HEATED MACHINERY SURFACES, VALVES, AND PIPING
Coating systems discussed in this section are applied to elevated temperature (125-200ºF) and high temperature (200-400ºF or 400-1200ºF) machinery surfaces, valves, and piping. These areas require cleaning and surface preparation using abrasive blasting and coating with aluminum heat-resistant paint. Whether insulated or not, surfaces that operate at temperatures above 149°C (300°F) require heat-resistant paint. Areas where heat radiates from hot surfaces into operating spaces need heat-resistant paint if the operating temperature exceeds 52°C (125°F).
The type of coating used is dependent on the temperature of the surface to be coated as specified in NAVSEA Standard Item (NSI) 009-32.
Epoxy coatings are capable of withstanding moderate service temperatures of up to 225ºF . The US Navy has limited their use to 200ºF. Elevated temperature surfaces are coated with two coats of traditional anticorrosion epoxy coatings qualified to MIL-DTL-24441, Type IV.
High-temperature machinery, valves, and piping with surface temperatures ranging from 200ºF to 400ºF are coated with one coat of Amercoat 829HS, which is a polysiloxane material specifically formulated for high temperature service.
High-temperature machinery, valves, and piping with surface temperatures ranging from 400ºF to 1200ºF are coated with two coats of TT-P-28, Heat-Resistant Aluminum.
To ensure coating adhesion, special attention should be paid to the surface preparation in accordance with NSI 009-32. Surfaces should be abrasive blasted in accordance with SSPC-SP 10/NACE No. 2, Near-White Blast Cleaning.
NSI 009-32 is the governing document for preservation requirements. Permitted coatings are specified in Table 5.
Ships force personnel are responsible for maintenance of heated machinery, valves, and piping 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 are painted in accordance with the ship build specification for that class of ship.
1. Schweitzer, P., Paints and Coatings: Applications and Corrosion Resistance, Pg. 110-111, 2006