Thanks for answers guys. I'll check those options. I've not modeled the mesh and i'ts modeled as is i.e. no time for changes/fixes nor do i have contact to initial perosn who made it but i've noticed that in past several times on some meshes from Solidworks and ProE.

As for double sided materials well that works for most of cases BUT in this particular case when at renderign fliped normals need to be emissive (glowing light) then it's not renderign in Octane so i need to make way to flip it to positive direction to be able to make them emitt light.

cheers