How to modify the appearance of view?

[Faouweb]

Hi,

I want to have in one view wireframe and solid in order to focus on a region as you can see on the picture:

I want the dark wich is between the pipe and the elbow as a solid and the rest of the drawing in wireframe.

I hope it's clear because my English is

And I want to know what do you think about my drawing i used Surface

Thank you.