If the end user so specifies - yes! They may wish to protect sensitive instruments from any particulates generated by the inevitable rusting of the steel.
Derek,
The instrument air is suppose to be dry, hence there is no chance for rust to develop in the receiver. In other words, the internal surface does not require surface protection.
This is the theory.
The practice showed that many times the system broke down and the receiver was shut-down with a lot of corrosive water inside. Depending on the temperature and the duration of that water stagnant in the vessel, the corrosion products (rust flakes) started flowing downstream blocking sensitive instrumentation relaying on clean air.
It's only you to determine how important is the system, to be protected for any event. I have been trapped in the situation where (silly of me) I assumed the fabricator will have the decency of de-scaleing the internal surface of the instrument air receiver, perhaps some blast cleaning. He did not. The Client had to pay additional money for cleaning an paint 2 pack epoxy on the internal surface, due to the sensitive application (and my mistake). If they are your Client asking for internal painting, charge them for additional work, so they'll learn next time to clearly specify the internal and external protection of an instrument air receiver. However, you may miss the next job(s)...as did my previous supplier!
cheers,
gr2vessels
Fit a cyclone separator at your air compressor outlet . This will remove 99% of your moisture and take a load off your air drier. Wright Austin are the main makers.
Air driers sometimes fail for all sorts of reasons. The cyclone ,if fitted with an auto drain trap, is virtually maintenance free and ultra reliable, no moving parts to go wrong.
