Luckily I managed to finish first layer of primer till late morning before rain started. I will lift the dome over the ground fifteen centimeters to make enough space so that I can paint primer on the bottom struts.
This brush is too big to do proper paint job on the pipe struts. Outer diameter of the pipe is 26.65 cm. Its width of five centimeter is too big. I gonna buy a smaller brush close to three centimeter.