Electrician’s Mate 3rd Class Nick Thorpe of Stockton, CA, secures a
ventilation motor in a fan room following repair work aboard the
NIMITZ-class aircraft carrier USS JOHN C. STENNIS (CVN 74).
U.S. Navy photo by Photographer’s Mate 3rd Class Mark J. Rebilas

Fan rooms are typically subjected to corrosive salt air and moisture from the outside environment. The equipment in these rooms circulates fresh air throughout a vessel. Corrosion in these rooms can easily get out of control, and they are often difficult to preserve due to their small size and cramped layout.

Typical Coatings Used

These surfaces are coated with an anti-corrosive coating qualified to MIL-PRF-23236, Coating Systems for Ship Structures, applied as both a primer as well as a top coat. Touch-up and repair is generally accomplished by ship’s force or by repair activities during maintenance availabilities. Because of this, these coating systems must be easily overcoatable and capable of being maintained by ship’s force.

Primer and Topcoat

Both the primer and topcoat are anti-corrosive coatings qualified to MIL-PRF-23236, Type VII, Class 15B or 17.

Surface Preparation

To ensure proper coating adhesion, special attention should be paid to the surface preparation of the fan rooms. NSI 009-32 requires a surface that meets one of the following cleanliness standards: SSPC-SP 10/NACE 2, Near-White Metal Blast; SSPC-SP 11, Power Tool Clean to Bare Metal; or SSPC-SP WJ-2/NACE WJ-2, Very
Thorough Waterjetting.

Depot Repairs

NSI 009-32 is the governing document for preservation requirements. Permitted coatings are specified in Table 3.

Ship’s Force Repairs

Ship’s force personnel are primarily responsible for maintaining the ship’s fan room coating systems until repair activity maintenance is scheduled. Naval Ships Technical Manual: Chapter 631 (NSTM 631), Preservation of Ships in Service – General provides requirements, instructions, and guidance for surface preparation and coating application.

New Construction Ships

New construction ships are painted in accordance with the ship build specification for that class of ship.