urgent help in pipe line desing

Regarding your questions, there is a lot of missing information that we need in order to help you.
1- I need block valve stations along the line or not , and haw I decide there position ?
You should have a block valve at the start of the line and another for the end of the line.
Will this 14" line be "Pigged"? If so then any 14" valve you install needs to be a "Full Port" valve.

sine there are 7 small branches from this line
What is the purpose of these small branches?
How small is small?
2- for corrosion protection system for the line , I need some guides haw I can design it
Will this line be underground?
If so what kind of soil is it?
Best case, you may only need a flanged joint and insulating gasket sets at the place where the pipe enters and leaves the ground.
Worst case you may need "Cothodic protection" on the underground portion of piping. (Google "Cathodic Protection")