Very impressive for your first model!
I do like the textures. I know you said they aren't yours, but, for your first model, you have unwrapped it well enough to get it to look good.
One thing i will say is, When you are modelling low poly pipes - as you have here - its best to hit the 'smooth shading' button. It gets rid of those ugly lines that you can see in your pipes.
Other than that. I think you have made a great start. Welcome to the world of modelling.
One last thing, if you are looking to use this in FPSC, i would try to keep the poly count a little lower than it is at the moment. If you were to have a number of these placed in your level to mimic corridors, your fps would drop badly.
What people tend to do when modelling wall segments, is too only model the side of the wall that you will actually see; and try to keep the level of detail to a minimum and manipulate the shader maps to get the desired look.