Two small blueprints with a few laser and flame turrets (a straight defense wall and a corner). They connect seamlessly together.
The two normale pipes of the straight wall blueprint can be used for either the input of fuel (light oil, heavy oil or crude oil), or to connect an intermediate stortage tank (acts as a buffer). Furthermore you could remove them and put another flame turrent in the position of the laser turrent in front of the normal pipes. Or you could put in a pump if needed...