MIL-STD-2199A APPENDIX B
e. Paint each repaired area in accordance with A.3.2.6.
B.3.1.2 Dry-dock inspection and repair. Waterborne main propulsion shaft coverings shall be inspected to the maximum extent possible every time a ship comes into drydock. Shaft coverings that have been in-service shall be inspected and repaired as follows:
B.3.1.2.1 Inspection.
a. Remove marine growth and/or loose paint from the GRP, including couplings and other areas, by scraping carefully, so as not to score or damage the GRP.
NOTE: The GRP may also be lightly sanded if hand scraping is unsuccessful. Abrasive blasting is also permitted, although not recommended, since it could potentially damage the covering, shattering the glass fibers. However, if abrasive blasting is utilized, fine or medium grit shall be used along with mild blasting conditions (for example, low air pressure, low-grit velocity).
b. Conduct, at close range, a careful visual inspection of the full length of all accessible/exposed GRP for evidence of deterioration, physical damage, lack of adhesion, and/or any other defects. Particular attention is to be paid to the GRP-to-shaft sleeve interfaces for indication of seawater penetration, as evidenced by rust color staining bleeding through at subject interfaces. If damaged or suspect conditions are found, mark all areas with chalk (do not use crayon or "grease" pencil as they have paraffin and waxes in their makeup).
NOTE: Evidence of loss of adhesion of shaft covering is typically characterized by one or more of the following: (1) Loss of GRP as a whole or in part.
(2) Rust stains where rust has leaked through the covering in the vicinity of a cut, joint, patch, or flaws,
such as pinholes or porosity.
c. Tap the GRP at regular intervals of about 18 inches along the length of the covering with a light hammer rap while holding the palm of one hand against the GRP adjacent to the area being tapped. Discernible vibration, movement of the GRP, or an audible hollow sound is evidence of a loose bond and shall be examined further. If suspect area(s) are found, mark with chalk accordingly (do not use crayon or "grease" pencil as they have paraffin and waxes in their makeup).
d. Carefully inspect the entire GRP for damage/porosity with a high frequency spark tester. Particular attention shall be given to the sleeve-to-GRP interfaces. If there are any areas that spark, mark with chalk accordingly (do not use crayon or "grease" pencil as they have paraffin and waxes in their makeup).
B.3.1.2.2 Repair (for shafts possessing the four-layer covering system).
B.3.1.2.2.1 Repair of visible surface defects. If the GRP contains visible surface defects such as scattered or isolated pinholes, pimples, porosity, or rough spots, none of which produced a spark during the spark test, coat subject areas with resin as follows:
NOTE: Use a 5x (minimum) magnifying glass to verify the presence of any suspected defects.
a. Sand the GRP lightly or abrasive blast lightly in way of the defective area. If the GRP had been treated
with anti-fouling paint, abrasive blasting may be necessary to remove the paint. When abrasive blasting, precautions shall be taken to avoid damage to the GRP by abrasion deeper than just surface roughening. Use fine or medium
grit and mild conditions (for example, low air pressure, low grit velocity). Do not dwell at one spot excessively. Careless or indiscriminate abrasive blasting will damage the GRP severely.
b. Clean away all sanding or abrasive blasting grit or residue and apply one coat of resin over the affected surface(s).
c. After the resin has hardened, re-examine the repaired area(s) with a 5x (minimum) magnifying glass for any evidence of remaining defects. Repeat application of the resin and re-inspect, as required, until there are no apparent defects remaining.
d. Paint each repaired area in accordance with A.3.2.6.
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