I always put the blanket on the fuselage/hatch or whatever area I'm trying to protect. Usually it's on the top of the fus or over servos/wires along the fus. Regular silicone glue around the edges holds it in place and allows it to be removed when you need to.

I'm not sure it's a good idea to put it directly over the pipe since the air passing over the pipe helps cool it.

FYI, the blankets are very effective.

Craig