Can water condensation appear on PCB in IP67 enclosure box?
If you are concerned about condensation and corrosion then IP67 will not prevent this.  However  it is possible for the reduce the issues with desiccants or back filling with dry nitrogen in a sealed case.

For your environment without force water ingress, your don't need IP6x  yet it is possible to have thermal shifts that induce condensation.

It will be necessary to evaluate non corrosive exposed conductors and/or use a conformal coating or forced air circulation such that metal case temp matches the inside air temp or perhaps use a thermal insulative plastic coating on the interior to avoid the internal air temp gradient.  

So some specifications for thermal shock and design work needs to be done on the enclosure to prevent corrosion from condensation and consider floor cleaning use of water.