MIL-STD-1330D(SH)
w/ Change 1
e. After flushing with NOC or TSP, immediately rinse the flask with Grade B water. For corrosion resistant flasks, Grade C water may be used followed by a Grade B water rinse. The water temperature shall be adequate to remove the cleaning agent. Continue rinsing until the effluent rinse water pH measured as specified in 5.13.4.2 is not greater than 8.0. Do not dry the flask between cleaning and rinsing.
f. Recirculate or spray Grade B water through the flask for not less than 5 minutes. The water temperature does not need to be elevated. Obtain a sample of the rinse effluent and verify particulate cleanliness as specified in
5.13.3. If the particulate analysis of 5.13.3 fails, repeat the rinse step.
5.3.4 Drying. Drying after exposure of a flask to water or moist gas, such as ambient air, shall be accomplished as follows:
a. Dry the flask as quickly as possible with nitrogen until a minus 20 °F dew point is reached. Nitrogen preheaters, strip heaters, or vacuum pumps have been successfully used. Appropriate precautions shall be taken to prevent damaging the flask or support piping and equipment from excessive heat.
b. While maintaining cleanliness as specified in 5.10, perform a visual inspection on the internal flask surfaces as specified in 5.13.1.2 and 5.13.1.3. Flask surfaces with evidence of oil, grease, ink, dye, particulate, or fibers shall be recleaned. Flask surfaces with evidence of corrosion shall be blasted or tumbled as specified in 5.3.5.3.
c. While maintaining cleanliness as specified in 5.10, install end fittings and seal weld, if required, in accordance with the applicable specification. Steel flasks shall be evacuated to 20 inches or less of mercury or purged with nitrogen to remove moist air, and then pressurized to 5 to 15 lb/in2 with nitrogen.
5.3.5 In-service interior inspection. When interior inspections of in-service flasks are required for recertification, the interior surfaces shall be inspected for evidence of corrosion, loose scale, particulate, grit, filings, paint, oil, and grease as specified in 5.13.1.2 and 5.13.1.3. Interior surfaces shall also be inspected and the outside surface of the flask marked to indicate the location of pits, cuts, burns, defects, and so forth. Pits, gouges, burns, arc strikes, and other surface defects shall be treated in accordance with NAVSEA S9086-SY-STM-010/CH-551, CGA C-6.1, or CGA C-6.2. Steel flasks shall be evacuated to 20 inches or less of mercury or purged with nitrogen to remove moist air, and then pressurized to 5 to 15 lb/in2 with nitrogen immediately after the internal inspection if satisfactory, or corrective action of 5.3.5.1 to 5.3.5.4 if unsatisfactory. Based on the interior inspection, flasks shall be classified in accordance with the following criteria:
a. Satisfactory: Not more than 10 percent of the internal surface has evidence of corrosion or particulate, and no evidence of loose scale, filings, paint, oil, or grease on the internal surface.
b. Unsatisfactory: More than 10 percent of the internal surface has evidence of corrosion or particulate, or any evidence of loose scale, filings, paint, oil, or grease on the internal surface.
5.3.5.1 Flasks classified as unsatisfactory because of oil and grease shall be cleaned as specified in 5.3.3.
5.3.5.2 Flasks classified as unsatisfactory because of particulate or grit shall be flushed as specified in 5.3.3(f)
or vacuumed until a satisfactory interior surface as specified in 5.3.5(a) is obtained.
5.3.5.3 Steel flask surfaces classified as unsatisfactory because of corrosion and loose scale shall either be blasted in accordance with MIL-F-22606 or tumbled in accordance with CGA C-6.1 and then flushed as specified in
5.3.3(f) or vacuumed to remove particulate until a satisfactory interior surface as specified in 5.3.5(a) is obtained. Aluminum flask surfaces classified as unsatisfactory because of corrosion and loose scale shall be tumbled in
accordance with CGA C-6.1 and then flushed as specified in 5.3.3(f) or vacuumed to remove particulate until a
satisfactory interior surface as specified in 5.3.5(a) is obtained.
5.3.5.4 Flasks classified as unsatisfactory because of internal paint shall be blasted or chemically cleaned until a satisfactory interior surface as specified in 5.3.5(a) is obtained. Flasks that have had interior paint removed by chemical methods shall be off-gas tested as specified in 5.9.3 to ensure removal of all chemical. Additionally, MIL- F-22606 flasks with evidence of internal paint shall be examined to determine the intended service of the flask.
Flasks identified as Service A, which are intended for air systems, shall be replaced with Service B flasks which are intended for oxygen service.
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