With most props, it would be enough to enable staticproplighting, as described in this article:
http://www.nodraw.net/2010/12/lighting-compile-options/
However, these pipe props do not support per-vertex lighting. You have two options:
Option A:
Place an info_lighting and give it some name. For example "info_light_01".
Move the info_lighting to be somewhere inbetween all of these pipes.
Next, go into the properties of the pipe and type the name of the info_lighting in the "Lighting Origin" field.
Use the same info_lighting for all four pipes Or use the same info_lighting for all props that are touching/connected.
Problems with this method: The lighting will not appear very realistic. However, it should be good enough.
Option B:
Download this set of pipe props
https://tf2maps.net/downloads/industrial-pipes-with-vertex-lighting.8551/
Replace all your pipes with the ones you just downloaded.
Enable the advanced lighting compile options as describe in the article above.
Problems this this method: The pipes will not be shiny. Judging from your screenshot, this won't be a problem anyways.