what means BLUED AND OILED CARBON STEEL 1

[Flo65]

Hi,

Asking for paint system, I would like to know what does mean "valves are supplied blued and oiled carbon steel".

usually I can see zinc phosphate or else.

thank you for your help

 

[CoryPad]

Steel after tempering can have a blue color due to the formation of a very thin oxide layer. A chemical conversion coating of a thicker iron oxide is known as bluing. You may have either of these. Neither of these processes provides much corrosion protection, hence an oil is added to help protect the surface.

You probably need to remove the entire surface oxide and oil, then perform your painting process. You may or may not need the phosphating.