ok, a quick tutorial. I'm not going to go into great detail but I'll give you my basic workflow.
First I start off by creating my basic shapes. In this case I am going to build a wall panel with 2 vents covered with a grate with pipes in the background.
here is the shape for the wall
the shape for the grate
and the shape for the pipes
not very exciting yet
with all three of the shapes I used a pattern fill and filled all of them with a seamless metal texture that I have pre-made. You probably want to use different textures or at least different variations for the different elements but in this case I used the same texture for all three layers.
the pipes... copy the pipe layer, select each of the pipes and fill with a gradient fill with a reflective gradient
change the layer property for the gradient pipes to 'soft light'. This is a very simple and quick way to make pipes.
from here is just a matter of going through each layer and adding filters, adding any additional details and finishing it off with a nice rusty texture on top set to 'soft light' to give the whole image a dirty rusty look.
the final texture, took me less than 5 min to create and I didn't do anything artistic. Normally I would touch it up some more and add more details but I don't think it looks that bad for a quickie texture.
, would like to see how you make this , maybe a video tutorial 
