossible to submerge the pieces in the container the time of the water cleaning process should.
6.3.9. – The container must be filled with a dilution of 10% of the BG cleaner a mentioned above and the main components as well as the rest of the parts of the valves (nuts, studs, packings, test caps, hand tools, etc) must be cleaned by immersion using stainless steel brushes or plastic ones previously cleaned using the BG cleaner.
6.3.10. – Components susceptible to being damaged like the packing may be cleaned by submerging them in the solution and applying moderate shaking.
6.3.11. – After the cleaning the pieces should be left to dry in a contamination free environment, the use of cloth or organic contaminant containing materials is prohibited. It’s also recommendable to avoid using the air of the compressor since this is usually contaminated with greases or light oils.
6.4. - Visual Inspection.-
6.4.1. – In order to certify that the components are free of contamination by greases, oil or organic materials a visual inspection using ultraviolet light. This test must take place in a completely dark environment, that is why it’s recommended that the metrology lab is used and that an UV Light lamp is employed in order to effectuate a direct visual inspection (Type 1 test 2 from ASTM G 93 norm), this test in total darkness causes most but not all of the organic greases and oil to acquire a fluorescence when they could have avoided detection at plain sight. The surface is observed in reduced light conditions or total darkness using a: wavelength λ between 250 and 370 nm and an intensity of 800 .
6.4.2. – The acceptance criteria is as follows; all the surfaces ot the pieces both internal and external must be watched and free on contaminants as grease, oil or organic materials. The presence of said materials is detected when fluorescent particles appear when they are under an UV Light beam, if this happens the cleaning process must be repeated as many times as needed in order to assure the absence of contaminants. The pieces are considered acceptable when their inspected surfaces are 98 % free of fluorescent particles
NOTE: Ultraviolet light may show fluorescence even when there is no contamination, if this happens. Clean the area one more time and inspect using UV light again, if fluorescence persist it must be assumed this as a false positive and ignored.
6.5. – Final assembly.
6.5.1. – If the result of the inspection is satisfactory , the valve is assemble again, the personnel involved must wear:
- Latex Gloves
- Plastic caps
- Overalls that prevent contamination
- Plastic boots
6.5.2. – Once that the valve is assembled, it must be submitted to the hydrostatic and pneumatic tests again (in the lab if possible) following the specifications of the engineering department.
It’s important to note that EACH and EVERY piece of equipment used in the assembly process including test caps, tools, connectors, etc, must by washed using the BG cleaner.
6.5.3. – Once the valve has approved the pneumatic and hydrostatic tests, it must be left to dry until there is certainty that there is not residual moisture.
6.6. - Packing.
6.6.1. – The aforementioned protective equipment must be worn at all times. For packing identification plates (previously washed with the BG industrial cleaner) are attached to the valve; then a plastic tube (previously washed with the BG industrial cleaner) is located in the interior of the valve to avoid the wedge moving during transportation, then affix the PTFE protective cover in the flanges followed by the aluminium covers, attaching them to the body using stainless steel or plastic nuts and (previously washed with the BG industrial cleaner)
6.6.2.- Affix a tag of 3.0 mm X 1.0 mm X 0.025 mm or 0.1181 in X 0.0394 in X 0,9843 in made of SS-304 stainless steel using a stainless steel wire of 0.045” (previously washed with the BG industrial cleaner) tied to one of the nuts of the valve with the following legend:
“CLEANED FOR OXIGEN SERVICE”
6.6.3. - Using chains (previously washed with the BG industrial cleaner) lift the valve and place it in a thick plastic bag (previously washed with the BG industrial cleaner), seal the bag with gray or duck tape to prevent contamination entering the bag. On top of the plastic bag place a paper label with the following legend:
“CLEANED FOR OXIGEN SERVICE”
6.6.4. – Using the chains place the valve inside its box which has its interiors previously covered with thick plastic; place some bags of moisture traps to avoid an excess of moisture during transportation. Close the box and label the four sides with the following legends: According to ASTM G93 Norm:
“CLEANED FOR OXIGEN SERVICE
“”
“DESCRIPTION OF THE VALVE”
“THIS PRODUCT WAS CLEANED ON DATE yy/mm/dd”
“RESPONSIBLE FOR CLEANING SERVICE: ”
“CLEANNED IN ACCORDANCE WITH ASTM G93”
“VERIFICATION TYPE II”
“TEST 1 TRHOUGH 4”
“TEST 1, LEVEL 1”
6.6.5. – Place another tag:
“DO NOT OPEN UNTIL READY FOR INSTALLATION”
7. - Identification and certification:
7.1. – For the valves meant to be used in oxygen service, the company’s test certificate must have the following:
7.1.1. - Valve cleaned for oxygen service in accordance with ASTM G93.
7.1.2. – Valve description.
7.1.3. – Date of the cleaning.
7.1.4. – Cleaning responsible: “”
7.1.5. – Type I Verification
7.1.6. – Tests 1 trough 4.
7.1.7. - Test 1 level 1.
8.- Equipment.
8.1.- Hydro-wash machine type
8.2.- Ultraviolet Lamp
8.3.- Liquid for cleaning components for Oxygen service (BG).
Developed by: Approved by:
