What primer to use on pressure vessel?

[minibenny]

We have built a spare shell out of mild carbon steel, and would like to apply an external primer to protect it while in storage. Once placed in service, it will be insulated.
I don't have the information for which type of insulation will be applied, but I assume it will be clad afterwards.
The max. design temperature of the pressure vessel is 580*F/304*C, and the minimum is -20*F/-29*C.
Is the risk of CUI increased when only a primer is applied to carbon steel in this temperature range? Is it better off with no primer at all when under insulation?
I was thinking of just using a grey shop primer, but am wondering if that would be more detrimental to the steel than leaving it bare when under insulation.
Is there a better primer that I should consider?
Any guidance would be appreciated.

 

[moltenmetal]

That's a very good question and I hope some seasoned coatings people chime in on what's best here. What we see often in large company specifications for hot equipment is the use of an inorganic zinc primer. Even though the zinc will be useless at those temperatures once under insulation and in service, it's not going to smoke or damage the equipment. A cheap alkyd primer may smoke when heated to those temperatures.