Hey there Guys
@ Crose you need to set the material to be 2-sided. Youll find that option in the material properties.
@SimpolJosh thanks for the tip, it helped and got rid of the invisibility of my pipes. Thanks 
@BladeandChalice well without a real concept thats quite a frustrating experience. So i decided to finish the scene and go on and learn some new tutorials so i can make the next scene better (for the most part in preparation, which i didnt invest enough time…)
The scenes purpose was mainly to get myself comfortable with the engine so thats been done.
Well enough talk, are the three last shots( click for higRes)
And thanks so much for all the help i got , you guys really rock.
Thanks a lot
With best regards,