Thermal Insulation of 316 SS, in Immersed condition

[FYS]

Hi,


Please advise, Thermal Insulation of instrument units (316 SS), in Immersed condition (High Water Table). The possibility of corrosion, due to differential concentration of oxygen (depletion of oxygen at fastener locations – tying strip) – CREVICE Corrosion, pitting and cyclic effect of water Table (dry/wet) condition. Normal Temperature.

Would it be better to coat the Instrument units, before covered with Thermal Insulation Materials, as the CP current will not be able to reach them?
et)condition. Normal Temperature.

 

[gr2vessels]

Yes Karaj, the coating is an important factor against Corrosion Under Insulation, particularly in environment where the 316 could become active. However, the normal painting is not infallible, so I would suggest to use hot aluminium spray (perhaps the cold spray?) to coat the stainless steel and for additional protection, use an organic paint top coat, then insulate. Remember to specify no chlorides in the insulation and request certification for it.
cheers,
gr2vessels

 

[FYS]

Hi,

Thank you very much for your reply.

Due to difficulty of access in the pit and availability of the spraying equipment, can we just use a suitable coating for stainless Steel (such as Epoxy Coating) instrument units?

Regards

 

[gr2vessels]

Yes, but holiday testing is mandatory and the sucess rate is not high in those working conditions. Contamination, uniform coverage, DFT measurement are all adverse conditions for painting in a pit...I would still try the cold spray aluminium (Intertherm 751), it can be used on site work. It is a relative new technology from International paint (AKZO NOBEL).
cheers,
gr2vessels