TASK 70-21-08-110-006
1 . General.
CAUTION:
DO NOT USE THIS PROCESS TO CLEAN PARTS MADE FROM PLASTICS, RUBBER OR ALLOYS WITH A PROTECTIVE METAL COATING.
A.This cleaning process makes use of an organic solvent bath, active when hot, to dissolve carbon and rubber deposits. This process may also be used to remove most paints. The bath must be covered with an oil seal layer of 4-8 inches (102-203 mm) to reduce evaporation, loss of solvent and to improve safety.
NOTE:
TASK 70-21-21-110-039, Cleaning Method No. 21 - Carbon Removal by Aqueous Base Carbon Remover, is considered a light-duty alternative to this procedure. Cleaning Method No. 21 will not easily remove paint or coked-on carbon deposits.
2 . Equipment.
Subtask 70-21-08-110-061
A.The following equipment is required for the application of this process.
(1)Safety equipment and devices which are standard equipment in surface treatment shops such as: eye bath, emergency showers, protective clothing against electroplating products and means for neutralizing acid or alkaline splashing.
(2)Processing plant for neutralizing waste and used solutions.
(3)Efficient ventilation system for extracting and neutralizing vapors.
(4)An alkaline cleaning tank made from stainless steel with a heating coil that is capable of heating the solution to 230°F (110°C).
(5)A water rinse tank made from stainless steel (or a carbon steel tank with a polypropylene lining) and an air/water spray gun.
3 . Materials.
Subtask 70-21-08-110-062
 
Solution for Removal of Carbon Deposits - Table 1
 
Solution
No.
Operating Temperatures °F (°C)
 
Ardrox 2302
S1187
176-230 (80-110)
 
Turco 5668
S1171
160-180 (71-82)
 
MagChem Kemstrip-596
S1155
176-230 (80-110)
 
MagChem Kemstrip-600
S1215
176-230 (80-110)
 
Cee-Bee A-477
S1160
160-212 (71-100)
4 . Procedure.
Subtask 70-21-08-110-063
WARNING:
ALKALINE SOLUTIONS ARE VERY ACTIVE AND CAUSE SERIOUS BURNS. AVOID CONTACT WITH SKIN, EYES, AND CLOTHING. IF CONTACT OCCURS, WASH IMMEDIATELY WITH ABUNDANT QUANTITY OF WATER. AVOID BREATHING VAPORS.
WARNING:
OPERATOR SHOULD WEAR FACE SHIELD, GLOVES, PROTECTIVE CLOTHING, AND PROTECTIVE SHOES.
CAUTION:
PARTS MUST BE FREE OF MOISTURE BEFORE IMMERSION IN THE ALKALINE CARBON REMOVAL SOLUTION OR DAMAGE TO THE SUBSTRATE MAY RESULT.
A.Immerse the part in a tank containing one of the alkaline carbon removal solutions listed in paragraph 3. and maintain the solution at the specified temperature. The alkaline carbon removal solutions are listed in Subtask 70-21-08-110-062 , Materials.
Duration: 30 to 45 minutes.
(1)Ensure that the part is fully immersed into the lower layer and soak.
B.Drain the part over the stripping tank to allow the excess remover to drain back into the tank.
CAUTION:
WATER RINSE MUST BE PERFORMED AWAY FROM THE STRIPPING TANK TO AVOID CONTAMINATION OF THE TANK WITH WATER.
C.Rinse the part by immersion in water, then drain and rinse using a pressurized water jet. Repeat operation if necessary.
CAUTION:
IF A SECOND IMMERSION CYCLE IN THE BATH IS REQUIRED THE COMPONENTS MUST BE COMPLETELY DRY BEFORE IMMERSION.
CAUTION:
TITANIUM PARTS MAY BE DAMAGED WHEN EXPOSED TO CHLORIDE CONTENT BEYOND ACCEPTABLE LIMITS.
D.Rinse by immersion in hot water at minimum 150ºF (66ºC) as follows:
(1)If this procedure is used on titanium, titanium is subject to the following requirements regarding chloride. Refer to TASK 70-00-05-800-006, Water Types (paragraph 3., Definitions and Test Protocol).
(a)If parts will be exposed to subsequent processing that operates above 500°F (260°C) (for example, welding or heat treating), the final rinse water used on the parts must not exceed 50 ppm chloride (10000 ohm-cm minimum resistivity, 100 Microsiemens/cm maximum conductivity).
(b)For parts that will not be exposed to subsequent processing that operates above 500°F (260°C), the final rinse water used on the parts can be potable water that must not exceed 250 ppm chloride (1800 ohm-cm minimum resistivity, 550 Microsiemens/cm maximum conductivity).
WARNING:
WHEN USING COMPRESSED AIR FOR CLEANING, COOLING, OR DRYING, DO NOT EXCEED 30 PSIG (207 KPA). WEAR EYE PROTECTION AND DO NOT DIRECT COMPRESSED AIR AT SELF OR OTHERS.
CAUTION:
PARTS MUST BE THOROUGHLY DRY PRIOR TO FPI INSPECTION. WATER ON THE PARTS MAY DEGRADE THE SENSITIVITY OF THE PROCESS, ESPECIALLY FOR THE WATER WASHABLE PENETRANT PROCESS.
E.Dry the part by one of the following two methods.
(1)Flash dry the part as follows:
(a)Keep the part submerged until the part reaches a temperature sufficient to provide for flash drying.
NOTE:
The time required will vary with part size, water temperature and tank size. Proper flash drying is indicated by seeing the water on the surface of a part start to "flash" or "whisk" off as the part is being removed from the hot water tank.
(b)Remove the part from the water. The part will flash dry as soon as it is removed from the water. Use repositioning, suction, blotting with a clean, absorbent material, or by blowing off with an oil and water filtered shop air gun to remove excess water.
(2)You can substitute drying the part in an air re-circulating oven for the dwell time in the hot water.
(a)Remove the part from the water. You can remove excess water by repositioning, suction, blotting with a clean absorbent material, or blowing the water off with an oil and water filtered shop air gun.
(b)Move the part to the oven and dry at 200°F ± 25°F (93°C ± 14°C) until the part reaches the oven temperature and all traces of surface water are removed.
5 . Quality Assurance.
Subtask 70-21-08-110-064
A.Visually check for the removal of all traces of carbon and rubber residues from the parts.